CA1258733A - Carbonate polymer containing an ignition depressant composition - Google Patents

Abstract

ABSTRACT

This invention relates to carbonate polymer compositions such as a bisphenol-A homopolycarbonate containing a small amount of a metal salt of an aromatic sulfonamide, a metal salt of a perhalometalate complex, or a metal salt of an inorganic acid, a halogenated organic compound and a melamine. These carbonate polymer compositions are suitable for use in the manufacture of molded parts such as automobile parts, e.g., air filters, for housings, exterior components, housings for electrical motors, appliances and the like. These carbonate polymer compositions are considerably more difficult to ignite and burn for a much shorter time than unmodified carbonate polymer resins or carbonate polymer compositions containing only the individual fire retardant additive components.

Description

25~3~33 CARBONATE POLYMER CONTAINING
AN IGNITION DEPRESSANT COMPOSITION

This invention relates to carbonate polymer compositions containing additives which act as flame retardants.

Carbonate polymers derived from reactions of dihydroxyorganic compounds, particularly the dihydric phenols, and carbonic-acid derivatives such as phosgene, have found extensive commercial application because of their excellent physical properties. These thermoplastic polymers are suitable fox the manufacture of molded parts wherein impact strength, rigidity, toughness, heat resistance and excellent electrical properties are re~uired.

. Unfortunately, however, these polymers exhibit a brief but definite burning time when contacted with an open flame. More importantly, as is often the case, the carbonate polymers contain stabilizers and other additives which are often more combustible than the unmodified carbonate polymer. As a result, the modified carbonate polymers frequently exhibit substantially 30,586-F -1-'~ , .

- ~2S~733 poorer resistance to com~ustion than does the unmodified carbonate polymer.

In attempts to increase the combustion resis-tance of carbonate pol~mers including the modified forms thereof, it has been a common practice to employ monomeric phosphites, phosphoric acid esters, thiophos-phoric acid esters containing halogenated alkyl radicals and halogenated organic compounds into the carbonate polymer. However, in order to obtain any noticeable improvement in combustion resistance, these additives have been employed in such large quantities that they often adversely affect many of the desirable physical and mechanical properties of the carbonate polymer.

In view of the deficiencies of conventional fire retardant carbonate polymer compositions, it wQuld be highly desirable to provide a carbonate polymer composition having improved resistance to burning when exposed to an ignition source.

The present invention is a carbonate polymer composition comprising a carbonate polymer having dispersed therein, in an amount sufficient to provide improved flame retardancy to said carbonate polymer composition, a fire retardant additive comprising (1~ a member of the group consisting of a metal salt of an aromatic sulfonamide and (2) a halogenated organic compound. In another aspect of khis invention, the carbonate polymer composition comprises a carbonate polymer having dispersed therein in an amount sufficient to provide improved 30,586-F -2-- lZ5~733 flame retardancy ~o said carbonate polymer composition, a fire retardant additive comprising (1) a member of the group consisting of a metal sal~ of an aromatic sulfonamide or a metal salt of an inorganic acid, and a metal salt of a perhalometalate complex, (2) a halo-gena~ed organic compound, and (3) a melamine. Herein-after, such compositions will be referred to as fire retardant carbonate polymer compositions. The fire retardant carbonate polymer compositions of the present invention exhibit surprisingly high resistance to combustion. In addition, said compositions exhibit physical properties comparable to a carbonate polymer containing no fire retardant additive.

The fire retardant carbonate polymer composi-tions of the present i~vention are suitably employed in most applications in which polycarbonates have been previously utilized. Applications of particular interest for the utilization of the said carbonate polymer compositions of this invention are as follows: automo bile parts, e.g., air filters, fan housings, exterior components, housings for electrical motors, appliances, business and office equipment, and photographic equip-ment, lighting and aircraft applications.

The carbonate polymers employed in the present invention are advantageously aromatic carbonate poly-mers such as the trityl diol carbonates described in U.S. Patent Nos. 3,036,036; 3,036,037; 3,036,038 and 3,036,039; polycarbonates of bis(ar-hydroxyphenyl)-alkylidenes (often called bisphenol-A type diols~
including ~heir aromatically and aliphatically substi-tuted derivatives such as disclosed in U.S. Patent 30,586-F -3-_4 ~5873~

Nos. 2,999,~35; 3,038,365 and 3,334,154; and carbonate polymers derived from other aromatic diols such as described in U.S. Patent No. 3,169,121.

