Resin compositions

Abstract

Ethylene urea used as a stabiliser of phenolic resins. The phenolic resins are preferably resole reins and the ethylene urea stabilises the viscosity, scavenges formaldehyde, and reduces reactivity of

Description

Field of the Invention

[0001] The present invention relates to phenolic foam compositions and methods of manufacture of phenolic foams. The present invention in particular relates to resins suitable for forming phenolic foams. Of particular interest is the use of ethylene urea as a stabiliser of phenolic resins. Those phenolic resins are used to prepare phenolic foams. Phenolic foams of the invention are typically for use in thermal insulation. Of particular interest are phenol-formaldehyde resins such as a resole resin. Background

[0002] Phenolic resins have been a preferred thermosetting plastic material for thermal insulation. Applications, include those in building and pipe insulation, where phenolic foams provide good thermal insulation.

[0003] In the production of phenolic foams a strong organic or inorganic acid commonly catalyses a phenolic resole resin. Possible acids include but are not restricted to sulphuric acid, phenol sulphonic acid, para toluene sulphonic acid, xylene sulphonic acid, phosphoric acid and blends thereof. For example, EP0170357A describes a process for the production of an acid cured phenolic resin foam. The selection of acid type is dependent on the desired curing time and temperature.

[0004] Cellular insulation foam is produced when the blowing agent that has been blended into the resin, starts to boil. Halocarbons and hydrocarbons are commonly used blowing agents. Expansion typically occurs in the temperature range 25 °C to 80 °C. A closed cell foam structure is highly desirable to maximise insulation performance. Insulation performance is often quantified by measuring thermal conductivity (lambda (A) value in W / m.K) as measured in accordance with EN 13166:2012 (Method 2 Annex C). The lower the thermal conductivity / lambda value the better from a thermal insulation viewpoint.

[0005] Blowing agents having low thermal conductivity are used to form thermal insulating foams. As the gas volume for a foam may account for 95 % of the volume of a foam, the amount and nature of the blowing agent trapped in the foam has a significant impact on the thermal insulating performance of the foam. In order to form thermal insulating foam, a total closed cell content of 85 % or more is generally required. One of the main determinants in the thermal insulation performance of foam is the ability of the cells of the foam to retain blowing agent having a low thermal conductivity.

[0006] One of the issues that arises in preparation of phenolic resins such as phenolic resole resins, is that the phenolic resin is not indefinitely stable. For example such a resin, once ready to use for production of a foam, may increase in viscosity with time.

[0007] Such increase in viscosity is undesirable as it makes blowing the resin to form the foam more difficult.

[0008] Moreover, because a foam production process is typically set to process resins in a consistent way, variations in viscosity of the resin may result in consequent and undesirable variations in the foam product produced. For example thickness and / or density in the foam product produced may change. So too may closed cell content in the foam product produced. (Typically a closed cell content of at least 85 %, for example at least 90 % as determined in accordance with ASTM D6226 is desirable within the foam.)

[0009] Or otherwise, production parameters such as temperature (for example in a laminator oven) may need to be varied to account for varying viscosity of a resin. Again this becomes an issue for output of a foam product with consistent characteristics. Introducing processing complexity is not favourable to obtaining a consistent output of a foam product with desirable characteristics.

[0010] And of course if the viscosity changes so that the resin become unusable, for example the viscosity increases so that the resin is more likely to clog up equipment such as an applicator head, then this results in the resin not being useable resulting in unnecessary waste and / or down time for removing clogging if used.

[0011] It is desirable to address these issues. Summary of the Invention

[0012] One way to decrease viscosity is to increase water content of the resin composition used for foam production. However increased water content may cause issues with obtaining closed cell foams a water egress during foam production may cause the formation of a higher amount of open cells. Also additional water needs to be dried off later.

[0013] In any event decreasing the initial viscosity of the resin composition does not by itself necessarily increase the time the resin remains useable. Or in other words the viscosity increase issues still remain.

[0014] And of course one could omit certain components that may contribute to a higher initial viscosity. However, the omission of components may have deleterious effects on the final properties of the foam.

[0015] It is an objective of the present invention to provide a resin composition that demonstrates more stable viscosity over time.

[0016] Reducing the viscosity of the resin upon completion of resin synthesis contributes towards increasing the lifetime of the resin itself, however this has no impact on the rate at which the resin ages. Increasing the water content of the resin does decrease the rate of ageing of the resin but this results in resin that is not suitable for foaming purposes. Ageing can be defined as the increase in resin viscosity and reactivity over time. Ageing, viscosity, and reactivity of the resin may be proportionate to the level of self-polymerisation which has occurred in the resin. Therefore, it would be favourable to produce a phenolicformaldehyde resin that exhibit lower reactivity, higher stability and that which does not contain excess water so that it would still be suitable for forming a foam product that is suitable for thermal insulation.

[0017] It is the object of the invention to overcome at least one of the aforementioned issues of phenolic foam resole resins.

[0018] In one aspect, in the present invention there is provided the use of ethylene urea as a stabiliser of a resin, for example as a stabiliser of a phenolic resin. The use of ethylene urea may be as a stabiliser of the viscosity of a resin. Accordingly, in accordance with the invention, the resin (including ethylene urea) has a more stable viscosity than a corresponding (control) resin without ethylene urea.

[0019] In accordance with the invention, the resin (including ethylene urea) has a more stable viscosity, thus experiencing a lower increase in viscosity, than a corresponding (control) resin without ethylene urea.

[0020] The ethylene urea thus imparts a viscosity stabilising effect. The ethylene urea thus imparts a viscosity stabilising effect against an increase in viscosity.

[0021] The addition of ethylene urea to a resin such as a phenolic resin may impart more stable viscosity of the resin (as compared to a control) which consequently increases the useable lifetime of the resin.

[0022] In accordance with the invention, the resin (including ethylene urea) has a more stable viscosity thus experiencing a lower increase in viscosity than a corresponding (control) resin without ethylene urea.

[0023] In this case “reduced resin viscosity” or similar references, is as compared to a control resin which is the same resin with urea, instead of ethylene urea, and measured in the same way, under the same conditions and time intervals.

[0024] It will be appreciated that a technical effect of the present invention is to slow or reduce an increase in viscosity that (otherwise) occurs over time.

[0025] The addition of ethylene urea to a resin such as a phenolic resin may impart better reactivity of the resin (as compared to a control) which consequently increases the useable lifetime of the resin.

[0026] It will be appreciated that a technical effect of the present invention is to slow or reduce a decrease in reactivity that occurs over time. A decrease in reactivity may occur due to reaction of the resin over time (and before curing is induced, for example by addition of acid catalyst). Or in other words the resin components may begin to react even in the absence of a curing catalyst such as an acid catalyst. So while the resin is being stored before use for foaming such reaction (in the absence of a curing catalyst) can take place. This is undesirable as it is more desirable to have a resin with unreacted components.

