Flame-retardant polyurethane foam system

TECHNICAL FIELD

The present invention relates to flame-retardant polyurethane foam system, in particular to low density flame-retardant polyurethane foam system, to the polyurethane foam produced therefrom, and to the preparation thereof, and to the use of the polyurethane foam in different applications.

BACKGROUND

Polyurethane foams are suitable for a large number of applications, for example cushioning materials, thermal insulation materials, packaging, automobile-dashboards, or construction materials. Many of these applications require effective flame retardancy. A very wide variety of flame retardants have therefore previously been described for polyurethanes.

Halogenated compounds are used by way of example as flame retardants. Halogenated flame retardants, however, in particular brominated flame retardants, are undesirable for toxicological, environmental, and regulatory reasons. Furthermore, halogenated flame retardants also cause increased smoke density in the event of fire, and can decompose to gaseous halogencontaining compounds such as HCI or HBr.

Phosphorus-containing compounds, especially organophosphorus compounds, are widely used flame retardants. Organophosphorus flame retardants are mostly based on phosphate esters, phosphonate esters, or phosphite esters. Known phosphorus-containing flame retardants, such as triethyl phosphate (TEP), tris(chloropropyl) phosphate (TCPP) or diethyl ethanephosphonate (DEEP), contribute by way of example to emissions from plastics, thus giving these an unpleasant odor. Besides, high percentage of liquid non-reactive organophosphorus flame retardants leads to a lower mechanical strength of polyurethane foam and a very high TVOC (Total Volatile Organic Compounds) values.

The use of fillers as solid flame retardants has also been proposed. For example, CN107619464A discloses a polyurethane composite heat-insulating material for a solar heatinsulating water tank. The polyurethane composite heat-insulating material is characterized by being prepared from the following components in parts by weight: 90 to 100 parts of compound polyether polyol, 110 to 130 parts of isocyanate, 1 to 3 parts of nano-kaolin, 2to 5 parts of a foaming agent, 0.1 to 0.5 parts of a foam stabilizing agent, 0.5 to 3 parts of a catalyst, 0.5 to 1 part of a cross-linking agent, and 0.1 to 0.5 part of a composite flame retardant. However, the flame retardant property is not tested in it.

CN102746642A describes a flame-retardant polyurethane composite material. An existing flame-retardant polyurethane foam material is poor in use effect. The flame-retardant polyurethane composite material is a mixed system composed of 70-99wt percent flameretardant polyurethane and 1-30wt percent of blended fire retardants, wherein the blended fire retardants comprise one or more of ammonium polyphosphate (APP), melamine, melamine cyanurate, polysiloxane, graphene, carbon nano tubes, kaolin and Montmorillonite, and the flame-retardant polyurethane is a random copolymer composed of a polycarbonate unit, a polyether unit and an isocyanate unit.

When solid flame retardants are used in foam system to produce a polyurethane foam for use of construction insulation, one solution is using ammonium polyphosphate or melamine which the price is very high. Furthermore, melamine tends to settle out from the melamine-containing polyurethane components within a short time, which brings with it a series of technological problems, and APP is water sensitive and may impact the heat resistance and mechanical property of polyurethane foam. Another way is to incorporate an organo-phosphorus polyol into the foam system together with the fillers to increase the flame retardant, however, the stability of the organo-phosphorus polyol is lower and easy to cause degradation. Besides, the flameretardant property could be enhanced by increasing the density of polyurethane foam, however, it does not fit the lightweight requirement in several applications.

China asks for higher FR Pll rigid foam (GB50404-2018, GB8624-2012) as thermal-insulation material for construction, however, current solutions to achieve higher FR is at the cost of sacrificing the mechanical strength or density.

Therefore, it is still required to provide a flame-retardant polyurethane foam system that shows successful flame retardant and, at the same time, lower cost and foam density.

SUMMARY OF THE PRESENT INVENTION

An object of this invention is to overcome the problems of the prior art discussed above and to provide a flame-retardant polyurethane system that shows successful flame retardant and, at the same time, lower cost and foam density.

Surprisingly, it has been found by the inventors that the above object can be achieved by a flame-retardant polyurethane foam system, comprising isocyanate component consisting of a) at least one isocyanate, and resin components consisting of b) at least one substance reactive toward isocyanate, c) optionally chain extender and/or crosslinking agent, d) flame retardant, e) blowing agent, f) catalysts, and g) optionally additives and/or auxiliaries, wherein the flame retardant (d) comprises liquid flame retardant and inorganic fillers which are selected from at least one of chalk, diatomaceous earth, coal ash, kaolin, silica fume, wollastonite, calcium carbonate, bentonite clay and montmorillonite, the amount of inorganic fillers is in the range of from 3 wt% to less than 50 wt%, based on the total weight of the resin components.

