DK147425B - FLAMMABLE PLASTIC MATERIALS CONTAINING A FLAMMABLE AGENT BASED ON RED PHOSPHOR - Google Patents

Description

i 14 7 Λ 2 5

The present invention relates to a flame retardant plastic material of the kind set forth in the preamble of claim 1.

Several patents refer to the use of red phos- phor for fire retardation of plastic materials. The red phos-5 phor is actually a very good fire retardant. Thus, for a given application, much less amounts of phosphorus can be used than, for example, halogen derivatives.

Furthermore, the use of red phosphorus leads to better mechanical properties and the electrical properties of the plastic material into which the red phosphorus is incorporated do not deteriorate.

However, its use is limited by such problems as pollution risk and difficulties in carrying out safe machining. Thus, the presence of the traces of water found in almost all polymers, in conjunction with the heat needed to process these polymers, produces very toxic phosphorus hydride which spontaneously burns in the the air.

German Patent Specification No. 2,308,104 discloses thermoplastic materials which are fire-retarded by red phosphorus and which contain metal oxides to prevent the release of phosphorus hydride during storage at room temperature.

25 In Belgian Patent Specification No. 817,020, which corresponds to United States Patent No. 3,931,081, it is stated that if polyolefins are processed fire retardant with a mixture of red phosphorus and an organic nitrogen compound which carbonizes under the action of the flame at 170 ° C. 230 ° C, phosphorus hydride is released which is released. To reduce this gas release, stabilizers based on amidosulfonic acid, a paraffin oil or silicone and pentaerythritol are used in this patent. A disadvantage associated with such mixtures is the hazardous handling thereof, since the red phosphorus in powder form is not shrouded and thus passivated.

5 It is also stated in DE publication no.

No. 2 408 488, which can be used as a fire retardant in plastic materials, homogeneous granules consisting of red phosphorus, a binder consisting of wax or waxy substances, and of various additives: nitrogenous compounds such as melamine, polyacrylonitrile or amidosulfonic acid or metal oxides. However, the use of these waxes as well as of the other additives presents the disadvantage that e.g. to a considerable extent, the mechanical properties of 15 shaped articles obtained with the formulations in question or by phenomena involving welding of the wax species deteriorate due to the use of excessive amounts of these waxes.

DE-2,249,638 also discloses the use as a fire retardant of mixtures composed of 80-98 wt. In red phosphorus and 2-20 wt.% Of an organic compound selected from paraffin oils, chlorinated paraffins, diocthylphthalate, tris-betachloroethyl phosphate, tricresyl phosphate, mineral oils boiling between 170 and 350 ° C, or an organosilicon compound selected from silicone-polyether copolymers or silicone oils.

The use of such compounds presents the disadvantages inherent in their nature: incompatibility with certain resins resulting from welding phenomena, or diminishing of mechanical properties, if, after all, these compounds are compatible with the resins into which they are introduced.

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Therefore, it is necessary to find a simple means enabling plastics to be processed without any release of phosphoric hydride, especially when the plastics materials are to be used to obtain shaped articles.

It has now surprisingly been found that this can be achieved by flame retardant red phosphorus coated materials as described in the characterizing part of claim 1, and the plastic materials according to the invention are therefore characterized by the characterizing part of claim 1.

Numerous plastic materials can be fire resistant according to the invention.

Thermoplastic materials include:

Polyolefins such as high and low density polyethylene, polypropylene, polyfluoroethylene and ethylene-propylene copolymers;

Polyvinyl polymers such as polyvinyl chloride and vinyl chloride copolymers;

Polystyrenes and acrylonitrile-butadiene-styrene copolymers, polyamides such as polyhexamethylene adipamide, polyhexamethylene dodecamide, polyhexamethylenedodecanedamide, polycaprolactam, polyhexamethylene sebacamide, polylauryl lactam and polyundecanamide; saturated polyesters such as ethylene glycol or butylene glycol polyterephathalates; polycarbona-ter; polyacetals; acrylic polymers such as polymethyl methacrylate; cellulose esters; polyurethanes and polyamide imides.