It is understood, of course, that the poly-carbonate may be derived from (1) two or more differentdihydric phenols or (2) a dihydric phenol and a glycol or a hydroxy- or acid-terminated polyester or a dibasic acid in the event a carbonate copolymer or interpolymer rather than a homopolymer is desired. Also suitable for the practice of this invention are blends of any one of the above carbonate polymers. Also included in the term "carbonate polymer" are the ester/carbonate copolymers of the types described in UOS~ Patent Nos. 3,169,121; 4,287,787; 4,156,069; 4,260,731 and 4,105,633. Of the aforementioned carbonate polymers, the polycarbonates of bisphenol-A and derivatives, including copolycarbonates of bisphenol-A, are pre-ferred. Methods for preparing carbonate polymers for use in the practice of this invention are well ~nown, for example, several suitable methods are disclosed in -the aforementioned patents which are hereby incorpo-rated by reference in their entirety.

The salt form of aromatic sulfonamides which are employed herein are advantageously represented by the formula:

[~rS02Ne~ ~M
n wherein Ar is an aromatic group, M is a suitable ca-tion such as a metal cation and n is a number corresponding to the valence of M. M is preferably an alkali metal.
.

30,586-F -4-~2S8~733 Alternatively, M is a divalent cation, preferably alkali earth or multivalent cation obtained from copper, aluminum, antimony, and the li~e. Representa-tive preferred sulfonamide salts include the alkali me~al salts of saccharin, N-(p-tolylsulfonyl)-p-toluenesulfonamide, N-(N'-benzylaminocarbonyl)-sulfanilamide, N-(phenylcarboxyl)-sulfanilamide, N-(2-pyrimidinyl)-sulfanilamide, N-(2-thiazolyl)sulfanil-amide and other salts of the sulfonamides disclosed in U.S. Patent No. 4,245,015, issued on March 3, 1981 to Thomas et al. Combinations of the above-identified s21ts can also be employed.
Metal salts of inorganic acids and metal salts of perhalometalate complexes are most preferably alkali metal salts which include, for example, trisodium hexa-fluoroaluminate, disodium hexafluorotitanate, disodium hexafluorozirconate, sodium pyrophosphate, sodium tetrafluoroborate, ~odium hexafluorophosphate, sodium bisulfate and sodium phosphate. Also preferred are the potassium form of the salts listed above. Calcium sulfate and aluminum sulfate can be employed. Combi-nations of the above-identified salts can al~o be employed.
The halogenated organic compound can be virtually any halogenated organic compound commonly used as a fire retardant additive. The preferred compounds are the halo-sub~tituted aromatic compounds 3 (halo is fluoro, chloro, or bromo~. Suitable compounds include, for example, decabromo diphenyloxide, tris-(tribromophenoxy)triazine, decabromo diphenyl carbonate, a tetrafluoroethylene polymer, and a carbon-ate copolymer o~ bisphenol A/tetrabromobisphenoi A.
Examples of other suitable monomeric and ?olymerlc 30,586-F -5--6- 1~587~33 halogenated compounds are disclosed in U.S. Patent No.
4,263,201, issued on April 21, 1981 to Mark et al.
The melamines of the present invention include cyanurotriamide and hexamethoxy methyl melamine as well as virtually any N-substituted melamine which is suf-ficiently pure and compatible with the carbonate polymer.
The fire retardant additives of this invention can comprise any amount of the aforementioned com-ponents in an effective combination which will provide improved fire retardancy to the carbonate polymer.
Most preferred additive combinations comprise from about 10 to about 35, preferably about 15 to about 25, weight percent of a salt of an aromatic sulfonamide, salt of a perhalometalate complex, or salt of an in-organic acid, from about 10 to about 35, preferably about 15 to about 25 weight percent melamine, and from about 30 to about 80, prefera-bly about 50 to about 70, weight percent halogenated organic compound, based on the total weight of the additive. It is also under-stood that the individual fire retardant additive com-ponents must be sufficiently heat stable and pure to survive processing temperatures common to carbonate polymers without causing severe molecular weight degradation of the carbonate polymer with which the component is blended.

