Process for producing polyurethane foam

Abstract

Processes for preparing flexible combustion modified polyurethane foam, specifically, flexible combustion modified high resilience polyurethane foam, combustion modified ether polyurethane foam and combustion modified viscoelastic polyurethane foam, comprising a fire retardant which is not melamine. The combustion modified polyurethane foams have good properties and fire resistance whist using a fire retardant that is currently compatible with EU regulations. Also provided is flexible combustion modified polyurethane foams prepared by the processes and flexible combustion modified polyurethane foams comprising a fire retardant which is not melamine.

Description

[0001] PROCESS FOR PRODUCING POLYURETHANE FOAM

[0002] Field of the Invention

[0003] The present invention relates to polyurethane foam, specifically, flexible combustion modified high resilience polyurethane foam, combustion modified ether polyurethane foam or combustion modified viscoelastic polyurethane foam. The invention also relates to processes for preparing polyurethane foam, specifically, flexible combustion modified high resilience polyurethane foam, combustion modified ether polyurethane foam or combustion modified viscoelastic polyurethane foam. The invention also relates to polyurethane foam prepared by the processes.

[0004] Background and Prior Art

[0005] Polyurethane foam is a polymer produced from the reaction of polyols and isocyanates. Polyurethane foam is typically resistant to a wide range of temperatures and has excellent thermal insulation properties. Polyurethane foam is resistant to relatively high load, and to fungi and mould. It is therefore a material that is well suited to a variety of purposes, including mattresses, mattress toppers, pillows, furniture, upholstered furniture cushions, automotive seat cushions and interior trim, and carpet cushion etc.

[0006] Flexible polyurethane foams are the most commonly used in the polyurethane market, they come in three main types: combustion modified ether foam, combustion modified high resilience foam and combustion modified viscoelastic foam. Combustion modified high resilience polyurethane foam is characterised by its ability bounce back up after pressing it whereas combustion modified viscoelastic polyurethane foams are also known as memory foam and are characterised by their ability to sink and rise back up very slowly.

[0007] As a result of the varied uses for polyurethane foam, it is vital that the foams are fire resistant. In the UK, for polyurethane foams to meet basic fire safety standards, the foam must pass The Furniture and Furnishings (Fire) (Safety) Regulations 1988 also known as the BS5852 Crib V standard. This testing method (also known as Ignition Source 5) involves a series of tests to determine the ignitability of the foam under specific conditions. Foams that pass the test may not be completely fire proof but flames are more likely to die out quickly and are less likely to spread if an item catches fire. Compliant foams can result in countless lives being saved, especially in densely populated residential buildings.

[0008] For many years melamine has been used as a fire retardant in polyurethane. However, melamine has recently been added to the EU Candidate list of Substances of Very High Concern (SVHC). Therefore, there is a desire to phase out the use of melamine and identify alternative fire retardants for use in polyurethane foams.

[0009] EP0307987 discloses flexible high elastical polyurethane foams comprising a fire retardant comprising at least one of (1) linear urea-formal oligomer mixture having the general formula NH2-CO-NH-[CH2-NH-CO-NH]n-CH2-NH-CO-NH2, where n can have the value from 0 to 50; (b) urea in powdered form; (3) dicyandiamide. However, there is still a need for viable alternative or improved combustion modified high resilient foams comprising non-melamine fire retardants. There is also a need for alternative foams, such as combustion modified ether polyurethane foams or combustion modified viscoelastic polyurethane foams comprising non-melamine fire retardants.

[0010] Summary

[0011] In a first aspect, there is provided a process for preparing a flexible combustion modified high resilience polyurethane foam, comprising mixing together a first polyol, dicyandiamide, an isocyanate, a catalyst, water and optionally additives to form a mixture, foaming the mixture to form a foamed mixture; and curing the foamed mixture, wherein the first polyol has a molecular weight of at least about 10,000 g / mol. Preferably, the first polyol has a molecular weight of at least about 11 ,000 g / mol, more preferably at least about 12,000 g / mol. A first polyol having a high molecular weight means that the polyol has a long chain. Using such a polyol to prepare the flexible combustion modified high resilience polyurethane foam results in a foam with high resilience and good stability.

[0012] In this aspect, the first polyol preferably has a nominal functionality of at least 5, preferably at least 6. This nominal functionality enables crosslinking to occur which boosts the stability of the foam without affecting the hardness. This has the added effect of meaning that a reactive SAN (styrene acrylonitrile) polyol may not be required for stability.

[0013] In this aspect, the first polyol is preferably a sorbitol based polyol. Sorbitol based polyols have a nominal functionality of 6 therefore the use of such a polyol increases crosslinking and boosts stability.

[0014] In this aspect, the dicyandiamide is preferably a slurry in a polyol. Dicyandiamide is a solid and so forming a slurry in a polyol make this dicyandiamide easier to handle.

[0015] The polyol preferably has a viscosity of about 800 to about 1200 mPas at 25°C. Using a polyol of such a viscosity has the effect of enabling control of the viscosity of the mixture. If the viscosity of the mixture increases too much then modifications to the plant apparatus might need to be made to cope with the high viscosity.

[0016] In this aspect, the mixture may comprise additives wherein the additives are selected from the group consisting of fillers, surfactants / stabilizers, cell regulators, colours, chain extenders, cross linkers, further flame retardants, blowing agents and / or cell openers. Such additives can be selected to provide the flexible combustion modified high resilience polyurethane foam with desirable properties and / or characteristics.

[0017] In one embodiment of this aspect, the mixing step further comprises mixing a polymeric polyol. Preferably, the polymeric polyol comprises particulate material in dispersed form. In some embodiments, the particulate material is selected from the group consisting of styreneacrylonitrile particles, polyurethane particles and polyurea particles. Such polymeric polyols have the effect of increasing the hardness of the foam.

[0018] As a result of the first polyol being a high molecular weight polyol, the use of a reactive SAN (styrene acrylonitrile) polyol may not be required for stability. Therefore, in some embodiments, the polymeric polyol may have a primary hydroxyl groups content of less than about 50%, preferably less than about 20%, more preferably about 0%, with respect to the sum of the primary and secondary hydroxyl groups. A polyol with such a low primary hydroxyl group content can be considered to be an unreactive polyol. The advantages of using a polyol with a low primary hydroxyl group content includes that they are easier to handle as they avoid the need for an extra storage tank and metering unit, they have lower viscosity which can make overall handling of the mixture easier and they are lower cost which is an economic advantage. Additionally, they may result in foams with better fire resistance due to the lower oxygen content in the polyol backbone.

[0019] In some embodiment of the first aspect, the additive is a further fire retardant which is selected from the group consisting of tris(chloropropyl)phosphate, alkylphosphate oligomer, phosphorus ester, ammonium polyphosphate, graphite and phosphorus-based polyols. The advantage of including a further flame retardant includes that the fire retardant properties are enhanced.

[0020] In some embodiments of the first aspect, the process involves mixing about 5-50 parts by weight of dicyandiamide per 100 parts of the total polyols in the mixture, preferably about IQ- 20 parts by weight of dicyandiamide per 100 parts of the total polyols. In some embodiments of the first aspect, the first polyol has a primary hydroxyl groups content of at least about 60%, preferably at least about 70%, more preferably at least about 80%, with respect to the sum of the primary and secondary hydroxyl groups. An advantage of using a first polyol with a high primary hydroxy group content is that the polyol may not need to be supported by strong silicone(s) as can be the case for less reactive polyols.

[0021] As part of the first aspect, there is also provided a flexible combustion modified high resilient polyurethane foam obtained by reacting a first polyol and an isocyanate in the presence of a catalyst, water, dicyandiamide, and optionally additives, wherein the first polyol has a molecular weight of at least about 10,000 g / mol, preferably at least about 11 ,000 g / mol, more preferably, at least about 12,000 g / mol.

[0022] There is also provided a flexible combustion modified high resilience polyurethane foam prepared by the method of the first aspect.

[0023] In a second aspect there is provided a process for preparing a combustion modified ether polyurethane foam, comprising mixing together a low primary hydroxyl group polyol having a molecular weight of less than about 4000 g / mol and a primary hydroxyl groups content of less than about 50% with respect to the sum of the primary and secondary hydroxyl groups, dicyandiamide, an isocyanate, a catalyst, water and optionally additives to form a mixture, foaming the mixture to form a foamed mixture, and curing the foamed mixture. The specific combination of a polyol having a relatively low molecular weight of less than 4000 g / mol, preferably less than 3,500 g / mol, and a low primary hydroxyl group content ensures that the foam stability is enhanced and the foam hardness is boosted.

[0024] In this aspect, the mixing step may further comprising mixing a further polyol selected from the group consisting of cross-link polyols and polymeric polyols. Where a polymeric polyol is used, the polymeric polyol preferably comprises particulate material in dispersed form. In some embodiments, the particulate material is selected from the group consisting of styreneacrylonitrile particles, polyurethane particles and polyurea particles. The addition of a polymeric polyol or cross-link polyol has the effect of further boosting the hardness of the foam and / or enhancing the foam stability.

[0025] In some embodiments, of this aspect, the low primary hydroxyl group polyol has a primary hydroxyl group content of less than about 20% with respect to the sum of the primary and secondary hydroxyl groups, preferably less than about 10%. In some embodiments, the low primary hydroxyl group polyol is a full polypropylene oxide based polyol and can thus be considered to have a primary hydroxyl content of about 0% with respect to the sum of the primary and secondary hydroxyl groups. An advantage of having a low primary hydroxyl group content is that it can result in better fire resistance due to the lower oxygen content in the polyol backbone.

[0026] In some embodiments of this aspect, the low primary hydroxyl group polyol has a nominal functionality of between 2 and 4, preferably 3. This nominal functionality results in foam with enough cross-linking to have good stability without starting to be a closed foam.

[0027] In this aspect, the mixture may comprise additives wherein the additives are selected from the group consisting of fillers, surfactants / stabilizers, cell regulators, colours, chain extenders, cross linkers, further flame retardants, blowing agents and / or cell openers. Such additives can be selected to provide the combustion modified ether polyurethane foam with desirable properties and / or characteristics.

