HK1123817B - Process for the preparation of self-extinguishing thermoplastic polyurehanes - Google Patents

Description

Process for preparing self-extinguishing thermoplastic polyurethanes

Technical Field

The invention relates to a method for producing self-extinguishing thermoplastic polyurethanes, optionally containing conventional additives and/or auxiliary substances.

Background

Thermoplastic Polyurethanes (TPU) are of great industrial importance due to their good elastomeric properties and thermoplastic processability. An overview of the preparation, properties and use of TPUs is given, for example, in Kunststoff Handbuch [ G.Becher, D.Braun ], volume 7, "Polyurethane", Munich, Vienna, Carl Hanser Verlag, 1983.

TPUs are generally composed of linear polyols (macrodiols), such as polyester diols, polyether diols or polycarbonate diols, organic diisocyanates and short-chain, usually difunctional, alcohols (chain extenders). They can be prepared continuously or discontinuously. The most known preparation processes are the conveyor belt process (GB-A1057018) and the extruder process (DE-A1964834).

The thermoplastically processable (thermoplastically processable) polyurethane elastomers can be produced in stages (prepolymer metering process) or by reacting all the components simultaneously in one stage (one-shot metering process).

One disadvantage of TPUs is their flammability. To reduce this disadvantage, flame retardants such as halogen-containing compounds are incorporated into the TPU. However, the addition of these products generally has an adverse effect on the mechanical properties of the TPU molding compositions obtained. Halogen-free, self-extinguishing TPU molding compositions are also of interest because of the corrosive action of halogen-containing substances.

Above all, the use of flame retardants that can be incorporated is of interest if high demands on mechanical properties are imposed. Said agents are described in particular in US-B7160974 and DE-B10238112. Among these, flame retardants based on phosphonate esters or phosphine oxides which can be incorporated are used in multistage processes. A TPU having the usual properties is obtained.

Disclosure of Invention

The present invention provides self-extinguishing thermoplastic polyurethanes which are free from halogen-containing flame retardants, which after ignition with a high-temperature flame extinguish without burning within a few seconds, which do not drip or form burning drips, and which have both excellent mechanical properties and processability (extrusion properties).

The invention from the followingDetailed DescriptionThese and other advantages and benefits of the present invention will be apparent.

Detailed Description

The present invention will now be described for purposes of illustration and not limitation. Other than in the operating examples, or where otherwise indicated, all numbers expressing quantities, percentages, OH numbers, functionalities and so forth in the specification are to be understood as being modified in all instances by the term "about". Unless otherwise indicated, equivalent weights and molecular weights expressed herein in daltons (Da) are average equivalent weights and number average molecular weights, respectively.

The present invention provides a one-shot process for incorporating organophosphonium oxides for flame retardant TPU.

The present invention provides a one-shot process for preparing self-extinguishing thermoplastic polyurethanes, optionally in the presence of a catalyst E), which involves reacting

A) At least one organic diisocyanate with

B) At least one polyol having on average at least 1.8 and at most 3.0 Zerewitinoff-active hydrogen atoms and a number average molecular weight M of 450 to 10,000_n；

C) At least one low molecular weight polyol or polyamine as chain extender, said polyol or polyamine having an average of at least 1.8 and at most 3.0 Zerewitinoff-active hydrogen atoms and a number average molecular weight M of from 60 to 400_n(ii) a And

D) at least one phosphine oxide-based organic phosphorus-containing compound having on average at least 1.5 and at most 3.0 Zerewitinoff-active hydrogen atoms and a number-average molecular weight M of 60 to 10,000 in an amount of 0.1 to 20 wt.%, based on the total amount of TPU_nHaving the following structural formula (I)

Wherein the content of the first and second substances,

R¹h, branched or unbranched alkyl radicals having from 1 to 24 carbon atoms, having from 6 to 20 carbon atomsA substituted or unsubstituted aryl group, a substituted or unsubstituted aralkyl group having 6 to 30 carbon atoms, or a substituted or unsubstituted alkaryl group having 6 to 30 carbon atoms, and

R²，R³a substituted or unsubstituted arylene group having 6 to 20 carbon atoms, a substituted or unsubstituted aralkylene group having 6 to 30 carbon atoms, or a substituted or unsubstituted alkarylene group having 6 to 30 carbon atoms, wherein R is a branched or unbranched alkylene group having 1 to 24 carbon atoms, wherein R is a substituted or unsubstituted aralkylene group having 6 to 30 carbon atoms²And R³Which may be the same or different from each other,

optionally using

F) Other flame retardants in amounts of 0 to 70 wt.%, based on the total amount of TPU, which do not contain zerewitinoff-active hydrogen atoms, and

G) 0 to 20 wt.%, based on the total amount of TPU, of further auxiliary substances and additives, where the characteristic number (obtained by multiplying the equivalence ratio of the isocyanate groups of (A) to the sum of the Zerewitinoff-active hydrogen atoms of the compounds (B), (C) and (D) by 100) is from 85 to 120.