Among the thermosetting polymers are:

Phenol formaldehyde resins, aminoplastics, unsaturated polyesters.

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Various elastomers, such as natural and synthetic rubber, silicones and polyurethanes, can also be fire resistant.

The plastic material-based fabrics may contain reinforcing agents such as e.g. glass fibers; agents designed to provide particular characteristics such as e.g. self-lubricating agents, or inert agents such as kaolin or talc.

Several additives may also be incorporated into the substance, e.g. antioxidants, heat stabilizers or light stabilizers, dyes or pigments.

Red phosphorus means all allotropic colored varieties: red, violet or black, commercially sold under the term red phosphorus, and this may contain 15 to 3 0 metal oxide or metal salt as a stabilizing agent.

Red phosphorus is used in the form of particles having an average diameter less than 200 µm and preferably less than 100 µm.

These particles are encapsulated in a polymer selected in such a way that, at the temperature at which the flame retardant plastic material is to be processed, they undergo the least possible degradation. The disclosed polymers for use in the encapsulation must be film-forming, ie. they must form a continuous film on the surface of the phosphorus particles.

The choice of polymer for encapsulation is made based on the nature of the plastic material to be fire-retarded and its working temperature.

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Unless machined temperature is understood the temperature or temperature range. suitable for machining the plastic material. This temperature, in addition to the nature of the plastic material, also depends on the processing technique, the apparatus used and to some extent the formulation used.

The polymers used for encapsulating the red phosphorus must, as stated in claim 1, not have a melting point or a softening point of less than 90 ° C, otherwise bonding problems may occur. Thus, e.g. low molecular weight polyethylene wax and melting point not applicable. For polymers that do not have a well-defined melting point or softening point, those are preferably chosen if the decomposition temperature is above 15 150 ° C, which roughly corresponds to the lowest working temperature of the polymers to be fire retarded.

The polymers for use in the coating are, as set forth in claim 1, selected from polycarbonates, polyamides, polymers derived from acrylic acid or acrylates, polyimide amides, phenol-formaldehyde resins, epoxy resins and polyimides based on maleic acid derivatives.

The phosphorus particles can be coated with these polymers in several ways, such as those described in "Encyclopedia of Polymer Sciences and Technology", Vol. 8, p. 719.

These methods are essentially of a chemical or physical nature. Among the most commonly used methods are: aqueous phase or interface coacervation, organic phase precipitation by the addition of a non-solvent, dry pulverization, fluidized bed application, interface polymerization or in-gas or liquid phase polymerization, vacuum deposition, electrostatic deposition, and other methods based on phase separation methods or on interface reactions.

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In order for the protection by the encapsulated polymer to be satisfactory, the amount of polymer as mentioned in claim 1 must be between 5 and 80% by weight relative to the red phosphorus.

It is further known that the addition of metal oxides or metal salts stabilizes red phosphorus, the red phosphorus sold commercially usually containing such compounds. Addition of metal oxides makes it possible to suppress any release of phosphoric hydride. The 10 metal oxides that lead to the best results are oxides of copper, zinc, silver, iron, tin, vanadium, antimony, magnesium or titanium, but copper oxide is preferably used.

The amount of metal oxide used may vary depending on the amount of polymer used and depending on the processing of the plastic material and the nature of the plastic material.

Up to 100% by weight metal oxide is used in relation to the encapsulated red phosphorus.

The use of encapsulated red phosphorus offers several advantages, among which can be mentioned: ease of handling before and during addition of the red phosphorus to polymer blends, reducing the risk of contamination during the manufacture of the flame retardant plastics materials, and especially the release of phosphorus hydride during processing. 25 of the plastic material when operating at temperatures above 200 ° C.

The following examples further illustrate the invention. In Examples 1-2, a polymer has been selected as a polyamide-6.6 whose moisture uptake, other than cellulose, is one of the highest among polymers and which, under the influence of heat and in the presence of red phosphorus, results in a very substantial phosphorus hydride release.