[0028] In this aspect, the additive may be a filler which is CaCCh. Using CaCCh as a filler can reduce the overall cost of the formulation. At the same time, the CaCCh can act as a heat sink to reduce the overall temperature of the foam formation process. Furthermore, it can bring some additional hardness to the foam.

[0029] In some embodiments of the second aspect, the additive is a further fire retardant which is selected from the group consisting of tris(chloropropyl)phosphate, alkylphosphate oligomer, phosphorus ester, ammonium polyphosphate, graphite and phosphorus-based polyols. The advantage of including a further flame retardant includes that the fire retardant properties are enhanced.

[0030] In some embodiments of the second aspect, the low primary hydroxyl group content polyol comprises at least about 50% of the total polyols in the mixture, preferably, at least about 80%, more preferably at least about 90%. Having all, or the majority, of the total polyols being a low primary hydroxyl group content polyol is preferable, for example, because it can result in better fire resistance due to the lower oxygen content in the polyol backbone.

[0031] In some embodiments of the second aspect, wherein the process involves mixing about 5-50 parts by weight of dicyandiamide per 100 parts of total polyols in the mixture, preferably about 10-30 parts by weight of dicyandiamide per 100 parts of the total polyols. As part of the second aspect, there is also provided a combustion modified ether polyurethane foam obtained by reacting a low primary hydroxyl group polyol having a molecular weight of less than about 4000 g / mol and a primary hydroxyl groups content of less than about 50% with respect to the sum of the primary and secondary hydroxyl groups, and an isocyanate in the presence of a catalyst, water, dicyandiamide, and optionally additives.

[0032] There is also provided a combustion modified ether polyurethane foam prepared by the process of the second aspect.

[0033] In a third aspect, there is provided a process for preparing a combustion modified viscoelastic polyurethane foam, comprising mixing together a low primary hydroxyl group polyol having a molecular weight of less than about 4000 g / mol and a primary hydroxyl groups content of less than about 50% with respect to the sum of the primary and secondary hydroxyl groups, a cross-link polyol, dicyandiamide, an isocyanate, a catalyst, water and optionally additives to form a mixture, foaming the mixture to form a foamed mixture, and curing the foamed mixture. The specific combination of a polyol having a relatively low molecular weight of less than 4000 g / mol, preferably less than 3,500 g / mol, and a low primary hydroxyl group content, and a cross-link polyol ensures that the foam stability is enhanced and the foam hardness is boosted.

[0034] In this aspect, the cross-link polyol may have a molecular weight of less than about 1000 g / mol. An effect of using a very low molecular weight cross-link polyol is that it boosts the stability of the foam by creating extra crosslinking. This enables the foam to work at lower index and provides a less resilient foam. Due to the short chain and additional cross linking the glass transition temperature of the foam is increased and the foam becomes viscoelastic.

[0035] In some embodiments, of this aspect, the low primary hydroxyl group polyol has a primary hydroxyl group content of less than about 20% with respect to the sum of the primary and secondary hydroxyl groups, preferably less than about 10%. In some embodiments, the low primary hydroxyl group polyol is a full polypropylene oxide based polyol and can thus be considered to have a primary hydroxyl content of about 0% with respect to the sum of the primary and secondary hydroxyl groups. An advantage of having a low primary hydroxyl group content is that it can result in better fire resistance due to the lower oxygen content in the polyol backbone. In some embodiments of this aspect, the low primary hydroxyl group polyol has a nominal functionality of between 2 and 4, preferably 3. The nominal functionality drives the degree of cross linking in the foam matrix and hence the stability of the foam. A low primary hydroxyl group polyol with this nominal functionality results in foam with enough cross-linking to have good stability without starting to be a closed foam.

[0036] In this aspect, the mixture may comprise additives wherein the additives are selected from the group consisting of fillers, surfactants / stabilizers, cell regulators, colours, chain extenders, cross linkers, further flame retardants, blowing agents and / or cell openers. Such additives can be selected to provide the combustion modified viscoelastic polyurethane foam with desirable properties and / or characteristics.

[0037] In this aspect, the additive may be a filler which is CaCCh. Using CaCCh as a filler can reduce the overall cost of the formulation. At the same time, the CaCCh can act as a heat sink to reduce the overall temperature of the foam formation process. Furthermore, it can bring some additional hardness to the foam.

[0038] In some embodiments of the third aspect, the additive is a further fire retardant which is selected from the group consisting of tris(chloropropyl)phosphate, alkylphosphate oligomer, phosphorus ester, ammonium polyphosphate, graphite and phosphorus-based polyols. The advantage of including a further flame retardant includes that the fire retardant properties are enhanced.

[0039] In some embodiments of the third aspect, the process involves mixing about 5-50 parts by weight of dicyandiamide per 100 parts of the total polyols in the mixture, preferably about IQ- 40 parts by weight of dicyandiamide per 100 parts of the total polyols.

[0040] As part of the third aspect, there is also provided a combustion modified viscoelastic polyurethane foam obtained by reacting a low primary hydroxyl group polyol having a molecular weight of less than about 4000 g / mol and a primary hydroxyl groups content of less than about 50% with respect to the sum of the primary and secondary hydroxyl groups, a cross-link polyol and an isocyanate in the presence of a catalyst, water, dicyandiamide, and optionally additives.

[0041] There is also provided a combustion modified viscoelastic polyurethane foam prepared by the process of the third aspect. Detailed Description

[0042] Polyurethane foam is a polymer generally produced from the reaction of polyols and isocyanates. This disclosure is concerned with preparing a flexible combustion modified high resilience polyurethane foam, a combustion modified ether polyurethane foam and a combustion modified viscoelastic polyurethane foam.

[0043] General

[0044] Polyols

[0045] Polyols are one of the building blocks of polyurethane foams.

[0046] Polyols used in polyurethane manufacture are hydroxyl-functionalised oligomers typically having a molecular weight in the range of 300-15,000 g / mol. The molecular weights of a polyol can be worked out from the composition of the polyol or can be calculated using the formula:

[0047] MW = (56100 x fn) I OH number

[0048] Where the constant 56100 is determined from the molecular weight of KOH multiplied by 1000 to convert it to mg / g and the OH number is the hydroxyl number discussed below.

[0049] Different molecular weights of polyols can provide different properties to the polyurethane foam. For Example, low molecular weight polyols tend to make rigid polyurethanes and high molecular weight polyols tend to make flexible polyurethanes.

[0050] Depending on the backbone structure, polyols used in polyurethane manufacture are typically classified into two main groups, namely, polyether polyols and polyester polyols. Polyether polyols are the most commonly used in polyurethane manufacture.

[0051] Polyols are typically made from monomer units comprising ethylene oxide and / or propylene oxide. They may also comprise starter molecules such as sucrose, sorbitol, glycerol, and / or glycol.

[0052] Polyols used in polyurethane manufacture typically have a nominal hydroxyl functionality or nominal functionality in the range of 1-8 equivalent per mole. The term "nominal hydroxyl functionality" or "nominal functionality" or "hydroxyl functionality" is used herein to indicate the functionality (number of hydroxyl (OH) groups per molecule) of the polyol composition on the assumption that this is the functionality (number of active hydrogen atoms per molecule) of the initiator(s) (starter molecules) used in their preparation. In practice, the “real functionality” can be somewhat less than the nominal functionality due to some terminal unsaturation.

[0053] Low nominal functionality polyols include glycerine-derived (glycerol-derived) polyols (nominal functionality = 3). High nominal functionality polyols include mannich base-based polyols (nominal functionality = 4); sorbitol-based polyols (nominal functionality = 6); and sucrose-based polyols (nominal functionality = 8).

[0054] Increasing the number of OH groups results in greater cross-linking. Greater cross-linking generally yields stiffer, harder products. Therefore, polyols with high nominal functionality are generally considered to produce harder polyurethane systems,.

[0055] Polyols used in polyurethane manufacture may be defined by their hydroxyl content. Hydroxyl number is a measure of the concentration of hydroxyl groups in a polyol, expressed as milligrams KOH equivalent to the hydroxyl groups in one gram of the polyol. Typically, a lower hydroxyl value indicates lower hydroxyl content and a higher molecular weight.

[0056] Hydroxyl number is directly correlated with the molecular weight and nominal functionality of the polyol and can be calculated by

[0057] OH number = (56100 x fn) I MW

[0058] The constant, 56100 is determined as outlined above.

[0059] Depending on which monomers they are made from, polyols used in polyurethane manufacture may contain primary and / or secondary hydroxyl groups. This can be expressed in terms of a percentage of primary hydroxyl groups with respect to the sum of the primary and secondary hydroxyl groups. This may also be referred to as percentage of ethylene oxide tips in the base polyol.

[0060] A higher percentage of primary hydroxyl groups and / or a higher percentage of ethylene oxide tips generally indicates a more reactive polyol since primary hydroxyl groups are more reactive than secondary hydroxyl groups.

[0061] Dicyandiamide The processes for making combustion modified high resilience foam, combustion modified ether foam and combustion modified viscoelastic foam disclosed herein all involve mixing dicyandiamide. Dicyandiamide is a nitrogen based fire retardant (flame retardant). Dicyandiamide may also be referred to as DICY, DCD, or Cyanoguanidine.

[0062] The fire extinguishing properties of dicyandiamide rely on thermal decomposition of the compound to release nitrogen gas. The nitrogen gas dilutes the available oxygen and flammable gases and supresses composition.

[0063] Dicyandiamide is a solid and may have limited solubility in the reactant components for preparing polyurethane foam. Therefore, in some embodiments, the dicyandiamide may be added as a slurry in a polyol. A slurry is a mixture of the insoluble dicyandiamide in a liquid polyol. Forming a slurry in a polyol may make the dicyandiamide easier to handle.

[0064] The polyol may be the same as the first polyol or may be a further polyol, or the polyol may be a different further polyol (a second polyol). When the dicyandiamide is added in a polyol, the polyol forms part of the “total polyol”.