In a preferred embodiment, the amount of inorganic fillers is in the range of 5 to 25 wt%, preferably 5 to 20 wt%, more preferably 10 to 15 wt%, based on the total weight of the resin components.

In a more preferred embodiment, the inorganic fillers are selected from calcium carbonate, kaolin, wollastonite, coal ash and diatomaceous earth.

In a still preferred embodiment, the liquid flame retardant is phosphorus-containing flame retardant comprises at least one of derivatives of phosphoric acid, phosphonic acid, and/or phosphinic acid.

In another preferred embodiment, the amount of said phosphorus-containing flame retardant is in the range of 5 to 50 wt%, preferably 10 to 35, more preferably 15 to 25 wt%, based on the total weight of the resin components.

In another preferred embodiment, the inorganic fillers are kaolin.

In another more preferred embodiment, the kaolin is a calcined kaolin or a water washed kaolin or the mixture there of.

In another more preferred embodiment, the kaolin has a particle size in the range of 50 to 5000 mesh, preferably 150 to 4500 mesh, more preferably 300 to 4000 mesh.

In a further aspect, the invention relates to a method for the production of flame-retardant polyurethane foam from the polyurethane foam system according to the invention, comprising the following steps:

- providing a polyol blend comprising the components (b)-(g);

- providing isocyanate component (a); and

- reacting the polyol blend and the isocyanate component (a) in a weight ratio of 1 :0.5 to 1 :2.5, preferably 1 :0.8 to 1 :2, more preferably 1 :1 to 1 :1.5.

In a further aspect, the invention relates to a flame-retardant polyurethane foam produced according to the invention.

In a further aspect, the invention relates to the use of the flame-retardant polyurethane foam according to the invention as insulators for noise abatement and/or as heat insulators in construction, in cooling and heating technology such as for household appliances for producing composite materials, such as sandwich elements, or as expanded leather cloth, as well as for decorating material, model-making material and packaging and upholstery material, or as lightweight supporting element. It has been surprisingly found in this application that, by adding inorganic fillers, particular kaolin into the polyurethane foam system, the polyurethane foam system shows successful flame retardant and, at the same time, lower cost and foam density. Besides, it also has good processing due to a small particle size of kaolin.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

Unless defined otherwise, all technical and scientific terms used herein have the meaning commonly understood by a person skilled in the art to which the invention belongs. As used herein, the following terms have the meanings ascribed to them below, unless specified otherwise.

As used herein, the articles "a" and "an" refer to one or to more than one (i.e. , to at least one) of the grammatical object of the article. By way of example, "an element" means one element or more than one element.

Unless otherwise identified, all percentages (%) are “percent by weight".

Unless otherwise identified, the temperature refers to room temperature and the pressure refers to ambient pressure.

Unless otherwise identified, the solvent refers to all organic and inorganic solvents known to the persons skilled in the art and does not include any type of monomer molecular.

In one aspect, the present invention provides a flame-retardant polyurethane foam system, comprising isocyanate component consisting of a) at least one isocyanate, and resin components consisting of b) at least one substance reactive toward isocyanate, c) optionally chain extender and/or crosslinking agent, d) flame retardant, e) blowing agent, f) catalysts, and optionally g) additives and/or auxiliaries, wherein the flame retardant (d) comprises liquid flame retardant and inorganic fillers which are selected from at least one of chalk, diatomaceous earth, coal ash, kaolin, silica fume, wollastonite, calcium carbonate, bentonite clay and montmorillonite, the amount of inorganic fillers is in the range of from 3 wt% to less than 50 wt%, based on the total weight of the resin components.

