DE2208951A1 - Urethane foams with low smoke generation - Google Patents

Description

Dr. Michael Hann. 24. F-brua

Patent attorney

635 Bad Nauheim. H / W (42J; ·. · -3 ·.

Burgallee 12b

PPG Industries, Inc., Pittsburgh, Pa., USA LOW SMOKE URETHANE FOAM Priority: USA / Ser. No. 119,952 of March 1, 1971

This invention relates to urethane foams containing a flame retardant and producing smoke has been reduced by using isophthalic acid in the mixture of starting materials.

In the art, increasing attention is paid to smoke generation, that of polyurethane foams occurs that contain flame retardants. It is obvious that also a polyurethane foam that Only a small spread of the flame allowed, which poses danger if on contact with a flame there is sufficient smoke to annoy the occupants of a room to such an extent that they are unable to see or "their breathing is impaired. It Therefore, methods have already been developed to determine the amount of smoke developed in this process, whereby such a method, e.g., in the Journal of Cellular Plastics (January 1967), pages 41-43 is described. The "Underwriters Laboratory" has also developed test methods and evaluations for measuring smoke development (e.g. UL-E84 tunnel tests and also UL-723).

It has now been found that the amount of smoke evolved in a polyurethane foam that contains phosphorus iges flame retardant, can significantly reduce the other properties of the foam significantly affecting the mix of the starting materials isophthalic acid. Which has isophthalic acid expediently added in finely divided form in addition, the advantageous effect that it prevents the spread of a flame or fire in the case of a polyurethane foam restricts. This is very surprising as most acids help lower either The formation of smoke and influencing the spread of a fire have no effect or the properties of the foam worsen to a great extent. The amount of isophthalic acid to be used may vary depending on the Composition of the other starting materials within wide limits

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fluctuate, but it can be determined by experiments without difficulty, with at least such amounts of isophthalic acid used to be that effective Reduction in smoke development occurs. In general, about 5 to about 40 wt.% Based on the Total weight of the mixture of raw materials, used. Amounts of about 15 to about 25% by weight of the are preferred Total preparation.

The polyurethane foams with low smoke development According to this invention, any flame retardant foam can be obtained by using an organic Reacts polyisocyanate with a material with active or reactive hydrogen, these starting materials Contain phosphorus-based flame retardant.

Any reactive hydrogen compounds can be used as the active hydrogen material are suitable as starting materials for urethane production. Preferably the active hydrogen material is one organic compound or resin having an isocyanate equivalent between about 70 and about 280. Currently For example, preferred such compounds are polyether polyols having a hydroxyl value between about 200 and about 800, such as the reaction products of a polyhydroxyl compound having from 3 to 8 hydroxyl groups and an alkylene oxide having from 2 to 4 carbon atoms. The most preferred Polyether polyols consist essentially of carbon, hydrogen and oxygen.

The compounds with reactive hydrogen that are commonly used in the manufacture of polyurethane foams include, as a class of major representatives, various long chain aliphatic polyols, polyether polyols, polyester polyols and like compounds. The aliphatic polyols that can be used in this invention include those diols that can be used by a carbon chain of 6 to 20 or more carbon atoms are separated. Since such diols are only bifunctional are, they are usually only in small quantities as starting materials in the masses to be foamed for the manufacture

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position of the new solid foams according to this invention available. For the purposes of this invention, small amounts of aliphatic diols in such amounts that neither the rigidity of the cured foam nor its excellent Impair dimensional stability.

Aliphatic triols such as hexanetriol and polyether polyols obtained by the oxyalkylation of these aliphatic Receives triplets, can in the formulations to be foamed according to the invention in small or large amounts be used. In the invention, however, additional compounds with reactive hydrogen are also preferred used that are higher than trifunctional, and it is also preferred, the trifunctional polyols and Use polyether in relatively small quantities. Among the aliphatic triols, which are used as a component with reactive Hydrogen can be used include aliphatic triols having 6 or more carbon atoms. Typical triplets are z. B.: trimethylolethane, trimethylolpropane, glycerine, 1,2,6-hexanetriol and the like. The production of Trifunctional polyether polyols particularly suitable for rigid polyurethane foams have hydroxyl numbers of greater than about 200 and especially hydroxyl numbers of greater than about 300.

