NL8802502A - Material on the basis of polymer which contains at least 20% of poly(phenylene ether) a, plasticizer and a small amount of fire-retardant and if required further customary additives - Google Patents

Abstract

The invention relates to a material on the basis of polymer which contains at least 20% of poly(phenylene ether) a plasticizer, and as a fire retardant, a combination of 0.2-15 wt% of a fluorinated polymer or copolymer and 0.05-10 wt% of boric acid, B2O3 or borate, based on the poly(phenylene oxide) and if required, and further customary additives. The fluorinated polymer is preferably poly(vinylidene fluoride).

Description

General Electric Company of Schenectady, New York, Ver. States of America.

Applicant mentions as inventors: M.P.J. Boogers, J.H.G.M. Lohmeijer, J. Bussink.

Material based on at least 20% polyphenylene ether-containing polymer, which contains a plasticizer and a small amount of flame retardant and, if desired, further usual additives.

The invention relates to a material based on at least 20% polyphenylene ether-containing polymer, which contains a plasticizer, a small amount of flame retardant and, if desired, further customary additives.

Polyphenylene ethers, also abbreviated as PEE, are being used on an increasingly large scale. They are high melting materials and easier to process, one can either add a plasticizer or mix them with styrene polymers. To improve the impact resistance, a rubber is often added, e.g. EPEM rubber or rubber-modified polystyrene. The right choice between these options depends on the ultimate goal of use.

By "polyphenylene ethers" here are meant not only polymers as described in, e.g., U.S. Pat. Nos. 3,306,874 and 3,306,875 to Allan S. Hay or U.S. Patent Nos. 3,257,357 and 3,257,358 from Gelu Stoeff Stamatoff, but also the various copolymers, as well as mixtures of polyphenylene ethers or polyphenylene ethers with various other polymers, e.g. the above additives, the only requirement being that the polymer component of the material contains at least 20% polyphenylene ether, since this already yields the improvement of the invention described below.

Several important applications, eg in aircraft, require high fire resistance and low smoke development. Therefore, for purposes with strict flammability requirements, the combination of polyphenylene ether with plasticizer is sometimes preferred. The plasticizer should then also not increase the flammability and smoke development too much, and therefore a plasticizer of a predominantly aromatic nature is therefore generally preferred.

Various approaches can be used to make polymeric materials flame retardant in general. For example, the amount of polymer in the material can be reduced by adding inorganic fillers. However, this requires large amounts which would unacceptably degrade the physical properties of the polyphenylene ethers. Another possibility is to mix with materials that split off water or carbon dioxide during burning, but such materials are precisely not useful for polymers with high processing temperatures, such as PEE. Usually, as fire retardants, polymer materials are used with compounds containing phosphorus, chlorine and / or bromine, sometimes in combination with an anti-mimic compound. Such fire retardants act by poisoning the flame. This results in incomplete combustion of the polymer, which in turn usually causes an increase in rod emission. Furthermore, the thermal stability of these agents is also limited, so that they are not readily suitable in polymers that require high-temperature processing. Fluorine-containing compounds have rarely been used as fire retardants. Often they are too stable and, moreover, fluorine does not appear to be as effective as vapor poison in the vapor phase as is the case with chlorine or broan.

Another and still little explored possibility is to achieve the fire-retardant effect by increasing the yield of carbonized material (residual weight on combustion); this also means that the emission of flammable gases and therefore of smoke is reduced.

Surprisingly, it has now been found that a combination of fluorinated polymers or polymers and boron oxide or a borate is a good flame retardant, not only for the combination of polyphenylene ether and plasticizer, which are used in stringent flammability requirements, but also for combinations which meet less stringent requirements and contain at least 20% polyphenylene ether in their polymer component.

The invention therefore provides a material of the type described in the preamble, characterized in that the fire retardant is a mixture of 0.2-15 wt.% Of a fluorinated polymer or oopolymer and 0.05-10 wt. .% 1¾¾ or borate, based on the polyphenylene ether.