The thermoplastic polyurethanes (also referred to as TPUs for short) are essentially linear thermoplastically processable polyurethanes which contain phosphine oxides and are known per se.

It was surprising and by no means foreseeable that it is possible to prepare TPUs having outstanding mechanical properties and very good extrusion properties by a one-shot process using organic phosphines which can be incorporated.

Organic diisocyanates A) which can be used in the process of the invention are aliphatic, cycloaliphatic, araliphatic (araliphatic), aromatic and heterocyclic diisocyanates or any desired mixtures of these diisocyanates (cf. HOUBEN-WEYL "Methoden der organischen Chemie", volume E20 "Makromolekulare Stoffe", Georg Thieme Verlag, Stuttgart, New York 1987, p.1587 1593 or Justus Liebigs Annalen Chemie, 562, p.75-136).

Mention may be made in particular, by way of example, of: aliphatic diisocyanates such as ethylene-diisocyanate, 1, 4-tetramethylene-diisocyanate, 1, 6-hexamethylene-diisocyanate and 1, 12-dodecane-diisocyanate; cycloaliphatic diisocyanates, such as isophorone diisocyanate, 1, 4-cyclohexane diisocyanate, 1-methyl-2, 4-cyclohexane diisocyanate and 1-methyl-2, 6-cyclohexane diisocyanate and the corresponding isomer mixtures, 4, 4 ' -dicyclohexylmethane diisocyanate, 2, 4 ' -dicyclohexylmethane diisocyanate and 2, 2 ' -dicyclohexylmethane diisocyanate and the corresponding isomer mixtures; and aromatic diisocyanates such as 2, 4-tolylene diisocyanate, mixtures of 2, 4-tolylene diisocyanate and 2, 6-tolylene diisocyanate, 4, 4 '-diphenylmethane diisocyanate, 2, 4' -diphenylmethane diisocyanate and 2, 2 '-diphenylmethane diisocyanate, mixtures of 2, 4' -diphenylmethane diisocyanate and 4, 4 '-diphenylmethane diisocyanate, urethane-modified liquid 4, 4' -diphenylmethane diisocyanate or 2, 4 '-diphenylmethane diisocyanate, 4, 4' -diisocyanato (diisocyanato) -1, 2-diphenylethane and 1, 5-naphthylene-diisocyanate. Preference is given to using 1, 6-hexamethylene-diisocyanate, 1, 4-cyclohexane-diisocyanate, isophorone-diisocyanate, dicyclohexylmethane-diisocyanate, diphenylmethane-diisocyanate isomer mixtures in which the 4, 4 '-diphenylmethane-diisocyanate content is greater than 96% by weight, in particular preferably 4, 4' -diphenylmethane-diisocyanate and 1, 5-naphthylene-diisocyanate. These diisocyanates can be used individually or in the form of mixtures with one another. They can also be used with up to 15 mol% (based on the total diisocyanate) of polyisocyanate, but the polyisocyanate should be added at most in such an amount that a still thermoplastically processable product is formed. Examples of polyisocyanates are triphenylmethane-4, 4', 4 "-triisocyanate and polyphenyl-polymethylene-polyisocyanates.

The polyols B) used according to the invention are those having an average of up toAt least 1.8 and at most 3.0 Zerewitinoff-active hydrogen atoms and preferably a number average molecular weight M of 450-_nThose of (a). They often contain small amounts of nonlinear compounds as a result of the process by which they are produced. These compounds may be referred to herein as "substantially linear polyols". Polyester diols, polyether diols or polycarbonate diols or mixtures thereof are preferred.