Tetrafunctional polyether polyols suitable for the invention and polyether polyols with higher functionality can be obtained by adding an alkylene oxide such as ethylene oxide, Propylene oxide or butylene oxide, reacted with a polyol with 4 or more free hydroxyl groups. Typical tetrafunctional parts Polyether polyols with higher functionality are obtained by oxyalkylation obtained from e.g. the following polyols: pentaerythritol, sucrose, 2,2,6,6-tetrakis (hydroxymethyl) cyclohexanol, Glucose, sorbitol, mannitol, degraded starches, degraded celluloses, diglycerin, <* · -methyl glucoside and the like. When such polyether polyols are used to produce the new solid foams according to the invention they should expediently have a hydroxyl number of greater than about 200, and especially greater than about 250, but which will give the best results when the polyether polyols have hydroxyl numbers higher than have about 300.

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In addition to aliphatic polyols and aliphatic .Polyether polyols, polyester resins with hydroxyl groups can also be used can be used for the production of the solid polyurethane foams according to the invention. One obtains such Polyester resins, by reacting an excess of a polyol with a polycarboxylic acid, in particular a dicarboxylic acid. The polyols can typically be can be used: ethylene glycol, propylene glycol, butylene glycol, glycerine, trimethylolpropane, trimethylolfthan, 1,2,6-hexanetriol, pentaerythritol, diethylene glycol, dipropylene glycol and the like. Typical dicarboxylic acids for this field includes: adipic acid, succinic acid, azelaic acid, phthalic acid, isophthalic acid, terephthalic acid, chlorenedic acid, tetrabromophthalic acid, and the like and also the corresponding anhydrides, as far as they occur. Long-chain dimer acids can also be used in order to obtain polyols suitable for the invention, e.g. by esterification with polyols, especially diols, such as ethylene glycol and the like. For the purposes of this invention, suitable polyesters should expediently have a minimum hydroxyl number of about 200, preferably of about 250, however, the best results are obtained with those polyesters which have hydroxyl numbers greater than about 300 to have.

Another suitable class of polyols that can be used in the invention are trialkanolamines from suitable molecular weight and the alkylene oxide adducts thereof formed by reaction with alkylene oxides. Examples of lower molecular weight trialkanolamines include triethanolamine, triisopropanolamine, and tributanolamine. The alkylene oxide adducts that are used are preferred are those in which the oxyalkylene moiety contains 2-4 carbon atoms.

Another class of suitable polyols that can be used are the alkylene oxide adducts of mono- and polyamines and also of ammonia. These connections can are referred to as aminic polyols.

The mono- and polyamines are preferably reacted with alkylene oxides containing 2-4 carbon atoms, e.g. Ethylene oxide, 1,2-epoxypropane, the epoxybutanes and mixtures thereof. The mono- and polyamines suitable for this reaction with alkylene oxides include, inter alia. Methylamine, ethyl

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anine, isopropylarain, butylamine, benzylamine, aniline, toluidine, naphthylamine, ethylenediamine, diethylenetriamine, triethylenetetramine, 1,3-butanedlamine, 1,3-propanediamine, 1,4-butanediamine, 1,2-, 1,3- _f 1.4- , 1,5 and 1,6-hexanediamine _t phenylenediamines, toluenediamines, naphthalenediamines and the like. Of the compounds of the above groups of particular interest are Ν, Ν, Ν ¹ , N ^f -Tetrakis (2-hydroxyäthyDäthylenediamine, Ν, Ν, Ν ¹ , N'-tetrakis (2-hydroxypropyl) ethylenediamine, Ν, Ν, Ν *, N ^l -pentakis (2-hydroxypropyl) diethylenetriamine, phenyldiisopropanolamine and the adducts of higher alkylene oxides with aniline, etc. Other compounds of this type which deserve special mention are the alkylene oxide adducts of aniline or substituted aniline / formaldehyde condensation products.

