PHENOLIC FOAM AND METHOD OF MANUFACTURE THEREOF

Abstract

A thermal insulating phenolic foam and method of manufacture thereof is provided. A phenolic foam is formed by foaming and curing a phenolic resin composition that comprises a phenolic resin, an acid catalyst, a blowing agent comprising a hydrocarbon having 6 carbon atoms or less, and an alkoxy alcohol. The resulting foam has low thermal conductivity and has excellent long term thermal stability.

Claims

1.-50. (canceled)

51. A phenolic foam formed by foaming and curing a phenolic resin foamable composition that comprises a phenolic resin, a surfactant, an acid catalyst, a blowing agent comprising a hydrocarbon having 6 carbon atoms or less, and an alkoxy alcohol having the formula: ##STR00005## wherein n is 0 to 4, and wherein R is a C1 to C6 aliphatic chain, R1 is H or alkyl, t foam has a closed cell content of 85% or more, and a density of from 10 kg/m3 or more and 100 kg/m3 or less.

52. The phenolic foam as claimed in claim 51, wherein the phenolic resin has a water content in the range of from 8 wt % to 16 wt % or wherein the water content of the phenolic resin foamable composition is in the range of from 7.5 wt % to 14 wt % based on the total weight of the phenolic resin foamable composition or a combination thereof.

53. The phenolic foam as claimed in claim 51, wherein n is 0, 1 or 2, preferably, n is 0 or 1.

54. The phenolic foam as claimed in claim 51, wherein R1 is H, or C1 to C6 alkyl, such as methyl, ethyl, propyl, butyl, pentyl or hexyl or isomers thereof.

55. The phenolic foam as claimed in claim 51, wherein R is selected from the group comprising methyl, ethyl, propyl, butyl, pentyl, hexyl and isomers thereof.

56. The phenolic foam as claimed in claim 51, wherein the alkoxy alcohol is present in an amount of from 0.5 to 15 parts by weight per 100 parts by weight of phenolic resin.

57. The phenolic foam as claimed in claim 51, wherein the hydrocarbon comprising 6 carbons atoms or less is one or more compounds selected from the group comprising butane, pentane, hexane, n-butane, isobutane, cyclobutane, n-pentane, isopentane, cyclopentane and cyclohexane, and isomers thereof.

58. The phenolic foam as claimed in claim 51, wherein the blowing further comprises a halogenated hydrocarbon comprising 6 carbon atoms or less, a hydrofluoroolefin, or a combination thereof.

59. The phenolic foam as claimed in claim 51, wherein the blowing agent further comprises propyl chloride dichloroethane, or isomers thereof.

60. The phenolic foam as claimed in claim 51, wherein the blowing agent further comprises a hydrofluoroolefin selected from the group consisting of 1-chloro-3,3,3-trifluoropropene, 1,3,3,3-tetrafluoropropene, 2,3,3,3-tetrafluoropropene and 1,1,1,4,4,4-hexafluoro-2-butene.

61. The phenolic foam as claimed in claim 51, wherein the blowing agent is present in an amount of from 1 to 20 parts by weight per 100 parts by weight of phenolic resin.

62. The phenolic foam as claimed in claim 51, wherein the phenolic resin has a molar ratio of phenol groups to aldehyde groups in the range of from 1:1 to 1.3.

63. The phenolic foam as claimed in claim 51, wherein the phenolic resin has a weight average molecular weight of from 700 to 2000, the phenolic resin has a number average molecular weight of from 330 to 800 or a combination thereof.

64. The phenolic foam as claimed in claim 51, wherein the pH of the foam is a pH of 4 or more.

65. The phenolic foam as claimed in claim 51, wherein the density of the foam is of from 10 to 60 kg/m3, suitably, the phenolic foam has a density of from 20 to 45 kg/m3.

66. The phenolic foam as claimed in claim 51, wherein the phenolic foam has a compressive strength of from 80 kPa to 220 kPa, such as from 90 kPa to 180 kPa.

67. The phenolic foam as claimed in claim 51, wherein the phenolic foam has an aged thermal conductivity 0.025 W/m.Math.K or less when measured at a mean temperature of 10° C. after heat ageing for 175±5 days at 70±2° C., in accordance with the procedure specified in European Standard BS EN 13166:2012.

