DE2447943C2 - Flame retardant, hydrophilic crosslinked polyurethane foams and processes for their manufacture - Google Patents

Description

The invention relates to new flame-retardant, hydrophilic polyurethane foams and a method for their Manufacturing.

Numerous attempts have been made to improve the flame retardant properties of polyurethane foams to improve. For example, from US Pat. No. 3,262,894 polyurethane foam materials are known which contain 0.215 to 1.5% by weight of phosphorus-containing and 11 to 30% by weight of aluminum oxide-containing flame-retardant materials Contain substances.

It has been found that the flame retardant properties, measured by the oxygen index, are in a increase the higher aluminum oxide hydrate content disproportionately. Will? R. When added to 100 parts by weight of polyurethane prepolymer i * / part by weight of aluminum oxide hydrate, the oxygen index is 25, which is 50 to 55 when introducing 20C Oew. parts aluminum oxide trihydrate can increase.

It has also been found that this high addition of flame-retardant additives in particular with certain It makes sense to use polyurethane foams that require a large amount of water for foaming and therefore

follow by introducing in the form of an aqueous slurry also much larger amounts of the

Allow additives than when using stoichiometric amounts of water to react with the NCO groups of the prepolymer is possible.

The invention thus relates to flame-retardant, hydrophilic, crosslinked polyurethane foams, obtainable by reacting an isocyanate-capped polyoxyalkylene polyol prepolymer with an aqueous suspension of an aluminum hydrate and a phosphorus-containing additive, at least 40 mol% of the oxyalkylene units being oxyethylene units and the amount of water is selected sufficient that the H ₂ O index has a value of 1,300 to 78,000, and the water has 50 to 400 parts by weight of aluminum hydrate and 1 to 200 parts by weight, preferably 2 to about 100 parts by weight. -Parts of phosphorus-containing additive per 100 parts by weight of prepolymer.

The polyurethane foams according to the invention preferably also contain antimony oxide. That Phosphorus-containing additive consists in particular of a chlorinated polyphosphonate.

It is true that DE-OS 22 63 005 also contains flame-retardant additives made from aluminum oxide hydrate and phosphate ester known, however, mainly in the case of polyvinyl chloride or other thermoplastic or thermosetting Polymers are used, which polyurethane foams generally do not belong to, The polyurethane compositions according to the invention generally have a hydrophilic polyurethane structure and contain an aluminum oxide hydrate additive and a phosphorus-containing additive, evenly distributed throughout, with both additives being in combination with one another.

The phosphorus-containing additives which have been found to be useful for the purposes according to the invention have include phosphites, polyphosphites, ammonium phosphates. Phosphate salts, polyphosphates, organic Phosphates, phosphonates and polyphosphonates and mixtures thereof. A good usable material corresponds to the structural formula

ClCH ₂ CH ₂ OPO-CH-

₂ CH

ClCH ₂ CH ₂ CH ₃

O CH,

p_0 - CH-

CHjCH ₃ Cl

0 -P (OCH ₂ -CH ₂ Cl) ₂

It is insoluble in water and can be added to the reaction system in the form of an emulsion, suspension or dispersion can be added.

Another phosphorus additive that is suitable for use in combination with aluminum hydrate An ammonium polyphosphate is suitable for the production of the polyurethane compositions according to the invention.

In general, phosphorus-containing materials are derivatives of P ₂ Os. phosphorous acid and phosphoric acid and phosphorus halides; Urea phosphoric acid, monophesiyl phosphate and the like; Sodium lexamethaphosphate, ammonium salts of phosphonomethylated ethers, and the like; Melamine phosphate, diammonium phosphate and the like; Melamine phosphate and salts of phosphorous acid or phosphoric acid with organic amines; Salts or urea-phosphoric acid, of monophenyl phosphate, phosphorus pentoxide and chlorides of partially esterified phosphoric acids, phosphonomethylated ethers, diethyl chlorophosphate, triallyl phosphate. Phosphorus oxytriamide can be used, as can tris (/? - chloroethyl) phosphate, tris (23-dibromoethyl) phosphate

Also trikre-ovlphosphat, cresyl-diphenylphosphat, 2-Äthylhexyldiphenylphosphat, trialkylphosphate and Triaryl phosphates or an ester of the formula

(C ₂ H ₅ O) ₂ P (O) CH ₂ N (CH ₂ CH ₂ OH) ₂

can be used.