EXAMPLE 1

A 24% by weight solution of a polyamide imide prepared by condensation in stoichiometric ratios of trimellitic anhydride and 4,4'-diisocyanate diphenyl methane is prepared in N-methylpyrrolidone (NMP). The polymer having an average molecular weight of 5000 and a softening point of 142 ° C has a viscosity number () measured at 25 ° C of 90 dl / g (0.5% by weight solution in N-methylpyrrolidone).

166.7 g of this solution is diluted with 100 µm NMP and 10 g with stirring 60 g of a red phosphorus powder having an average particle size of 20-30 µm are added.

In a 5 liter container fitted with a bucket stirrer rotating 2800 rpm. per minute, pour 4 liters of water.

After stirring, the dispersion of the red phosphorus is poured into the water and allowed to stir for 2 hours. Then filter and wash the residue with methanol (200, 3 cm). Rinse two more times with 200 cm of ether and dry at 50 ° C. 98.4 g of encapsulated red phosphorus are obtained.

In an autoclave with a heat jacket, where the autoclave has a capacity of 1 liter and is provided with a helical stirrer which rotates 20 rpm. 30 g of encapsulated red phosphorus and 300 g of polyhexamethylene adipamide having an average molecular weight of 20,000 and a logarithmic viscosity number are determined at 25 ° C in a solution of 25 0.5 g per 100 ml. m-cresol of 1.3 dl / g. Heat slowly and with stirring until the mixture reaches a temperature of 285 ° C over one hour. This temperature is kept for one hour.

To measure the amount of phosphorus hydride that is possibly released, the gas from the autoclave exit is passed through two 30 cm bottles in series of 1000 cm 2 containing 750 cm 2 of a 2% aqueous solution of mercuric chloride and the resulting acid is titrated with methyl orange as indicator. This method of analysis is described in "Compte-rendus de l'Académie des Sciences" 185, p. 206, 1927.

The amount of phosphorus hydride released relative to 1 g of red phosphorus is 17.5 mg.

A comparison experiment conducted under the same conditions but with non-encapsulated red phosphorus (18 g) results in a phosphorus hydride release of 33.5 mg per day. grams of red phos-10 phor.

From the mixture of polyamide and encapsulated red phosphorus and from polyamide alone, plates are produced by cold sintering under a pressure of 300 kg / cm. These boards have the following dimensions: 100 mm long, 6 mm wide and 3 mm thick.

15 LOI index is measured according to the standard ASTM D 2863.

The following results are obtained:

Index LQI

Polyamide alone 20.8

Polyamide + Encapsulated 20 Red Phosphorus 26 EXAMPLE 2 In 150 ml of chloroform dissolve 24 g of bisphenol A polycarbonate with an average molecular weight of 33,000 and a glass transition temperature of 145 ° C and softening point approx. 230 ° C. With stirring, 36 g of a red phosphorus powder having a mean particle size of 20-30 µm are added with stirring.

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This suspension is stirred for 15 minutes. Then as in Example 1, it is poured into 3 liters of methanol. After filtration, rinsing with ether and drying, 69 g of encapsulated red phosphorus powder is obtained.

5 Then proceed as in Example 1.

A phosphorus hydride release of 2.7 mg per g red phosphorus.

Thereafter, the analysis of the LOI index is performed as indicated in Example 1.

For the red phosphorus polyamide mixture encapsulated in polycarbonate, the following results are obtained: 25.5 - 26.

EXAMPLE 3 In a 1 liter reactor, 400 ml of o-dichlorobenzene, then 22 g of pyrocatechin, 30 ml of aqueous formaldehyde solution, 1 ml of concentrated hydrochloric acid and 42 g of red phosphorus powder with an average particle size of 20-30 µm are charged. With stirring, heat to 70 ° C for 30 minutes. Then heat to 90 ° C for 1 hour. After cooling, filter, wash with acetone, then ether and dry. 63.5 g of encapsulated red phosphorus are collected which can be used at up to approx. 163 ° C, which is the softening point of the polymer used. It has an average molecular weight of approx. 3000, and melting point approx. 170 ° C. Then proceed as in Example 1, and a phosphorus hydride release of 2.3 mg per ml is obtained. g 25 red phosphorus. An LOI index of 25.5 - 26 is obtained.