68. The phenolic foam as claimed in claim 51, wherein the phenolic foam has an aged thermal conductivity in the range of from 0.025 W/m.Math.K to 0.016 W/m.Math.K when measured at a mean temperature of 10° C. after heat ageing for 175±5 days at 70±2° C., in accordance with the procedure specified in European Standard BS EN 13166:2012.

69. The phenolic foam as claimed in claim 51, wherein the viscosity of the phenolic resin, including the surfactant and alkoxy alcohol is in the range of from 2500 to 7000 mPa.Math.s at 25° C.

70. A method for manufacturing a phenolic foam comprising the steps of: foaming and curing a foamable composition comprising: a phenolic resin, a surfactant, an acid catalyst, a blowing agent comprising a hydrocarbon having 6 carbon atoms or less, and an alkoxy alcohol having the formula: ##STR00006## wherein n is 0 to 4, and wherein R is a C1 to C6 aliphatic chain, R1 is H or alkyl, wherein said foam has a closed cell content of 85% or more, and a density of from 10 kg/m3 or more and 100 kg/m3 or less.

Description

DETAILED DESCRIPTION b

[0071] The manufacture of phenolic resin foams involves foaming and curing a phenolic resin composition comprising a phenolic resin, a surfactant and a blowing agent in the presence of an acid catalyst. In a factory setting, phenolic foam is often manufactured using a heated continuous foam laminator. A phenolic resin composition comprising phenolic resin with surfactant premixed in, and a blowing agent may be pumped to a mixing head where it is mixed with acid catalyst to form a foamable composition which is immediately deposited on to a suitable carrier facing. An exotherm is generated upon the addition of the acid catalyst to the phenolic resin composition and foam formation commences. The foaming composition is conveyed to a heated continuous foam laminator, where the composition is heated and cured. Curing leads to cross-linking of the phenolic resin. Controlling the exotherm is essential to ensure the formation of a phenolic foam having a high closed cell content and stable low thermal conductivity. While high water content can act as a heat sink for the exotherm, a downside of having a phenolic resin composition having high water content can be greater open cell content due to rupture of cells by water vapour generation.

[0072] The water content of the resin has a significant impact on the viscosity of the foamable composition and on the thermal conductivity of foams made therewith. While foams having stable long term thermal conductivity values may be formed using phenolic resin having low water content i.e. less than 8 wt % based on the total weight of the resin, such phenolic resins are very viscous at 25° C. and in order to facilitate pumping of such resins around a factory, the resin must be heated. This increases manufacturing costs and also decreases the shelf-life of resin. While using higher water content resins increases the ease of conveying the materials through conduits and manifolds around a factory, increasing water content of a phenolic resin can have a deleterious impact on the thermal conductivity of foam formed from phenolic resin foamable compositions comprising high water content phenolic resins. There is increased difficulty in forming closed cell foams using such high water content resins.

[0073] The materials used to form phenolic foams vary in their hydrophilicity and miscibility. Hydrocarbon blowing agents for example are hydrophobic, whereas the acid catalysts may be hydrophilic and both acids and resins may have varying water contents. The present inventors conducted an extensive screening program to identify a diluent which would decrease the viscosity of a phenolic resole resin having a water content in the range of from 8 wt % to 16 wt %, thereby enabling phenolic resin foam formation using a phenolic resin foamable composition having a water content of from around 7.5 wt % to 14 wt %, with said phenolic resin foam having excellent long term thermal stability and low thermal conductivity despite using a hydrocarbon blowing agent such as propane, butane, pentane or hexane. Such hydrocarbon blowing agents have considerably different hydrophilicities to traditional blowing agents such as CFCs, HCFCs and HFCs. While CFCs such as Freon 11 and Freon 113, are effective blowing agents in high water content phenolic resin compositions such as those described in EP'357, when such blowing agents are replaced with hydrophobic hydrocarbon blowing agents, this necessitates the reduction of water content in the phenolic resin, raising resin viscosity considerably, to manufacture phenolic foams having stable thermal insulation performance.

[0074] The present inventors posited that an organic diluent capable of increasing the miscibility of phenolic resole resins having high water content of around 8 to 16 wt % and containing a surfactant, with a hydrocarbon blowing agent and an acid catalyst may facilitate the formation of phenolic resin foams having excellent thermal conductivity and excellent long term thermal insulation performance. The organic diluent would also substantially lower the viscosity of a foamable composition formed therewith. A plethora of organic compounds was assessed for miscibility with blowing agents and acid catalysts.