Isocyanate component (a) Isocyanates (a) used for producing the polyurethanes of the invention comprise all isocyanates known for producing polyurethanes. These comprise aliphatic, cycloaliphatic, araliphatic and/or aromatic isocyanates, such as tri-, tetra-, penta-, hexa-, hepta- and/or octamethylene diisocyanate, 2-methylpentamethylene 1 ,5-diisocyanate, 2-ethylbutylene 1 ,4-diisocyanate, pentamethylene 1 ,5-diisocyanate, butylene 1 ,4-diisocyanate, 1-isocyanato-3,3,5-trimethyl-5- isocyanatomethylcyclohexane (isophorone diisocyanate, IPDI), 1 ,4- and/or 1 ,3- bis(isocyanatomethyl)cyclohexane (HXDI), cyclohexane 1 ,4-diisocyanate, 1 -methylcyclohexane 2,4- and/or 2,6-diisocyanate and/or dicyclohexylmethane 4,4’-, 2,4’- and 2,2’-diisocyanate, diphenylmethane 2,2‘-, 2,4‘- and/or 4, 4‘-diisocyanate (MDI), polymeric MDI, naphthylene 1 ,5- diisocyanate (NDI), tolylene 2,4- and/or 2,6-diisocyanate (TDI), 3,3‘-dimethyl diphenyl diisocyanate, 1 ,2-diphenylethane diisocyanate and/or phenylene diisocyanate. Particular preference is given to using 2,2‘-, 2,4‘- and/or 4, 4‘-diisocyanate, and polymeric MDI.

Other possible isocyanates are given by way of example in "Kunststoffhandbuch, Band 7, Polyurethane" [Plastics handbook, volume 7, Polyurethanes], Carl Hanser Verlag, 3rd edition, 1993, chapters 3.2 and 3.3.2.

Component (b)

Substance reactive toward isocyanate (b) can be any of the compounds used for polyurethane production in the art and having at least two reactive hydrogen atoms. By way of example, it is possible to use polyether polyamines and/or polyols selected from the group of the polyether polyols and polyester polyols, or a mixture thereof.

The polyols preferably used are polyether polyols with a molecular weight between 200 and 6000, preferably from 200 to 2000, more preferably from 250 to 1000, OH value between 20 and 1000mg KOH/g, preferably from 120 to 500 mg KOH/g, and/or polyester polyols with molecular weights between 300 and 2000, preferably from 350 to 650, OH value between 60 and 650mg KOH/g, preferably from 120 to 350 mg KOH/g. The following polyols are preferred in the invention: LUPRANOL® 2095 (BASF), LUPRANOL® 2090 (BASF), LUPRANOL® VP 9345 (BASF), LUPRANOL® 3905 (BASF), LUPRAPHEN® 3907 (BASF), LUPRAPHEN® 3915 (BASF), STEPANPOL® PS 3152, PS 2412, PS 1752; CF 6925 (Jiangsu FUTURE).

The polyether polyols that can be used in the invention are produced by known processes. By way of example, they can be produced from one or more alkylene oxides having from 2 to 4 carbon atoms in the alkylene radical via anionic polymerization using alkali metal hydroxides, such as sodium hydroxide or potassium hydroxide, or using alkali metal alcoholates, such as sodium methoxide, sodium ethoxide or potassium ethoxide, or potassium propoxide as catalysts, with addition of at least one starter molecule which comprises from 2 to 8 reactive hydrogen atoms, or via cationic polymerization using Lewis acids, such as antimony pentachloride, boron fluoride etherate, etc., or bleaching earth as catalysts. Examples of suitable alkylene oxides are propylene 1,2-oxide, butylene 1,2-oxide or butylene 2,3-oxide, styrene oxide, and preferably ethylene oxide and propylene 1 ,2-oxide. The alkylene oxides can be used individually, in alternating succession, or as a mixture.

Examples of starter molecules that can be used are ethylene glycol, propylene glycol, water, glycerine, sorbitol, sucrose, tetrahydrofuran..

Polyester polyols can by way of example be produced from dicarboxylic acids having from 2 to 12 carbon atoms, preferably from 4 to 6 carbon atoms, and from polyhydric alcohols. Examples of dicarboxylic acids that can be used are: aliphatic dicarboxylic acids, such as succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, and sebacic acid, and aromatic dicarboxylic acids, such as phthalic acid, isophthalic acid, and terephthalic acid. The dicarboxylic acids can be used individually or in the form of mixtures, e.g. in the form of a mixture of succinic, glutaric, and adipic acid. Examples of polyhydric alcohols are glycols having from 2 to 10, preferably from 2 to 6, carbon atoms, e.g. ethylene glycol, diethylene glycol, 1,4-butanediol, 1,5- pentanediol, 1,6-hexanediol, 1 ,10-decanediol, 2,2-dimethyl-1,3-propanediol, 1,3-propanediol, and dipropylene glycol, triols having from 3 to 6 carbon atoms, e.g. glycerol and trimethylolpropane, and, as higher-functionality alcohol, pentaerythritol. The polyhydric alcohols can be used alone or optionally in mixtures with one another, in accordance with the properties desired.

The amount of polyether polyol and/or polyester polyol, based on the total weight of the resin components, is preferably from 0 to 80% by weight, particularly preferably from 5 to 55% by weight, and in particular from 10 to 45% by weight.