30, 586-F -6-~;

-7~ ~X58~33 The fire retardant carbonate polymer composi-tions of the presen~ in~ention are suitably prepared by combining the carbonate polymer with an effPctive amount of fire retardant additive using any of a variety of blending procedures conventionally employed for incorporating additives into carbonate polymer resins.
For e~ample, dry particulates of the carbonate polvmer and the fire retardant additive can be dry blended and the resulting dry blend ex-trud~d into the desired shape. By "effective amount" is meant that combination of the desired fire retardant additive components is sufficient to provide improved fire retardant character to the carbonate polymer with which it is blended.

While any amount of the fire retardant addi-tive that imparts to the carbonate polymer an improvedfire retardancy is suitable, preferred amounts of ~he fire retardant additive are in the range from 0.001 to 10, especially from 0.005 to 2, weight percent based on the weight of the carbonate pol~mer.

Fire retardant carbonate polymer compositions are considerably more difficult to ignite than unmodi-fied carbonate polymer resins or carbonate polymer compositions containing only the individual fire retar-dant additive components. The fire retardant carbonate polymer compositions of this invention rapidly form a char at the surface of the sample once ignition is achieved. In addition, the compositions of this inven-tion burn for a much shorter time than unmodified carbonate polymer resins or carbonate polymer composi-tions containing only the individual fire retardantadditive components.

30,586-F -7-s~

In addition tc the aforementioned fire re~ar-dant additives, other additives can be included in the carbonate polymer composition of the present invention such as fillers (i.e., a tetrafluoroethylene polymer or glass fibers), pigments, dyes, antioxidants, stabili-zers, ultraviolet light absorbers, mold release agents and other additives commonly employed in carbonate polymer composi~ions.
The following examples are given to further illustrate the invention and should not be construed as limiting its scope. In the following examples, all parts and percentages are by weight unless otherwise indicated.
ExamDle 1 Sa~ples are prepared using a 3000-g portion of a bisphenol-A polycarbonate sold under the brand name Merlon~ M50F-1000 by Mobay Chemical Corporation, and a fire retardant additive comprising varying amounts of sodium N-(p-tolylsulfonyl)-p-toluenesulfonamide, deca-bromo diphenyloxide and hexamethoxy methyl melamine.
The constituents are mixed using a Hobart~ brand mixer until thoroughly and evenly dispersed~ The mixture is dried at 250F for 4 hours, and extruded on a single screw, 1 1/4 inoh, 20:1 L/D extruder operated at a barrel temperature of 525F and a screw speed of 80 rpm.
The extruded sample is redried at 250F for 4 hours.
The pellets are molded into test specimens usin~ an injection molding machine under the following condl-tions: barrel temperature = 575F, mGld tempera~ure =
175F, injection polymer pressure sufficient to fill the cavity. The molded bars are tested for combustibility (oxygen index and fire resistance). Data is presented in Table I.

30,586-F -8-9 ~:5~7~

a~ X N ~ N~ ~ D O ~ ~ O ~0 O O
ti- a) ~ u~ g 0 cn o ~ ~ o ~1 ~ ~D 0 X ~ N ~ t~ N
0 ~

O ~I N N N O O O
t~
.~ m P ~ D P
~C j ` O ~i ` ~i N N O O O O O O O
m I I I I I I I I I I
m ~ Dm P ~ ~ P D ~ ~ I> ~ ~>

s~
Q~
~ ~ ,~
~ ~ E~ ~ ~1 o ~ r~
~1 . ~ ~ ~1 ~ ~ ~ i I N ~1 ~1 0 0 0 0 ~1 ~j N ~1~1 U~
I ~1 0 ~1 0 r-l O ~1 0 ~I N Lr) O O
I...........
~-1O O O ~10 ~10 ~10 ~1000 ~1 ~ E~,~