Miscibility Studies

[0075] Various organic liquids (diluents) were added to cyclopentane to determine miscibility therewith. To the mixture of cyclopentane and diluent was added liquid aryl sulfonic acid and the effect on the resulting mixture was observed.

[0076] Table 1 provides details for miscibility studies with a variety of liquid organic diluents.

[0077] It was considered that the formation of a homogenous solution i.e. no separation of layers, (only one chemical layer of the mixture), would indicate compatibility between cyclopentane and the selected organic diluent. To the cyclopentane-diluent mixture, was then added a blend of toluene sulfonic acid/xylene sulfonic acid 65/35 weight ratio and the resulting mixture was stirred for 5 minutes. The extent of separation of cyclopentane, diluent and acid was observed and is shown in Column 4 of Table 1 below.

[0078] Of the diluents tested, only ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, and 2-ethoxyethanol formed a homogenous single layer solution when mixed with 10 g of cyclopentane and 20 g of the aryl sulfonic acid blend.

TABLE-US-00001 TABLE 1 Effect of Effect of adding 20 g of Mix Organic Diluent adding 10 g toluene/xylene sulfonic Number 10 g cyclopentane acid (TX Acid) 1 None Not applicable 2 separate layers 2 Monoethylene 2 separate layers 2 separate layers glycol (MEG) 3 Diethylene glycol 2 separate layers 2 separate layers (DEG) 4 Propane-1,2,3-triol 2 separate layers 2 separate layers 5 Dipropylene glycol 2 separate layers 2 separate layers 6 1,4 butane diol 2 separate layers 2 separate layers 7 Eugenol (4-allyl-2- 1 layer 2 separate layers methoxy phenol) 8 1,3-dioxolane 1 layer separate layers 9 Ethylene glycol 1 layer 1 layer (No separation) monobutyl ether 10 Diethylene glycol 1 layer 1 layer (No separation) monobutyl ether 11 2 ethoxy ethanol 1 layer 1 layer (No separation) 12 Coconut oil 1 layer Minor separation out, 2nd layer just visible Opaque 13 Oleic acid 1 layer Minor separation out, 2nd layer just visible Opaque 14 *TOFA Resoline 1 layer 2 layers BD30 15 *TOFA Resoline 1 layer Minor separation out, 2nd layer BD2 just visible Opaque 16 Olive Oil 1 layer Minor separation out, 2nd layer just visible Opaque *Tall oil fatty acids (TOFA). TOFA comprises oleic, linoleic, palmitic, stearic and linolenic acids).

[0079] Similar miscibility studies were conducted using n-pentane, see Table 2.

TABLE-US-00002 TABLE 2 Effect of adding Effect of 20 g of toluene/ Mix Organic Diluent adding 10 g xylene sulfonic Number 10 g n-pentane acid (TX Acid) 1 None Not applicable 2 separate layers 2 Monoethylene glycol 2 separate layers 2 separate layers (MEG) 3 Diethylene glycol 2 separate layers 2 separate layers (DEG) 4 Propane-1,2,3-triol 2 separate layers 2 separate layers 5 Dipropylene glycol 2 separate layers 2 separate layers 6 1,4 butane diol 2 separate layers 2 separate layers 7 Eugenol (4-allyl-2- 1 layer 2 separate layers methoxy phenol) 8 1,3-dioxolane 1 layer 2 separate layers 9 Ethylene glycol 1 layer 1 layer monobutyl ether 10 Diethylene glycol 1 layer 1 layer monobutyl ether 11 2 ethoxy ethanol 1 layer 1 layer 12 Coconut oil 1 layer 2 separate layers, Opaque 13 Oleic acid 1 layer 2 separate layers, Opaque 14 *TOFA Resoline 1 layer 2 separate layers, BD30 Opaque 15 *TOFA Resoline 1 layer 2 separate layers, BD2 Opaque 16 Olive Oil 1 layer 2 separate layers, Opaque *Tall oil fatty acids (TOFA). TOFA comprises oleic, linoleic, palmitic, stearic and linolenic acids).