[0027] As the curing of the resin under acid catalyst conditions (to form a foam product) is exothermic, the exotherm of the curing process can be used an indication of the reactivity of the resin. The greater the exotherm the greater the reactivity. Or put the other way, the greater the exotherm the less the resin has reacted during storage and before curing of the resin under acid catalyst conditions.

[0028] As the curing of the resin under acid catalyst conditions (to form a foam product) releases water as a by-product, the water content of the resin during the curing process can be used an indication of the reactivity of the resin. The greater the water content the greater the reactivity. Or put the other way, the greater the water produced by this reaction the less the resin has reacted during storage and before curing of the resin under acid catalyst conditions.

[0029] Reaction of the resin, such as a resole resin occurs between the phenolic component and the formaldehyde with the consequent release of water. Accordingly monitoring the water content of the resin is one way to determine if such reaction has taken place. The amount of additional water can thus be used to determine the degree to which reaction has taken place.

[0030] The invention thus provides a method of stabilising the viscosity of a resin by adding ethylene urea to the resin.

[0031] The resin composition is utilised in the formation of a foam body and desirably a thermally insulating foam body.

[0032] Phenolic resole resins are used in the manufacture of phenolic foams. These are typically condensation products of phenol and formaldehyde and often with an excess of formaldehyde. These resole resins may be made under aqueous conditions for example aqueous basic conditions. Such resins are employed in the present invention.

[0033] In general, phenolic resins used in phenolic foam manufacture are viscous liquids with water concentrations of from about 1 to 25 wt.%. The phenolic resins typically have methylol groups as reactive substituents.

[0034] The wt.% (or wt% or percentage by weight) is based on the total weight of the composition unless otherwise stated.

[0035] Cross-linked phenolic foam may be formed by heating and curing a mixture of phenolic resin, blowing agent, surfactant and acid catalyst. Upon addition of an acid catalyst to a mixture comprising resin, blowing agent and surfactant, an exothermic reaction occurs between methylol groups and phenolic rings to form methylene bridges, which cross-link polymeric chains, and water of condensation polymerisation is produced.

[0036] The viscosity of a resin employed in the manufacture of a foam within the present invention may be determined by methods known to the person skilled in the art for example using a Brookfield viscometer (model DV-ll+Pro) at a controlled temperature water bath, maintaining the sample temperature at 25°C, with spindle number S29 rotating at 20 rpm or appropriate rotation speed and spindle type or suitable test temperature to maintain an acceptable mid-range torque for viscosity reading accuracy.

[0037] The composition of the resole resin, the quantity and nature of the acid curing catalyst and the chemical and physical properties of the blowing agent and any surfactant present in the foam reactants greatly influence the final properties of the foam product formed. For example, these components may influence ability to control a resulting exothermic reaction and thus in turn the ability to form closed cell foam.

[0038] A composition for forming a phenolic foam, in accordance with the invention, may contain a resole resin and water. Often it additionally contains surfactant(s) and optionally other components such as fillers, stabilisers, fire / flame retardants, scavengers such a formaldehyde scavengers including urea, neutralising agent such as calcium carbonate etc. Such a composition, with or without one or more of the additional components may be stabilised by ethylene urea in accordance with the invention.

[0039] To form a foamable reactive composition a catalyst such as an acid catalyst is added. In accordance with the present invention the ethylene urea is used to stabilise a resin composition which does not include such a catalyst.

[0040] Typically addition of such a catalyst is done by mixing just prior to formation of a foam from the resin. The addition prior to formation of the foam substantially accelerates curing of the resin and the curing resin is blown while curing by the blowing agent.

[0041] To blow / foam a foamable reactive composition a blowing agent is added. In accordance with the present invention the ethylene urea is used to stabilise a resin composition which does not include such a blowing agent.

[0042] Typically addition of such a blowing agent is done by mixing just prior to formation of a foam from the resin.

[0043] An example of a phenolic foam with a stable low thermal conductivity, in accordance with the invention, is as described and claimed in European Patent No. EP1922357 which describes a phenolic foam which is made by foaming and curing a foamable phenolic resin, a blowing agent, and an acid catalyst. Foamable resin composition may include an inorganic filler.

[0044] The blowing agent used, in accordance with the invention, may comprise aliphatic hydrocarbon containing from 1 to 8 carbon atoms or any blend such aliphatic hydrocarbons.

[0045] An inorganic filler used, in accordance with the invention, may be at least one selected from a metal hydroxide, a metal oxide, a metal carbonate and a metal powder.

[0046] In the present invention the resin may be a phenolic resin.

[0047] In the present invention the resin may be a phenol-formaldehyde resin.

[0048] In the present invention the resin may be a resole resin.

[0049] The resin viscosity may be in the range of from about from about 2,500 mPas to about 20,000 mPa s.

[0050] The resin viscosity may be at least one of the following: such as about 7,000 mPa-s to about 9,000 mPa-s after 1 day when stored at 21 °C, from about 9,000 mPa-s to about 12,000 mPa-s after 8 days when stored at 21°C, from about 12,000 mPa-s to about 16,000 mPa-s after 21 days when stored at 21 °C, and from about 25,000 mPa-s to about 35,000 mPa-s after 43 days when stored at 21 °C.

[0051] The viscosity of a resin employed in the present invention may be determined by methods known to the person skilled in the art, for example using a Brookfield viscometer (model DV-ll+Pro) at a controlled temperature water bath, maintaining the sample temperature at 25 °C, with spindle number S29 rotating at 20 rpm or appropriate rotation speed and spindle type or suitable test temperature to maintain an acceptable mid-range torque for viscosity reading accuracy.

[0052] The phenolic resin may have a viscosity of at least one of: from about 7,000 mPa-s to about 9,000 mPa-s after 1 day when stored at 5 °C, from about 8,000 mPa-s to about 18,000 mPa-s after 27 days when stored at 5 °C, from about 9,000 mPa-s to about 19,000 mPa-s after 44 days when stored at 5 °C, from about 10,000 to about 22,000 after 73 days when stored at 5 °C, and from about 15,000 mPa-s to about 25,000 mPa-s after 119 days when stored at 5 °C. The viscosity of a resin in the present invention may be determined by methods known to the person skilled in the art for example using a Brookfield viscometer (model DV-ll+Pro) at a controlled temperature water bath, maintaining the sample temperature at 40 °C, with spindle number S29 rotating at 130 rpm or appropriate rotation speed and spindle type or suitable test temperature to maintain an acceptable mid-range torque for viscosity reading accuracy.