Other active hydrogen materials used in the new urethane foams of this invention are phenol-formaldehyde condensation products, amine compounds, such as lethanolamine, triethanolamine and the same. Another material used in making the foams of this invention is castor oil and its derivatives. Furthermore, the oxyalkylation products of Polyamine polyamide compounds suitable as they are at the reaction of dicarboxylic acids with polyamines.

It is obvious that where the connection is with active hydrogen containing halogen, such as bromine or chlorine, or nitrogen, a smaller amount of phosphorus is required is, as when using compounds with active hydrogen, consisting only of carbon, hydrogen and oxygen exist, since the elements mentioned help to increase the flame retardancy.

Among the organic polyisocyanates that react with the compounds with active hydrogen to form the polyurethane foams can be implemented include the following:

Toluene diisocyanate, chlorophenyl-2,4-diisocyanate, ethylene diisocyanate, 1,4-tetramethylene diisocyanate, paraphenylene diisocyanate, Hexamethylene diisocyanate and the like.

Although it is possible to form the above diisocyanates directly with the active hydrogen material of foams to implement, but prepolymers of these diisocyanates are preferred if they are used for the

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Production of rigid or hard foams, used will.

If desired, the polyurethane foams directly of an organic polyisocyanate and an active hydrogen material without producing a prepolymer to produce, polynuclear polyisocyanates of the following type are preferably used:

Diphenyl diisocyanate, triphenyl diisocyanate, 3,3'-dimethyl-4,4 ^l b-phenylene diisocyanate, 3,3'-dimethoxy-4,4'-biphenylene diisocyanate, polymethylene-polyphenyl ^{isocyanate, diphenylmethane-4,4 1} -diisocyanate, triphenylmethane triisocyanate, 1,5- Naphthalene diisocyanate, 3,3 * -dimethyldiphenylmethane-4,4'-diisocyanate and the like.

Of the preferred polyisocyanates, it has been found that the best results are achieved when the polymeric polyisocyanates have a functionality greater than 2.0. Examples of polymeric polyisocyanates include the following compounds:

Crude diphenylmethane-4,4'-diisocyanate, commonly referred to as crude ¹¹ MDI "and having a functionality of about 2.5 to 2.6. Although it is possible to use solid organic polyisocyanates in the present invention by using it melts before the reaction with the other starting materials for the foams, liquid organic polyisocyanates are preferably used.

Another organic polyisocyanate that is particularly useful is crude tolylene diisocyanate, commonly known as raw "TDI" is called and about 85% TDI and about 15% on a polymeric diisocyanate and has a functionality of about 2.1.

Polymethylene polyphenyl isocyanate, which is referred to here as “PAPI” and has an isocyanate functionality of greater than about 2.4, has been found to be particularly suitable.

In the production of the polyurethane foams one uses about 1 equivalent of the active hydrogen material or resin with one equivalent of an organic polyisocyanate. It is often beneficial to use a small amount of a urethane catalyst to add and usually Suitable emulsifiers and blowing agents are added to the preparations of the starting materials for foam production.

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The relative proportion of the organic isocyanate used for the polyurethane foams can be varied within wide limits. In general, the isocyanate component is used in an amount stoffaton as a reactive isocyanate group on each reactive hydrogen "corresponding to the other compound, said compound is usually a polyol, a polyamine or a similar V _e rbindung with reactive hydrogen. However, some of the organic polyisocyanates tend to volatilize and it may therefore be desirable to compensate for such losses. Most of the time one can work within a range of 0.5 to about 2 equivalents of organic polyisocyanate per equivalent of the polyol component in the finished material, but smaller or larger amounts can be used with good results. In order to promote the formation of the polyurethane reactions during the final curing of the polyurethane resins, catalysts are generally added. Such catalysts include, for example tertiary amines, hydroxy! ₉ amines, organic tin salts and the like. An incomplete list of such known catalysts is given below

Tetramethylethylenediamine (anhydrous) (TMÄDA) Tetramethylguanidine (TMG)
Tetramethyl-1,3-butanediamine (TMBDA) triethylenediamine of the formula:

Dimethylethanolamine (DMÄA)

Tin esters, such as tin (II) oleate, tin (II) octoate, Dibutyl tin dilaurate, dibutyl tin diacetate and the like.