The amount of aluminum oxydhyrate is preferably 100 to 275 parts by weight and the amount of the phosphorus-containing additive is 2 to 100 parts by weight.

The Aluminiumoxydhydrate used for the purpose of this invention are known per se, and put them in highly purified state organic, white, granular, crystalline powder of the formula Al ₂ O j · χ H ₂ O. They are generally obtained by the Bayer process from bauxite and contain small amounts of soda, iron oxide and silicon dioxide. They are chemically inert and are used as fillers.

The particle size of the usable aluminum oxide hydrates ranges from about 0.5 to about Γα? μΐπ. Finer ones Particles that have a size of about 6.5 to about 9.5 μm are particularly suitable. Where the color of the Polyurethane foam is important, the aluminum oxide hydrate should be snow white.

A group of polyurethanes which can be used for the purposes of the invention is disclosed in DE-OS 23 19 70ö described and are generally crosslinked polyurethane foams that are produced using a blocked polyoxyethylene glycol component and large amounts of water.

The polyoxyethylene polyols used in the present invention are water-soluble reaction products resulting from the polymerization of ethylene oxide in the presence of a polyfunctional one Starter compounds such as water, ethylene glycol, glycerin, pentaerythritol, sucrose and the like originate. The molecular weights can be varied within a wide range, through appropriate settings. development of the relative proportions of the ethylene oxide monomer to the starter compound.

Here, the polymerization products based on ethylene oxide can also be polymerized in varying amounts of relatively hydrophobic co-monomers such as propylene oxide or butylene oxide as a copolymer, block copolymer or in both forms in such a way that the copolymers remain hydrophilic but have other features, such as improved low temperature Flexibility, improved resistance to deformation after compression, or improved resilience. Up to 40 to 60 mol%, recommended about 25 to 45 mol- ¹ Vb of the relatively hydrophobic co-monomers can be copolymerized with the ethylene oxide monomers, with hydrophilic echoes with a cross-linked network structure still being able to be obtained, all of these Polyol derivatives have a hydroxyl functionality of about 2 or above and an ethylene oxide content of about 40 mol% up to about 100 mol%, preferably above about 55 mol%.

Polyoxyäthylenpoliyole, which are used as a reaction component for the production of the prepolymer, can have average molecular weights from about 200 to about 20,000, preferably from about 600 to about 6,000, and the hydroxyl functionality is about 2 or more, preferably about 2 to about 8.

The polyoxyethylene polyols are obtained by reaction with a polyisocyanate or with polyisothiocyanates capped, d. H. terminally substituted or closed. Suitable capping materials are polyaryl polyisocyanate, as described in US Pat. No. 2,683,730, tolylene diisocyanate, triphenylmethane-4,4 ', 4 "-triisocyanate, ßenzene-1,3,5-triisocyanate, toluene-2,4, 6-triisocyanate, diphenyl-2,3,3'-triisocyanate, hexamethylene diisocyanate, xylene diisocyanate, chlorophenylene diisocyanate, diphenylmethane-4,4'-diisocyanate, naphthalene-1,5-diisocyanate, xylene-A / t'-diisothiocyanate, 33'- Dimethyl-4,4'-biphenylene diisocyanate, 33'-dimethoxy-4,4'-bi- phenylene diisocyanate, 22 ', 5,5'-tetramethyl-4,4'-biphynylene diisocyanate, 4,4'-methylene-bis (phenyl isocyanate), 4,4'-sulfonyl-bis (phenyl isocyanate), 4,4'-methylene-di-o-tolyl isocyanate, ethylene diisocyanate, ethylene diisothiocyanate, trimethylene diisocyanate and the like.

Capping of the polyoxyethylene polyol can be accomplished using either about stoichiometric amounts of the reactants or an excess of isocyanate to ensure complete capping ensure the polyol.

Particularly useful foams can be produced from a prepolymer in which a polyoxyethylene polyol is capped with a polyisocyanate in such a way that the capped product has a reaction functionality of more than two.

Polyurethane foams according to the invention are then produced by adding water to the prepolymer is incorporated together with aluminum oxide hydrate and a phosphorus-containing additive as a flame-retardant material in the stated amounts.

For the purpose of further improvement, a dispersant or an emulsifier can be incorporated into the prepolymer.