[0053] The phenolic resin may have a low free formaldehyde content of from about 0.1% to about 0.5% as a wt.% of the phenolic resin, preferably from about 0.1% to about 0.3% as a wt.% of the phenolic resin when measured by potentiometric titration according to ISO 11402:2004 using hydroxylamine hydrochloride procedure. A free formaldehyde content of from about 0.1% to about 0.5% as a wt.% of the phenolic resin is desirable.

[0054] In general, phenolic resins used in phenolic foam manufacture are viscous liquids with water concentrations of from about 1 to 25 wt.%. The phenolic resins typically have methylol groups as reactive substituents. Cross-linked phenolic foam may be formed by heating and curing a mixture of phenolic resin, blowing agent, surfactant and acid catalyst. Upon addition of an acid catalyst to a mixture comprising resin, blowing agent and surfactant, an exothermic reaction occurs between methylol groups and phenolic rings to form methylene bridges, which cross-link polymeric chains, and water of condensation polymerisation is produced.

[0055] A composition for forming a phenolic foam may contain the resole resin and water. Often it additionally contains surfactant(s) and optionally other components such as fillers, stabilisers, fire / flame retardants, scavengers such a formaldehyde scavengers including urea, neutralising agent such as calcium carbonate etc.

[0056] A catalyst such as an acid catalyst is added too, but often this is done by mixing just prior to formation of a foam from the resin. A blowing agent is added too, but often this is done by mixing just prior to formation of a foam product from the resin

[0057] The viscosity of the resin may be at least one of: from about 7000 mPa-s to about 9000 mPa-s after 3 days when stored at 25 °C, from about 8,000 mPa-s to about 10,000 mPa-s after 10 days when stored at 25 °C , from about 10,000 mPa-s to about 12,000 mPa-s after 17 days when stored at 25 °C, from about 13,000 mPa-s to about 15,000 mPa-s after 29 days when stored at 25 °C, from about 18,000 mPa-s to about 21,000 mPa-s after 37 days when stored at 25 °C, from about 24,000 mPa-s to about 26,000 mPa-s after 45 days when stored at 25 °C, and from about 32,000 mPa-s to about 34,000 mPa-s after 49 days when stored at 25 °C.

[0058] The viscosity of a resin employed in the present invention may be determined by methods known to the person skilled in the art for example using a Brookfield viscometer (model DV-ll+Pro) at a controlled temperature water bath, maintaining the sample temperature at 40 °C, with spindle number S29 rotating at 130 rpm or appropriate rotation speed and spindle type or suitable test temperature to maintain an acceptable mid-range torque for viscosity reading accuracy.

[0059] The ethylene urea may reduce the rate of ageing of a resin.

[0060] The ethylene urea may act as a scavenger.

[0061] The ethylene urea may as a formaldehyde scavenger.

[0062] The ethylene urea may reduce the reactivity of the resin. The reactivity of the resin at least in the present disclosure can be defined as the rate at which the resin reacts in the absence of a curing catalyst such as an acid catalyst. Such reaction takes place upon storage of the resin. Typically the effect of stabilising is seen over a period from about 1 to about 10 days, such as about 1 to about 8 days, for example up to 7 days.

[0063] The invention also relates to a method for stabilising a resin comprising the step of adding ethylene urea.

[0064] The method may comprise a step of adding ethylene urea, wherein the step comprises adding from about 2 to about 10, such as about 2.5 to about 8 for example about 3 to about 7, such as about 4 to about 5, for example about 4.5, parts by weight of ethylene urea to a resin.

[0065] The step of adding the ethylene urea to the resin may be at room temperature.

[0066] The ethylene urea can be added before or after the surfactant.

[0067] The amount of ethylene urea added to the resin is based on the number of active sites of ethylene urea in comparison to urea. Urea may be used as a formaldehyde scavenger in the manufacturing of resole resin. Therefore, the amount of ethylene urea to be added to the resin can be calculated as follows. 2 ethylene urea (q) = mass of resin (q) x 5% x ---------------- y a J No. of active sites The active sites on the ethylene urea are the secondary amines on the molecule, therefore ethylene urea has two active sites.

[0068] Advantageously in addition to acting as a stabiliser for the resin the ethylene urea may also act as a formaldehyde scavenger.

[0069] Desirably the phenol resin of the invention comprises a number of components. It typically contains at least phenol, formaldehyde and water. Often it additionally contains surfactant and optionally other components such as fillers, stabilisers, fire / flame retardants, scavengers such a formaldehyde scavengers including urea, neutralising agent such as calcium carbonate etc.

[0070] It is usual to include a surfactant. Surfactants are generally used in phenolic resin foamable compositions to facilitate the formation of cells which are structurally more stable, which in turn reduces loss of blowing agent from the resulting foam over time. Surfactants may also aid in the emulsification of blowing agent within phenolic foam resin. This in turn can lead to the production of a foam which is more stable against blowing agent loss and indeed better blowing agent retention. Surfactants may also influence the brittleness of phenolic foams, partly due to residual water in the foam. This is particularly the case for lower density phenolic foams below around 32 kg / m3 density.

[0071] The blowing agent may comprise a Ci - C? hydrocarbon. Ci - C? hydrocarbons are advantageous as blowing agents as they have low thermal conductivity, may be used to form closed cell foams having stable excellent thermal insulation performance, and have low environmental impact. They are also relatively low cost.

[0072] The blowing agent may comprise a Ci - C7 hydrocarbon, the Ci - C7 hydrocarbon comprising at least one of butane, pentane, hexane, heptane, and isomers thereof. Desirably, the butane is isobutane or cyclobutane. Desirably the pentane is isopentane or cyclopentane.

[0073] The blowing agent may comprise a C2-C5 halogenated hydrocarbon, for example, the blowing agent may comprise a chlorinated aliphatic hydrocarbon, for example the blowing agent may comprise a chlorinated aliphatic saturated or unsaturated hydrocarbon. Suitably, the chlorinated aliphatic hydrocarbon having from 2 to 5 carbon atoms will have from 1 to 4 chlorine atoms. Suitably, the chlorinated aliphatic hydrocarbon containing 2 to 5 carbon atoms is selected from the group consisting of dichloroethane, 1,2-dichloroethylene, n-propyl chloride, isopropyl chloride, butyl chloride, isobutyl chloride, pentyl chloride, isopentyl chloride, 1,1-dichloroethylene, trichloroethylene, and chloroethylene.

[0074] The blowing agent may comprise a combination of said Ci - C7 hydrocarbons and said halogenated hydroolefins.