[0065] The ratio of dicyandiamide in the second polyol to form the slurry may be any ratio. Preferably, the slurry is a 1 :1 to 1 :2 mixture of dicyandiamide to polyol. In some embodiments, the slurry is a 1 :1 mixture of dicyandiamide to polyol.

[0066] Isocyanate

[0067] The production of polyurethane foam requires the presence of an isocyanate. The isocyanate can be any isocyanate known in the art for polyurethane production.

[0068] In some embodiments, the isocyanate is a toluene diisocyanate. For example, the isocyanate may be Desmodur™ T-80 NP isocyanate or Desmodur™ T-65 N isocyanate, or a mixture thereof.

[0069] In some embodiments, the isocyanate is a methylene diphenyl diisocyanate.

[0070] In some embodiments, the isocyanate may be a mixture of a toluene diisocyanate and a methylene diphenyl diisocyanate.

[0071] The catalyst The processes disclosed herein requires a catalyst. The catalyst may be any catalyst known in the art for preparing polyurethane foam. The process may include one or more catalysts.

[0072] Catalysts for polyurethane systems can generally be divided into two broad classes: gelling catalysts and blowing catalysts. Gelling catalysts are more selective to catalysing the reaction of the isocyanate with the polyol, whereas blowing catalysts are foaming catalysts; they are more selective to catalysing the reaction of the isocyanate with water to produce CO2 gas to generate the foam.

[0073] Therefore, in some embodiments, the catalyst in the process is a blowing catalyst and / or a gelling catalyst.

[0074] In some embodiments, the gelling catalyst is a metal based catalyst. Preferably, the gelling catalyst is a tin based catalyst. An example of a suitable tin based catalyst is KOSMOS T900 made by Evonik.

[0075] In some embodiments, the gelling catalyst is an amine catalyst. Preferably, the amine gelling catalyst is a tertiary amine based catalyst. An example of a suitable amine catalyst is DABCO® 33- LV by Evonik.

[0076] In some embodiments, the blowing catalyst is an amine catalyst. Preferably, the amine blowing catalyst is a tertiary amine based catalyst. An example of a suitable amine catalyst is Niax™ A1 by Momentive Performance Materials.

[0077] Water

[0078] The processes disclosed herein require the presence of water. The water may be “added water” which is specifically added to the starting materials or may be present already in the starting materials. Water has the function of reacting with the isocyanate to produce CO2 which enables foaming to occur.

[0079] Additives

[0080] The process for preparing flexible polyurethane foam may include one or more additives in the mixture with the base polyol, secondary polyol (where present).

[0081] Additives are optionally included if they would improve the performance of the polyurethane foam, or if they would provide specific, desirable, properties to the polyurethane foam. Any additive known in the art for polyurethane foam may be used. In some embodiments, the additive is selected from the group consisting of fillers, surfactants / stabilizers, cell regulators, colours, chain extenders, cross linkers, further flame retardants, blowing agent and / or cell openers.

[0082] Fillers

[0083] Fillers may be added to polyurethane foams for several reasons, for example, they may reduce the cost of the polyurethane foams and / or they may improve the properties of the foam. The fillers may be natural or synthetic. The fillers may be in any suitable form, for example, powders, fibers, flakes, or slurries thereof. Examples of suitable fillers include, but are not limited to, calcium carbonate, barium sulfate, silica, talc, cellulose and chitin.

[0084] In some embodiments, the filler may be CaCCh. Using CaCCh as a filler can reduce the overall cost of the formulation. At the same time, the CaCCh can act as a heat sink to reduce the overall temperature of the foam formation process. Furthermore, it can bring some additional hardness to the foam.

[0085] Surfactants / stabilisers

[0086] Surfactants may be added to help improve the emulsification of the raw materials, prevent coalescence, increase ingredient compatibility and decrease surface tension. Preferably, the surfactant is a polysiloxane polymer, more particularly a polyoxyalkylene polysiloxane polymer having a molecular weight of 5000 to 60,000 g / mol.

[0087] Foam stabilizers may be added to help provide sufficient nucleation and stabilize the expansion of the flexible polyurethane foam. Examples of suitable foam stabilizers include, but are not limited to, polysiloxane, polyoxyalkylene block copolymers such as TEGOSTAB B and Niax™ silicones available from Momentive™.

[0088] Silicone surfactants can act as both foam stabilisers and surfactants.

[0089] Cell regulators

[0090] Cell regulators may be added to assist with regulating the size and number of the cells present in the flexible polyurethane foam. An example of a suitable cell regulator is Ortegol CC2 which is a dispersion of wax in fatty acid.

[0091] Colours

[0092] A colour additive may be included if coloured flexible polyurethane foam is desired. Chain extenders and / or crosslinkers

[0093] A chain extender and / or crosslinker may be included in the mixture to increase the length of the polymer chain. A chain extender can aid with improving melt viscosity, improving impact strength and / or increase elongation at break.

[0094] In this disclosure, a crosslinker additive is a molecular crosslinker. Molecular crosslinkers include diethanolamine (DEOA), glycerol and sorbitol. Such molecular crosslinkers may have a nominal functionality of between 3 and 8 and / or a hydroxyl number of between about 550 and 2000 mgKOH / g.

[0095] It is also possible to have crosslinkers that are polyols (also referred to herein as rigid polyols). These cross-link polyols are considered for the purposes of this disclosure to be further polyols and are discussed below.

[0096] Suitable chain extenders include, but are not limited to, dipropylene glycol, and polyethylene glycol (PEG).

[0097] Further Fire Retardants

[0098] Flame retardants are widely used additives in polyurethane foams. They are added when it is desirable to reduce the flammability of the flexible polyurethane foam. Examples of suitable additional flame retardants include, but are not limited to, tris(2-chloro-1 -methylethyl) phosphate (TCPP), tris[2-chloro-1-(chloromethyl)ethyl] phosphate (TDCP), alkyl phosphate oligomer, phosphorus ester, ammonium polyphosphate, phosphorus-based polyols and graphite. Including a further flame retardant has the advantage that the fire retardant properties may be enhanced.

[0099] Blowing agent

[0100] The mixture may comprise a blowing agent as an additive. Blowing agents are substances that are capable of forming a cellular structure through a foaming process. Any substance that can act as a blowing agent may be used in the processes herein. Preferably, the blowing agent is a physical blowing agent such as methylene chloride or carbon dioxide.

[0101] Cell Openers

[0102] Polyurethane foam can be an open celled material. Therefore it may be desirable to include a cell opener additive. Cell openers are additives that help to ensure that the foam structure has predominantly open cells, enabling it to ‘breathe’ and to enhance the flexibility of the foam. Cell openers may also be referred to as pore regulators. Suitable cell openers include, but are not limited to, Ortegol 500, Ortegol 501, Ortegol VCO by Evonik. In some embodiments, the cell opener may be a cell opening polyol. In these embodiments, the cell opening polyol is considered for the purposes of this disclosure to be a further polyol and is discussed below.

[0103] Where the cell opener is a cell opening polyol, this forms part of the “total polyol”.

[0104] Foaming

[0105] Once the mixing of the basic ingredients has been undertaken to form a mixture, the mixture is foamed.

[0106] The foaming may be undertaken by any method known in the art. For example, the mixture may be foamed through slabstock, molded, or spray technologies.

[0107] Slabstock foaming involves pouring the mixture onto a moving conveyor to form a continuous loaf of foam. The polymer system foams or rises as it spreads across the conveyor. Slabstock foaming can be a continuous process or a discontinuous process like “foam in the box”. Molded foaming is used create products with intricate shapes such as seat cushions. The process is usually a discontinuous process involving pouring or injecting the mixture into a preheated mold. The components react inside the mold causing the polymer system to foam and rise. Spray foaming involves spraying the mixture on a surface or inside a cavity.

[0108] Curing

[0109] Once the mixture has foamed, the foamed mixture is subject to curing. Curing is generally a step that simply occurs over time. The foam is allowed to stand and as the foam stands, it produces its own heat which fuels the curing reactions. Generally, curing takes at least 24 hours and it can take up to 14 or even 21 days.

[0110] Temperatures reached by the foamed mixture during the curing step can be greater than 150°C, for example, about 155°C or about 160°C.

[0111] Processes for producing Flexible Combustion Modified High Resilience Polyurethane Foam In a first aspect, there is provided a process for preparing a flexible combustion modified high resilience polyurethane foam. Combustion modified high resilience polyurethane foam is generally buoyant and springy. It has a high responsiveness which allow it to quickly return to its shape when pressure is applied and released. The resilience of a combustion modified high resilience foam may be greater than 40% for a 25 kg / m3grade foam. Resilience may be measured according to DIN EN ISO 8307. In this process, a standardized steel ball falls onto the foam test piece from a defined initial height and bounces back. The rebound height is measured and expressed as a percentage of the initial height.

[0112] The processes for preparing a flexible combustion modified high resilience polyurethane foam, comprise mixing together a first polyol, dicyandiamide, an isocyanate, a catalyst, water and optionally additives to form a mixture, foaming the mixture to form a foamed mixture; and curing the foamed mixture.

[0113] First Polyol

[0114] The first polyol has a molecular weight of at least about 10,000 g / mol. Preferably, the first polyol has a molecular weight of at least about 10,500 g / mol, more preferably 11 ,000 g / mol, even more preferably at least about 11 ,400 g / mol, most preferably at least about 12,000 g / mol. In some embodiments, the first polyol has a molecular weight of at least about 11 ,400 g / mol.

[0115] The first polyol may be referred to as a high molecular weight polyol. A first polyol having a high molecular weight means that the polyol has a long chain. Using such a polyol to prepare the flexible combustion modified high resilience polyurethane foam results in a foam with high resilience and good stability.

[0116] The first polyol preferably has a nominal functionality of at least 5, preferably at least 6. This nominal functionality enables crosslinking to occur which boosts the stability of the foam without affecting the hardness. This has the bonus effect of meaning that a reactive SAN (styrene acrylonitrile) polyol may not be required for stability.

[0117] The first polyol is preferably a sorbitol based polyol. Sorbitol based polyols have a nominal functionality of 6 therefore the use of such a polyol increases crosslinking and boosts stability.