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Numerous other catalysts can be used in place of these catalysts. The amount of used Catalysts can range from about 0.05 to about 5% or more, based on the total weight of the polyols used. Mixtures of the aforementioned and / or other catalysts can also be used.

To the polyol-polyisocyanate mixture a foam-like or to impart cellular structure becomes a suitable blowing agent or propellant or a mixture of such Agent added or generated in situ. Such agents are in particular liquid, but relatively easily volatile Halogenated hydrocarbons suitable, such as the following perhalogenated hydrocarbons, the 1, 2 or up to 4 Contain carbon atoms. Such agents include, for example, the following:

CCl ₃ F CHCl ₂ F CCl ₂ F ₂ CClF ₃ C ₂ Cl ₂ F ₄ CHClF ₂

The halogenated hydrocarbons having one and two carbon atoms are preferred and of these, trichloromonofluoromethane and dichlorodifluoromethane are most particularly suitable for a large-scale application. These remedies are called liquid celes in amounts of about 10% or less to about 20% or more, based on the total weight of the preparation for the polyol-polyisocyanate mixtures added or one or more components of the preparation. You will essentially be in the liquid Mixture evaporates to induce cell formation. Subsequently, the mixture becomes in the cellular state hardened.

Although the halogenated hydrocarbons are particularly suitable as blowing agents if they have very good insulating properties If desired, other blowing agents such as water, carbon dioxide, and the like can also be used in the invention will.

In order to achieve the most uniform possible distribution of the various components of the liquid system and around the To ensure the desired cell formation, an emulsifier and / or another surface-active agent can be added to the mixture attached. These materials only have a physical influence and are by no means always necessary,

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especially when foams of higher density getting produced. There are very many such products and several hundred such products are available in stores * borrowed. Some of these are published in the publication "DETERGENTS AND EMULSIFIERS - UP TO DATE" by John W. McCutcheon, Inc., 475 Fifth Avenue, New York, New York.

Examples of surfactants that can be used are e.g. B. the so-called "Pluronics", which have been described as condensates of ethylene oxide with a hydrophobic base from the condensation of propylene oxide with propylene glycol. They have molecular weights in the range of about 2,000 to about 8,000 and should correspond to the following structure:

Another class of surfactants includes the so-called "tetronics", which result from the accumulation of Propylene oxide on ethylene diamine is formed with the subsequent addition of ethylene oxide. These connections correspond of the following structure:

HO (C ₂ H ₄ O) _t (C ₃ H ₆ O

NCH ₂ CH ₂ N

Another well-suited class of surfactants includes the so-called "tweens", which are known as monoesters of higher fatty acids, such as lauric acid, stearic acid and oleic acid, and polyoxyethylene sorbitan are known. Another Class of surfactants used to maintain cell structure during foaming and hardening of Polyurethane resins have proven to be very suitable, is formed from soluble, liquid derivatives of silicones. Such a product roughly corresponds to the structure

_R '»Si

O (R ₉ SiO) _r (C _n H _2n O) _z R ""

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In this formula, R ¹ "and R ^{IMI are} monovalent hydrocarbon radicals, whereas R _{q is} a divalent hydrocarbon radical; p, q and r are integers of at least 1, but they can also be significantly higher, e.g. 2, J, 4, 5, 6 or higher numbers up to about 20; η is an integer from about 2 to about 4 and ζ is an integer of at least 5 or a higher number, e.g. 6, 7, 8, 9, 10 or more up to about 25. One of these products is known commercially as "Dow-Corning 199". Another also very suitable silicone surfactant is the so-called "Silicone L-521" according to the following formula:

A (C3H6O) C ₄ H ₉

C2H5 Si O (-SiO -) - (C ₂ H ₄ O) - (C ₃ H ₆ O) C4H9

/ 50 V 750

C ₂ H ₄ OF 3H ₆ O] C ₄ H ₉

Other surface-active agents can also be used, in particular liquid and / or soluble non-ionic agents of this type. The surface-active agents, which can also be referred to here as foam generators, are conveniently used in amounts of about 0.1 to about 3 wt. -% used, based on the mixture of the polyol component and the organic polyisocyanate component. In the case of relatively heavy foams, for example those with a density of 0.080 to 0.096 g / ecm and higher, the use of the foam generator can be dispensed with at all. The foams of this invention are self-extinguishing as determined by ASTM D-1962-59T. In general, the minimum phosphorus content is from about 0.5 to about 2%, depending on the composition of the mixtures. _t

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- ⁿ "■ 22D8951

The phosphorus compound used for flame-proofing can be in the form of a reactive or a non-reactive phosphorus compound. The reactive phosphorus compound can be either a phosphorus compound having active hydrogen atoms, such as a polyol, or a phosphorus-containing isocyanate. It follows that the behavior of the phosphorus compound in the formation of the polyurethanes depends on the type of groups it contains. As can be seen from this description, the selection of the individual means for the production of flame-retardant polyurethane foams is not essential to the invention, but the invention is to be seen in the use of fumaric acid in the production of the flame-resistant, phosphorus-containing polyurethane foams, whereby the smoke formation of such foams in a fire or is significantly reduced when it comes into contact with a flame. Numerous compounds can be added to the polyurethane foams as phosphorus-containing compounds. Such phosphorus-containing additives are known in the art and are in patent class 260, subclass 2.5 of the V.St.A. numerous examples of these phosphorus compounds have been described. It therefore does not seem necessary to enumerate all possible materials of this type, since compounds of this type are readily available to the person skilled in the art from the known prior art. The phosphorus-containing polyols can be derived, for example, from phosphorous acid, phosphonic acid, phosphoric acid or pyrophosphoric acid. The polyols of these acids can be prepared in a variety of processes, for example by reacting the acids with alkylene oxides or with halogen-substituted alkylene oxides or by esterifying these acids or by transesterifying acid esters with polyalkylene glycols and polyoxyalkylene glycols. A particularly suitable group of polyols of this type is the oxyalkylation product of an acid ester of an oxyacid of phosphorus and a monohydric alcohol as described in the patent of V.St. 3 407 150. Other phosphorus-containing polyols that can be used include diethyl Ν, Ν ¹ -diethanolaminomethyl phosphonate (Fyrol i + 6), bis (hydroxypolypropoxypropyl) -N, N'-diethanolaminomethyl phosphonate, tris (hydroxypropyl) phosphate, Trisfoctakis (2-hydroxypropyl) sucrose phosphite, trisdipropylene glycol phosphite, Tris ft etrakis (2-hydroxypropyl) i-methylglycos id phosphite.

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Flame retardants containing phosphorus without reactive Groups are e.g. tris (chloroethyl) phosphate, tris (chloropropyl) phosphate, tris (2,3-dichloropropyl) phosphate, tris (2,3-dibromopropyl) phosphate, bis (beta-chloroethyl) vinyl phosphate.

Examples of phosphorus-containing polyisocyanates are ethyl diisocyanate of phosphorous acid, CH ₅ P (O) (NCO) ₂ ; the phenyl diisocyanate of hypophosphorous acid, called C ₂ H ₅ P (NCO) ₂ .

In the following examples, some are currently preferred Embodiments of the invention explained in more detail. All information Parts and percentages are given by weight, unless expressly stated otherwise.

example 1

This example used a sucrose polyether polyol such as that described in U.S. Patents 3,085,085, 3,153,002, and 3,222,357. This product was based on one mol of sucrose, 0.4 mol of diethylenetriamine, 14.5 mol of propylene oxide and 4 mol of ethylene oxide and had an OH value of 470.