[0075] The blowing agent may comprise a halogenated hydroolefin which is selected from the group consisting of 1-chloro-3,3,3-trifluoropropene, 1-chloro-2,3,3,3-tetrafluoro-1-propene, 1,3,3,3-tetrafluoro-1-propene, 2,3,3,3-tetrafluoro-1-propene, 1,1,1,4,4,4-hexafluoro-2-butene, 1,1,1,3,3-pentafluoro-2-propene and combinations thereof.

[0076] The blowing agent may comprise 1-chloro-3,3,3-trifluoropropene, 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.

[0077] The blowing agent my comprise trans-1,1,1,4,4,4-hexafluoro-2-butene, cis-1,1,1,4,4,4-hexafluoro-2-butene, cis-1-chloro-3,3,3-trifluoro-1-propene, cis-1 -chloro-2,3,3,3-tetrafluoro-1-propene, 2,3,3,3-tetrafluoro-1-propene, 1,3,3,3-tetrafluoro-2-propene, 1,1,1,3,3-pentafluoro-1-propene, trans-1,2-dichoroethylene, or methyl formate or combinations thereof.

[0078] The blowing agent may comprise a Ci -C7 hydrocarbon selected from at least one of, butane, pentane, hexane, heptane, and isomers thereof. The blowing agent may comprise an alkyl halide such as isopropyl chloride.

[0079] The blowing agent may comprise a hydrocarbon and additionally a halogenated hydroolefin.

[0080] The blowing agent of the composition from which the foam product of the invention is formed may comprise 20% to 80% Ci - C7 hydrocarbon based on the total weight of the blowing agent of the composition.

[0081] The blowing agent of the composition from which the foam product of the invention is formed may comprise 20% to 80% halogenated hydroolefin based on the total weight of the blowing agent of the composition.

[0082] The blowing agent may comprise from about 30 wt.% to about 50 wt.% 1-chloro-3,3,3-trifluoropropene and from about 50 wt.% to about 70 wt.% Ci - C? hydrocarbon based on the total weight of the blowing agent.

[0083] Suitably, in the composition from which the foam product of the invention, such as a phenolic foam is formed, the blowing agent may be present in an amount of from 1 to 20 parts by weight per 100 parts by weight of the phenolic resin. Preferably, in the composition for forming a foam product of the invention, the blowing agent is present in an amount of from 5 to 15 parts by weight per 100 parts by weight of the phenolic resin, for example 8 to 10 parts by weight of the blowing agent per 100 parts by weight of phenolic resin.

[0084] The blowing agent may comprise at least one of the following: at least one saturated or unsaturated C3-C6 hydrocarbon; at least one saturated or unsaturated C3-C6 compound that is substituted at least once by one or more of fluorine and chlorine for example isopropyl chloride.

[0085] Desirably the blowing agent comprises at least one of isopropyl chloride or a saturated C3-C6 hydrocarbon such as pentane for example isopentane.

[0086] Desirably the blowing agent comprises at least one of hydrofluoroolefin or chlorinated hydrofluoroolefin.

[0087] The blowing agent may comprise at least one of the following: at least one saturated or unsaturated C3-C6 hydrocarbon;

[0088] at least one saturated or unsaturated C3-C6 compound that is substituted at least once by one or more of fluorine and chlorine for example isopropyl chloride.

[0089] For example the blowing agent may comprise a blend of at least one of hydrofluoroolefin or chlorinated hydrofluoroolefin with a C3-C6 hydrocarbon such as pentane for example isopentane.

[0090] Desirably each of the at least one hydrofluoroolefin and the at least one chlorinated hydrofluoroolefin have a thermal conductivity of 0.0135 W / m.K or less at 10°C.

[0091] Suitably, each of the at least one hydrofluoroolefin and the at least one chlorinated hydrofluoroolefin have a thermal conductivity of 0.0125 W / m.K or less. For example, each of the at least one hydrofluoroolefin and the at least one chlorinated hydrofluoroolefin have a thermal conductivity of 0.0125 W / m.K or less at 25°C.

[0092] The foam may have a total heat release of 7.5 MJ or less, such as 7.0 MJ or less, or 6.5 MJ or less, or 6.25 MJ or less, or 6.0 MJ or less, or 5.75 MJ or less, or 5.5 MJ or less, or 5.25 MJ or less, or 5.15 MJ or less, or 5.0 MJ or less, or 4.8 MJ or less, or 4.6 MJ or less, or 4.4 MJ or less, when measured according to EN13823.

[0093] The foam desirably has a closed cell content of 90% or more, such as 95% or more, preferably 98% or more, as determined in accordance with ASTM D6226.

[0094] The cells of the foam may have an average cell diameter in the range of from 50 to 250 pm, such as in the range of from 80 to 180 pm.

[0095] Suitably, the foam has a thermal conductivity of 0.020 W / mK or less, suitably of 0.018 W / mK or less, desirably 0.0175 W / mK or less, or 0.0170 W / mK or less, or 0.0165 W / mK or less, 0.0162 W / m K or less when measured at a mean temperature of 10°C, in accordance with EN 13166:2012.

[0096] The foam may have a limiting oxygen index of 34% or more, preferably 35% or more, suitably 36% or more, such as 37% or more as determined in accordance with ISO 4589-2.

[0097] Suitably, the foam has a stable moisture (water) content of from 3% to 5% by weight added when determined at 23 (± 2)°C and a relative humidity of 50 (± 5)% in accordance with EN12429:1998 - Thermal insulating products for building applications: conditioning to moisture equilibrium under specified temperature and humidity conditions.

[0098] If stable moisture content exceeds 5% there is a risk of thermal conductivity of the foam increasing with age in application. If the stable moisture content is below 3%, then FIGRA may increase. So an optimum stable moisture content of phenolic foam can assist in obtaining low FIGRA without compromising low thermal conductivity over an extended time period in its insulation application.

[0099] The at least one chlorinated hydrofluoroolefin may be selected from 1-chloro-3,3,3-trifluoropropene (HCFO-1233zd) and 1-chloro-2,3,3,3-tetrafluoropropene (HCFO-1224yd).

[00100] The HCFO-1233zd may be the E or Z isomer, or a mixture thereof, i.e. the HCFO-1233zd may be HCFO-1233zd(E), HFCO-1233zd(Z) or a mixture thereof. For example, the HCFO-1233zd may comprise 90 wt.% or more (such as 95 wt.% or more) HCFO-1233zd(E), or the HCFO-1233zd may comprise 90 wt.% or more (such as 95 wt.% or more) HCFO-1233zd(Z). Desirably, the HCFO-1233zd comprises 95 wt.% or more HCFO-1233zd(E).