[0080] It was considered that no separation (only one layer) would indicate compatibility between the organic diluent, n-pentane and the blend of aryl sulfonic acids. Only the alkoxy alcohols in rows 9 to 11 formed single layer solutions when mixed with n-pentane and the blend of aryl sulfonic acids in the specified amounts.

[0081] Miscibility of the alkoxy alcohol diluents from rows 9 to 11 of Tables 1 and 2, with phenolic resin was also investigated, and surprisingly, when mixed with a phenolic resole resin having a water content of approximately 12 to 13 wt % a single layer solution was formed.

[0082] The alkoxy alcohols demonstrate good miscibility with water, phenolic resin, hydrocarbons such as pentane, and aryl sulfonic acids. Accordingly, the ability to form phenolic foams using alkoxy alcohols as diluents, and the properties of such foams were investigated.

[0083] Suitable testing methods for measuring the physical properties of phenolic foam are described below.

(i) Foam Density:

[0084] This was measured according to BS EN 1602:2013—Thermal insulating products for building applications—Determination of the apparent density.

(ii) Thermal Conductivity:

[0085] A foam test piece of length 300 mm and width 300 mm was placed between a high temperature plate at 20° C. and a low temperature plate at 0° C. in a thermal conductivity test instrument (LaserComp Type FOX314/ASF, Inventech Benelux BV). The thermal conductivity (TC) of the test pieces was measured according to EN 12667: “Thermal performance of building materials and products—Determination of thermal resistance by means of guarded hot plate and heat flow meter methods, Products of high and medium thermal resistance”.
(iii) Thermal Conductivity After Accelerated Aging: [0086] This was measured using European Standard BS EN 13166:2012—“Thermal insulation products for buildings—Factory made products of phenolic foam (PF)”. The thermal conductivity is measured after exposing foam samples for 25 weeks at 70° C. and stabilisation to constant weight at 23° C. and 50% relative humidity. This thermal ageing serves to provide an estimated thermal conductivity for a time period of 25 years at ambient temperature. Alternatively samples may be heat aged for 14 days at 110° C. Details for thermal ageing and determination of thermal conductivity are specified in Annex C section C.4.2. The mean plate temperature was 10° C.
(iv) pH: [0087] The pH was determined according to the standard BS EN 13468.

(v) Closed-Cell Ratio:

[0088] The closed-cell ratio was determined according to ASTM D6226 test method.

(vi) Compressive Strength:

[0089] The compressive strength was measured according to test method EN 826

(vi) Viscosity:

[0090] The viscosity was measured using a Brookfield viscometer (model DV-II+Pro) with a controlled temperature water bath, maintaining the sample temperature at 25° C., with spindle number S29 rotating at 20 rpm.

[0091] The phenolic foam of the present invention is formed by foaming and curing a phenolic resin foamable composition that comprises a phenolic resin, a surfactant, an acid catalyst, a blowing agent comprising a hydrocarbon having 6 carbon atoms or less, and an alkoxy alcohol having the formula:

##STR00003##

wherein n is 0 to 4, and wherein R is a C.sub.1 to C.sub.6 aliphatic chain, R.sup.1 is H or alkyl. R may be methyl, ethyl, propyl, butyl or isomers thereof; preferably, R is butyl, e.g. n-butyl. When R.sup.1 is alkyl, R.sup.1 may be methyl, ethyl, propyl, butyl, pentyl, hexyl or isomers thereof; preferably, R.sup.1 is H or methyl. The phenolic resin and the alkoxy alcohol are combined by mixing. Blowing agent is added to the resulting mixture and acid catalyst is subsequently added with mixing and foaming commences. The resulting foam is then cured under heat and pressure.

[0092] Suitably, the alkoxy alcohol is present in an amount of from about 0.5 wt % to about 10 wt % based on the total weight of the phenolic resin foamable composition, for example, the alkoxy alcohol may be present in an amount of from about 0.5 wt % to about 8 wt % based on the total weight of the phenolic resin foamable composition.

[0093] The phenolic foam of the invention has a closed cell content of 85% or more. Preferably, the phenolic foam has a closed cell content of 90% or more, more preferably, the phenolic foam has a closed cell content of 95% or more, such as 98% or more.