[0118] The first polyol is preferably a highly reactive polyol. Accordingly, the first polyol preferably has a primary hydroxyl groups content of at least about 60%, preferably at least about 70%, more preferably at least about 80%, with respect to the sum of the primary and secondary hydroxyl groups. An advantage of using a first polyol with a high primary hydroxy group content is that the polyol may not need to be supported by strong silicone(s) as can be the case for less reactive polyols.

[0119] The first polyol may be referred to as herein the base polyol or the main polyol.

[0120] Further Polyols

[0121] This process, and all processes disclosed herein, may comprising mixing one or more further polyols in the mixture. The further polyols may be any suitable polyol known in the art. The further polyols may be selected to impart desirable properties on the resulting foam.

[0122] Polymeric polyols

[0123] In some embodiments of this aspect and all aspects disclosed herein, the further polyol is a polymeric polyol. A polymeric polyol may have the effect of hardening, or stiffening the resultant foam. Polymeric polyols may also have the effect of helping with the cell opening of the foam.

[0124] Polymeric polyols may have a molecular weight of about 3000 to 5000 g / mol. They may typically have a functionality of 3.

[0125] Polymeric polyols may comprise particulate material in dispersed form - i.e. particles of one material are dispersed in the continuous phase of the polyol. In some embodiments, the particulate material is selected from the group consisting of styrene-acrylonitrile particles, polyurethane particles and polyurea particles. The particulate material acts as a filler for the foam. When the polymeric polyol comprises particulate material, the polymeric polyol may have a solids content of at least about 10%, preferably at least about 20%, or at least about 30% or at least about 40%.

[0126] In this aspect of the present disclosure, because the first polyol is a high molecular weight polyol, the use of a reactive SAN (styrene acrylonitrile) polyol may not be required for stability. Therefore, in some embodiments, the polymeric polyol may have a primary hydroxyl groups content of less than about 50%, preferably less than about 20%, more preferably less than about 5%, even more preferably about 0%, with respect to the sum of the primary and secondary hydroxyl groups. A polyol with such a low primary hydroxyl group content can be considered to be an unreactive polyol. The advantages of using a polyol with a low primary hydroxyl group content includes that they are easier to handle as they avoid the need for an extra storage tank and metering unit, they have lower viscosity which can make overall handling of the mixture easier and they are lower cost which is an economic advantage.

[0127] In other embodiments, the polymeric polyol may have a primary hydroxyl groups content of more than about 50%, preferably more than about 60%, with respect to the sum of the primary and secondary hydroxyl groups.

[0128] Cross-link polyols

[0129] In some embodiments of this aspect and all aspects disclosed herein, the further polyol may be a cross-link polyol. Cross-link polyols (also referred to herein as rigid polyols), are high hydroxyl group polyols having a hydroxyl number of between about 140 and 550 mgKOH / g, preferably between about 150 and 400 mgKOH / g. The cross-link polyol may be a short chain polyol having a molecular weight of less than about 2000 g / mol. In some embodiments, the cross-link polyol has a molecular weight of less than about 1000 g / mol, preferably less than 750 g / mol.

[0130] The cross-link polyol may preferably have a nominal functionality between 3 and 8, preferably 3-4. The cross-link polyol may preferably have a primary hydroxyl groups content of less than about 50%, preferably less than about 20%, more preferably about 0%, with respect to the sum of the primary and secondary hydroxyl groups.

[0131] Cross-link polyols typically have a low equivalent weight. Equivalent weight is calculated as follows:

[0132] Equivalent weight = molecular weight I nominal functionality

[0133] Cross-link polyols typically have an equivalent weight of less than 1000, preferably less than 500.

[0134] Cell opening polyols

[0135] In some embodiments of this aspect and all aspects disclosed herein, the further polyol may be a cell-opening polyol. Typically, cell opening polyols are high EO polyols, they typically have ethylene oxide as the main (or only) building block (monomer). Cell opening polyols typically therefore have a high ethylene oxide content with respect to the sum of ethylene oxide and propylene oxide, for example more than 65% ethylene oxide with respect to the sum of ethylene oxide and propylene oxide, preferably more than 70%, such as 70-100%. Such cell opening polyols may have a high or low primary hydroxyl groups content with respect to the sum of primary and secondary hydroxyl groups. In some embodiments, the cell opening polyols have a primary hydroxyl groups content of greater than 70% with respect to the sum of primary and secondary hydroxyl groups.

[0136] High resilience polyol

[0137] In some embodiments of this aspect and all aspects disclosed herein, the further polyol may be a high resilience (HR) polyol. In some embodiments, the HR polyol has a molecular weight of about 4000 to 8000 g / mol. In some embodiments, the HR polyol has a nominal functionality of 2-6, preferably 3. In some embodiments, the HR polyol has a primary hydroxyl groups content of at least about 60%, preferably at least about 70%, more preferably at least about 80%, with respect to the sum of the primary and secondary hydroxyl groups. The HR polyols typically have an ethylene oxide tip which provides an ethylene oxide content with respect to the sum of ethylene oxide and propylene oxide of less than 30%, preferably less than 25%, even more preferably less than about 20%.

[0138] In some embodiments, a further polyol may be used to form a slurry of dicyandiamide to enable easier handling of the solid dicyandiamide (see below for further information). In these embodiments, the further polyol may be referred to as a second polyol.

[0139] The process may involve mixing 0 to 60 parts by weight of further polyol per 100 parts of total polyols in the mixture.

[0140] In embodiments comprising a further polyol, the process may involve mixing 5 to 60 parts by weight of further polyol per 100 parts of total polyols in the mixture, preferably 10 to 50 parts by weight of further polyol per 100 parts of total polyols.

[0141] Dicyandiamide

[0142] In this process, the first polyol is mixed with dicyandiamide. The dicyandiamide may be added to the mixture as a solid. Alternatively, to make the dicyandiamide easier to handle, the dicyandiamide may be added as a slurry. The slurry may comprise a polyol. The polyol may be the same as the first polyol or it may be a further polyol, or the polyol may be a different further polyol (a second polyol). In some embodiments, the dicyandiamide is preferably a slurry in a second polyol. The second polyol may be any suitable polyol. The second polyol may have any molecular weight and any nominal functionality. In embodiment of this aspect, the second polyol is preferably a high resilience polyol. The second polyol is preferably a low viscosity polyol. For example, the second polyol may have a viscosity of about 800 to about 1200 mPas at 25°C. Using a second polyol of such a viscosity has the effect of enabling control of the viscosity of the mixture. If the viscosity of the mixture increases too much then modifications to the plant apparatus might need to be made to cope with the high viscosity.

[0143] In some embodiments of the first aspect, the process involves mixing about 5-50 parts by weight of dicyandiamide per 100 parts of the total polyols in the system, preferably about IQ- 20 parts by weight of dicyandiamide per 100 parts of the total polyols.

[0144] Where the dicyandiamide is prepared as a slurry in a second polyol, the slurry may be prepared as a 1 :1 to 1:2 slurry of dicyandiamide in the second polyol. In some embodiments, the slurry is a 1 :1 mixture of dicyandiamide to second polyol.

[0145] Accordingly, the content of the second polyol in the mixture may be about 5-50 parts by weight per 100 parts of the total polyols in the mixture, preferably about 10-20 parts by weight per 100 parts of the total polyols. In particularly preferred embodiments the content of the second polyol in the mixture may be about 15 parts by weight of dicyandiamide per 100 parts of the total polyols.

[0146] Isocyanate

[0147] The isocyanate used in the processes for preparing a flexible combustion modified high resilience polyurethane foam may be any suitable isocyanate as discussed above. Preferably, the isocyanate is toluene diisocyanate.

[0148] In some embodiments, the process involves mixing 20 to 85 parts by weight of isocyanate per 100 parts of total polyols in the mixture, preferably 30 to 70 parts by weight of isocyanate per 100 parts of total polyols.

[0149] Catalyst

[0150] The catalysts used in the processes for preparing a flexible combustion modified high resilience polyurethane foam may be any suitable catalyst as discussed above.

[0151] In some embodiments, the process involves mixing 0.05 to 3 parts of catalyst(s) per 100 parts of the total polyols in the mixture. In preferred embodiments, the process involves mixing about 0.05 to about 2 parts of catalyst(s) per 100 parts of the total polyols. In even more preferred embodiments, the process involves mixing about 0.05 to about 1 parts of catalyst(s) per 100 parts of the total polyols.

[0152] Water

[0153] As outlined above, the process for preparing a flexible combustion modified high resilience polyurethane foam requires water.

[0154] In some embodiments, the process involves adding 1-6 parts of added water per 100 parts of the total polyols in the mixture. In preferred embodiments, about 2-4 parts of added water per 100 parts of the total polyols is used

[0155] Additives

[0156] The mixture may comprise additives. The additives may be any of those discussed above, or any additives known in the art.

[0157] The additives in some embodiments include cell opening polyol, silicone surfactant / stabiliser and a further flame retardant. In some embodiments of the first aspect, the additive is a further fire retardant which is selected from the group consisting of tris(chloropropyl)phosphate, alkylphosphate oligomer, phosphorus ester, ammonium polyphosphate, graphite and phosphorus-based polyols. An advantage of including a further flame retardant includes that the fire retardant properties are enhanced.

[0158] The amount of additives used in the process will be any amount required to achieve the desired properties.

[0159] In some embodiments, the process involves mixing 0-30 parts by weight of additives per 100 parts of total polyols in the mixture. In preferred embodiments, the process involves mixing about 5-25 parts by weight of additives per 100 parts of total polyols. In some embodiments, the process involves mixing about 20-25 parts by weight of additives per 100 parts of total polyols.

[0160] The process

[0161] The process of the first aspect provides a flexible combustion modified high resilience polyurethane foam having good properties and good fire resistance as demonstrated in the Examples below.

[0162] Processes for producing Combustion Modified Ether Polyurethane Foam In a second aspect, there is provided a process for preparing a combustion modified ether polyurethane foam.