EXAMPLES 4-6 Similarly, the autoclave treatment as set forth in Examples 1-3 is carried out with red phosphorus encapsulated in polyamide, polycarbonate and pyrocatechin formaldehyde, however 6 g of copper oxide is added to each experiment. No phosphorus hydride release is found.

EXAMPLE 7 In 150 ml of a mixture of 20 parts by weight of water and 80 parts by weight of methanol, 20 g of polyamide obtained by condensation of 50 mold parts of caprolactam and 30 mold parts of the condensation product between sebacic acid and hexamethylenediamine and 20 mold parts of the condensation product between adipic acid 10 are dissolved. and hexamethylenediamine. This copolyamide has a melting point of 150 DC and an average molecular weight of 20,000.

To the above solution is added, with stirring, 30 g of a red phosphorus powder having an average particle size of 20-30 µm. This suspension is poured into a container equipped with a stirrer containing 5 liters of acetone. It is filtered, rinsed twice with 200 ml of ether and then dried at 50 ° C. 47.5 g of encapsulated red phosphorus are obtained.

The autoclave as described in Example 1 is then used, using 300 g of polyamide and 28.5 encapsulated red 20 phosphorus. A phosphorus hydride release of 5.2 mg per grams of red phosphorus. The analysis shows an LOI index of 25.5.

EXAMPLES 8-10

For the purpose of testing Examples 4 - 6 on an industrial scale, a laboratory screw press is used whose screw has a length of 415 mm and a diameter of 15 mm. This screw press is provided with a cylindrical nozzle with a diameter of 3 mm. The temperature is as follows: 250 ° C at the inlet, 280 ° G at the center and 270 ° DC at the nozzle.

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Under industrial conditions, the simple preparations A, B and C are prepared, which are prepared per minute. 100 g of polyhexamethylenedipamide having an average molecular weight of 20,000 and a logarithmic viscosity number determined at 25 DC in a 5 0.5 g wt% solution in m-cresol of 1.3 dl / g containing 2 g of copper oxide and containing 10 g respectively , 9.13 g, 9.58 g encapsulated red phosphorus according to Examples 1, 3 and 7.

The preparations are fed to the worm press and their some rods are extruded.

Throughout the operation, various locations on the worm press for a possible presence of phosphoric hydride are examined by means of a "DRAEGEF ^ CH 31101" tube.

Furthermore, phosphorus hydride is examined when the rod was cut, just when it is extruded and still hot.

No trace of phosphorus hydride could be detected at any point.

EXAMPLE 11

A solution of NOVOLAK-type phenol formaldehyde resin 40 g containing 3% hexamethylene tetramine (commercially sold under the name "RES0PHENE") is prepared.

PB3 "from Rhone-Poulenc) in 150 ml of acetone. The average molecular weight of this product is difficult to determine accurately but is between 2000 and 3000. Its softening point is 158 ° C.

While stirring, 60 g of powdery red phosphorus with a mean particle size of 20-30 µm are added with stirring. This dispersion is poured into a container equipped with a deaerator and provided with a stirrer and containing 1500 ml of water heated to 50-60 ° C. Then heat to 90-100 ° C for 30 minutes with vigorous stirring. It is filtered and 82.5 g of encapsulated red phosphorus are obtained.

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The following mixture is prepared by simple mixing in a rotating drum: 66.5 g of polyhexamethylene adipamide containing 30% glass fiber 0.2 g of "Cepretol" (polyethylene glycollaurate as lubricant) 0.75 g of powdered copper oxide 7.5 g of encapsulated red phosphorus

A screw press is extruded under the conditions described in Example 8. A good quality rod is obtained without the slightest release of phosphoric hydride being detected.

EXAMPLE 12

Using the encapsulated phosphor in Example 11, plastics materials are prepared from the following polymers: (a) polytherephthalate of tetramethylene glycol (3,500 poise) (b) polypropylene of density 0.903 and melting point 165-170 ° C, melt index = 6 (230 ° C (c) density polystyrene of 1.05, TQ Uicat = 96 ° C, melt index = 4 - 4.5 (at 200 ° C under 5 kg).