Although the invention is not dependent upon or limited by theoretical considerations, it is now believed that the fire retardants of the invention exert their action in that the fluorohydride polymer and the boron compound react with each other to form boron trifluoride or boron oxyfluoride, which apparently of the polyphenylene ether. This crosslinking reaction works in the opposite way to the polymer degradation that occurs during burning, and thus the amount of carbonization product is increased and a fire-retardant effect is achieved, while also the smoke development is reduced.

The reaction between the two components of the fire retardant was verified by the combination of polyvinyl i-dene fluoride and different boron compounds. Bolyvinylidene fluoride itself only decomposes above 480 ° C and the decomposition is endothermic. However, the thermal stability of this polymer is lowered by the addition of boron compounds. With DSC (differential scanning calorimetry), this could be observed as a tightly limited exothermic reaction, which, depending on the nature of the boron compound selected, occurs at 280 ° C to 470 ° C.

Following are the DSC-determined reaction temperatures of polyvinylidene fluoride (abbreviated as PVDF) with some boron compounds.

Combination Reaction temperature

PvDF / sodium tetraborate 290 ° C

FVDF / zinc borate 300 ° C

PVDF / boron oxide, 320 ^

PTDF / lithium metaborate 370 ° C

PVDF / sodium metaborate 470 ° C

On the basis of this it is possible to choose a combination which will exert its fire-retardant and smoke-limiting effect at a certain desired temperature.

On the other hand, of course, the fire-retardant should not start prematurely, i.e. during the processing of the plastic material. However, this problem is easy to overcome, e.g. by encapsulating one of the components of the fire retardant or by adding one of the components only towards the end of the material processing cycle. Thus, any desired combination of fluorinated polymer or cc polymer and B2O3 or borate can be used.

In this regard, it should be noted that although the invention has been primarily developed for plasticizer polyphenylene ethers or the so-called "pure" polyphenylene ethers, which contain only a small amount of rubber to improve impact strength, the combination of the invention, as already mentioned , can also be successfully applied to materials with less polyphenylene ether in the poly-alpha carpanent, eg combinations of polyphenylene ether with impact resistant polystyrene or EPEM-ruhber, combinations which may contain large or even predominant (up to 80%) amounts of polystyrene or rubber. The latter types are by their nature much more flammable, but also the flammability of these is reduced by the present combination of fire retardants, although this does not achieve as great an inhibition of flammability and smoke development as with the PFE- ^ materials, which must meet the above-mentioned strict fire-hair requirements Do it.

As already mentioned, the plasticizer is sometimes preferably predominantly aromatic in nature. For example, polyarcmatic esters are suitable, e.g. diphenyl phthalate and the like. A commercially available and proven plasticizer is pentaerythritol tetrabenzoate (commercial product Benzoflex S552). However, often suitable non-aromatic plasticizers can also be used.

The fluorine-containing polymer is preferably an incompletely fluorinated polymer or cc polymer, although a fully fluorinated polymer, such as polytetrafluoroethylene, also works, although larger amounts are required. Particularly suitable incompletely fluorinated polymer products are polyvinylidene fluoride and ethylene and tetrafluoroethylene polymers, the gross composition of which corresponds approximately to that of polyvinylidene fluoride. Polyviryl fluoride also starts the desired reaction, but does so at a lower temperature, so that in that case addition of the two-component fire retardant is never possible before or during processing. However, as has already been stated, this drawback can easily be overcome by encapsulating one of the two components in a material that melts quickly in the event of a fire, or by adding one of the two components only at the end of the processing. For example, B2O3 spart can be added, either at the exit end of the extruder or at the injection molding machine.

Both components of the present flame retardant are stable substances below their reaction temperature, which are not reactive to plasticizers or other additives contained in the polymer component.

According to the invention, a combination of 0.2-3 wt.% Polyvinylidene fluoride and 0.2-3 wt.% Or borate, based on the polymer component, is preferably chosen. The combination of polyvinylidene fluoride with B2O3 is currently most preferred.

If polytetrafluoroethylene is used, a combination of 3-7% by weight thereof with 1.5-3.5% B2O3 or borate is preferably used.