Suitable polyether diols can be prepared by reacting one or more alkylene oxides having from 2 to 4 carbon atoms in the alkylene radical with a starter molecule containing 2 bonded active hydrogen atoms. Alkylene oxides which may be mentioned are, for example: ethylene oxide, 1, 2-propylene oxide, epichlorohydrin and 1, 2-butylene oxide and 2, 3-butylene oxide. Preference is given to using ethylene oxide, propylene oxide and mixtures of 1, 2-butylene oxide and ethylene oxide. The alkylene oxides can be used individually, alternately one after the other or as mixtures. Possible starter molecules are, for example: water, aminoalcohols (e.g., N-alkyl-diethanolamines, such as N-methyl-diethanolamine), and diols (e.g., ethylene glycol, 1, 3-propanediol, 1, 4-butanediol, and 1, 6-hexanediol). Mixtures of starter molecules may also optionally be used. Further suitable polyether alcohols are tetrahydrofuran polymerizates, wherein the tetrahydrofuran polymerizates contain hydroxyl groups. Trifunctional polyethers can also be used in proportions of from 0 to 30 wt.%, based on the bifunctional polyethers, but in amounts of up to that which leads to products which are still thermoplastically processable. The substantially linear polyether diol preferably has a number average molecular weight M of 450 to 6,000_n. They may be used individually or in the form of mixtures with one another.

Suitable polyester diols can be prepared, for example, from dicarboxylic acids having from 2 to 12 carbon atoms, preferably from 4 to 6 carbon atoms, and polyhydric alcohols. Possible dicarboxylic acids are, for example: aliphatic dicarboxylic acids such as succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid and sebacic acid; or aromatic dicarboxylic acids such as phthalic acid, isophthalic acid and terephthalic acid. The dicarboxylic acids can be used individually or as mixtures, e.g. with succinic, glutaric and adipic acidsIn the form of a substance. For the preparation of the polyester diols, it may be advantageous, where appropriate, not to use dicarboxylic acids, but to use the corresponding dicarboxylic acid derivatives, such as carboxylic acid diesters having 1 to 4 carbon atoms in the alcohol radical, carboxylic acid anhydrides or carboxylic acid chlorides. Examples of polyols are diols, preferably having from 2 to 10 carbon atoms, more preferably having from 2 to 6 carbon atoms, such as ethylene glycol, diethylene glycol, 1, 4-butanediol, 1, 5-pentanediol, 1, 6-hexanediol, 1, 10-decanediol, 2-dimethyl-1, 3-propanediol, 1, 3-propanediol or dipropylene glycol. Depending on the desired properties, these polyols can be used individually or in mixtures with one another. Other suitable are: esters of carbonic acid with the diols mentioned, in particular diols having from 4 to 6 carbon atoms, for example 1, 4-butanediol or 1, 6-hexanediol, condensation products of omega-hydroxycarboxylic acids, for example omega-hydroxycaproic acid, or polymerization products of lactones, for example optionally substituted omega-caprolactones. Preferred for use as polyester diols are ethanediol polyadipates, 1, 4-butanediol polyadipates, ethanediol 1, 4-butanediol polyadipates, 1, 6-hexanediol neopentyl glycol polyadipates, 1, 6-hexanediol 1, 4-butanediol polyadipates and polycaprolactones. These polyester diols preferably have a number average molecular weight M of 450-10,000_nAnd may be used alone or in admixture with each other.

The chain extenders C) have an average of 1.8 to 3.0 Zerewitinoff-active hydrogen atoms and have a molecular weight of 60 to 400. In addition to compounds containing amino, thiol or carboxyl groups, these compounds are also understood to mean those having from 2 to 3, preferably 2, hydroxyl groups.

Aliphatic diols having from 2 to 14 carbon atoms are preferably used as chain lengtheners, such as ethylene glycol, 1, 2-propanediol, 1, 3-propanediol, 1, 4-butanediol, 2, 3-butanediol, 1, 5-pentanediol, 1, 6-hexanediol, diethylene glycol and dipropylene glycol. However, esters of terephthalic acid with diols having 2 to 4 carbon atoms, such as, for example, terephthalic acid bis-ethylene glycol or terephthalic acid bis-1, 4-butanediol, hydroxyalkylene ethers of hydroquinone, such as, for example, 1, 4-bis (. beta. -hydroxyethyl) -hydroquinone, ethoxylated bisphenols, such as, for example, 1, 4-bis (. beta. -hydroxyethyl) -bisphenol A, (cyclo) aliphatic diamines, such as, for example, isophoronediamine, ethylenediamine, 1, 2-propylenediamine, 1, 3-propylenediamine, N-methyl-propylene-1, 3-diamine and N, N' -dimethylethylenediamine, and aromatic diamines, such as, for example, 2, 4-tolylenediamine, 2, 6-tolylenediamine, 3, 5-diethyl-2, 4-tolylenediamine or 3, 5-diethyl-2, 6-toluenediamine or primary mono-, di-, tri-or tetraalkyl-substituted 4, 4' -diaminodiphenylmethanes are also suitable. Ethylene glycol, 1, 4-butanediol, 1, 6-hexanediol, 1, 4-di (. beta. -hydroxyethyl) -hydroquinone or 1, 4-di (. beta. -hydroxyethyl) -bisphenol A are particularly preferably used as chain lengtheners. Mixtures of the above-mentioned chain extenders may also be used. In addition, relatively small amounts of triols can also be added.