It is also possible to use as a prepolymer a capped polyoxyethylene polyol which has a functionality of approximately 2%, and in this case a polyfunctional, reactive member, for example one containing 3 or more to about 8 reactive amine, hydroxy -, thiol or carboxylate sites per Average molecule incorporated into it to form a three-dimensional crosslinked product. To the in

Polyfunctional, reactive members in question include materials such as diethylenetriamine. Triethylenetetramine, tetraethylenepentamine. Polyethyleneimine, glycerine. Trimethylolpropane, pentaerythritol, tolylene-2,4,6-triamine, Ethylenediamine, trimethylenediamine, tramethylenediamine, pentamethylenediamine, hexamethylenediamine, Aminoethanol, diethanolamine, hydrazine, triethanolamine. Benzene 1,2,4-tricarboxylic acid, Niirilolriacetic acid, Citric acid and 4,4'-methylene-bis - (<* - chloroaniline) and the like.

Although the foaming of the resin component used according to the invention in the manner mentioned is easy to carry out, it is also possible - although not absolutely necessary - foaming to use supporting supplementary materials, as they are known from the manufacture of artificial sponges.

ίο How significant is the addition of aluminum oxide hydrate and a phosphorus-containing material, can be based on the determination of the oxygen index for testing the flammability of plastics in accordance with ASTM D-2863-70. This is the minimum concentration of oxygen in one slowly ascending mixture of oxygen and nitrogen measured, which just about to burn can maintain, expressed as a volume percentage, under the equilibrium conditions of a candle-lit

is men-like burning, taking a balance between the heat from the combustion of the test specimen and the heat that is lost to the environment takes place.

In addition, the polyurethane foams according to the invention have a low smoke density in comparison to other polyurethane foams which the additives are not incorporated.

Polyurethane foams that do not have any additives in the special Aüuitiv-Kümbinaiicn, as they are according to the teaching of the invention has been found to be essential, have oxygen index values from about 15 to about 30 on. In contrast to this, the polyurethane compositions according to the invention have corresponding oxygen index values up to about 70 and above.

The aqueous component can be used as water, as an aqueous slurry or suspension, as an aqueous emulsion or aqueous solution in which water-soluble materials are present.

In prior art polyurethane formation reactions it is known to use an excess of To use water in the prepolymer foam formulations to improve properties (Saunders and Frisch “Polyurethanes”, edited by Interscience Publishers. page 43). When water is used in sub-stoichiometric amounts, the screen becomes more networked and is stronger and has a lower elasticity and higher density. According to the findings, a large excess of water is required the authors on the free isocyanate groups and leaves isocyanate groups in one for effective Crosslinking in an insufficient amount and thus results in the formation of many free amino-eno groups. If the water content increases, the foam density decreases, and a water excess of 30 to 5C% over the stoichiometric amount also has a noticeable deterioration in physical properties Episode.

According to the prior art, is a water index

WMjertndex

Equivalents of NCO

* o of 100 normal, with 1 mol of water ultimately consuming 2 NCO groups, ie 1.0 mol of H ₂ O-2 equivalents -OH, reacting with 2 equivalents of NCO. A small excess of isocyanate, generally from 3 to 5%, is common practice here, especially in the production of elastic foams (HjO index 103-105).

If the resin component according to the invention and the water are used in amounts of about OJ mol H20 / M0I NCO groups (H ₂ O index value 100) up to about 2 mol H ₂ O / mol NCO groups (H ₂ O index Weri

400), this results in only very slight foaming, unless materials such as surface-active ones Substances and catalysts or the like are incorporated. Amounts up to about 2 moles H2O / MOI NCO (HjO index value 400) require the use of a catalyst. Using about 6.5 moles HjO / mol NCO groups (HjO index value 1300) up to about 390 mol H2O / MOI NCO groups (HjO index value 78,000), surprisingly, the result is the formation of good foams, the key figures of which change with

improve so increasing molar amounts of water. Therefore, the available water content in the aqueous component is from about 6.5 to about 390 mol H ^ / NCO groups in the resin component, & h. the H ₂ U index value is from about 1300 to 78,000, preferably from about 4,000 to about 40,000, which means the presence of about 20 to about 200 mol of H 1 / NCO groups.

What is meant here is the water that is available for the reaction with the resin component, and

although without taking into account the water that can separate out during the reaction, or the additional introduced water, which because of further water-absorbing or water-binding components or Additives may be required which are present in the aqueous reaction component and form this.