Chain extender and/or crosslinking agent (c)

Chain extenders and/or crosslinking agents (c) that can be used are substances having a molar mass which is preferably smaller than 500 g/mol, particularly preferably from 60 to 250 g/mol, wherein chain extenders have 2 hydrogen atoms reactive toward isocyanates and crosslinking agents have 3 hydrogen atoms reactive toward isocyanate. These can be used individually or preferably in the form of a mixture. It is preferable to use diols and/or triols having molecular weights smaller than 500, particularly from 60 to 400, and in particular from 60 to 250. Examples of those that can be used are aliphatic, cycloaliphatic, and/or araliphatic diols having from 2 to 14, preferably from 2 to 10, carbon atoms, e.g. ethylene glycol, 1 ,3-propanediol, 1,4- butanediol, 1,6-hexanediol, 1,10-decanediol, 1,2-, 1,3-, and 1,4-dihydroxycyclohexane, diethylene glycol, dipropylene glycol, tripropylene glycol, diethanolamine, or triols, e.g. 1,2,4- or 1 ,3,5-trihydroxycyclohexane, glycerol, and trimethylolpropane.

The amount of chain extender and/or crosslinking agent c), if present, is preferably from 0 to 20% by weight, particularly preferably from 1 to 10% by weight, based on the total weight of the resin components. Flame retardant (d)

Flame retardants (d) used are flame retardants which comprise liquid flame retardant and inorganic fillers as solid flame retardant.

The flame retardant comprises liquid flame retardant, such as halogen-containing flame retardant, phosphorus-containing flame retardant. As liquid flame retardant, it is preferable to use tris(1-chloro-2-propyl) phosphate (TCPP), triethyl phosphate (TEP) and Saytex RB-79 (bromine-containing diester/ether diol of tetrabromophthalic anhydride from ALBEMARLE Corporation). The amount of liquid flame retardant is in the range of 5 to 50 wt%, preferably 10 to 35 wt%, more preferably 15 to 25 wt%, based on the total weight of the resin components.

Inorganic fillers are well known in the art. If exposed Inorganic, non-halogenated FR fillers include, for example, metal hydrates such as aluminum hydrate and magnesium hydrate, metal hydroxides such as magnesium hydroxide (Mg(OH)2) and aluminum trihydroxide (ATH) (e.g., Apyral 40CD (Nabeltec)) metal oxides such as titanium dioxide, silica, alumina, huntite, antimony trioxide, potassium oxide, zirconium oxide, zinc oxide and magnesium oxide, carbon black, carbon fibers, expanded graphite, talc, clay, organo-modified clay, calcium carbonate, red phosphorous, wollastonite, mica, ammonium octamolybdate, frits, hollow glass microspheres, glass fibers, expanded graphite and the like. The suitable inorganic fillers in the invention as solid flame retardant include chalk, diatomaceous earth, coal ash, kaolin, silica fume, wollastonite, calcium carbonate, bentonite clay and montmorillonite. In order to improve their dispersibility, the inorganic fillers may be subjected to surface treatment with silane couplers, titanium couplers or the like.

The amount of the inorganic fillers used in the invention is usually in the range of from 5% by weight to less than 25% by weight, based on the total weight of the resin components. It is preferable to use from 5 to 20% by weight of inorganic fillers, based on the total weight of the resin components.

According to the present invention, there is provided a particulate inorganic filler material for a flame retardant polyurethane foam system, the filler material comprises of at least one particulate kaolin clay. Kaolin was produced 150 million years ago. Its main content is kaolinite, occurring with other silicates such as mica, feldspar, and quartz or metallic oxides such as hematite and rutile. It is an aluminum silicate represented as AI2O3-2SiO2-2H2O. In form it consists of thin pseudo-hexagonal lamellar particles. When heated to above 500°C, kaolinite loses its water of crystallization and changes to metakaolinite, which is stable up to 960°C. Both water-washed and calcined grades are suitable for use in the present invention.

A range of particulate kaolins are available, which have the required particle size, or can easily be processed in ways well known to the skilled worker to arrive at the required particle size. Suitable particulate kaolin for use in the present invention has a particle size in the range of 50 to 5000 mesh, preferably 150 to 4500 mesh, more preferably 300 to 4000 mesh. Blowing agent (e)

The blowing agent (e) used according to the invention could be chemical and/or physical blowing agents in the art. Chemical blowing agents are compounds which form gaseous products through reaction with isocyanate, an example being water or formic acid. Physical blowing agents are compounds which have been dissolved or emulsified in the starting materials for polyurethane production and which vaporize under the conditions of polyurethane formation. By way of example, these are hydrocarbons, halogenated hydrocarbons, and other compounds, such as perfluorinated alkanes, e.g. perfluorohexane, fluorochlorocarbons, and ethers, esters, ketones and/or acetals.