The phosphine oxide-based flame retardants D) have on average at least 1.5 and at most 3.0, preferably from 1.8 to 2.5, more preferably 2 Zerewitinoff-active hydrogen atoms. The phosphine oxide has a number average molecular weight M of preferably 60-10,000, more preferably 100-5,000, most preferably 100-1,000_n。

Compounds of the formula (I) below are preferably used as phosphine oxides:

wherein the content of the first and second substances,

R¹a branched or unbranched alkyl group having 1 to 24 carbon atoms, a substituted or unsubstituted aryl group having 6 to 20 carbon atoms, a substituted or unsubstituted aralkyl group having 6 to 30 carbon atoms, or a substituted or unsubstituted alkaryl group having 6 to 30 carbon atoms, and

R²，R³a branched or unbranched alkylene group having 1 to 24 carbon atoms, a substituted or unsubstituted arylene group having 6 to 20 carbon atoms, a substituted or unsubstituted aralkylene group having 6 to 30 carbon atoms, or a substituted or unsubstituted alkarylene group having 6 to 30 carbon atoms, wherein R is²And R³May be the same or different.

The phosphine oxide is preferably used in an amount of 0.1-20 wt.%, more preferably 0.5-10 wt.%, most preferably 1-10 wt.%, based on the total amount of TPU.

Other flame retardants F) may also optionally be used, see for example h.zweifel, Plastics additives handbook, 5 th edition, Hanser Verlag Munich, chapter 2001, 12; green, J.of FireSciences, 1997, 15, pages 52-67 or Kirk-Othmer Encyclopedia of chemical technology, 4 th edition, volume 10, John Wiley & Sons, New York, page 930-.

Suitable catalysts E) include tertiary amines known to the person skilled in the art, such as triethylamine, dimethylcyclohexylamine, N-methylmorpholine, N' -dimethylpiperazine, 2- (dimethylamino-ethoxy) ethanol, diazabicyclo [2, 2, 2] octane and the like, and, in particular, organometallic compounds, such as titanic acid esters, iron compounds or tin compounds, for example tin diacetate, tin dioctoate, tin dilaurate or the dialkyltin salts of aliphatic carboxylic acids, for example dibutyltin diacetate or dibutyltin dilaurate or the like. Preferred catalysts are organometallic compounds, in particular titanic acid esters, iron compounds and tin compounds. The total amount of catalyst in the TPU is preferably 0 to 5 wt.%, more preferably 0 to 2 wt.%, based on the total amount of TPU.

Compounds which are monofunctional with respect to isocyanates can be used as so-called chain terminators in a proportion of up to 2 wt.%, based on the TPU. Suitable compounds are, for example, monoamines, such as butylamine and dibutylamine, octylamine, stearylamine, N-methylstearylamine, pyrrolidine, piperidine or cyclohexylamine, and monoalcohols, such as butanol, 2-ethylhexanol, octanol, dodecanol, stearyl alcohol, the various pentanols, cyclohexanol and ethylene glycol monomethyl ether.