The use of large molar excesses of water has several technically important advantages

compared to conventional polyurethane foam compounds with flame-retardant properties. So must z. In contrast to conventional polyurethane foam compositions, for example, the water content cannot be carefully adjusted to the theoretically required amount, usually to an H ₂ O index value well below 400 (2.0 mol H ₂ O / NCO groups in the polyurethane-forming reaction components) and the flame retardants must be incorporated separately. This low water content dictates the use of a catalyst in order to advance the rate of the polymerization foaming reaction and it makes an intensively operated mixing stage necessary in order to bring about good mixing of the reaction components and the catalyst and thus ensure the formation of a controllable and uniform cell product, whereby a The addition of other additives is avoided. In contrast to this, the method according to the invention requires very large but controlled excesses of water, for example

typically correspond to a H2O index value of from about 1,300 to about 78,000. When applying this Work technique, the product quality and uniformity is not very dependent on the accuracy of the Metering in or mixing of the aqueous component, and the use of a polymerization catalyst or accelerator, are only possible as an optional measure. Hence the additives according to the invention incorporated into the polyurethane structure at the time of foaming.

The hydrophilic foams of the invention can be formulated so that they are flexible in nature, are semi-hard or hard and that - depending on your wishes - they are mainly of the open-cell type or the Hau ^ rjache belong to the closed-cell type.

They can therefore be used for upholstering furniture and vehicles, for mattresses and foam covers Mattress covers and pillows, upholstery par excellence, mattress cylinders, sound-absorbing wall coverings, Back coverings of carpets and coarse woolen blankets and the like find technical application.

Example I.

It is a prepolymer of 2 moles of polyethylene glycol 1000, 1 mole of trimethylolpropane and 7.7 moles of the technical 80:20 mixture made of 2,4- and 2,6-tolyl diisocyanate. Then 200 g of the prepolymer are mixed with 2 g of a polyoxyalkylene polysiloxane as a surface-active silicone. Next, 200 g of water are added to this and the mixture is stirred with a motor-driven propeller stirrer. To the ZcriCtiäüiViCN is the mBicTiäi in an open molding box VOiTi format 15.24 Cni X! 5.24 CnI X 15.24 CiTi filled, removed after 10 minutes, dried for 16 hours in a drying cabinet at 70 ° C and then cut into strips of the format 12.7 mm 12.7 mm χ 12.7 mm. The strip pieces are then further dried in a drying cabinet at 70 ° C for 16 hours and then equilibrated in a room with a relative humidity of 50% for 16 hours at 25 ° C. The oxygen index value determined according to the standard test was 26.2%.

Example 2 ■■ $ The procedure is as in Example 1, with the modification that from 100 g of the prepolymer of Example 1.1 g ί |

of the surface-active silicone, 0.1 g of blue pigment in one phase and 100 g of calcium carbonate and 100 g Water is run out in the other phase. The oxygen index value, which was determined on a vertically cut-out sample, was 223%. A similar value was found for a sample cut out horizontally.

Example 3

The procedure is as in Example 2 with the modification that 200 g of CaCOj and 200 g of water in the aqueous Phase can be used. The Ssufirstoffindex-Weri was at a vertike! cut out Te-i! pieces 30.2% and 30.8% for a horizontally cut section.

Example 4 4C

The procedure was as in Example 2, with the modification that 100 parts by weight of the prepolymer, 1 part by weight of the surface-active silicone product L-520.0.1 part by weight of blue dye and 200 parts by weight Water can be used. The amount of water also contained 200 parts by weight of aluminum oxide trihydrate and 22.2 parts by weight of ammonium polyphosphate. The oxygen index value was found to be 70.2% both for the vertically and for the horizontally cut part.

Example 5

The procedure was as in Example 4 with the modification that 22.2 parts by weight of a polyphosphonate so instead of ammonium polyphosphate and an additional 2 parts by weight of antimony oxide were used. Of the The oxygen index value was determined to be 693% for both the vertical and horizontal sections.

Example 6

The procedure was as in Example 4 with the modification that 12 parts by weight of ammonium caseinate as Dispersants for the aluminum hydrate were also used. The foam produced had an oxygen index value of about 60%.

Example 7

The procedure was as in Example 4, with the modification that the ammonium polyphosphate was completely was omitted. The oxygen index value was about 39%.