[0163] The processes for preparing a combustion modified ether foam comprise mixing together a low primary hydroxyl group polyol having a molecular weight of less than about 4000 g / mol and a primary hydroxyl groups content of less than about 50% with respect to the sum of the primary and secondary hydroxyl groups, dicyandiamide, an isocyanate, a catalyst, water and optionally additives to form a mixture foaming the mixture to form a foamed mixture, and curing the foamed mixture.

[0164] Low primary hydroxyl group polyol

[0165] The processes involve a low primary hydroxyl group polyol. The low primary hydroxyl group polyol has a primary hydroxyl groups content of less than about 50% with respect to the sum of the primary and secondary hydroxyl groups.

[0166] In some embodiments, the low primary hydroxyl group polyol has a primary hydroxyl group content of less than about 20% with respect to the sum of the primary and secondary hydroxyl groups, preferably less than about 10%. In some embodiments, the low primary hydroxyl group polyol is a full polypropylene oxide based polyol and can thus be considered to have a primary hydroxyl content of about 0% with respect to the sum of the primary and secondary hydroxyl groups. An advantage of having a low primary hydroxyl group content is that it can result in better fire resistance due to the lower oxygen content in the polyol backbone.

[0167] The low primary hydroxyl group polyol also has a molecular weight of less than about 4000 g / mol. Preferably, the molecular weight is less than about 3500 g / mol. In some embodiments, the low primary hydroxyl group has a molecular weight of between about 2500 g / mol and about 4000 g / mol, preferably between about 3000g / mol and about 3500 g / mol. If the low primary hydroxyl group polyol has a molecular weight that is below 2500 g / mol, it may result in a foam which is too stiff.

[0168] The specific combination of a polyol having a relatively low molecular weight of less than 4000 g / mol, preferably less than 3500 g / mol and a low primary hydroxyl group content of less than about 50% with respect to the sum of the primary and secondary hydroxyl groups ensures that the foam stability is enhanced and the foam hardness is boosted. The low primary hydroxyl group polyol preferably has a nominal functionality of between 2 and 4, preferably 3.

[0169] In some embodiments of the second aspect, the low primary hydroxyl group content polyol comprises at least about 50% of the total polyols in the mixture, preferably, at least about 80%, more preferably at least about 90%. Having all, or the majority, of the total polyols being a low primary hydroxyl group content polyol is preferable, for example, because it can result in better fire resistance due to the lower oxygen content in the polyol backbone.

[0170] The low primary hydroxyl group polyol preferably has a hydroxyl number of less than 140 mgKOH / g, more preferably less than 100 mgKOH / g, even more preferably less than 60 mgKOH / g.

[0171] The low primary hydroxyl group polyol preferably has an equivalent weight (as defined above) of at least 1000.

[0172] The low primary hydroxyl group polyol may be referred to as the base polyol or the main polyol in this process.

[0173] Further Polyols

[0174] This process may comprising mixing one or more further polyols in the mixture. In some embodiments, the further polyol is selected from the group consisting of cross-link polyols and polymeric polyols, as outlined above.

[0175] Where a polymeric polyol is used, the polymeric polyol preferably comprises particulate material in dispersed form. In some embodiments, the particulate material is selected from the group consisting of styrene-acrylonitrile particles, polyurethane particles and polyurea particles.

[0176] The addition of a polymeric or cross-link polyol has the effect of further boosting the hardness of the foam and / or enhancing the foam stability. The polymeric polyol typically has a nominal functionality of 3. The cross-link polyol may have a nominal functionality of at least 3, preferably at least 5 or 6. A benefit of a high nominal functionality may be that it increases cross-linking which in turn increases hardness and stability of the foam.

[0177] In some embodiments, the further polyol may be a high resilience polyol as outlined above. In some embodiments, the process may involve mixing 0 to 40 parts by weight of further polyol per 100 parts of total polyol in the mixture, preferably 5-20 parts by weight of further polyol per 100 parts of total polyols.

[0178] Dicyandiamide

[0179] In this embodiment, the low primary hydroxyl group polyol is mixed with dicyandiamide. The dicyandiamide may be added to the mixture as a solid. Alternative to make the dicyandiamide easier to handle, the dicyandiamide may be added as a slurry. The slurry may comprise a polyol. The polyol may be the same as the low primary hydroxyl group polyol or may be a further polyol. In some embodiments, the dicyandiamide is preferably a slurry in the low primary hydroxyl group polyol.

[0180] In these embodiments, adding the dicyandiamide as a slurry in the low primary hydroxyl group polyol is particularly preferred when the low primary hydroxyl group polyol has a low viscosity. For example, a viscosity of about 400 to about 800 mPas at 25°C.

[0181] In some embodiments of this aspect, the process involves mixing about 5-50 parts by weight of dicyandiamide per 100 parts of the total polyols in the mixture, preferably about 10-25 parts by weight of dicyandiamide per 100 parts of the total polyols.

[0182] Isocyanate

[0183] The isocyanate used in the processes for preparing a flexible combustion modified ether polyurethane foam may be any suitable isocyanate as discussed above. Preferably, the isocyanate is toluene diisocyanate.

[0184] In some embodiments, the process involves mixing 30 to 90 parts by weight of isocyanate per 100 parts of the total polyols in the mixture, preferably 40 to 80 parts by weight of isocyanate per 100 parts of the total polyols.

[0185] Catalyst

[0186] The catalysts used in the processes for preparing a flexible combustion modified ether polyurethane foam may be any suitable catalyst as discussed above.

[0187] In some embodiments, the process involves mixing 0.05 to 3 parts of catalyst(s) per 100 parts of the total polyols in the mixture. In preferred embodiments, about 0.05 to about 2 parts of catalyst(s) per 100 parts of the total polyols. In particularly preferred embodiments, about 0.05 to about 2 parts of catalyst(s) per 100 parts of the total polyols. Water

[0188] As outlined above, the process for preparing a flexible combustion modified ether polyurethane foam requires adding water.

[0189] In some embodiments, the process involves mixing 2-6 parts of added water per 100 parts of the total polyols in the mixture. In preferred embodiments, about 3-5 parts of water per 100 parts of the total polyols are used

[0190] Additives

[0191] The mixture may comprise additives. The additives may be any of those discussed above, or any additives known in the art.

[0192] The additives in some embodiments include a filler, crosslinker, silicone, blowing agent and / or a further flame retardant.

[0193] In some embodiments of this aspect, the additive is a filler. Preferably, the filler is CaCCh. Using CaCCh as a filler can reduce the overall cost of the formulation. At the same time, the CaCCh can act as a heat sink to reduce the overall temperature of the foam formation process. Furthermore, it can bring some additional hardness to the foam. The filler may be added as a slurry in a polyol. The polyol may be the low primary hydroxyl content polyol or may be a further polyol.

[0194] In some embodiment of the this aspect, the additive is a further fire retardant which is selected from the group consisting of tris(chloropropyl)phosphate, alkylphosphate oligomer, phosphorus ester, ammonium polyphosphate, graphite and phosphorus-based polyols. The advantage of including a further flame retardant includes that the fire retardant properties are enhanced.

[0195] The amount of additives used in the process will be any amount required to achieve the desired properties.

[0196] In some embodiments, the process involves mixing 0-35 parts by weight of additives per 100 parts of the total polyols in the mixture. In preferred embodiments, the process involves mixing about 5-30 parts by weight of additives per 100 parts of the total polyols. In some embodiments, the process involves mixing about 15-25 parts by weight of additives per 100 parts of total polyols. The process

[0197] The process of the second aspect provides a combustion modified ether polyurethane foam having good properties and good fire resistance as demonstrated in the Examples below.

[0198] Processes for producing Combustion Modified Viscoelastic Polyurethane Foam

[0199] In a third aspect, there is provided a process for preparing a combustion modified viscoelastic polyurethane foam. Viscoelastic foams are also known as memory foam and are characterised by their ability to sink and rise back up very slowly.

[0200] The processes for preparing a combustion modified viscoelastic polyurethane foam comprise mixing together a low primary hydroxyl group polyol having a molecular weight of less than about 4000 g / mol and a primary hydroxyl groups content of less than about 50% with respect to the sum of the primary and secondary hydroxyl groups, a cross-link polyol, dicyandiamide, an isocyanate, a catalyst, water and optionally additives to form a mixture foaming the mixture to form a foamed mixture, and curing the foamed mixture.

[0201] Low primary hydroxyl group polyol

[0202] The processes involve a low primary hydroxyl group polyol, as defined above for combustion modified ether polyurethane foam.

[0203] The low primary hydroxyl group polyol may be referred to as the base polyol or the main polyol in this process.

[0204] Cross-link Polyol

[0205] The processes for preparing combustion modified viscoelastic polyurethane foams involve mixing a cross-link (or rigid) polyol in the mixture.

[0206] Cross-link polyols are as defined above. In some embodiments, of this aspect, the cross-link polyol preferably has a molecular weight of less than about 1000 g / mol, preferably less than 750 g / mol, for example, about 700 g / mol. The effect of using a very low molecular weight cross-link polyol includes increasing the cross linking of the foam. This allows working at lower index and enables a less resilient foam to be obtained. Due to the short chain and additional cross linking the glass transition temperature of the foam is increasing and the foam becomes visco-elastic. The amount of cross-link polyol used in the formulation may be any amount necessary to impart the desired properties on the foam. In some embodiments, the process involves mixing 10 to 60 parts by weight of cross-link polyol per 100 parts of total polyols in the mixture, preferably, 20 to 50 parts by weight of cross-link polyol per 100 parts of total polyols.

[0207] Further Polyols

[0208] This process may comprising mixing one or more further polyols in the mixture. In some embodiments, the further polyol is a high resilience polyol, as defined above. The addition of high resilience polyol in combustion modified viscoelastic foam helps the foam to remain flexible and crushable. The high resilience polyol can also help the initial stability of the foam due to its higher activity compared to the cross-link polyol.

[0209] In some embodiments, the further polyol is a cell opening polyol, as defined above.

[0210] The process may involve mixing 0 to 60 parts by weight of further polyol per 100 parts of total polyols in the mixture.