The thermoplastic polyurethane elastomers may contain conventional and known auxiliary substances and additives G) in amounts of up to 20% by weight, based on the total amount of TPU. Typical auxiliary substances and additives are lubricants and mold-release agents, for example fatty acid esters, their metal soaps, fatty acid amides, fatty acid ester amides and siliconesKetone compounds, antiblocking agents, inhibitors, stabilizers against hydrolysis, light, heat and discoloration, dyes, pigments, inorganic and/or organic fillers, plasticizers, for example phosphates, phthalates, adipates, sebacates and alkylsulfonates, fungistatic and bacteriostatic active substances and fillers, and mixtures thereof, and reinforcing agents. Reinforcing agents are in particular fibrous reinforcing substances, for example inorganic fibres which are prepared according to the prior art and may also be provided with a sizing agent (size). For more detailed information on the auxiliary substances and additives, technical literature can be found, for example "High Polymers" from J.H.Saunders and K.C.Frisch, volume XVI, Polyurethane, parts 1 and 2, Verlag Interscience Publishers 1962 and 1964; and R is shown in the specification.And Taschenbuch fur Kunststoff-Additive (Hanser Verlag Munich 1990) or DE-A2901774 from H.M muller.

For the preparation of TUP according to the invention, the building components a), B), C) and D) are reacted in the presence of the flame retardant F) and optionally the catalyst E) and auxiliary substances and/or additives G) in the following amounts: the amounts are such that the equivalent ratio of NCO groups of the diisocyanate A) to the sum of the Zerewitinoff-active hydrogen atoms of the components B), C) and D) is from 0.85 to 1.2.

The TPU molding compositions obtained by the one-shot process of the invention are self-extinguishing, do not drip or form flaming drips, and have good mechanical properties and processability.

The process according to the invention is preferably carried out in the following manner:

the components are continuously mixed at a temperature above their melting point, preferably at a temperature of 50 to 220 ℃, preferably in a mixing unit with high shear energy. For example, mixing heads or high-speed tubular mixers, nozzles, tubes, static mixers or multi-screw extruders (e.g., ZSK twin-screw extruders) may be used. Static mixers are described, for example, in Chem-Ing.Techn.52, No.4, pages 285 to 291 and "Mischen von Kunststoff und Kautschukprodukten", VDI-Verlag, Dusseldorf 1993. Mention may be made, by way of example, of the SMX static mixer from Sulzer.

If an extruder is used, the temperature of the extruder housing is selected such that the reaction components are completely converted and possible incorporation of the abovementioned auxiliary substances or further components can be carried out with optimum protection of the product.

After preparation, the TPU can optionally be further processed, for example by conditioning and by comminuting or granulating in a mill or mill to prepare sheets or blocks, by devolatilization and by melt granulation. Preferably, the TPU is passed through a unit for continuous devolatilization and extrudate formation. This unit may be, for example, a multi-screw extruder (ZSK).

TPUs are preferably used for the production of injection-molded articles and extruded articles.

The invention is explained in more detail with the aid of the following examples.

Examples

Abbreviations used hereinafter:

TERATHANE 1000 molecular weight M_n1,000g/mol of a polyether; du Pont

Products of de Nemours

MDI methylene-4, 4' - (phenylisocyanate)

IHPO isobutyl-bis (hydroxypropyl) -phosphine oxide, flame retardants

BDO 1, 4-butanediol

IRGANOX 1010 Ciba Specialty Chemicals Inc. of Tetrakis (methylene-

(3, 5-di-tert-butyl-4-hydroxycinnamate)) methane

Release agent for LICOWAX C Clariant Turtz GmbH

BDP bisphenol A diphenyl phosphate, oligomeric mixtures

Phosphate-based flame retardants of EXOLIT OP 910 Clariant GmbH (No)

Zelivwei Qunuofu-active hydrogen atom)

Example 1: (comparative example; one-shot Process and flame retardant which cannot be incorporated)

A mixture of 1,159g TERATHANE 1000, 139g BDO, 200g EXOLIT OP 910, 7g IRGANOX 1010 and 10g LICOWAX C was heated to 160 ℃ while stirring at 500 revolutions per minute (rpm) using a paddle stirrer. Thereafter 684g of MDI were added. The mixture was then stirred for 110 seconds. Thereafter, the TPU is poured off. Finally, the material was worked up for 30 minutes at 80 ℃. The finally obtained TPU is cut, granulated and further processed.

Example 2: (comparative example; prepolymer method and flame retardant capable of being incorporated)

TERATHANE 1000(650g/min) with IHPO (51g/min) and tin dioctoate (100ppm based on the amount of TERATHANE 1000) in which BDP (10 wt.%, based on the total amount of TPU) and IRGANOX 1010(0.4 wt.%, based on the total amount of TPU) are dissolved are heated to 180 ℃ and the mixture is continuously metered by means of a gear pump into the 1 st jacket (housing) of ZSK53 (twin-screw extruder of Werner & Pfleiderer).