Blowing agents (e) which can be used are the chlorofluorocarbons (CFCs) generally known from polyurethane chemistry and also highly fluorinated and/or perfluorinated hydrocarbons. However, for ecological reasons, the use of these materials is being greatly restricted or completely stopped. Besides the HCFCs and HFCs, alternative blowing agents which can be used are, in particular, aliphatic and/or cycloaliphatic hydrocarbons, particularly pentane and cyclopentane or acetals such as methylate.

These physical blowing agents are usually added to the polyol component of the system. However, they can also be added to the isocyanate component or as a combination both to the polyol component and to the isocyanate component.

The amount of blowing agent or blowing agent mixture used is from 1 to 25% by weight, preferably from 1 to 15% by weight, based on the total weight of the resin components. Furthermore, it is possible and customary to add water as blowing agent in an amount of from 0.5 to 25% by weight, preferably from 0.5 to 3% by weight, based on the total weight of the resin components.

The addition of water can be combined with the use of the other blowing agents described.

Catalyst (f)

As catalyst (f), it is possible to use all compounds which accelerate the reaction of the compounds containing hydroxyl groups and with the modified or unmodified polyisocyanates. Such compounds are known and are described, for example, in "Kunststoffhandbuch, volume 7, Polyurethane", Carl Hanser Verlag, 3rd edition 1993, chapter 3.4.1. These comprise amine- based catalysts and catalysts based on organic metal compounds.

As catalysts based on organic metal compounds, it is possible to use, for example, organic tin compounds such as tin(ll) salts of organic carboxylic acids, e.g. tin(ll) acetate, tin(ll) octoate, tin(ll) ethylhexanoate and tin(ll) laurate, and the dialkyltin(IV) salts of organic carboxylic acids, e.g. dibutyltin diacetate, dibutyltin dilaurate, dibutyltin maleate and dioctyltin diacetate, and also bismuth carboxylates, e.g. bismuth(lll) neodecanoate, bismuth 2-ethylhexanoate and bismuth octanoate, or alkali metal salts of carboxylic acids, e.g. potassium acetate or potassium formate.

Preference is given to using amine-based catalysts as catalyst (f), such as N,N,N',N'- tetramethyldipropylenetriamine, 2-[2-(dimethylamino)ethyl-methylamino]ethanol, N,N,N'- trimethyl-N'-2-hydroxyethyl-bis-(aminoethyl)ether, bis(2-dimethylaminoethyl) ether, N,N,N,N,N- pentamethyldiethylenetriamine, N,N,N-triethylaminoethoxyethanol, dimethylcyclohexylamine, trimethyl hydroxyethyl ethylenediamine, dimethylbenzylamine, triethylamine, triethylenediamine, pentamethyldipropylenetriamine, dimethylethanolamine, N-methylimidazole, N-ethylimidazole, tetramethylhexamethylenediamine, tris(dimethylaminopropyl)hexahydrotriazine, dimethylaminopropylamine, N-ethylmorpholine, diazabicycloundecene and diazabicyclononene. Here, examples which may be mentioned are Jeffcat ZF10 (CAS No. 83016-70-0), Jeffcat DMEA (CAS No. 108-01-0), Lupragen N203 (BASF), Lupragen N301 (BASF) and Dabco PT304 (CAS No. 1391700-54-1).

The amount of catalyst (f), based on the total weight of the resin components, is preferably from 1 to 10% by weight, particularly preferably from 2 to 6% by weight.

Additives and/or auxiliaries (g)

Additives and/or auxiliaries (g) that can be used comprise surfactants, cell opener, preservatives, colorants, antioxidants, reinforcing agents, stabilizers and other fillers. In preparing polyurethane foam, it is generally highly preferred to employ a minor amount of a surfactant to stabilize the foaming reaction mixture until it cures. Such surfactants advantageously comprise a liquid or solid organosilicone surfactant, which is employed in amounts sufficient to stabilize the foaming reaction mixture. Typically, the amount of auxiliaries, especially surfactants, is preferably from 0 to 3% by weight, more preferably from 0.5 to 2% by weight, most preferably from 0.6 to 1 .5% by weight, based on the total weight of the resin components.