A ρ, ρ'-diphenylmethane diisocyanate was used as the polyisocyanate (NCO-20) with a functionality of 2.5 to 2.6 and an NCO equivalent of 133 was used.

Diethyl N, N'-diethanolaminomethylphosphonate was used as the flame retardant additive.

The following approach was made:

Parts by weight

Polyol (as above) 57.2

flame retardant (as above) 6.4

surface-active silicone 1.0

Dibutyl tin diacetate 0.4

Trichloromonofluoromethane 35.0

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All of these foams are obtained by foaming 100 parts of the batch with a mixture of 90 parts of the stated isocyanate with 32 parts of finely divided isophthalic acid. The batch of the polyol was with the mixing
a temperature of 20 ° C (68 ° F) and the mixture of isocyanate at 23.9 ° C (75 ° F). All foamable mixtures
were mixed for 6 seconds.

Properties of the foam

Density (open blow core) 1.8 - 2.0

Dimensional stability (volume change in%)

one week at 65.6 ° C (150 ° F) (relative humidity 95%) 9.8

one week at 93 ° C (200 ° F) (relative humidity 95%) 7.5

one week at -26.7 ° C (-16 <> F) (relative humidity 95%) -0.5

Compressive strength 1.8 kg / cm ²

(25.78 psi)

In a fire test, this foam showed degradation the smoke development of at least 30% compared to a foam made from the same raw materials, but without Isophthalic acid.

Through further tests it was found that even when in use the other isocyanates mentioned in the description, hydrogen-containing reactive materials and phosphorus compounds similar results can be obtained. In a similar way, other additives can also be used, such as blowing agent, emulsifier, catalyst and the like.

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Claims (1)

Claims ; Process for the production of a polyurethane foam with low smoke development, characterized in that one (A) an organic polyisocyanate, (B) a material which can react with the polyisocyanate to form polyurethane reactive hydrogen, (C) a phosphorus-containing flame retardant material, (D) finely divided isophthalic acid and (E) a propellant converts. 2. The method according to claim 1, characterized in that (B) an isocyanate equivalent of about 70 to 280 and (D) in an amount of about 5 to 40%, based on the total weight of the starting materials, is present. 3. The method according to claim 1, characterized in that that (B) includes a polyether polyol which is the reaction product of a polyhydroxyl compound with 3 to 8 hydroxyl groups and an alkylene oxide having 2 to A carbon atoms in the molecule. A method according to claim 3, characterized in that (B) has a hydroxyl value of about 200 to about 800 and (D) in an amount of about 5 to about 40%, based on the total weight of the starting materials, is available. 209 8 38/1068 5. The method according to claim 4, characterized in that that the propellant (E) is a halogenated hydrocarbon is. 6. The method according to claim 4, characterized in that the polyol contains a sucrose polyether polyol. 7. The method according to claim 6, characterized in that that the propellant (E) is a halogenated hydrocarbon. 8. The method according to claim 1, characterized by that one converts a mixture from (A) an organic polyisocyanate, (B) an organic material capable of reacting with the polyisocyanate to form polyurethane and with reactive hydrogen and an isocyanate equivalent of about 70 to about 280 ₁ (C) a phosphorus-containing flame retardant agent, (D) about 15 to about 25% isophthalic acid by weight on the total weight of the raw materials, (E) a propellant and (F) an emulsifier for the mixture. 9. The method according to claim 8, characterized in that (B) is a polyether polyol which is the reaction product of a polyhydroxyl compound with 3 to 209838/1 068 8 hydroxyl groups and an alkylene oxide having 2 bie 4 carbon atoms per molecule. 10. The method according to claim 9, characterized in that that (B) has a hydroxyl value of about 250. 11. The method according to claim 10, characterized in that that the propellant (E) is a halogenated hydrocarbon. 12. The method according to claim 10, characterized in that the polyol is a sucrose polyether polyol is. 13. The method according to claim 12, characterized in that that the propellant (E) is a halogenated hydrocarbon. r, r,