DESMODUR 44M (461 g/min; 60 ℃) and LICOWAX C (5 g/min; 0.4 wt.% based on the total amount of TPU) were metered continuously together into the same shell.

Butanediol (98g/min) was then metered continuously into jacket 3.

The jacket 1-3 of the extruder was heated to 80 ℃ and the jacket 4-8 was heated to 210 ℃ while cooling the last 4 jackets. The screw speed was 290 rpm.

At the end of the screw, the hot melt was taken out as a strand, cooled in a water bath and granulated.

Example 3: (according to the invention; one-shot process and phosphine oxide which can be incorporated)

TERATHANE 1000(650g/min) having BDP (10 wt.%, based on the total amount of TPU), IRGANOX 1010(0.4 wt.%, based on the total amount of TPU) and tin dioctoate (100ppm, based on the amount of TERATHANE 1000) dissolved therein was heated to 180 ℃ and continuously metered by means of a gear pump into the 1 st housing of ZSK53 (twin-screw extruder of Werner & Pfleiderer).

Butanediol (98g/min) and IHPO (51 g/min; 60 ℃) were metered continuously into the same shell together with LICOWAX C (5 g/min; 0.4 wt.% based on the total amount of TPU).

DESMODUR 44M (461 g/min; 60 ℃) was then metered continuously into the jacket 3.

The jacket 1-3 of the extruder was heated to 80 ℃ and the jacket 4-8 was heated to 210 ℃ while cooling the last 4 jackets. The screw speed was 290 rpm.

At the end of the screw, the hot melt was taken out as a strand, cooled in a water bath and granulated.

Example 4: (according to the invention; one-shot process and phosphine oxide which can be incorporated)

TERATHANE 1000(550g/min) having IRGANOX 1010(0.4 wt.%, based on the total amount of TPU) and tin dioctoate (100ppm, based on the amount of TERATHANE 1000) dissolved therein was heated to 180 ℃ and continuously metered by means of a gear pump into the 1 st shell of ZSK53 (twin-screw extruder from Werner & Pfleiderer).

Butanediol (107g/min) and IHPO (78 g/min; 60 ℃) were metered continuously into the same shell together with LICOWAX C (5 g/min; 0.4 wt.%, based on the total amount of TPU).

DESMODUR 44M (517 g/min; 60 ℃) was then metered continuously into jacket 3.

The jacket 1-3 of the extruder was heated to 80 ℃ and the jacket 4-8 was heated to 210 ℃ while cooling the last 4 jackets. The screw speed was 290 rpm.

At the end of the screw, the hot melt was taken out as a strand, cooled in a water bath and granulated. Measurement of MVR value (melt volume rate)

The MVR value of the particles was measured according to ISO1133 using a 10kg load.

Preparation of injection-molded articles

The specific TPU granules of examples 1 to 4 were melted in a D60 injection molding machine (screw No. 32 from Mannesmann; melt temperature of approximately 230 ℃) and shaped into sheets (125 mm. times.50 mm. times.2 mm).

Pipe extrusion

The TPU pellets were melted in an 30/25D single-screw extruder (Plasticorr PL2000-6 from Brabender; metering 3 kg/h; temperature 230-. Mechanical testing at Room temperature

The tear strength and the elongation at break of the injection-molded articles were measured in accordance with DIN 53405.

Measurement of flame retardancy

The flame retardant properties of the Test specimens were measured at a thickness of 3mm in accordance with UL94V (described in underwriters laboratories Inc. Standard of Safety, "Test for flexibility of Plastic Material for Parts in Devices and applications", page 14 and subsequent pages, North brook 1998 and J.Triotzsch, "International Plastics flexibility Handbook", page 346 and subsequent pages, Hanser Verlag, Munich 1990).

In this test, a V0 rating indicates no combustion dripping. Products with this grade are therefore described as having flame resistance. The V2 rating indicates flaming dripping, i.e., no flame resistance.

TABLE 1

Examples	Properties of examples	MVR210℃	Tensile Strength (MPa)	Elongation at Break (%)	Quality of extrusion	Shrinkage (%)	UL-94
								1	Comparative example; one-shot process, incorporable flame retardants	40	47	410	Good, uniform, unacceptable deposit	1.5	V-0
2	Comparative example; prepolymer process, phosphine oxides capable of being incorporated	40	32	364	Nonuniformities, many nodules	1.1	V-0
								3	According to the invention; disposable method	45	43	402	Good and uniform	0.9	V-0
4	According to the invention; disposable method	40	36	345	Good and uniform	0.9	V-0

In comparative example 1, a flame retardant (EXOLIT OP 910) that could not be incorporated was used in a one-shot process. The properties of the TPU, such as mechanical properties, shrinkage properties and flammability properties, are acceptable. The extrusion quality was actually good, but a dirty surface deposit was formed. Therefore, the tube is unacceptable and unusable.

