Phenolic foam

Abstract

A phenolic foam comprising a solid phenolic resin comprising cells containing a cell gas, wherein the cell gas comprises 1-chloro-2,3,3,3-tetrafluoropropane. The cell gas may comprise a C3-6 hydrocarb

Description

Field of the invention

[0001] The field of the invention is phenolic foams and the manufacture of phenolic foams. Background to the invention

[0002] Thermal insulation materials include phenolic foams. Generally phenolic foams have superior thermal insulation characteristics as compared to other foams such as polyisocyanurate foams (PIR) or polyurethane foams (PU).

[0003] Phenolic foam is produced by expanding and curing a foamable composition prepared by mixing a phenolic resin, a surfactant, a blowing agent, and an acid catalyst. Other additives can be optionally mixed into the resin such as plasticisers, flame retardants, or pigments.

[0004] During expansion of the foam the blowing agent is trapped as a gas within cells in the phenolic foam during manufacture of the phenolic foam. Blowing agents are chosen for certain benefits such as their thermal performance and flammability. Ideally most of the blowing agent will be trapped as cell gas.

[0005] Notwithstanding the state of the art, it would be desirable to provide a phenolic foam with excellent thermal insulation performance. Summary of the invention

[0006] The present invention provides a phenolic foam comprising a solid phenolic resin comprising cells containing a cell gas, wherein the cell gas comprises l-chloro-2,3,3,3-tetrafluoropropane. The cell gas comprising l-chloro-2,3,3,3-tetrafluoropropane provides the phenolic foam with excellent thermal insulation performance. The cell gas comprising 1-chloro-2,3,3,3-tetrafluoropropane provides the phenolic foam with excellent fire performance characteristics.

[0007] The cell gas may comprise a C3-C6 hydrocarbon. The C3-C6 hydrocarbon may comprise butane, for example isobutane, and / or pentane, desirably isopentane. The C3-C6 hydrocarbon may be unsaturated for example butene, pentene such as isopentene. The cell gas comprising one of these gases may reduce the cost of manufacture of the phenolic foam as they tend to be lower cost than l-chloro-2,3,3,3-tetrafluoropropane.

[0008] The cell gas may consist essentially of l-chloro-2,3,3,3-tetrafluoropropane, a C3-C6 hydrocarbon, nitrogen and oxygen. Nitrogen and oxygen are the main components of air. Air in the cells is to be minimised where possible. Air may be trapped during the formation of the foam. Over time air will permeate through the cured resin such that the cell gas will nitrogen and oxygen.

[0009] The cell gas may comprise a saturated or unsaturated C3-C6 compound that is substituted at least once by one or more of fluorine and chlorine, for example isopropyl chloride. The cell gas comprising one of these gases may reduce the cost of manufacture of the phenolic foam as they tend to be lower cost than l-chloro-2,3,3,3-tetrafluoropropane.

[0010] The cell gas may comprise at least one of isopropyl chloride or a saturated C3-C6 hydrocarbon such as pentane for example isopentane. These cell gases tend to lower costs compared to l-chloro-2,3,3,3-tetrafluoropropane alone. These cell gases may themselves have excellent thermal insulation performance.

[0011] The cell gas may comprise a blend of isopropyl chloride and a saturated C3-C6 hydrocarbon such as pentane for example isopentane. These cell gases tend to lower costs compared to l-chloro-2,3,3,3-tetrafluoropropane alone. These cell gases may themselves have excellent thermal insulation performance.

[0012] The cell gas may comprise at least one of a hydrofluoroolefin or a chlorinated hydrofluoroolefin. These cell gases may themselves have excellent thermal insulation performance.

[0013] The presence of l-chloro-2,3,3,3-tetrafluoropropane in the cell gas may be determined by gas chromatography (GC). Similarly, the presence of other components, such as those listed above, may be determined by GC, as can the relative ratios of the components present in the cell gas.

[0014] The phenolic foam may have an initial thermal conductivity of less than 0.0160 W / m-K as measured according to EN 13166:2012. A phenolic foam with an initial thermal conductivity of less than 0.0160 W / m.k is preferred as a lower initial thermal conductivity means that the foam has better initial thermal insulation performance.