Further information concerning the mode of use and of action of the abovementioned auxiliaries and additives, and also further examples, are given by way of example in "Kunststoffhandbuch, Band 7, Polyurethane" [“Plastics handbook, volume 7, Polyurethanes”], Carl Hanser Verlag, 3rd edition 1993, chapter 3.4.

In another aspect, the present invention further provides a method for the production of flameretardant polyurethane foam from the polyurethane foam system according to the invention, comprising the following steps:

- providing a resin component blend comprising components (b)-(g),

- providing isocyanate component (a); and

- reacting the resin component blend and isocyanate component (a) in a weight ratio of 1 :0.5 to 1 :2.5, preferably 1 :0.8 to 1 :2, more preferably 1 :1 to 1 :1.5. The foams can be prepared batchwise or continuously by the prepolymer process or by the one-shot process using conventional low pressure or impingement mixers. The foam ingredients may be mixed at from 5° to 90° C, preferably at 20° to 35° C, and introduced into an open mold optionally preheated, or poured or sprayed onto a substrate or into a cavity.

The present invention provides a flame-retardant polyurethane foam produced according to the invention.

The polyurethane foam obtained by the present invention has a foam density between 25 and 47 Kg/m ³ , measured according to GB/T 6343-2009, B2-fire test value of less than 10 cm, preferably less than 8 cm, measured according to GB/T 8626-2007, compressive strength between 100 and 250 KPa, measured according to GB/T 8813-2008.

The present invention further provides use of the flame-retardant polyurethane foam according to the invention as insulators for noise abatement and/or as heat insulators in construction, in cooling and heating technology such as for household appliances for producing composite materials, such as sandwich elements, or as expanded leather cloth, as well as for decorating material, model-making material and packaging and upholstery material, or as lightweight supporting element

The present invention will now be described with reference to Examples and Comparative Examples, which are not intended to limit the present invention.

The following starting materials were used:

• Isocyanate:

PM DI, commercially available under trade name CH2062 C-B from BASF

• Polyether polyol: commercially available under trade name LUPRANOL 9345 from BASF, OH number: -405 mg

KOH/g; Molecular weight: -550

• Polyester polyol: aromatic polyester polyol, commercially available under trade name Lupranol 3915/1 from

BASF, OH number: 260 mg KOH/g; Molecular weight: 490 aromatic polyester polyol, commercially available under trade name CF 6925 from Jiangsu

Future New Material Co. Ltd., OH number: 300 mg KOH/g; Molecular weight: 430 aromatic polyester polyol, commercially available under trade name Lupranol 3905/2 from BASF, OH number: 430 mg KOH/g; Molecular weight: 468

• Solid flame retardant: melamine (CAS No:108-78-1), available from Presafer (Qingyuan) Phosphor Chemical Co., Ltd., 5000 mesh ammonium polyphosphate (APP), available from Presafer (Qingyuan) Phosphor Chemical Co., Ltd., 200 mesh expandable graphite (EG) from Qingdao Huatai Graphite Co., Ltd., 80 mesh flux-calcinated diatomaceous earth, available under trade name Celite499 from IMERYS Wollastonite (calcium inosilicate mineral) fine powder, available under trade name XYNFW-SA from Xinyu South Wollastonite Co., Ltd.

Coal Ash, Pulverized Flue Ash, Pozzolona, available under trade name ASHCRETE (Fly Ash) from TSG Impex India Pvt ltd.

Light Calcium Carbonate, available from Jiangsu Qunxin Powder Technology Co., Ltd.

Kaolin 1 , calcined kaolin, available under trade name Ansilex® 93 from BASF, 325 mesh

Kaolin 2, calcined kaolin, available under trade name KL325 from from Borun New Material Technology Co., Ltd., 325 mesh

Kaolin 3, calcined kaolin, available under trade name KL1250 from Borun New Material

Technology Co., Ltd., 1250 mesh

Kaolin 4, calcined kaolin, available under trade name DS2000 from Yanxi Minerals Co., Ltd., 2000 mesh

Kaolin 5, calcined kaolin, available under trade name KL4000 from Borun New Material

Technology Co., Ltd., 4000 mesh

Kaolin 6, washed kaolin, available under trade name SX400 from Yanxi Minerals Co., Ltd., 400 mesh

• Liquid flame retardant: tris(1-chloro-2-propyl) phosphate (TCPP), CAS No: 13674-84-5, commercially available from Jiangsu Yoke Technology Co., Ltd.

Triethyl phosphate (TEP), CAS No:78-40-0, commercially available from Jiangsu Yoke Technology Co., Ltd.

Mixed ester of tetrabromophthalic anhydride with diethylene glycol and propylene glycol, commercially available under trade name Saytex RB-79 from ALBEMARLE.