[0211] In embodiments comprising a further polyol, the process may involve mixing 10 to 60 parts by weight of further polyol per 100 parts of the total polyols in the mixture.

[0212] Dicyandiamide

[0213] In this embodiment, the low primary hydroxyl group polyol is mixed with dicyandiamide. The dicyandiamide may be added to the mixture as a solid. Alternative to make the dicyandiamide easier to handle, the dicyandiamide may be added as a slurry. The slurry may comprise a polyol. The polyol may be the same as the low primary hydroxyl group polyol or may be a further polyol. In some embodiments, the dicyandiamide is preferably a slurry in the low primary hydroxyl group polyol.

[0214] In these embodiments, adding the dicyandiamide as a slurry in the low primary hydroxyl group polyol is particularly preferred when the low primary hydroxyl group polyol has a low viscosity. For example, a viscosity of about 400 to about 800 mPas at 25°C.

[0215] In some embodiments of this aspect, the process involves mixing about 5-50 parts by weight of dicyandiamide per 100 parts of the total polyols in the mixture, preferably about 10-40 parts by weight of dicyandiamide per 100 parts of the total polyols. Most preferably, about 25 parts by weight of dicyandiamide per 100 parts of the total polyols. Isocyanate

[0216] The isocyanate used in the processes for preparing a flexible combustion modified viscoelastic polyurethane foam may be any suitable isocyanate as discussed above. In some embodiments, the isocyanate is toluene diisocyanate. In other embodiments, the isocyanate is a methylene diphenyl diisocyanate.

[0217] In some embodiments, the process involves mixing 10 to 80 parts by weight of isocyanate per 100 parts of total polyols in the mixture, preferably 30 to 60 parts by weight of isocyanate per 100 parts of the total polyols.

[0218] Catalyst

[0219] The catalysts used in the processes for preparing a flexible combustion modified viscoelastic polyurethane foam may be any suitable catalyst as discussed above.

[0220] In some embodiments, the process involves mixing 0.05 to 3 parts of catalyst(s) per 100 parts of total polyols in the mixture. In preferred embodiments, about 0.05 to about 2 parts of catalyst(s) per 100 parts of the total polyols are used. In particularly preferred embodiments, about 0.05 to about 1 parts of catalyst(s) per 100 parts of the total polyols are used.

[0221] Water

[0222] As outlined above, the process for preparing a flexible combustion modified viscoelastic polyurethane foam requires adding water.

[0223] In some embodiments, the process involves mixing 1-6 parts of water per 100 parts of the total polyols in the mixture. In preferred embodiments, about 2-4 parts of water per 100 parts of the total polyols are used

[0224] Additives

[0225] The mixture may comprise additives. The additives may be any of those discussed above, or any additives known in the art.

[0226] The additives in some embodiments include a filler, crosslinker, silicone and a further flame retardant.

[0227] In some embodiments of this aspect, the additive is a filler. Preferably, the filler is CaCCh. Using CaCCh as a filler can reduce the overall cost of the formulation. At the same time, the CaCCh can act as a heat sink to reduce the overall temperature of the foam formation process. Furthermore, it can bring some additional hardness to the foam. The filler may be added as a slurry in a polyol. The polyol may be the low primary hydroxyl content polyol or may be a further polyol.

[0228] In some embodiment of the this aspect, the additive is a further fire retardant which is selected from the group consisting of tris(chloropropyl)phosphate, alkylphosphate oligomer, phosphorus ester, ammonium polyphosphate, graphite, and phosphorus-based polyols. The advantage of including a further flame retardant includes that the fire retardant properties are enhanced.

[0229] The amount of additives used in the process will be any amount required to achieve the desired properties.

[0230] In some embodiments, the process involves mixing 0-40 parts by weight of additives per 100 parts of total polyols in the mixture. In preferred embodiments, the process involves mixing about 0-30 parts by weight of additives per 100 parts of total polyols.

[0231] The process

[0232] The process of the third aspect provides a combustion modified viscoelastic polyurethane foam having good properties and good fire resistance as demonstrated in the Examples below.

[0233] Physical Characteristics of the Foams

[0234] As a part of the first aspect, there is also provided a flexible combustion modified high resilient polyurethane foam obtained by reacting a first polyol and an isocyanate in the presence of a catalyst, water, dicyandiamide, and optionally additives, wherein the first polyol has a molecular weight of at least about 10,000 g / mol, preferably at least about 11 ,000 g / mol, more preferably, at least about 12,000 g / mol. There is also provided a flexible combustion modified high resilience polyurethane foam prepared by the method of the first aspect.

[0235] As part of the second aspect, there is also provided a combustion modified ether polyurethane foam obtained by reacting a low primary hydroxyl group polyol having a molecular weight of less than about 4000 g / mol and a primary hydroxyl groups content of less than about 50% with respect to the sum of the primary and secondary hydroxyl groups, and an isocyanate in the presence of a catalyst, water, dicyandiamide, and optionally additives. There is also provided a combustion modified ether polyurethane foam prepared by the process of the second aspect.

[0236] As part of the third aspect, there is also provided a combustion modified viscoelastic polyurethane foam obtained by reacting a low primary hydroxyl group polyol having a molecular weight of less than about 4000 and a primary hydroxyl groups content of less than about 50% with respect to the sum of the primary and secondary hydroxyl groups, a crosslink polyol and an isocyanate in the presence of a catalyst, water, dicyandiamide, and optionally additives. There is also provided a combustion modified viscoelastic polyurethane foam prepared by the process of the third aspect.

[0237] The flexible combustion modified high resilience polyurethane foams, combustion modified ether polyurethane foams and combustion modified viscoelastic polyurethane foams of the present disclosures, i.e. comprising dicyandiamide rather than melamine, all have the properties that would be expected from polyurethane foams comprising melamine as a fire retardant. Such properties include density, hardness, air permeability, tensile, elongation, compression set dry, resilience and, most importantly, BS5852 Crib V fire safety standard and burning time.

[0238] Crib V Fire Safety Standard and Burning time - The furniture and Furnishings (Fire)(Safety) Regulations 1988 (BS 5852:1982)

[0239] The Crib V test is conducted according to the furniture and Furnishings (Fire) (Safety) Regulations 1988 (BS 5852:1982).

[0240] As can be seen by the Examples below, foams comprising dicyandiamide according to the present disclosure comply with Schedule 1 part 1 , The furniture and furnishings (Fire)(Safety) regulations 1988 based upon Crib 5 test methods defined in BS5852 1982. The foams have a burning time of less than 5 minutes and therefore the flames have extinguished themselves well within the 10 minute time frame.

[0241] In some embodiments, the polyurethane foams disclosed herein may have a Crib V burning time of less than 5 minutes, preferably less than 4 minutes and most preferably less than 3 minutes.

[0242] Whether a foam passes the Crib V test can also be determined by measuring the mass of the sample that is lost after the test. A loss of up to 60g is considered to pass the test. As can be seen in the Examples below, all of the foams comprising dicyandiamide according to the present disclosure have a weight loss of less than 50g and therefore pass the test.

[0243] In some embodiments, the polyurethane foams disclosed herein may have a Crib V weight loss of less than 50g, preferably less than 40g, most preferably less than 20g.

[0244] Density (ISO 845)

[0245] Density is determined according to Standard ISO 845.

[0246] The densities of the dicyandiamide containing polyurethane foams according to the present disclosure are comparable to the densities of comparable foams comprising melamine as the fire retardant, as can be seen by the Examples below.

[0247] For the flexible combustion modified high resilience polyurethane foams, the density is about 20 kg / m3to 70 kg / m3, preferably about 25 kg / m3to 50 kg / m3.

[0248] For the combustion modified ether polyurethane foams, the density is about 20 kg / m3to 50 kg / m3, preferably about 25 kg / m3to 40 kg / m3.

[0249] For the combustion modified viscoelastic polyurethane foams, the density is about 30 kg / m3to 80 kg / m3, preferably about 40 to 60 kg / m3.

[0250] Hardness (ISO 3386-1 or ISO 2439)

[0251] Hardness, or firmness, may also be referred to as Compression Load Deflection (CLD). CLD is determined according to Standard ISO 3386-1 and is expressed in kPa while the Indentation Load Deflection (ILD) is determined according to Standard ISO 2439 and is expressed in Newtons (N), at a given percentage deflection / indentation of the foam.

[0252] The CLD and / or ILD of the dicyandiamide containing polyurethane foams according to the present disclosure are comparable to the CLD or ILD of comparable foams comprising melamine as the fire retardant, as can be seen by the Examples below.

[0253] For the flexible combustion modified high resilience polyurethane foams, the CLD may be about 1 kPa to about 6 kPa at a 40% deflection of the foam. The ILD can be about 40 up to 240 N at 40% indentation. For the combustion modified ether polyurethane foams, the CLD may be about 3 kPa to about 6 kPa at a 40% deflection of the foam. The ILD can be about 100 newtons to about 240 newtons at a 40% indentation.

[0254] For the combustion modified viscoelastic polyurethane foams, the CLD may be about 1.2 kPa to about 6 kPa at a 40% deflection of the foam. The ILD can be about 50 newtons to about 240 newtons at a 40% indentation.

[0255] Air Permeability (ISO 7231 :2023)

[0256] Air permeability is the measure of the volume of air per minute that can be pulled through a sample of foam and is expressed in Liters per minute or per second.

[0257] ISO 7231 :2023 is a method to test the air permeability of flexible cellular polymeric materials - the air flow passing perpendicularly through a foam under specified conditions of test area, pressure drop and time.

[0258] A sample of 51 * 51 * 25 (±0.3) mm (25 cm2) is placed in sample holder. A differential pressure of 125 Pa is being created across the test piece and the corresponding air flow required to obtain this pressure differential is recorded in dm3 / s. In this disclosure, this air volume may be referred to as a measurement for air permeability or as a measurement for porosity.