~4 E~
~ ~ ~ o o o ~ ~ ~ o l l o o o ~
~ o ~ o o o o o p o ~ ~ o o o ~ ~ l ~ o l l o ~o o ~ ~ ~9 ~
oQ I I I . .
~3 o,1 o o o o ~ o ,1 ., ~ ~ U) o ' o o ,~ o I I I I O ~ O O ~1 ~ d4 o ~t I o ~ o o o o o o o ~Z

q~
,1 ~ *
~d V ~ C.) C.) C,) V V U~ M U3 U~
V~

' 30, 586-F -9--10- ~2587~3 ~n ~J rl h .,1 h ~1 o U~
~ a~
O ~1 O
U~
~,q .
.J ,--i O
~ ~i $
~1 0 ~ ~
o ~ a U~ o ~ ,, ,1 . ~ o o ~ U ~, ~ ~ ~ U
o P, ~ ~ o .,~ _ .,, ,~ ~ o , I X
X o a~
o ~ ~1 ~ ~ a~
",~
a~ ~ ~ u o o o ol 1 ~ toC ~a) ~ ~ I
a~ ~ o .~ Q
~1 0 ~ ~ ~~r4 U
x ,s~ 3~l r~ r¢
o a~ o P
u ~
~ 0 :~ O Ra) ~ ~ o ~3 Z ~ ~ ~

30, 586-F -10-25~3733 Example 2 Samples are prepared and tPsted as in Example 1.
The molded bars are tested for combustibility. Data is presented in Table II.

30,586-F -11--12~ ~25~37~

~U~
~ ~ N 19 ~ ~ ~ r~
t~) aJ
~ ~ ~ ~ ~ ~ dl O H

O O O O O O
l l l l l l ~1 ~
` O O O O O O
(~ ~:1 1 1 1 1 1 1 ~ ~.~ ~ O ~
P. ~ ~ ~~i N O ~ ~1 ~ a:
P; ~ ~ ~, O ~, O ~, O
~ ~ g ' O ~, O ~, O ~, .~ E~
~ ~ I

~ ol ~ ~ ~
I I I I o n~ ,1 a.~ ~ ~
~D ~ ~ 0 ~1 I I I I I O ~ ~ 0~ ~ U
3 ~ ' I o o ~ " X

$ ~ ~ ~
~o ~1 o ~ ~o ~ ~ ~o ,~ I o o ~ ~ . ~
O E-l I o t~ o (~ H
~ !~ o o c~ o ~ u~
0 ~ E~ ~ u E~ E~
Q ~1 or~l t`~ ~ z .~ ~ m ~ a~
U~ U V~ , ~, N ~ ~ U~

30,586 F

--13 ~ 2 5 87 ~

As evidenced by the data shown in Ta~les I
and II, the fire retardant additives, when blended with the polycarbonate in amounts within the scope of this invention, provide substantial improvement in that the compositions e~hibit a reduced tendency to burn.

- 30,586-F -13-

Claims (6)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS
FOLLOWS:

1. A carbonate polymer composition comprising a carbonate polymer having dispersed therein, in an amount sufficient to provide improved flame retardancy to said carbonate polymer, a fire retardant additive comprising (1) a metal salt of an aromatic sulfonamide, an inorganic acid or a perhalometalate complex, (2) a halogenated organic compound and (3) a melamine.

2. A composition of Claim 1 wherein the fire retardant additive comprises from 10 to 35 weight percent aromatic sulfonamide salt; inorganic acid salt or a perhalometalate complex salt; from 10 to 35 weight percent melamine; and from 30 to 80 weight percent halogenated organic compound, based on the total weight of the additive.

3. A composition of Claim 1 wherein said metal salt of an aromatic sulfonamide is represented by the formula:

wherein Ar is an aromatic group, M is a metal cation and n is a number corresponding to the valence of M.

4. A composition of Claim 1 wherein the carbonate polymer is a polycarbonate of bisphenol-A, and in the fire retardant additive component (1) is the sodium or potassium salt of N-(p-tolylsulfonyl)-p-toluenesulfonamide and (2) is tri-(2,4,6-tri-bromophenoxy)-triazine or decabromo diphenyl carbonate.

5. A composition of Claim 1 wherein said fire retardant additive is present in an amount from 0.001 to 10 weight percent based on the weight of the carbonate polymer.

6. A composition of Claim 1 wherein said fire retardant additive is present in an amount from 0.05 to 2 weight percent based on the weight of the carbonate polymer.