[00101] The HCFO-1224yd may be the E or Z isomer, or a mixture thereof, i.e. the HCFO-1224yd may be HCFO-1224yd(E), HFCO-1224zd(Z) or a mixture thereof. For example, the HCFO-1224yd may comprise 90 wt.% or more (such as 95 wt.% or more) HCFO-1224yd(E), or the HCFO-1224yd may comprise 90 wt.% or more (such as 95wt.% or more) HCFO-1224yd(Z). Desirably, the HCFO-1224yd comprises 95wt.% or more HCFO-1224yd(Z).

[00102] The at least one hydrofluoroolefin desirably comprises 1,1,1,4,4,4-hexafluoro-2-butene (HFO-1336mzz). The HFO-1336mzz may be the E or Z isomer, or a mixture thereof, i.e. the HFO-1336mzz may be HFO-1336mzz(E), HFO-1336mzz(Z) or a mixture thereof. For example, the HFO-1336mzz may comprise 90wt.% or more (such as 95wt.% or more) HFO-1336mzz(E), or the HFO-1336mzz may comprise 90wt.% or more (such as 95wt.% or more) HFO-1336mzz(Z). Desirably, the HFO-1336mzz comprises 95wt.% or more HFO-1336mzz(Z). The at least one alkyl halide may for example comprise isopropyl chloride.

[00103] The at least one (saturated) C3-C6 hydrocarbon may comprise butane, for example isobutane, and / or pentane, desirably isopentane.

[00104] The at least one unsaturated C3-C6 hydrocarbon may comprise butene and / or pentene.

[00105] Suitably, each blowing agent used has a thermal conductivity of 0.0125 W / m.K or less at 25°C. If a blend of blowing agents is used then it will be appreciated that one or more blowing agents in that blend may not have a thermal conductivity of 0.0125 W / m.K or less at 25°C. In such a case it is desirable that the blend used has a thermal conductivity of 0.0125 W / m.K or less at 25°C.

[00106] Suitably the at least one hydrofluoroolefin or at least one chlorinated hydrofluoroolefin or the at least one alkyl halide or the at least one chlorinated alkene wherein each of the at least one hydrofluoroolefin or the at least one chlorinated hydrofluoroolefin or the at least one alkyl halide or the at least one chlorinated alkene have a thermal conductivity of 0.0125 W / m.K or less at 25°C; and the at least one C3-C6 hydrocarbon are blended. For example, the blowing agent components i.e. the at least one hydrofluoroolefin, the at least one chlorinated hydrofluoroolefin, the at least one alkyl halide or the at least one chlorinated alkene and the at least one C3-C6 hydrocarbon may be blended prior to being mixed with the phenolic resin.

[00107] The blowing agent may comprise at least one hydrofluoroolefin and at least one chlorinated hydrofluoroolefin; and said blowing agent further comprising at least one C3-C6 hydrocarbon.

[00108] The at least one chlorinated hydrofluoroolefin may comprise 1-chloro-3,3,3-trifluoropropene (HCFO-1233zd) and / or 1-chloro-2,3,3,3-tetrafluoropropene (HCFO-1224yd).

[00109] The at least one hydrofluoroolefin may comprise 1,1,1,4,4,4-hexafluoro-2-butene (HFO-1336mzz).

[00110] The at least one C3-C6 hydrocarbon may comprise butane, preferably isobutane, and / or pentane, preferably isopentane.

[00111] Suitably, the blowing agent comprises 1-chloro-3,3,3-trifluoropropene and / or 1-chloro-2,3,3,3-tetrafluoropropene and 1,1,1,4,4,4-hexafluoro-2-butene.

[00112] A list of suitable blowing agents that may be used are set out in the table below. Commercial name / IUPAC name MW (g / mol) BP °C vapour pressure (bar, 20°C) Thermal Conductivity (mW / m K) at 25°C dipole moment (D) solubility in water (g / kg) Flammability ODP GWP Hydro(chloro) fluoroolefins HCFO-1224yd(Z) (Z)-1-Chloro-2,3,3,3,-Tetrafluoro-propene 148 14 1.51* 12.2 0.34 none 0 <1 HFO-1336mzz(Z) cis-1,1,1,4,4,4-hexafluoro-2-butene 164 33 0.72 10.7 3.19 3.8 none 0 5 HFO-1336mzz(E) (E)-1,1,1,4,4,4-Hexafluoro-2-butene 164 7.5 2 11.5 0 7 HCFO-1233zd(E) trans-1-chloro-3,3,3-trifluoropropene 131 19 1.06 10.2 1.44 1.9 none 0 5 HFO-1234ze(E) trans-1,3,3,3-tetrafluoro-propene 114 -19 4.9 13 1.44 0.037 none 0 6 HFO-1234yf 2,3,3,3-tetrafluoro-propene 114 -30 6.1 14 2.54 0.2 yes 0 4 Perfluorochemicals Perfluoro(4-methyl-2-pentene) Perfluoro(4-methyl-2-pentene) 300 49 0.355 none 0 Perfluoropropene Hexafluoro-propene 150 -28 6.3 0 none 0 0.25 Perfluoroethylene Tetrafluoro-ethene 100 -76.3 32.4 yes 0 0.02 Perfluoro-1,3-butadiene Hexafluoro-1,3-butadiene 162 6 0.8 0 yes 0 0.03 Perfluorocyclo-hexene Decafluoro-cyclohexene 262 52 0 Perfluorobenzene Hexafluorobenzene 186 80.1 0.11 high 0 Chlorofl uorocarbons CFC-11 trichlorofluoromethane 137 23.7 0.883 8.2 4.1 1.1 none 1 4750 hydroch lorofluorocarbons HCFC-141b 1,1 -dich loro-1 -fluoroethane 117 32.2 0.69 9.8 4.32 4 none 0.1 725 Hydrofl uorocarbons HFC-134a 1,1,1,2-tetrafluoroethane 102 -26.2 4.826 12 2.06 1.5 none 0 1430 HFC-143a 1,1,1-trifluoroethane 84 -47.6 >10 74.7 2.34 0.76 yes 0 4470 HFC-245fa 1,1,1,3,3-pentafluoropropane 134 15.3 1.227 12.2 1.57 7.18 none 0 1030 HFC-152a 1,1-difluoroethane 66 -24.7 5.13 18.2 2.26 0.29 yes 0 124 Hydrocarbons Isopentane Methylbutane 72 27.8 0.99 14.5 0 0 yes 0 5 Cyclopentane Cyclopentane 70 49.3 0.338 12 0 0 yes 0 <0,1 Isobutane Methylpropane 58 -12 3.1 14.3 0 0.05 yes 0 3 n-pentane n-Pentane 72 36 0.648 14.4 0.01 0 yes 0 <15 n-hexane n-Hexane 86 68.5 0.18 23.4 0 0.01 yes 0 3 Neohexane 2,2-Dimethylbutane 86 49.7 0.37 18 0 0 yes 0 Diisopropyl 2,3-Dimethylbutane 86 57.9 0.26 18.8 0 0 yes 0

[00113] The phenolic resin suitably has a weight average molecular weight of from about 700 to about 2000, and / or wherein the phenolic resin has a number average molecular weight of from about 330 to about 800, such as from about 350 to about 700.