Example 8 The procedure was as in Example 4, with the modification that the aluminum hydrate was omitted completely

T /

became. The oxygen index value was approximately 28%.

Example 9

The procedure was as in Example 5, with the modification that the aluminum hydrate was omitted completely became. The season index value was about 27%.

Example 10

The procedure was as in Example 9, with the modification that the Anlimonoxyd was also omitted from the formulation. The measured oxygen index value was about 25%.

Test report

A polymer was prepared from 2 mol of polyethylene glycol, 1 mol of trimethylol propylene and 7.7 mol of 2,4- and 2,6-toluene diisocyanate (mixture 80:20). In 100 g of this prepolymer, 1 g of polyoxyalkylene siloxane (L-520 from Union Carbide) and 200 g of water were added and mixed vigorously, and the mixture was placed in a 500 cm ¹ paper cup. After 10 minutes the foam formed was removed, dried for 16 hours at 70 "C" and cut into strips of cn. 1 cm χ! 2 c-. cut and these dried again and ifc h bsi 25 "C and 50% relative humidity equilibrated. The oxygen index was 23.9%.

Another series of foams were made in the same manner, but with varying amounts Ammonium polyphosphate and Al2O] · 3 H ^ O were added to the water before mixing with the prepolymer became. The oxygen indiccs obtained are shown in Table I. From the attached graphic The illustration shows the disproportionate increase in the oxygen indices with the increasing addition of the

Flame retardants. This oxygen index was measured according to ASTM D-2863-74.

Prepolymers were also made by mixing polyols with oxyethylene groups and trimethylolpropane and addition to toluene diisocyanate (95% of the theoretical amount) and heating to 50 "C. After 16 Hours were 100 parts prepolymer / u 257 parts of a mixture of 130 parts Al (OH) i, 22 parts NH <-polyphosphate, 4 parts cellulose acetate. 1 part of Tcnsid (Pluronic) and 100 parts of water are added. The received

The values are given in Table II for 4 comparative experiments, which show that the oxygen index also rises as the oxyethylene content in the polyol rises.

Table I. 35

Foam no. InGew.-Tcilen per 100 (low. · ¹ Part I " repolymer Oxygen- NlU polyphosphate ΛΙ, Ο i-trihydrate Index. % I. 8th 0 23.5 2 20th 0 23.5 3 0 50 252 4th 8th 50 25.2 5 20th 50 26.8 6th 0 100 27.8 7th 8th 100 29.4 8th 20th 100 33.3 CT 0 150 33.8 10 8th 150 37.4 11th 20th 150 39.4 ! 2 0 200 38.0 13th 8th 200 51.4 14th 20th 200 54.0 Tables attempt Polyol / TMOP % Ethylene oxide Prepolymer Oxygen- No. Molar ratio in the polyol Parts Index,% 1 1: 1 10 100 27.0 2 3: 1 50 100 40.0 3 3: 1 75 100 46.2 4th 3: 1 100 100 51.0 1 sheet of drawings

Claims (5)

Patent claims: 1. Flame-retardant, hydrophilic, crosslinked polyurethane foams, obtainable by reacting an isocyanate-capped polyoxyalkylene polyol prepolymer with an aqueous slurry of an aluminum moxydhydrates and a phosphorus-containing additive, wherein at least 40 mol% of the oxyalkylene units are oxyethylene units and the amount of water is sufficient that the H2O index is one Value of 1300 to 78,000 and the water has 50 to 400 parts by weight of aluminum oxide hydrate and 1 to Contains 200 parts by weight of phosphorus-containing additive per 100 parts by weight of prepolymer 2. Poryurethane foam according to claim I _1, characterized in that it also contains antimony oxide and the phosphorus-containing additive consists of a chlorinated polyphosphonate 3. Polyurethane foam according to claim 1 to 2, characterized in that the aluminum oxide hydrate amount is 100 to 275 parts by weight and the amount of the phosphorus-containing additive is 2 to 100 parts by weight. 4. A method for producing the flame-retardant polyurethane foam according to claim 1 to 3, characterized characterized that the Prepoiymer water together with aluminum oxide hydrate and a phospliorhal term additive incorporated as a flame retardant material in the amounts specified in claim 1 will. 5. The method according to claim 4, characterized in that a dispersant or an emulsifier is incorporated for the purpose of further improvement.