[0094] The phenolic foam has a density of from 10 kg/m.sup.3 to 100 kg/m.sup.3. Suitably, the foam has a density of from 10 kg/m.sup.3 to 60 kg/m.sup.3, preferably from 20 kg/m.sup.3 to 45 kg/m.sup.3.

[0095] The alkoxy alcohol has the formula:

##STR00004##

wherein n is 0 to 4, and wherein R is a C.sub.1 to C.sub.6 aliphatic chain, R.sup.1 is H or methyl.

[0096] For example, the alkoxy alcohol may be selected from the group consisting of [0097] ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, [0098] ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, [0099] ethylene glycol monopentyl ether, ethylene glycol monohexyl ether, [0100] diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, [0101] diethylene glycol monopropyl ether, diethylene glycol monobutyl ether [0102] diethylene glycol monopentyl ether, diethylene glycol monohexyl ether [0103] triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, [0104] triethylene glycol monopropyl ether, triethylene glycol monobutyl ether, [0105] triethylene glycol monopentyl ether, triethylene glycol monohexyl ether, [0106] propylene glycol monomethyl ether, propylene glycol monoethyl ether, [0107] propylene glycol monopropyl ether, propylene glycol monobutyl ether, [0108] propylene glycol monopentyl ether, propylene glycol monohexyl ether, [0109] dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, [0110] dipropylene glycol monopropyl ether, dipropylene glycol monobutyl ether, [0111] dipropylene glycol monopentyl ether, dipropylene glycol monohexyl ether [0112] tripropylene glycol monomethyl ether, tripropylene glycol monoethyl ether, [0113] tripropylene glycol monopropyl ether, tripropylene glycol monobutyl ether, [0114] tripropylene glycol monopentyl ether and propylene glycol monohexyl ether.

[0115] Preferably, the alkoxy alcohol is selected from the group consisting of ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, and diethylene glycol monobutyl ether.

EXAMPLES

[0116] The phenolic resins used in the invention are phenolic resole Resins A and B and are described as follows.

Example (1)

“Resin A” Preparation

[0117] On a weight basis, Resin A was prepared by mixing under reflux 50.7 parts of phenol, 2.7 parts of water and 0.94 parts of 50% potassium hydroxide at 20° C. The temperature was raised to 74 to 76° C. under reflux and 35.5 parts of 91% paraformaldehyde was added over 2 hours. The temperature was then raised to 82 to 85° C. and the temperature was maintained there until the viscosity of the resin reached was 6500 mPa.Math.s. Cooling was commenced whilst adding 0.3 parts of 90% formic acid. Below 50° C. the following were sequentially added: 4.5 parts of urea and 3.2 parts of ethoxylated castor oil (surfactant). The resulting phenolic resin composition (Resin A) contained 12.6% water, below 4% free phenol, and less than 1% free formaldehyde. The viscosity of the phenolic resin composition was 7000 to 14000 mPa.Math.s at 25° C.

Example (2)

“Resin B”

[0118] Resin B is a resole resin; more specifically Resin B is a liquid phenol-urea-formaldehyde resin. Resin B is commercially available from Hexion UK under the trade name “IDP445”. This resin has a viscosity of 7,000-11,000 mPa.Math.s at 25° C., pH 7.5 to 8.0.

[0119] Resin B resin contained from 3 wt % to 4 wt % free phenol and below 0.5 wt % free formaldehyde. Water content was 10 to 11 wt %, (measured by Karl-Fisher analysis). Resin B contained 2 to 4% surfactant as described previously herein.

[0120] Blowing agent blends used in the examples and comparative examples are described in Table 3.

TABLE-US-00003 TABLE 3 Blowing Agent Composition (wt ratio) D Cyclopentane/isopentane (85:15) E n-pentane/isopentane (85:15) F Perfluoropentane (C.sub.5F.sub.12) G DIF (95:5) H E/F (95:5)

[0121] TX acid catalyst is a toluene sulphonic acid/xylene sulphonic acid blend (65%/35% by weight).

[0122] The following Examples and Comparative examples show how foam samples of the invention are made.

Example (3)

Phenolic Foam Preparation Containing 2-Ethoxy Ethanol as the Alkoxy Alcohol

[0123] Phenolic resin compositions having various amounts of 2-ethoxy ethanol were prepared according to the formulations specified in Table 4. Foams were formed using said phenolic resin compositions and the density, initial thermal conductivity and aged thermal conductivity of the foams were measured.