[00114] Suitably, the phenolic resin has a molar ratio of phenol groups to aldehyde groups in the range of from about 1:1 to about 1:3, suitably from about 1:1.5 to about 1:2.3. The phenol may be a substituted phenol such as cresol. Naturally occurring phenols may be used including naturally occurring phenolic macromolecules. Other aldehydes may be used including dialdehydes such as glyoxal. The molar ratio above may be adjusted to take account of aldehyde functionality

[00115] The water content of the phenolic resin foamable composition (which optionally excludes water from the acid catalyst and surfactant) may be in the range of from about from 5 wt.% to 12 wt.%, such as from 5 wt.% to 10 wt.%, for example 7 to 10% wt.% based on the total weight of the phenolic resin foamable composition.

[00116] Average water content % of the resin employed in the present invention may be determined by methods known to the person skilled in the art, for example by using auto titration instrumentation, such as KF-Titrino auto titration instrumentation.

[00117] The phenolic resin used to form the phenolic resin foamable composition of the present invention, may have a water content in the range of from about 7.5 wt.% to about 14 wt.% i.e. in its uncured state.

[00118] The phenolic resin may have a viscosity of from about 2,500 mPas to about 20,000 mPas or 18,000 mPa s when measured at 25°C, such as from about 3,500 mPa s to about 16,000 mPa s when measured at 25°C for example from about 4,000 mPa s to about 8,000 mPa s when measured at 25°C.

[00119] The blowing agent is suitably present in an amount of from about 5 to about 20 parts by weight per 100 parts by weight of the phenolic resin.

[00120] The phenolic foam of the present invention may further comprise an inorganic filler. For example, calcium carbonate may be added, as a filler and / or to increase pH. The higher pH value of the foam ensures less residual acid, with benefits for example that metallic material in contact with the phenolic foam is at reduced risk of corrosion. The calcium carbonate may be added to the foamable composition forming the phenolic foam of the invention.

[00121] The foam may have a compressive strength in the range of from about 95 kPa to about 200 kPa as determined in accordance with standard EN826.

[00122] Surfactants such as polysiloxane surfactants and / or castor oil can be included in the phenolic composition of the invention. Polysiloxane surfactants may provide enhanced stability to the cells of phenolic foams by lowering the surface tension of the liquid phase of the phenolic resin and by providing an interface between the highly polar phenolic resin and the relatively less polar blowing agent.

[00123] A surfactant for use in the invention may comprise a combination of a castor oil and a polysiloxane.

[00124] For example the surfactant may comprise: (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.

[00125] The polysiloxane desirably has a molecular weight of from about 9,500 to about 25,000 g / mol.

[00126] The surfactant may have a hydrophilic to lipophilic balance (HLB) of between about 9 to about 13 such as from about 7 to about 11.

[00127] Optionally the side chain comprises propylene oxide.

[00128] The polysiloxane may comprise a block copolymer of a dimethylsiloxane and a polyoxyalkylene.

[00129] Optionally the polysiloxane has a HLB of from about 7 to about 11.

[00130] The ethoxylated castor oil may have a HLB of from about 12 to about 14.

[00131] A composition for forming a foam may comprise ethoxylated castor oil from about 0.5 to about 10 parts per 100 parts of the phenolic resin, for example from about 1 to about 8 part per 100 parts of the phenolic resin. Surfactants as described in International Patent Publication No. WO202243561A1 are useful in a resin composition and the contents of which are hereby incorporated by reference.

[00132] Flame retardants (FRs) can facilitate improved fire performance in phenolic foams, can be included in the phenolic composition of the invention. Any suitable flame retardant may be included. A phenolic resin composition may comprise 1 to 5% by weight red phosphorus based on the weight of the phenolic compositionor the phenolic foam may comprise 1 to 5% by weight red phosphorus based on the weight of the phenolic foam. Flame retardants as described in International Patent Publication No. WO 2021 / 186072 are useful in a resin composition and the contents of which are hereby incorporated by reference.

[00133] Desirably a foam product formed from a phenolic composition of the invention can also achieve Euroclass B or as a minimum Euroclass C in terms of thermal insulation performance. The red phosphorus may act as a flame retardant as well as a formaldehyde scavenger and may impart enhanced stability and thermal insulation performance.

[00134] Usually the resin composition is mixed with a catalyst such as an acid (which is typically aqueous) to effect cure.

[00135] Also a blowing agent is added, typically by mixing into the resin composition as resin is laid down for foaming.

[00136] Foaming then occurs as the blowing agent foams the resin. Curing of the resin forms the final foam product.

[00137] It is desirable to have a stable form of the resin / resin composition for use in the production of foam products. In particular it is desirable to have a resin composition that is storage stable so that it can be prepared in advance and used over a period of time.

[00138] For example it is desirable to have a viscosity change (increase) of less than about 2000 mPa.s after 3 days when stored at 5 °C or when stored at 21 °C as determined by methods known to the person skilled in the art for example using a Brookfield viscometer (model DV-ll+Pro) at a controlled temperature water bath, maintaining the sample temperature at 25 °C, with spindle number S29 rotating at 20 rpm or appropriate rotation speed and spindle type or suitable test temperature to maintain an acceptable midrange torque for viscosity reading accuracy. Brief Description of the Figures

[00139] Figure 1. Viscosity comparison of resin with ethylene urea to urea at 25 °C. Bars on the left are resin with ethylene urea added, bars on the right are resin with urea added.

[00140] Figure 2. Ageing Viscosity of the ethylene urea resin at 2 different addition conditions and 3 different storage temperatures.

[00141] Figure 3. Ageing viscosity of ethylene urea resin and urea resin stored at 21 °C over 43 days.

[00142] Figure 4. Ageing viscosity of ethylene urea resin and urea resin stored at 5 °C over 120 days.

[00143] Figure 5. Percentage water content of resin samples over 120 days stored at 5 °C.

[00144] Figure 6. Percentage free formaldehyde in resin samples over 120 days stored at 5 °C. Detailed Description

[00145] Suitable methods for the manufacturing of phenolic resole resins with the addition of ethylene urea as a resin stabiliser are described herein.