In each experiment, 88 g of polymer (a), (b) or (c) 2 g of powdered copper oxide are mixed 10 g of encapsulated red phosphorus.

25 The preparations are introduced into the worm press and extruded into rods. Traces of phosphorus hydride are nowhere detected. The LOI index is then analyzed and the following results are obtained: 13 147425

Comparison- Experiment with ninq test *) phosphorus

Polytherephthalate 21 23.5

EXAMPLE 13 40 g of a prepolymer obtained by an addition reaction of the N1 groups in 1 mole of 4,4'-diaminodiphenylmethane on the double bonds in 2.5 moles of bisphenol. maleimido-4,41-diphenyl methane having a softening point of 100 ° C is dissolved in 100 cm of dimethylformamide. With stirring, 50 g of red phosphorus with an average particle size of 20-30 µm are added. Stir for 10 minutes, then allow to stand for 12 hours.

The phosphorous suspension is poured into a mixture of 1 liter methanol and 2 liters of water vigorously stirred with a vane stirrer. Filter, wash with 200 ml of methanol and rinse twice with 200 ml of ether. After drying, 20 88 g of powdery red phosphorus are obtained which are coated with the above-mentioned polyimide resin having a molecular weight greater than 2000 and which do not exhibit actual melting point.

a 1 liter autoclave with heat jacket and provided with a helical stirrer at a speed of 20 rpm. per minute and heated by a thermo-liquid, 25.6 g of the above prepared, encapsulated red phosphorus and 300 g of polyhexamethylenedipamide having an average molecular weight of 20,000 and a logarithmic viscosity number determined at 25 ° C in solution of 0.5 g in 100 ml m cresol of 1.3 30 dl / g. Heat vigorously and with stirring over an hour until the mixture reaches a temperature of 285 ° C. This temperature is kept for one hour.

The amount of phosphorus hydride that is optionally released is analyzed analogously to Example 1. The amount of phosphorus hydride released relative to 1 g of red phosphorus is 1.4 mg.

A comparison experiment carried out under the same conditions, but with 18 g of phosphorus, resulted in a phosphorus hydride release of 33.5 mg per ml. grams of red phosphorus. In order to test the fire-retardant effect, by cold sintering under a pressure of 300 kg / mm, sheets of 100 mm x 6 mm with a thickness of 3 mm are produced. Analyzes for LOI index as listed in Example 1. The following results are obtained:

Index LOI

Polyamide 20.8

Polyamide + Encapsulated Red Phosphorus 27 - 28 EXAMPLE 14 15 g of bis-maleine imido-4,4'-diphenylmethane is dissolved in 150 ml of dimethylformamide. With stirring, 60 g of a red phosphorus powder having a mean particle size of 20-30 µm are successively added. Stir for 5 minutes to obtain a homogeneous suspension. This is poured into a mixture of 20 liters of methanol and 2 liters of water stirred vigorously by means of a bucket stirrer.

Filter, wash with 200 ml of methanol and rinse with 2 x 200 ml of ether. After drying, 97 g of powdery red phosphorus are obtained, upon which is deposited bis-maleine imido-4,41-diphenylmethane.

Then proceed as in Example 13 with 29.1 g of red phosphorus prepared above. Bis-maleinimido-4,4'-diphenylmethane becomes crosslinked at a processing temperature to a polyimide having a molecular weight greater than 2000 and which does not exhibit actual softening or melting point. There is a very low release of phosphoric hydride, a total of 0.9 mg / ml. grams of red phosphorus used. The LOI index is analyzed as in Example 1 and an index of 27.5-28 is obtained.

EXAMPLE 15 37.5 g of a "NOVOLAK" liquid resin in which the phenol groups have been epoxidized with an epoxy equivalent weight of 180 are dissolved in 70 g of diethylene glycol also called diglyme. Then, with stirring, 68.7 g of red phosphorus in powder form with a particle size between 20 and 30 µm are suspended. Stir for 5 minutes to obtain a homogeneous suspension and add a solution containing 10.1 g of diaminodiphenylmethane (hardener) and 20 g of diglyme. Still stirring is heated to 170 ° C for 2 hours. The product thereby forms a gel.