The material of the invention may additionally contain one or more additives customary for such materials, such as fillers, reinforcing fibers, stabilizers, pigments and dyes, plasticizers, mold release agents, notched impact enhancers. If it is desired to add further flame retardants, these are preferably not the usual flame poisons, such as the relatively low molecular weight phosphorus compounds. However, stable high molecular weight phosphorous compounds are useful and these compounds simultaneously act as plasticizers and as fire retardants.

Insofar as there is a sufficient difference between the processing temperature of the material and the reaction temperature of the fire-retardant combination, the components of the fire-retardant used according to the invention can be incorporated into the base polymer at any suitable time, e.g. by simply mixing the materials before the usual extrusion or optionally during the extrusion, e.g. about half way or at the extrusion point. Furthermore, the addition can also take place during final processing, e.g. during injection molding or extrusion molding. Furthermore, one can prepare a Masterbatch of one of the two components and add it to the basic mixture. In choosing between the various possibilities, one will generally be guided by the said difference between the temperature at which the fire-retardant mixture becomes reactive and the processing temperature of the material.

It should also be noted that EP-A-0.245.207 describes the use of phosphonic acid salts as flame retardants. These can be salts with a metal or metalloid from the group IIA, IIB, UIA and VA of the periodic table. Although a boron compound is included herein, boron is not further mentioned; the preferred salts are aluminum salts. Furthermore, these are again compounds which exert their fire-retardant effect through flame poisoning. Furthermore, it should also be mentioned that Dutch patent application 6603028 describes a method for rendering flame-resistant polyurethane materials using a combination of polyvinylidene fluoride, antimony oxide and a compound of an element which is capable of dehydrofluorination of polyvinylidene fluoride at a lower temperature. then expire in the absence of this connection. Borio bonds are mentioned as one of the possibilities, but are not further elucidated in the exemplary embodiments and, apart from the fact that the system is not intended for polyphenylene ethers, the combination described there can again be regarded as a flame poison.

The examples below serve to illustrate the invention in more detail and have not existed in any way to limit the invention in any way. In these examples, poly (2,6-dimethylphenylene) ether with an intrinsic viscosity of 46 ml / g was used as polyphenylene ether.

Example 1

Composition of mt-gaal r qpg.riglen

Polyphenylene ether 80 80 80 80 80 80 80

Pantaerythritol tetrabenzoate (Benzoflex S552, plasticizer) 20 20 20 20 20 20 20

Polyvinylidene fluoride (PVDF) 0 0.5 0.25 0.5 1 2 1

Boron oxide 0 o 0.09 0.18 0.36 0.72 l

Flame retardant properties (according to UL-94, total extinction time, seconds (10 ignitions, 5 test bars) (1.6 mm) 94 96 106 77 42 20 20 (3.2 m) 53 39 39 24 17 10 10 UI rating VI VI VI VI V0 V0 V0

Smoke density in Ds units according to AS1M E-662 (1.5 min) 84 56 25 44 30 20 25 (4.0 min) 337 230 284 244 162 87 120 (10 min) 425 316 433 334 380 197 290

As can be seen from the above, PVDF itself already has a clear influence on smoke development. The best combination in terms of fire retardancy is that with 2 wt% PVDF and 0.72 wt% boron osd.

Example 2

In a mixture of 85 wt. parts PEE and 15 wt. parts Benzoflex S552, the following fire retardants and other additives were included with the results reported below.