[0015] The phenolic foam may have an aged thermal conductivity of less than 0.0170 W / m-K as measured according to EN 13166:2012 after aging for 110° C for 14 days and conditioned according to EN 13166:2012 (Method 2 Annex C). As a phenolic foam ages the cell gas is slowly replaced by air which has a higher thermal conductivity. Ideally as little cell gas as possible is lost over time. An aged thermal conductivity of less than 0.0170 W / m-K is preferred as it means that the phenolic foam retains its thermal insulation performance over time.

[0016] The phenolic foam may have a conditioned thermal conductivity of less than about 0.0175 W / m-K.

[0017] The phenolic foam may have a compressive strength at yield of at least about 140 kPa as measured according to BS EN826:2013. Strength at yield refers to the pressure required for the first crack or fault to be present in the foam. Higher compressive strength at yield is preferable.

[0018] The phenolic foam may have a peak compressive strength of at least about 155 kPa as measured according to BS EN826:2013. Peak compressive strength is the maximum pressure observed during the test. Higher peak compressive strength is preferable.

[0019] The phenolic foam may have a friability of less than about 25% as measured according to ISO 6187. Minimising friability reduces the tendency of the foam to break into smaller pieces under duress.

[0020] The phenolic foam of any preceding claim having a closed cell content of 90% or more, such as 95% or more, preferably 98% or more, as determined in accordance with ASTM D6226. A higher percentage of closed cells may mean that more cells will contain cell gas. This may lead to improved thermal conductivity.

[0021] The cells of the phenolic foam may have an average cell diameter in the range of from 50 to 250 pm, suitably in the range of from 80 to 180 pm. Small cells may be more robust than larger cells. This means that the cells will better retain their cell gas.

[0022] The phenolic foam may have a density of from about 15 kg / m3 to about 60 kg / m3. Less dense phenolic foam is preferable as it is preferable for handling and fitting of insulation to provide a lighter foam to cover an area to be insulated.

[0023] In a further aspect the invention relates to a method of making a phenolic foam comprising: mixing a phenolic resin and a blowing agent comprising l-chloro-2,3,3,3-tetrafluoropropane; and expanding and curing the mixture of phenolic resin and l-chloro-2,3,3,3-tetrafluoropropane to form a solid phenolic resin comprising cells containing a cell gas, wherein the cell gas comprises l-chloro-2,3,3,3-tetrafluoropropane.

[0024] The method maybe performed in a continuous manner. Performing the method in a continuous manner allows large scale production of phenolic foam. Examples

[0025] The present invention will be explained in detail with reference to examples hereinafter, while the present invention will not be limited by these examples.

[0026] Phenolic foam products obtained in the examples and comparative examples were measured for physical properties according to the following methods.

[0027] Thermal conductivity was measured according to EN 13166:2012 (Method 2 Annex C).

[0028] 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.

[0029] 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.

[0030] pH of the phenolic foam was measured according to EN 13468:2001(e).

[0031] Density of the phenolic foam was measured according to ASTM D1622-14.

[0032] Compressive strength of the phenolic foam was measured according to BS EN826:2013.

[0033] Friability of the phenolic foam may be measured according to ISO 6187.

[0034] Closed cell content of the phenolic foam was measured according to ASTM D2856.

[0035] Water content was determined by Karl Fischer analysis and was performed using a Metrohm 870 KFTitrino.

[0036] Viscosity was determined using a Brookfield viscometer DV TT +Pro instrument with a water batch attachment to measure viscosities at 25°C. A spindle is selected, and spindle rotation speed (RPM) required to achieve a torque between 35-55% (typically 20RPM). Example 1 Resin A synthesis

[0037] 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 5000 -15000 cPs at 25°C, weight average molecular weight 700 to 900, and pH 7 to 9.