The gel is poured into a container containing 2 liters of water and provided with a stirrer. 112 g of powder consisting of red phosphorus are obtained with a crosslinked epoxy resin of undetermined molecular weight, however larger than 2000, and without any actual softening or melting point which is isolated and dried.

In one liter autoclave with heat jacket provided with a helical stirrer rotating 20 rpm. 30 g of red phosphorus wrapped and 300 g of polyhexamethylene adipamide having an average molecular weight of 20,000 and a logarithmic viscosity number determined at 25 ° C in a solution of 0.5 g in 100 ml of m-cresol are charged. of 1.3 dl / g. Heat progressively with stirring for one hour until the mixture reaches the temperature of 285 ° C. This temperature is kept for an additional hour.

The amount of phosphorous hydride that is optionally released is measured analogously to Example 1. The weight of phosphoric acid released per grams of red phosphorus is 7 mg.

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A comparison experiment carried out under the same conditions but with 18 g of red phosphorus resulted in a release of phosphorus hydride of 33.5 mg per day. grams of red phosphorus.

To investigate the fire-retardant effect obtained by red phosphorus and the epoxy resin, 100 mm x 6 mm sheets having a thickness of 3 mm at cold 2 sintering under a pressure of 300 kg / cm are prepared.

The LOI index according to the standard ASTM D 2863 is measured.

The following results are obtained: 10 LOI index

Polyamide alone 20.8

Polyamide + Encapsulated Red Phosphorus 26 - 27 EXAMPLE 16

Red phosphor encapsulated is prepared as follows: While stirring in a rotating cylinder, 120 g of red powdery phosphorus are mixed with 65.3 g of epoxy resin having an epoxy equivalent weight of 845 (m.p. = 90-100 ° C) and 14.7 g. melamine. The mixture thus obtained is placed in a layer of approx. 1 cm on a plate and then heated in an oven for 3 hours at 120 ° C and then 3 hours at 150 ° C.

The plate, consisting of encapsulated red phosphorus obtained after cooling, is decomposed and granulated. The encapsulating material is an undetermined molecular weight cross-linked epoxy resin, however larger than 2000, and without any actual softening or melting point.

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The following preparation is prepared by simple mixing: 87.8 g of tetramethylene glycol polyterephthalate in granules (viscosity 3,500 poise); 0.3 g of "Cepretol" (polyethylene glycollaurate as lubricant); 2 g of powdered copper oxide; 10 g encapsulated red phosphorus.

This mixture is introduced into the worm press used in Examples 8 - 10 and then extruded into bars. The temperature of the screw press was as follows: 215 ° C at the entrance of the material, 240 ° C at the center, 235 ° C at the nozzle. No phosphorus hydride release could be detected at any site.

EXAMPLE 17 30 g of a sodium acrylonitrile-methyl-methallylsulfonate terpolymer of molecular weight 1500 and melting point 150 ° C (marketed by Rhone-Poulenc Textile under the designation "TPC9") are dissolved in 400 cm 2 of dimethylformamide.

45 grams of red phosphorus of particle size 20-30 µm are added 20 with stirring to this solution. The suspension thus obtained is poured into 3.2 liters of water in a vessel equipped with a turbine stirrer. Man-filter, wash the precipitate with methanol and dry. In this way, 72.2 g of encapsulated red phosphorus are obtained.

By simple mixing in a rotating cylinder, the mixture is prepared: - 100 g of average molecular weight polyhexamethylene adipamide 20,000 and logarithmic viscosity number (determined at 25 ° C in a solution of 0.5 g in 100 cc m-cresol) of 1, third dl / g, 18 g - 2 g of powdered copper oxide, and - 10 g of encapsulated red phosphorus.

This mixture is extruded analogously to Example 8 by means of a single screw extruder. Good quality sticks are obtained and the release of phosphoric hydride cannot be measured.