• Surfactant: silicone surfactant commercially available as DABCO DC193 from Evonik

• Catalyst,

Potassium acetate catalyst, CAS No: 83016-70-0, commercially available under trade name KX 324 from BASF and DABCO PC46 from Evonik pentamethyldiethylenetriamine catalyst, CAS No: 3030-47-5, commercially available under trade name Lupragen N 301 from BASF triethylenediamine (TEDA) Catalyst, commercially available under trade name Lupragen N 201 and Lupragen N 203 from BASF

Dimethylethanolamine (DMEA), CAS No: 108-01-0

S-Triazine catalyst, CAS No: 15875-13-5, available under trade name Lupragen N 600 from BASF amine catalyst, commercially available under trade name Dabco PT304 from Evonik

Tin Catalyst, commercially available under trade name DABCO 120 from Evonik

• Blowing agent:

Deionized water

1 ,1-Dichloro-1-fluoroethane (HCFC-141b) The following methods were used to determine properties:

Density in kg/m ³ : GB/T 6343-2009

LOI in %: GB/T 2406.2-2009

B2-fire test in cm GB/T 8626-2007

Compressive strength in kPa: GB/T 8813-2008

Example 1

A polyol blend was prepared by mixing the following materials for 1 minutes at 1800 rpm in a beaker: 42.3 g CF 6925, 12 g TCPP, 4 g TEP, 1.5 g DABCO DC193, 0.5 g Lupragen N301 , 1.5 g Dabco PC46, 2 g Lupragen N201 , 0.4 g DABCO 120, 1.8 g water and 14g HCFC 141b. Then, to the mixture was added 20 g CaCOs fillers, and the mixture was stirred for 3 minutes at 1800 rpm. Finally, 100 g CH2062 C-B was added, and the mixture was stirred for 3 seconds at 1800 rpm. The foam was allowed to rise under free rise conditions.

Example 2-5

All the procedures are repeated according to example 1 except that the fillers used were altered differently as shown in the following Table 1.

Example 6

A polyol blend was prepared by mixing the following materials for 1 minutes at 1800 rpm in a beaker: 33.5 g Lupranol 3915/1 , 8g SAYTEX RB-79, 30 g TCPP, 5 g TEP, 2 g DABCO DC193, 0.9 g Lupragen N301, 2.5 g KX 324, 0.5 g Lupragen N203, 1.1 g water and 12g HCFC 141b. Then, to the mixture was added 5 g Kaolin 1 , and the mixture was stirred for 3 minutes at 1800 rpm. Finally, 110 g CH2062 C-B was added, and the mixture was stirred for 3 seconds at 1800 rpm. The foam was allowed to rise under free rise conditions.

Example 7-9

All the procedures are repeated according to example 6 except that the amounts of Kaolin 1 , and TEP were altered as shown in the following Table 2.

Example 10

A polyol blend was prepared by mixing the following materials for 1 minutes at 1800 rpm in a beaker: 32.2 g Lupranol 3905/2, 10g Lupranol VP9345, 17 g TCPP, 1.5 g DABCO DC193, 1.5 g DMEA, 0.8 g Lupragen N301 , 1.5 g Dabco PT304, 1.5 g Lupragen N600, and 0.9 g water. Then, to the mixture was added 17 g Kaolin 1 , and the mixture was stirred for 3 minutes at 1800 rpm. Finally, 100 g CH2062 C-B was added, and the mixture was stirred for 3 seconds at 1800 rpm. The foam was allowed to rise under free rise conditions.

Example 11-16

All the procedures are repeated according to example 10 except that the fillers used were altered differently as shown in the following Table 3.

Comparative Example 1

A polyol blend was prepared by mixing the following materials for 1 minutes at 1800 rpm in a beaker: 58.6 g CF 6925, 15 g TCPP, 5 g TEP, 1.5 g DABCO DC193, 0.5 g Lupragen N301 , 1.5 g Dabco PC46, 2 g Lupragen N201 , 0.4 g DABCO 120, 1.8 g water and 14g HCFC 141b. Then, 100 g CH2062 C-B was added, and the mixture was stirred for 3 seconds at 1800 rpm. The foam was allowed to rise under free rise conditions.

Comparative Example 2

A polyol blend was prepared by mixing the following materials for 1 minutes at 1800 rpm in a beaker: 33.5 g Lupranol 3915/1 , 8g SAYTEX RB-79, 35 g TCPP, 5 g TEP, 2 g DABCO DC193, 0.9 g Lupragen N301, 2.5 g KX 324, 0.5 g Lupragen N203, 1.1 g water and 12g HCFC 141b. Then, 110 g CH2062 C-B was added, and the mixture was stirred for 3 seconds at 1800 rpm. The foam was allowed to rise under free rise conditions.