[0124] To 111.3 parts by weight of “Resin A” at 11-15° C. was added with mixing 2-ethoxy ethanol, in the amounts specified in Table 4 below. Next, 8.5 parts by weight of Blowing Agent D at 1 to 3° C. were mixed into the resin mixture. The resin mixture was cooled to between 2° C. and 8° C. Next, 21 parts by weight of TX acid at 8° C. were quickly mixed into the resin mixture. High speed mixing at 1000 to 3000 rpm was used. 295±10 g of the resulting formulated resin composition was transferred into a closed picture frame mould of dimensions 400 mm×350 mm×50 mm at 70° C. for 10 minutes to form a 50 mm thick rigid phenolic foam. The base plate had a polythene sheet that could easily be removed from the cured foam or a suitable facing such as a glass fibre mat was applied. Similarly a top sheet of polythene sheet or glass mat facing was placed on top of the rising phenolic foam.

[0125] A pressure of 15 kPa is applied to the lid of the mould to pressurise the rising foam. The foam sample is then removed from the mould and post-cured in an oven for 16 hours at 70° C. to 75° C. The foam boards produced have a dry cured density of approximately 41 kg/m.sup.3.

[0126] Drift upwards in aged thermal conductivity (λ) is significantly reduced for foams containing 2-ethoxy ethanol.

[0127] Excellent aged thermal conductivity is achieved when from about 0.5 to 12.5 parts by weight of alkoxy alcohol was added per 100 parts by weight of phenolic resin as shown in Table 4. The addition of 2-ethoxyethanol also improves initial thermal conductivity relative to the foam without 2-ethoxy ethanol.

TABLE-US-00004 TABLE 4 pbw Sample reference Control 1 2 3 4 5 6 7 Resin A. 111.3 111.3 111.3 111.3 111.3 111.3 111.3 111.3 2-ethoxy ethanol 0 1 2.5 5 7.5 10 12.5 15 Blowing Agent D 8.5 8.5 8.5 8.5 8.5 8.5 8.5 8.5 TX Acid 21 21 21 21 21 21 21 21 Total % Water Content 9.96 9.89 9.78 9.62 9.45 9.29 9.15 9.00 of the foamable chemical mixture Properties Initial Thermal 25.08 24.61 24.02 23.23 22.82 22.15 20.84 23.01 Conductivity (mW/m .Math. K) Aged Thermal 28.77 22.98 22.98 24.48 23.2 23.66 25.18 25.76 Conductivity Lambda after 14 days at 110° C. (mW/m .Math. K) Dry Foam Density 41 41.7 41.8 41.3 41.4 41.4 41.7 41.7 (kg/m.sup.3) after 4 days at 70° C.

Example (4)

Phenolic Foam Preparation Containing Butyl Diglycol as the Alkoxy Alcohol

[0128] Phenolic resin foamable compositions containing butyl diglycol were prepared according to the formulations specified in Table 5. Foams were formed using said phenolic resin foamable compositions and the initial thermal conductivity and aged thermal conductivity of the foams were measured.

[0129] To 110.5 parts by weight of the specified resin at 11-15° C. was added with mixing 6 parts by weight of butyl diglycol. Next, 8 to 10 parts by weight of 100% isopentane was added at 1 to 3° C. with mixing. The resin mixture was cooled to between 0° C. and 3° C. Next, 18 to 21.5 parts by weight of TX acid at 8° C. were quickly mixed into the resin mixture. High speed mixing at 2000 to 3000 rpm was used. Approximately 75 g of the resulting formulated resin composition was transferred into a closed picture frame mould of dimensions 280 mm×235 mm×25 mm at 70° C. for 10 to 15 minutes to form a 25 mm thick rigid phenolic foam. The base plates of the mould had either a polythene sheet that could easily be removed from the cured foam or have suitable facings such as a glass fibre mat.

[0130] A pressure of 15 kPa was applied to the lid of the mould to pressurise the rising foam. The foam sample was then removed from the mould and post-cured in an oven for 16 hours at 70° C. to 75° C. The foam boards produced had dry cured density values of around 45 kg/m.sup.3.

[0131] Drift upwards in aged thermal conductivity (λ) is significantly reduced for foams containing butyl diglycol.