In comparative example 2, a TPU having a tensile strength of 32MPa was prepared in a prepolymer process. The flame retardant properties were good, but the extrusion quality was not acceptable.

In example 3 according to the invention, the preparation of the TPU was carried out in a one-shot process using phosphine oxides which can be incorporated. The TPU has good flame retardant properties (UL-94V-0), excellent mechanical properties, 43MPa tensile strength and also excellent extrusion quality.

In example 4 according to the invention, the one-shot method was also carried out, but no reopos BAPP was used (therefore the mechanical values cannot be compared with the other examples). In this example, the TPU also has good flame retardant properties (UL-94V-0) and good extrusion quality.

The data show that only with phosphine oxides that can be incorporated and the preparation of the TPU carried out in a one-shot process, self-extinguishing TPU with good mechanical properties, good extrusion quality, low shrinkage and no blooming (blooming) can be obtained.

Although the invention has been described in detail in the foregoing for the purpose of illustration, it is to be understood that such detail is solely for that purpose and that variations can be made therein by those skilled in the art without departing from the spirit and scope of the invention except as it may be limited by the claims.

Claims (6)

1. A process for the manufacture of thermoplastically processable polyurethane elastomers (TPUs) with self-extinguishing properties, which comprises reacting

A) At least one organic diisocyanate with

B) At least one polyol having an average of at least 1.8 and at most 3.0 Zerewitinoff-active hydrogen atoms and a number average molecular weight M of 450 to 10,000_n；

C) At least one low molecular weight polyol or polyamine as chain extender, said polyol or polyamine having an average of at least 1.8 and at most 3.0Zerewitinoff-active hydrogen atoms and a number-average molecular weight M of from 60 to 400_n(ii) a And

D) at least one phosphine oxide-based organic phosphorus-containing compound having on average at least 1.5 and at most 3.0 Zerewitinoff-active hydrogen atoms and a number-average molecular weight M of 60 to 10,000 in an amount of 0.1 to 20 wt.%, based on the total amount of TPU_nHaving the following structural formula (I)

Wherein the content of the first and second substances,

R¹a branched or unbranched alkyl group having 1 to 24 carbon atoms, a substituted or unsubstituted aryl group having 6 to 20 carbon atoms, a substituted or unsubstituted aralkyl group having 6 to 30 carbon atoms, or a substituted or unsubstituted alkaryl group having 6 to 30 carbon atoms, and

R²，R³a branched or unbranched alkylene group having 1 to 24 carbon atoms, a substituted or unsubstituted arylene group having 6 to 20 carbon atoms, a substituted or unsubstituted aralkylene group having 6 to 30 carbon atoms, or a substituted or unsubstituted alkarylene group having 6 to 30 carbon atoms, wherein R is²And R³Which may be the same or different from each other,

optionally comprising

F) Other flame retardants in amounts of 0 to 70 wt.%, based on the total amount of TPU, which do not contain zerewitinoff-active hydrogen atoms, and

G) from 0 to 20% by weight, based on the total amount of TPU, of other auxiliary substances and additives,

wherein the characteristic number is from 85 to 120, said characteristic number being obtained by multiplying the equivalence ratio of the isocyanate groups of (A) to the sum of the Zerewitinoff-active hydrogen atoms of the compounds (B), (C) and (D) by 100.

2. The process according to claim 1, wherein the diisocyanate A) is an aromatic diisocyanate.

3. The process according to claim 1, wherein the polyol B) is a polyether diol.

4. The process according to claim 1, wherein the polyol C) is selected from the group consisting of ethylene glycol, butanediol, hexanediol, 1, 4-di (. beta. -hydroxyethyl) -hydroquinone and 1, 4-di (. beta. -hydroxyethyl) bisphenol A.

5. The process according to claim 1, wherein component D) has a functionality of 2 on average.

6. In a process for making one of an injection molded article or an extruded article, the improvement comprising the thermoplastically processable polyurethane elastomer prepared in accordance with claim 1.