Fire retardant Ul-94, 1.6 mm

None 82.5 2 parts by weight PVDF +0.25 parts by weight B2O3 + 0.75 parts by weight L1BO2 45 2 parts by weight. parts of polytetrafluoroethylene (ΡΓΕΈ) + 1 wt. parts B2O3 25 2 wt. parts of PVDF + 1 part by weight of B2O3, 0.5 part by weight of carbon black (pigment) and 1.5 parts by weight. parts of polyoctenylene rubber (to improve the impact resistance) 20 2 parts by weight of PTFE, 1 part by weight of B2O3 and 0.5 part by weight of carbon black 25

Example 3

A comparative smoke density study was conducted with the following mixtures and with the following results:

Parts by weight PEE 85 85 85 85 85

Benzoflex 15 15 15 15 15 PVDF - 2 - 2 PTFE - - 2 - 2 B2O3 - 0.72 111

Carbon black - - - 0.5 0.5

Polyoctenylene rubber - - - 1.5

Smoke density, Ds (1.5 min) 100 20 25 10 25 (4 min) 370 90 140 60 140 (10 min) 400 190 200 200 250

Example 4

A number of tests were again performed with the plasticizer, pentaerythritol tetrabenzoate, abbreviated as EETB in the table below. Furthermore, polyoctenylene rubber is abbreviated as PO in this table.

PPE 85 85 85 85 85 85 85 85 85 85 85 85 80 80 80 80 80 80 80 85 ΡΕΓΒ 15 15 15 15 15 15 15 15 15 15 15 15 20 20 20 20 20 20 20 15 PVDF 2 0.5 0.25 0.5 1 2 1 2 ΡΙΓΈ 1235722332 B2O3 0.5 1 1.5 2.5 3.5 233011 0.09 0.18 0.36 0.72 0.25 PO 1.5 ÜBO2 0.75

Carbon black 0.5 0.5

Utr-94, 1.6 ram (sec) 85 49 <- <20 -> 90 <20 <20 94 96 106 77 42 <20 <20 45 rating VI <- V-0 -> v-1 V-0 V -0 Vl Vl Vl Vl V-0 Vo v-0 V-0

Smoke density 1.5 "100 40 25 16 12 14 11 10 14 110 25 10 84 56 25 44 30 20 25 20 4" 370 187 140 92 60 60 79 90 71 385 140 60 377 230 284 244 162 87 120 110 10 "400 300 200 160 95 107 145 130 109 410 300 200 425 316 433 334 380 197 290 230

Char a) (%) 28 30 31 33 37 36 36 36 36 28 31 37 28 28 29 30 32 37 36 36 a) Residual weight in therirogravimetric analysis (determined at 600 * C, under nitrogen, heating rate 200 ° C / min)

As can be seen from the table above, a very good result was obtained in the tests with polytetrafluoroethylene with different combinations, which was also the case with a number of combinations with polyvinylidene fluoride. In the latter combinations somewhat smaller amounts of both components were sufficient.

Example 5

The example below shows that the combination of the invention also leads to better results in the so-called Char test in the case of combinations of PPE and polystyrene with high impact strength, indicated in the table below as HIPS. Also, for comparison, tests are carried out with the HIPS as the only polymeric component.

Parts by weight PPE 50 50 30 30 0 0 0 HIPS 50 50 70 70 100 100 100 PVDF 2 2 2 5 B2O3 2 2 2 5

Char (%) 18 30 8 23 0 1 3

It can be seen from the table that even with a predominantly HIPS combination of PPE and HIPS, the present fire retardant combination showed a marked effect, whereas this was not the case with the HIPS as the only polymer component. The effect of the fire-retardant combination therefore appears to be linked to the presence of a certain minimum content of PPE in the polymer component; this minimum is about 20%.

Claims (6)

2. Material according to claim 1, characterized in that the fluorinated polymer or cc polymer is an incompletely fluorinated polymer or copolymer. Material according to claim 2, characterized in that the incompletely fluorinated polymer is polyvinylidene Netflixaride or a cc polymer of ethylene and tetrafluoroethylene. 4. The material according to claim 3, characterized in that the fire retardant is a phosphation of 0.2-3% by weight of polyvinylidene fluoride and 0.2-3% by weight of 1% or borate. Material according to claim 1, characterized in that the fluorinated polymer or cc polymer is a fully fluorinated polymer or cc polymer. The material according to claim 5, characterized in that the fully fluorinated polymer is polytetrafluoroethylene. Material according to claim 6, characterized in that the fire retardant is a combination of 3-7% by weight polytetrafluoroethylene and 1.5-3.5% by weight B2O3 or borate.