TABLE-US-00005 TABLE 5 pbw Sample reference Control 8 9 10 Resin A. 110.5 110 0 0 Resin B 0 0 110 110 Butyl Diglycol 0 6 6 6 Isopentane 10 8 8 6 TX Acid 18 21.4 21.4 20 Total % water content of the 10.00 9.53 7.94 8.13 foamable chemical mixture Properties Initial Thermal Conductivity 29.64 20.9 21.2 20.6 (mW/m•K), mean plate temperature of 10° C. Aged Thermal Conductivity after >30 22.9 22.1 22.9 14 days at 110° C. (mW/m•K), mean plate temperature of 10° C. Dry Foam Density (kg/m.sup.3) after 45 45 45 45 4 days at 70° C.

COMPARATIVE FOAM EXAMPLES

Comparative Example 1

Ethylene Glycol Diluent

[0132] Foam samples were prepared in the same way as described in Example 3, replacing the alkoxy alcohol with mono-ethylene glycol as the organic diluent. Table 6 below shows that all thermally aged thermal conductivity values exceed 25 mW/m.Math.K and even initial thermal conductivity values were generally high.

TABLE-US-00006 TABLE 6 Pbw Sample reference Control 11 12 13 14 Resin A. 111.3 111 111 111 111 Mono-ethylene glycol 0 2.5 5 7.5 10 Blowing Agent D 8.5 8.5 8.5 8.5 8.5 TX Acid 21 21 21 21 21 Properties Initial Thermal Conductivity 28.66 25.21 25.63 23.73 24.67 (mW/m•K), mean plate temperature of 10° C. Aged Thermal Conductivity 29.47 27.04 28.43 27.68 28.67 Lambda after 14 days at 110° C. (mW/m•K), mean plate temperature of 10° C. Dry Foam Density (kg/m.sup.3) 41 41.7 41.8 41.3 41.4 after 4 days at 70° C.

[0133] Low viscosity fatty acid compounds such as oleic acid, olive oil, coconut oil and TOFA Resoline BD2 demonstrate complete miscibility when they are individually blended with a hydrocarbon such as cyclopentane or n-pentane, (a single layer homogeneous solution is formed).

[0134] When such a miscible solution of hydrocarbon and fatty acid compound is mixed with an aryl sulfonic acid, such as “Acid TX”, separation into 2 layers is observed on standing.

[0135] The efficacy of fatty acid additives as diluents was further investigated to determine whether or not in foam formation, such additives would assist in obtaining low aged thermal conductivity for phenolic foams blown with either cyclopentane or n-pentane isomers.

Comparative Example 2

Oleic Acid Diluent

[0136] Foam samples were prepared in the same way as specified in Example 3 using either blowing agent D or blowing agent E and employing 2-3 parts by weight of 95% oleic acid instead of the alkoxy alcohol. The resulting foams had initial thermal conductivity values of approximately 25 mW/m.Math.K however, the thermal conductivity values significantly exceeded 25 mW/m.Math.K at 10° C. mean plate temperature after the foams were aged at 70° C.

[0137] These thermal conductivity results show thermal conductivity drifts upwards on ageing when oleic acid was employed as an additive.

Comparative Example 3

Fatty Acid Additives

[0138] It is generally known that the addition of perfluoroalkanes to hydrocarbon blowing agents results in a finer cell phenolic foam. It was considered whether or not forming foams having finer cells would aid aged thermal conductivity performance with fatty acids as additives.

[0139] Comparative Example 3 below repeats Comparative Example 2 but with a perfluoroalkane as a co-blowing agent to the pentane blowing agents. In addition, the efficacy of other fatty acid organic diluents from Table 2 was investigated.

[0140] To 111 parts by weight of Resin “A” at 11-15° C. was mixed 2.25 parts by weight of a fatty acid compound as provided in Table 2. Next, 10 to 11 parts by weight of the specified blowing agent at 1° C. to 3° C. was mixed into the resin. The mixture was cooled to between 3° C. and 8° C. Next, 18 to 20 parts by weight of acid at 8° C. was quickly mixed into the resin mixture. High speed mixing, up to 3000 rpm was used. 110±10 g of the resulting resin emulsion was transferred into a picture-frame mould of dimensions 300 mm×300 mm×25 mm at 70° C. for 20 minutes to form a 25 mm thick rigid phenolic foam. The base plate had a polythene sheet that could easily be removed from the cured foam. Similarly a top sheet of polythene sheet was placed on top of the rising foam.