[0259] The air permeability of the dicyandiamide containing polyurethane foams according to the present disclosure are comparable to the air permeability of comparable foams comprising melamine as the fire retardant, as can be seen by the Examples below. For example, the air permeability of the flexible combustion modified high resilience polyurethane foam disclosed herein has a comparable air permeability to a flexible combustion modified high resilience foam comprising melamine. As another example, the combustion modified ether polyurethane foam disclosed herein has a comparable air permeability to a combustion modified ether polyurethane foam comprising melamine. Also, the combustion modified viscoelastic polyurethane foam disclosed herein has a comparable air permeability to a combustion modified viscoelastic polyurethane foam comprising melamine.

[0260] For the flexible combustion modified high resilience polyurethane foams, the air permeability may be about 100 to about 250 l / min. For the combustion modified ether polyurethane foams, the air permeability may be about 20 to about 130 l / min.

[0261] For the combustion modified viscoelastic polyurethane foams, the air permeability may be about 20 to about 100 l / min.

[0262] Tensile Strength (ISO 1798)

[0263] Tensile strength is a measure of the amount of force required to break a specific area of foam as it is pulled apart. Tensile strength is expressed in kPa and is measured according to Standard ISO 1798.

[0264] The tensile strength of the dicyandiamide containing combustion modified polyurethane foams according to the present disclosure are comparable to the tensile strength of comparable foams comprising melamine as the fire retardant.

[0265] For the flexible combustion modified high resilience polyurethane foams, the tensile strength may be about 60 kPa - 120 kPa depending on the density.

[0266] For the combustion modified ether polyurethane foams, the tensile strength may be about 60 to about 120 kPa.

[0267] For the combustion modified viscoelastic polyurethane foams, the tensile strength may be about 50 kPa to 120 kPa.

[0268] Elongation (ISO 1798)

[0269] Elongation is a measure of the extent to which a foam can be stretched before it breaks. It is expressed as a percentage of its original length. Elongation is measured according to Standard ISO 1798.

[0270] The elongation of the dicyandiamide containing combustion modified polyurethane foams according to the present disclosure are comparable to the elongation of comparable foams comprising melamine as the fire retardant.

[0271] For the flexible combustion modified high resilience polyurethane foams, the elongation may be about 80 -130 %. For the combustion modified ether polyurethane foams, the elongation may be about 80% to about 130% of the original length.

[0272] For the combustion modified viscoelastic polyurethane foams, the elongation may be about 70 to 110 %.

[0273] Compression set dry (ISO 1856)

[0274] Compression set dry is a measure of the permanent deformation of a foam after it has been compressed between two metal plates for a controlled time period and temperature condition. Compression set dry is measured according to Standard ISO1856. The foam is compressed to a thickness given as a percentage of its original thickness . Compression set dry is expressed as the percentage of its original thickness that remained “set”. The compression set can be done at 50% or 75% of the original thickness and is done by placing the sample for 22 hrs in an oven at 70°C.

[0275] The compression set dry of the dicyandiamide containing polyurethane foams according to the present disclosure are comparable to the compression set dry of comparable foams comprising melamine as the fire retardant.

[0276] For the flexible combustion modified high resilience polyurethane foams, the compression set dry may be less than about 12% when compressed for 50%, preferably less than about 8%.

[0277] For the combustion modified ether polyurethane foams, the compression set dry may be up to about 30% when compressed to 75% of its original thickness. In preferred embodiments, the compression set dry is less than about 9% when compressed to 50% of its original thickness. This means that the foams did not recover about 9% of their original thickness.

[0278] For the combustion modified viscoelastic polyurethane foams, the compression set dry may be less than about 11% when compressed to 50% of its original thickness. This means that the foams did not recover about 11% of their original thickness.

[0279] Resilience (ISO 8307)

[0280] Resilience is a measure of the elasticity of a foam. It is expressed as a percentage of return and measured according to Standard ISO 8307. The resilience of the dicyandiamide containing combustion modified polyurethane foams according to the present disclosure are comparable to the resilience of comparable foams comprising melamine as the fire retardant, as can be seen by the Examples below.

[0281] For the flexible combustion modified high resilience polyurethane foams, the resilience may be about 30% to about 50%, preferably above 40%.

[0282] For the combustion modified ether polyurethane foams, the resilience may be about 20% to about 40%, preferably above 30%.

[0283] For the combustion modified viscoelastic polyurethane foams, the resilience is preferably less than 20%, even more preferably less than 15%.

[0284] Examples

[0285] The following examples are specific embodiments of the present invention but are not intended to limit the present invention.

[0286] Example 1 - Combustion Modified High Resilience Polyurethane foam

[0287] The substitution of melamine with dicyandiamide in combustion modified_high resilience polyurethane foams was explored. In this example, first (sorbitol based) polyol of molecular weight of about 12,000 g / mol and nominal functionally 6 was used as the base polyol. This was mixed with a 1 :1 slurry of melamine (Comparative Example 1) or dicyandiamide (Example 1) in a second polyol. The second polyol had a molecular weight of about 5000 g / mol and a viscosity of about 800-900 mPa. Also in the mixture was a further polyol, which is a polymeric polyol comprising styrene-acrylonitrile particles. The polymeric polyol was a non-reactive polyol (standard SAN polyol). Also in the mixture was a cell-opening polyol (additive) as well as other additives including silicone, crosslinkers, chain extender, amines, and a further flame retardant. The mixture was stirred for 40-50 seconds before a tin catalyst was added and the mixture mixed for a further 10 seconds. Toluene diisocyanate was then added and the mixture mixed for a further 7 seconds. After this, the mixture was poured into an open mould and foamed to form the foamed mixture. The foamed mixture was then cured to form a flexible combustion modified high resilience polyurethane foam. The quantities of starting materials are outlined in the table below.

[0288] The resulting foams had the following properties: It can be seen from the table above that the replacement of melamine with dicyandiamide has no significant effect on the properties of the foam. It can also be seen that there is an improvement in the fire-resistance of the foam because the BS5852 Crib V test resulted in a loss of only 30g for the dicyandiamide example compared with 35g for the melamine reference foam.

[0289] Example 2 - Combustion Modified High Resilience Polyurethane foam

[0290] The substitution of melamine with dicyandiamide in combustion modified_high resilience polyurethane foams was explored further in foams with a larger proportion of the first polyol and a smaller proportion of the non-reactive SAN polyol (polymeric polyol). The foams were prepared as for those of Example 1. The quantities of starting materials are outlined in the table below.

[0291] The resulting foams had the following properties:

[0292] It can be seen from the table above that the replacement of melamine with dicyandiamide has no significant effect on the properties of the foam. It can also be seen that there is an improvement in the fire-resistance of the foam because the BS5852 Crib V test resulted in a loss of only 30g for the dicyandiamide example compared with 35g for the melamine reference foam.

[0293] Example 3 - CME foams

[0294] The substitution of melamine with dicyandiamide in combustion modified ether (CME) foams was explored. In this example, a low primary hydroxyl group polyol having a molecular weight of 3000 g / mol, a nominal functionality of 3 and a primary hydroxyl groups content of about 0% was used as the base polyol. This was mixed with a further polyol which was a cross-link polyol. The cross-link polyol was a sorbitol based polyol having a nominal functionality of 6 and a molecular weight of about 2000 g / mol. These polyols were mixed with melamine (Comparative Example 3) or dicyandiamide (Example 3). Also in the mixture was a filler additive which was a slurry of CaCCh in an alternative low primary hydroxyl content polyol (1:1). Also in the mixture was other additives including a silicone surfactant, a crosslinker, amines, and a further flame retardant. The mixture was stirred for 40-50 seconds before a tin catalyst was added and the mixture mixed for a further 10 seconds. Toluene diisocyanate was then added and the mixture mixed for a further 7 seconds. After this, the mixture was poured into a mould and foamed to form the foamed mixture. The foamed mixture was then cured to form a combustion modified ether (CME) foam. The quantities of starting materials are outlined in the table below.

[0295] The resulting foams had the following properties: It can be seen from the table above that the replacement of melamine with dicyandiamide has no significant effect on the properties of the foam, although the dicyandiamide foam had a slightly lower air permeability.

[0296] It can also be seen that there is an improvement in the fire-resistance of the foam because the BS5852 Crib V test resulted in a loss of only 20g for the dicyandiamide example compared with 30g for the melamine reference foam.

[0297] Example 4 - CME foams

[0298] The substitution of melamine with dicyandiamide in CME foams was explored in a further Example. The foams were prepared as for those of Example 3, with the exception that the mixture did not contain the CaCCh slurry but did contain methylene chloride as a blowing (foaming) agent. The quantities of starting materials are outlined in the table below.

[0299] The resulting foams had the following properties: It can be seen from the table above that the replacement of melamine with dicyandiamide has no significant effect on the properties of the foam.

[0300] Example 5 - CME foam

[0301] An alternative combustion modified ether (CME) foam was prepared as for those of Example 4, with the exception that the mixture did not contain a further polyol or blowing agent

[0302] (methylene chloride). The quantities of starting materials are outlined in the table below.

[0303] The resulting foam had the following properties: It can be seen from the table above that a CME foam not containing a further polyol had excellent properties.

[0304] Example 6 - CME foam

[0305] An alternative combustion modified ether (CME) foam was prepared as for those of Example 3, with the exception that the mixture did not contain a further polyol. The quantities of starting materials are outlined in the table below. The resulting foam had the following properties: It can be seen from the table above that a CME foam not containing a further polyol had excellent properties.

[0306] Example 7 - CME Foams containing a HR polyol Several foams were prepared comprising a further polyol which was a HR polyol:

[0307] The resulting foam had the following properties:

[0308] Example 8 - Combustion Modified viscoelastic foams

[0309] The substitution of melamine with dicyandiamide in combustion modified viscoelastic foams (VE) was explored. In this example, low primary hydroxyl group polyol (full polypropylene) polyol having a molecular weight of about 3000 g / mol and a nominal functionality of 3 was used as the base polyol. This was mixed with a cross-link polyol which had a molecular weight of about 700 g / mol and a nominal functionality of 3. These polyols were mixed with dicyandiamide. Also in the mixture was a filler additive which was CaCCh. Also in the mixture were other additives including a silicone surfactant, crosslinkers, chain extender, amines, and a further flame retardant. The mixture was stirred for 40-50 seconds before a tin catalyst was added and the mixture mixed for a further 10 seconds. Toluene diisocyanate was then added and the mixture mixed for a further 7 seconds. After this, the mixture was poured into a mould and foamed to form the foamed mixture. The foamed mixture was then cured to form a combustion modified viscoelastic polyurethane foam. The quantities of starting materials are outlined in the table below. The resulting foam had the following properties: As can be seen from the above table, the combustion modified viscoelastic foam had good properties and excellent fire resistance with a loss of only 36g under the BS5852 Crib V test.