[0038] Resin "A" resin contains from 2% to 4% free phenol, 0.1% to 0.5% free formaldehyde, and a water content of 10 to 15% as measured by Karl Fisher analysis. Foam product preparation

[0039] 100 parts by weight of Resin A, 5 parts by weight urea and 3.5 parts by weight ethoxylated castor oil surfactant, 21.2 parts by weight sulphonic acid blend, 15.2 parts by weight blowing agent blend consisting of 95:5 parts by weight l-chloro-2,3,3,3-tetrafluoropropane and isopentane, and 7.7 parts by weight polyol / calcium carbonate blend (polyol / calcium carbonate ratio 1:1.86 ) were mixed at a mixing head before dispensing onto a facer material on a moving conveyor belt. The conveyor belt was moving at between 7-20 m / min. The facer material was a glass tissue facer. A second glass tissue facer was applied on top of the foam composition. Both facers were Owens Corning glass tissue facers from 70-80 gsm (O.C 170 EFW-ZA75 1217mm). Example 2

[0040] Example 2 was prepared in the same manner as Example 1. Comparative example 1

[0041] Comparative example 1 was prepared in the same manner as Example 1 except for the following: the blowing agent was a blend of 95 parts by weight of trans-l-chloro-3,3,3-trifluoropropene and 5 parts by weight of isopropane.

[0042] The characteristics of the examplesand comparative examples are shown in table 1. Table 1 Comparative example 1 Example 1 Example 2 Initial lambda (mW / mK) 16.0 15.6 15.5 Aged lambda (mW / mK) 17 16.6 16.7 Conditioned lambda (mW / mK) 17.1 17.3 17.4 Compressive stength at yield (kPa) 138 148 144 Peak compressive stength (kPa) 164 159 157 Friability 14% 23% 18%

[0043] 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.

[0044] 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 5 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 subcombination.

Claims

1. A phenolic foam comprising a solid phenolic resin comprising cells containing a cell gas, wherein the cell gas comprises l-chloro-2,3,3,3-tetrafluoropropane.2 . The phenolic foam of claim 1 wherein the cell gas comprises a C3-C6 hydrocarbon.3 . The phenolic foam of any preceding claim wherein the cell gas comprises a saturated orunsaturated C3-C6 compound that is substituted at least once by one or more of fluorine and chlorine, for example isopropyl chloride.

4. The phenolic foam of any preceding claim wherein the cell gas comprises at least one of isopropyl chloride or a saturated C3-C6 hydrocarbon such as pentane for example isopentane.5 . The phenolic foam of any preceding claim wherein the cell gas comprises a blend of isopropyl chloride and a saturated C3-C6 hydrocarbon such as pentane for example isopentane.6 . The phenolic foam of any preceding claim wherein the cell gas comprises nitrogen and oxygen.7 . The phenolic foam of any preceding claim having an initial thermal conductivity of less than 0.0160 W / m-K as measured according to EN 13166:2012.8 . The phenolic foam of any preceding claim having an aged thermal conductivity of less than 0.0170 W / m-K as measured according to EN 13166:2012 after aging for 110° C for 14 days and conditioned according to EN 13166:2012 (Method 2 Annex C).9 . The phenolic foam of any preceding claim having a conditioned thermal conductivity of less than about 0.0175 W / m-K as measured according to EN 13166:2012.

10. The phenolic foam of any preceding claim having a compressive strength at yield of at least about 140 kPa as measured according to BS EN826:2013.

11. The phenolic foam of any preceding claim having a peak compressive strength of at least about 155 kPa as measured according to BS EN826:2013.1 2 . The phenolic foam of any preceding claim having a friability of less than about 25% as measured according to ISO 6187.13 . The phenolic foam of any preceding claim having a closed cell content of 90% or more, such as 95% or more, preferably 98% or more, as determined in accordance with ASTMD6226.14 . The phenolic foam of any preceding claim wherein the cells have an average cell diameter in the range of from 50 to 250 pm, suitably in the range of from 80 to 180 pm.15 . The phenolic foam according to any preceding claim having a density of from about 15 kg / m3 to about 60 kg / m3, such as from about 20 kg / m3 to about 50 kg / m3, suitably of from about 24 kg / m3 to about 48 kg / m3.

16. A method of making a phenolic foam comprising:a. mixing a phenolic resin and a blowing agent comprising l-chloro-2,3,3,3-tetrafluoropropane; andb. expanding and curing the mixture of phenolic resin and l-chloro-2,3,3,3-tetrafluoropropane to form a solid phenolic resin comprising cells containing a cell gas, wherein the cell gas comprises l-chloro-2,3,3,3-tetrafluoropropane.17 . The method of claim 16 wherein the method is performed in a continuous manner.TOMKINS &CO.