[0141] A pressure of 15 kPa was applied to the lid of the mould to pressurise the rising foam. The foam sample was then post-cured in an oven for 12 to 16 hours at 70° C. The foam boards produced had dry cured density values as indicated in Table 7. No facing materials (such as aluminum foil) were present on the surfaces of the foam board sample during thermal ageing.

[0142] Table 7 below summarises thermal conductivity (λ) results for hydrocarbon/perfluoropentane blown phenolic foam modified with fatty acid present.

[0143] Whilst drift upwards in aged thermal conductivity (λ) is clearly shown, foams containing fatty acid are marginally better than the control sample containing no fatty acid. However, the useful application requirement of an aged thermal conductivity of below 0.025 W/mK is not achieved.

TABLE-US-00007 TABLE 7 Initial A (W/m•K), Blowing Fatty Density mean plate 70° C. Aged A Agent Acid (kg/m.sup.3) temperature of 10° C. (W/m•K) D + F Not 31.6 0.0274 0.0303 (after 7 (Control) Added days) D + F Oleic acid 44 0.0212 0.0309 (after 5 days) E + F Oleic acid 32.3 0.0211 0.0298 (after 26 days) E + F Oleic acid 39.7 0.0226 0.0284 (after 25 days) E + F Oleic acid 35.6 0.0242 0.0287 (after 5 days) E + F TOFA 47.9 0.0267 0.0288 (after 5 BD2 days) D + F TOFA 38.3 0.0299 0.0317 (after 5 BD2 days) D + F Olive Oil 42.6 n/a 0.0330 (after 5 days) D + F Coconut 43.0 0.0330 n/a oil E + F Coconut 40.8 0.0328 n/a oil *Tall oil fatty acids (TOFA) TOFA comprises oleic, linoleic, palmitic, stearic and linolenic acids).

[0144] Prior art phenolic foams achieved stable low thermal conductivity for phenolic foam by either: [0145] (i) Employing saturated fluorinated blowing agents such as CFCs, HCFCs or HFCs with phenolic resins having water content in the range of 8 to 20 wt % based on the weight of the phenolic resin; [0146] (ii) Employing hydrocarbon blowing agents such as pentane with viscous, phenolic resins having low water content i.e. less than 8 wt % based on the weight of the phenolic resin; or [0147] (iii) Employing hydrocarbon blowing agents such as pentane with phenolic resins having medium to high water content 10 to 16 wt % based on the weight of the phenolic resin, with diluents such as polyester polyols.

[0148] The present invention is a next generation approach which employs a liquid organic diluent additive (i.e. liquid at room temperature), specifically an alkoxy alcohol additive as specified herein, which facilitates the formation of phenolic foams having stable low thermal conductivity despite using phenolic resin compositions having medium to high water contents. Advantageously, the incorporation of these alkoxy alcohol additives into phenolic resin decreases the viscosity of the resulting phenolic resin foamable compositions thereby facilitating easy pumping of the resin through conduits, manifolds and mixing heads. The alkoxy alcohol additives have low viscosity values—significantly lower than prior art polyester polyol additives for example, and the viscosity of phenolic resins incorporating said alkoxy alcohol additives is much lower than those comprising prior art additives such as polyester polyols. Table 8 illustrates the viscosity reduction achieved that aids foam processing. Furthermore, foams formed using phenolic resins comprising alkoxy alcohol additives, which are blown with hydrocarbon blowing agents have low thermal conductivity and have stable thermal stability. Advantageously, the foams of the present invention are less brittle than prior art foams.

TABLE-US-00008 TABLE 8 Viscosity With Viscosity Without 6 parts/100 parts Phenolic Butyl Diglycol of Butyl Diglycol Resin Used (mPa•s at 25° C.) (mPa.s at 25° C.) Resin A 9450 5520 Resin B 7600 4500

[0149] In preferred embodiments of the invention, the viscosity of the phenolic resin including surfactant, and alkoxy alcohol is in the range of from about 2,500 to 7,000 mPa.Math.s at 25° C. such as from about 4000 to 6000 mPa.Math.s at 25° C.

[0150] 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.

[0151] 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.