[0310] Example 9 - Combustion Modified viscoelastic foam

[0311] An alternative combustion modified viscoelastic foam was prepared as for that of Example 8, with the exception that the mixture contained methylene diphenyl diisocyanate instead of toluene diisocyanate and contained further polyols which were a HR polyol and a cell opening polyol. The cell opening polyol was a high EO polyol (also referred to as a soft polyol). The HR polyol had a molecular weight of about 6000 g / mol and a nominal functionality of 3, it had a primary hydroxyl group content of >70% with respect to the sum of the primary and secondary hydroxyl groups. The cell-opening polyol had a molecular weight of about 5000 g / mol, a nominal functionality of 3 and a primary hydroxyl group content of about 80-85% . This mixture did not contain the CaCCh filler. The quantities of starting materials are outlined in the table below.

[0312] The resulting foam had the following properties:

[0313] As can be seen from the above table, the combustion modified viscoelastic foam had good properties and excellent fire resistance with a loss of only 26g under the BS5852 Crib V test.

[0314] For the avoidance of any doubt, the terms “a”, “an” and “the” are intended, unless specifically indicated otherwise or the context requires otherwise, to include plural alternatives, e.g., at least one.

[0315] "Optional" or "optionally" means that the subsequently described event or circumstance can or cannot occur, and that the description includes instances where the event or circumstance occurs and instances where it does not.

[0316] Various other modifications to the present invention will be readily apparent to those skilled in the art.

Claims

1. Claims1. A process for preparing a flexible combustion modified high resilience polyurethane foam, comprising:- mixing together a first polyol, dicyandiamide, an isocyanate, a catalyst, water and optionally additives to form a mixture;- foaming the mixture to form a foamed mixture; and- curing the foamed mixture; wherein the first polyol has a molecular weight of at least about 10,000 g / mol.

2. The process according to claim 1 , wherein the first polyol has a molecular weight of at least about 11 ,000 g / mol, preferably at least 12,000 g / mol.

3. The process according to claim 1 or 2, wherein the first polyol has a nominal functionality of at least 5, preferably at least 6.

4. The process according to any one of claim 1 to 3, wherein the first polyol is a sorbitol based polyol.

5. The process according to any one of claims 1 to 4, wherein the dicyandiamide is a slurry of dicyandiamide in a polyol.

6. The process according to claim 5, wherein the second polyol has a viscosity of about 800 to about 1200 mPas at 25°C.

7. The process according to any one of claims 1 to 6, wherein the additives are selected from the group consisting of fillers, surfactants / stabilizers, cell regulators, colours, chain extenders, cross linkers, further flame retardants, blowing agents and / or cell openers.

8. The process according to any one of claims 1 to 7, wherein the mixing step comprises mixing a polymeric polyol.

9. The process according to claim 8, wherein the polymeric polyol comprises particulate material in dispersed form.

10. The process according to claim 9, wherein the particulate material is selected from the group consisting of styrene-acrylonitrile particles, polyurethane particles and polyurea particles.

11. The process according to any one of claims 8 to 10, wherein the polymeric polyol has a primary hydroxyl groups content of less than about 50%, preferably less than about 20%, more preferably about 0%, with respect to the sum of the primary and secondary hydroxyl groups.

12. The process according to any one of claims 1 to 10, wherein the additive is a further fire retardant which is selected from the group consisting of tris(chloropropyl)phosphate, alkylphosphate oligomer, phosphorus ester, ammonium polyphosphate, graphite and phosphorus-based polyols.

13. The process according to any one of claims 1 to 12, wherein the process involves mixing about 5-50 parts by weight of dicyandiamide per 100 parts of the total polyols in the mixture, preferably about 10-20 parts by weight of dicyandiamide per 100 parts of the total polyols.

14. The process according to any one of claims 1 to 13, wherein the first polyol has a primary hydroxyl groups content of at least about 60%, preferably at least about 70%, more preferably at least about 80%, with respect to the sum of the primary and secondary hydroxyl groups.

15. A flexible combustion modified high resilient polyurethane foam obtained by reacting a first polyol and an isocyanate in the presence of a catalyst, water, dicyandiamide, and optionally additives, wherein the first polyol has a molecular weight of at least about 10,000 g / mol, preferably a least about 11,000 g / mol, more preferably at least 12,000 g / mol.

16. A flexible combustion modified high resilient polyurethane foam prepared by the process of any one of claims 1 to 14.

17. A process for preparing a combustion modified ether polyurethane foam, comprising:- mixing together a low primary hydroxyl group polyol having a molecular weight of less than about 4000 g / mol and a primary hydroxyl groups content of less than about 50% with respect to the sum of the primary and secondary hydroxyl groups, dicyandiamide, an isocyanate, a catalyst, water and optionally additives to form a mixture;- foaming the mixture to form a foamed mixture; and- curing the foamed mixture.

18. The process according to claim 17, wherein the mixing step further comprises mixing a further polyol selected from the group consisting of cross-link polyols and polymeric polyols.

19. The process according to claim 18, wherein the polymeric polyol comprises particulate material in dispersed form, preferably, wherein the particulate material is selected from the group consisting of styrene-acrylonitrile particles, polyurethane particles and polyurea particles.20 The process according to any one of claims 17 to 19, wherein the low primary hydroxyl group polyol has a primary hydroxyl group content of less than about 20% with respect to the sum of the primary and secondary hydroxyl groups, preferably less than about 10% .

21. The process according to any one of claims 17 to 20, wherein the low primary hydroxyl group polyol is a full polypropylene oxide based polyol.

22. The process according to any one of claims 17 to 21 , wherein the low primary hydroxyl group polyol has a nominal functionality of between 2 and 4, preferably 3.

23. The process according to any one of claims 17 to 22, wherein the additives are selected from the group consisting of fillers, surfactant / stabilizers, cell regulators, colours, chain extenders, cross linkers, further flame retardants, blowing agents and / or cell openers.

24. The process according to any one of claims 17 to 23, wherein the additive is a filler which is CaCCh.

25. The process according to any one of claims 17 to 24, wherein the additive is a further fire retardant which is selected from the group consisting of tris(chloropropyl)phosphate, alkylphosphate oligomer, phosphorus ester, ammonium polyphosphate, graphite and phosphorus-based polyols.

26. The process according to any one of claims 17 to 25, wherein the low primary hydroxyl group content polyol comprises at least about 50% of the total polyols in the mixture, preferably, at least about 80%, more preferably at least about 90%.

27. The process according to any one of claims 17 to 26, wherein the process involves mixing about 5-50 parts by weight of dicyandiamide per 100 parts of the total polyols in the mixture, preferably about 10-30 parts by weight of dicyandiamide per 100 parts of the total polyols.

28. A combustion modified ether polyurethane foam obtained by reacting a low primary hydroxyl group polyol having a molecular weight of less than about 4000 g / mol and a primary hydroxyl groups content of less than about 50% with respect to the sum of the primary and secondary hydroxyl groups, and an isocyanate in the presence of a catalyst, water, dicyandiamide, and optionally additives.

29. A combustion modified ether polyurethane foam prepared by the process of any one of claims 17 to 27.

30. A process for preparing a combustion modified viscoelastic polyurethane foam, comprising:- mixing together a low primary hydroxyl group polyol having a molecular weight of less than about 4000 g / mol and a primary hydroxyl groups content of less than about 50% with respect to the sum of the primary and secondary hydroxyl groups, a cross-link polyol, dicyandiamide, an isocyanate, a catalyst, water and optionally additives to form a mixture;- foaming the mixture to form a foamed mixture; and- curing the foamed mixture.

31. The process according to claim 30, wherein the cross-link polyol has a molecular weight of less than about 1000 g / mol.

32. The process according to claim 30 or claim 31 , wherein the low primary hydroxyl group polyol has a primary hydroxyl group content of less than about 20% with respect to the sum of the primary and secondary hydroxyl groups, preferably less than about 10% .

33. The process according to any one of claims 30 to 32, wherein the low primary hydroxyl group polyol is a full polypropylene oxide based polyol.

34. The process according to any one of claims 30 to 33, wherein the low primary hydroxyl group polyol has a nominal functionality of between 2 and 4, preferably 3.

35. The process according to any one of claims 30 to 34, wherein the additives are selected from the group consisting of fillers, surfactant / stabilizers, cell regulators, colours, chain extenders, cross linkers, further flame retardants, blowing agents and / or cell openers.

36. The process according to any one of claims 30 to 35, wherein the additive is a filler which is CaCCh.

37. The process according to any one of claims 30 to 36, wherein the additive is a further fire retardant which is selected from the group consisting of tris(chloropropyl)phosphate, alkylphosphate oligomer, phosphorus ester, ammonium polyphosphate, graphite and phosphorus-based polyols.

38. The process according to any one of claims 30 to 37, wherein the process involves mixing about 5-50 parts by weight of dicyandiamide per 100 parts of the total polyols in the mixture, preferably about 10-40 parts by weight of dicyandiamide per 100 parts of the total polyols.

39. A combustion modified viscoelastic polyurethane foam obtained by reacting a low primary hydroxyl group polyol having a molecular weight of less than about 4000 and a primary hydroxyl groups content of less than about 50% with respect to the sum of the primary and secondary hydroxyl groups, a cross-link polyol and an isocyanate in the presence of a catalyst, water, dicyandiamide, and optionally additives.

40. A combustion modified viscoelastic polyurethane foam prepared by the process of any one of claims 30 to 38.

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