[00146] The preparation of Resin A

[00147] To a reaction vessel was added on a weight basis (pbw = parts by weight) 50.0 pbw phenol, 1 to 4 pbw water and 0.9 ± 0.2 pbw of 50% potassium hydroxide at 20 °C. The temperature was raised from 70 to 76 °C and 70 ± 2 pbw of 50% ± 2% formalin was added slowly over 1 to 3 hours. The temperature was then raised to and maintained in the range of from 82 to 88 °C until the viscosity of the resin reaches 7,500 mPa s +1-1500 mPa s at 25 °C. The resin is allowed to cool to 35 to 50 °C before it is quenched with 0.3 pbw of acid aqueous solution until the pH reaches pH 6. The resulting resin is Resin A.

[00148] Example 1 - Addition of Ethylene Urea to Resin A

[00149] 1167.92 g of Resin A was heated to 50 °C. Ethylene urea (58.4 g, 0.68 moles) was added to the heated resin and the mixture was stirred at 127 rpm for 1 hour. The resin was cooled to 40 °C. Castor oil ethoxylate surfactant (43.8 g) was added and left to stir for 30 minutes (127 rpm, 40 °C).

[00150] Example 2

[00151] 200 g of Resin A was added to a beaker, followed by 10 g ethylene urea and 6 g castor oil ethoxylate at room temperature. The reaction mixed was left to stir for 1.5 hours. The ethylene urea dissolved in resin approximately 20 minutes after addition. No separation was observed in the resin once the resin cooled. The total resin mass was 1270.12 g, with a weight ratio of 100: 5.0: 3.75 -> resin: ethylene urea: surfactant.

[00152] Examples

[00153] Viscosity testing of resin from examples 1 and 2 at 25 °C

[00154] Viscosity samples of Resin A (without ethylene urea and surfactant) was 7043 mPa-s (7043 cP) at 24.8 °C and with the addition of ethylene urea and surfactant was 8580 mPa-s (8580 cP) at 25.2 °C. After 48 hours the viscosity of the resin with ethylene urea did not change. These results were compared with using urea as a control. The rate of ageing of the resin with ethylene urea added determined by the increasing viscosity is less than that in which urea was added. This demonstrates that the resin ageing / visocity increase is slower for resin with ethylene urea than that of resin with urea. The control is Resin A with urea instead of ethylene urea using the equivalent quantities of urea. Results are shown in Figure 1.

[00155] Example 4

[00156] Viscosity ageing

[00157] Viscosity ageing studies were conducted with the resin from examples 1 and 2 and the same control which is Resin A with urea instead of ethylene urea using the equivalent quantities of urea. This is done with and without heating the samples to 50 °C as per example 1. This is done with and without heating the samples to room temperature as per example 2. The samples were stored at different temperatures as shown in table 1. Results shown in figure 2. and table 1. demonstrate that the addition of ethylene urea (Ell) at room temperature (RT) and at 50°C show a slower rate of ageing than with urea added at 50 °C. This is seen for all samples which were stored at 5°C, 15°C, and 25°C. Overall the results show that around 21 days at ambient temperature will increase the viscosity from 7000 mPa-s (7000 cP) to 11000 mPa-s (11000 cP) for an ethylene urea-containing resin. When refrigerated this can be increase to 80 days. The full table of results are shown below. Table 1. Results from Viscosity Ageing Study. I Viscosity mPa.s Ethylene Urea addition with I heating to SOX (Example 1) i Ethylene Urea addition at room temperature (Example 2) urea addition with heat | Storing j * * * I temperature I 5 | 15 | 25 j 5 i 15 15 I Degrees s i celcius I t t t § Day 0 j I 8200 i i 9820 I Day 2 to 3 I 7950 | 8383 i 8367 i 7333 i 7540 10420 Day 7 i | | | i 15900 I Day 9 to 10 1 8100 i 9780 i 9680 i 7386 i 8500 i Day IS to 17 i 8380 | 10940 ( 11120 ( 7840 i 10280 i Day 28 to 29 | 8783 i 14400 i 14430 i 8183 i 13050 i Day 36 to 37 i 8817 | 16800 ( 19800 ( 8767 i 15230 i Day 44 to 45 1 9580 i 20750 i 25300 i 8560 i 18850 § Day 49 j 10620 | 21600 ( 33950 ( 9140 i 21050 I Day 59 1 10440 i ( ( 9675 i i Day 63 i 10820 | | | 9600 i | Day 71 | 11240 | i i 10100 i i Day 91 ( 15630 | | | 14000 i

[00158] When storing the resin at temperatures between 5 °C and 25 °C the resin increased viscosity between 100 mPa-s and 1,000 mPa-s (100 cP and 1000 cP) in the first 10 days. When storing the phenolic resole resin at 5 °C, the resin increased from 8,200 mPa-s to 10,820 mPa-s (8,200 cP to 10,820 cP) in 63 days, whereas storing the phenolic resole resin at roughly 15 °C caused the resin viscosity to increase from 8200 mPa-s to 10490 mPa-s (8,200 cP to 10,490 cP) in 15 days. The resole resin ageing does not show any large increase in water content nor increase in free formaldehyde content which is indicative of less reaction taking place. The phenolic resole resin can also be frozen and defrosted for use for even greater stability over time.

[00159] Desirably the phenolic resin has a viscosity of from about 2,500 mPa-s to about 18,000 mPa s when measured at 25 °C, such as from about 2,500 mPa s to about 16,000 mPa s when measured at 25 °C for example from about 4,000 mPa s to about 8,000 mPa-s when measured at 25 °C.

[00160] Examples

[00161] Viscosity ageing study for resin samples 1, 2, and 3 (below) stored at 5 °C and 21 °C

[00162] The viscosity ageing properties of resin samples stored at 5 °C and 21 °C were studied. Ageing studies for samples stored at 5 °C were conducted over 120 days, and ageing studies for samples stored at 21 °C were conducted over 43 days. The end-point of the experiments were defined as when the samples stored at 21 °C reached a viscosity of 30,000 mPa-s (cP) and when the samples stored at 5 °C reached a viscosity of 20,000 mPa-s (cP). Percentage free formaldehyde in accordance with the invention is determined according to methods known to the skilled person in the art, for example by the method described in Example 7.