Comparative Example 3-5

All the procedures are repeated according to example 10 except that the fillers used were altered differently as shown in the following Table 3. a. Effect of the different inorganic fillers as solid flame retardant

The inventors tested the effect of different inorganic fillers as solid flame retardant on polyurethane foam. Various inventive compositions were prepared according to the procedure stated above for Example 1 , except that the fillers used were altered differently as shown in the following Table 1. The comparative example 1 did not contain fillers.

The Foam density (kg/m3), B2 (cm), LOI (%) and Compressive strength (KPa), were tested according to the methods stated above. The results were summarized in the following Table 1. able 1

It can be seen from the Table 1 that, Examples 1-5, comprising solid flame retardants and lower content of liquid flame retardant, showed B2-fire test less than 9 cm and Compressive strength higher than 115 KPa for Example 2-5, whereas Comparative Example 1 , comprising only liquid flame retardant at a higher ratio, showed B2-fire test of 10.4 cm which cannot meet the increasing high flame retardant requirement as thermal-insulation material for construction. b. Effect of the contents of solid flame retardant

The inventors conducted another experiment to test the effect of the contents of solid flame retardant on polyurethane foam. Various comparative and inventive compositions were prepared according to the procedure stated above for Example 6, except that the amounts of Kaolin 1 , and TEP were altered as shown in the following Table 2.

Table 2

It can be seen from the Table 2 that, the total amounts of flame retardant are controlled at 40 wt%, based on the total weight of the resin components. The Example 6 to Example 9 show better B2-fire performance of less than 7 cm while keep a greater compressive strength of higher than 200 KPa. The inventors surprisingly found that, Comparative Example 2, comprising only liquid flame retardant of 35 wt% TCPP and 5 wt% TEP, displays a worse B2-fire performance of 7.6 cm and lower compressive strength of 187 KPa. In sum, the result proves that Inventive Examples comprising a mixture of liquid flame retardant and inorganic fillers in specific amounts according to the invention showed better B2-fire performance and at the same time good mechanical property. In contrast, Comparative Example 2, comprising only liquid flame retardant, had a worse B2-fire performance with lower Compressive strength. c. Effect of the different source of kaolin fillers with different particle size as solid flame retardant

The inventors further conducted another experiment to test the effect of different source of kaolin fillers with different particle size as solid flame retardant on polyurethane foam. Various inventive compositions were prepared according to the procedure stated above for Example 10, except that the fillers used were altered differently as shown in the following Table 3.

able 3

It can be seen from the Table 3 that, Examples 10-15, comprising lower solid flame retardants and lower content of liquid flame retardant, show B2-fire test equal or less than 9 cm and Compressive strength at Density of 30kg/m ³ higher than 115 KPa. The examples with calcined kaolin (Example 10-14) showed better compressive strength performance than example 15 with washed kaolin. Meanwhile, the particles size of kaolin showed less impact to the foam properties which means a large scope of kaolin can be used in this invention.

Comparative Example 3, with the filler of melamine though also showed good flame-retardant performance, however, melamine tends to settle out from the melamine-containing polyurethane components within a short time which causes processing problem during manufacturing and may bring a series of technological problems. Besides, the cost of melamine is almost four times higher than kaolin.

Comparative Example 4, with the filler of APP also showed similar good flame-retardant performance, however, APP is water sensitive of an extremely high water absorption which affects the water absorption performance and thermal insulation performance of the polyurethane foam product. Besides, due to the larger particle size, APP is also easier to settle out from the APP-containing polyurethane components.

Comparative Example 5, with the filler of EG showed excellent LOI performance, however, the large particle size of EG makes it easy to settle and agglomerate in the polyol system. During the actual manufacture, it also may produce inevitable clogging in the injection port when foaming machine is used to produce foam.

From the observation of experiments, the inventors surprisingly found that kaolin can be stably dispersed in the polyurethane reacting components which brings great advantage for processing and production.

The structures, materials, compositions, and methods described herein are intended to be representative examples of the invention, and it will be understood that the scope of the invention is not limited by the scope of the examples. Those skilled in the art will recognize that the invention may be practiced with variations on the disclosed structures, materials, compositions, and methods, and such variations are regarded as within the ambit of the invention. Thus, it is intended that the present invention cover such modifications and variations as come within the scope of the appended claims and their equivalents.