[00163] Viscosity ageing study for resin samples 1, 2, and 3 (below) stored at 5 °C

[00164] Urea or ethylene urea was added to the samples according to methods previously described. Sample 1 is resin of example 2 with 5 pbw urea added, sample 2 is a resin of example 2 with 4.5 pbw ethylene urea, and sample 3 is a repeat of sample 2. On day zero the viscosity of each sample was measured at 7,680 mPa-s (7,680 cP). Each sample was tested for its percentage free formaldehyde as determined according to the method described in Example 7, percentage average water content, and viscosity according to methods as previously described. At day 120 the percentage free formaldehyde in the resin sample 1 is significantly less than that of the phenolic resins of 2 and 3. At day 119 the samples demonstrated that % water content was less for the samples 2 and 3 wherein ethylene urea was added, in comparison to that of sample 1 wherein urea was added to the resin. Furthermore, results shown in Table 3 and Figure 4. demonstrates that the viscosity of samples wherein ethylene urea was added (samples 2 and 3) increases at a significantly slower rate compared to the sample wherein urea was added (sample 1). Together, these results indicate that the rate of ageing is slower for the resins wherein ethylene urea is added when compared to the resin wherein urea is added and demonstrates that ethylene urea is an effective phenolic resin stabiliser. 5 Table 2. Results of percentage average water content testing for samples stored at 5 °C day sample average water content (%) 10 1 11.94 10 3 12.20 10 2 12.19 44 2 12.44 44 3 12.41 44 1 12.29 119 1 12.51 119 3 12.32 119 2 12.42 Table 3. Results of free formaldehyde testing for samples stored at 5 °C Sample day Free formaldehyde (%) 1 10 0.36 3 10 0.90 2 10 0.72 1 44 0.48 3 44 1.14 2 44 1.05 1 120 0.30 3 120 0.97 2 120 1.01 Table 4. Results of viscosity testing for samples stored at 5 °C day Sample 1 mPa-s (cP) Sample 2 mPa-s (cP) Sample 3 mPa-s (cP) 0 7680 7680 7680 1 7060 8620 8440 6 10760 7 9800 9020 17 14980 9860 9800 27 17200 10870 29 9767 44 15940 10200 10220 59 21080 10880 11240 73 21600 11460 11500 98 23200 11750 11580 119 23070 13000 13130

[00165] Example 6

[00166] Viscosity ageing study for resin samples 1,2, and 3 stored at 21 °C

[00167] Viscosity ageing studies for resin samples 1,2, and 3 stored at 21 °C were conducted in the same manner as for phenolic resins in example 5. Results of the viscosity testing for samples stored at 21 °C (Table 6, Figure 3.) demonstrates that the viscosity of the samples wherein ethylene urea was added (sample 2 and sample 3) increases at a slower rate over time demonstrating a decrease in the ageing of the resin over time when compared with the sample wherein urea was added (sample 1). These results further support ethylene urea as an effective phenolic resin stabiliser.

[00168] The viscosity of a resin employed in the present invention may be determined by methods known to the person skilled in the art for example using a Brookfield viscometer (model DV-ll+Pro) at a controlled temperature water bath, maintaining the sample temperature at 25 °C, with spindle number S29 rotating at 20 rpm or appropriate rotation speed and spindle type or suitable test temperature to maintain an acceptable midrange torque for viscosity reading accuracy.

[00169] Example 7

[00170] Determination of % free formaldehyde in resin samples 1, 2, and 3. Percentage free formaldehyde is determined using standard ISO-11402.

[00171] 5g of resin sample is added to a conical flask and dissolved in 100ml of a 90:10 blend of THF and water. Sample is stirred until fully dissolved. A pH probe is used to determine the initial pH of the resin solution. 1M HCI is then added dropwise to the solution (with continuous stirring) until the pH is measured at ~3 (2.7 -3.3 pH). 20 ml of 10% aqueous hydroxylamine hydrochloride is then added to the solution and allowed sit for 5 minutes. After 5 minutes the sample is stirred and the pH probe is used to determine the pH of the reaction mixture. Using a burette, 1M NaOH is added dropwise to the solution until the pH is adjusted back to pH 3. The volume of 1M NaOH used to adjust the pH is 5 used to determine the % free formaldehyde content as per ISO-11402. Table 5. Results of percentage water content testing for samples stored at 21 °C. day sample Average water content (%) 3 2 11.18 3 1 12.97 3 3 11.81 16 1 13.3 16 3 12.54 16 2 12.76 37 1 13.13 43 3 13.09 43 2 13.36 Table 6. Results of percentage free formaldehyde testing for samples stored at 21 °C. Sample day Free formaldehyde (%) 1 7 0.54 3 7 0.84 2 7 0.99 3 43 1.72 2 43 1.30 1 37 0.48 Table 7. Results of viscosity testing for samples stored at 21 °C day Sample 1 (mPa-s) Sample 2 (mPa-s) Sample 3 (mPa-s) 0 7680 7680 7680 1 7060 8620 8440 8 11360 10480 10260 16 15770 13500 13300 21 15200 22 19070 15670 28 18870 17700 29 25230 36 23800 37 34400 38 25000 43 30480 30330

[00172] 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 5 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.

[00173] 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, to described in the context of a single embodiment, may also be provided separately or in any suitable sub-combination.

Claims

1. Use of ethylene urea as a stabiliser for a resin.

2. Use according to Claim 1, wherein the resin is a phenolic resin.

3. Use according to any preceding claim, wherein the resin is phenol-formaldehyde resin.

4. Use according to any preceding claim, wherein the resin is a resole resin.

5. Use according to any preceding claim wherein the ethylene urea acts a stabiliser against increased viscosity of the resin.

6. Use according to any preceding claim, wherein the resin viscosity has a viscosity in the range of from about 2,500 mPas to about 20,000 mPas when measured at 25 °C as determined using a Brookfield viscometer (model DV-ll+Pro) at a controlled temperature water bath, maintaining the sample temperature at 25 °C, with spindle number S29 rotating at 20 rpm.

7. Use according to any preceding claim, wherein the viscosity of the resin is from about 7,000 mPa s to about 15,000 mPa s after 3 days.

8. Use according to any preceding claim, wherein the ethylene urea reduces the rate of decay of a resin.

9. Use according to any preceding claim, wherein the ethylene urea acts as a scavenger.

10. Use according to any preceding claim, wherein the ethylene urea reduces the reactivity of the resin.

11. Use according to any preceding claim, wherein the ethylene urea scavenges formaldehyde.

12. Use according to any preceding claim, wherein 3 to 8 parts by weight of the ethylene urea is added to the resin.

13. A method of stabilising a resin comprising the step of adding ethylene urea to the resin.

14. A method according to claim 13, wherein the step of adding ethylene urea to the resin comprises adding between 3 to 8 parts by weight of ethylene urea to the resin.

15. A method according to any of claims 13 to 14, wherein the percentage by weight of ethylene urea added is at from about 3% to about 5% such as about 4.5% by weight.

16. A method according to any of claims 13 to 15, wherein the step of adding the ethylene urea to the resin is at room temperature.

17. A method according to any of claims 13 to 16, wherein the ethylene urea is added to a resin compositions wherein the resin composition has a pH range in the range from about 6 to about 8.

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