GB1570198A

GB1570198A - Smoke-retardant chlorinated polymer compositions

Info

Publication number: GB1570198A
Application number: GB47770/76A
Authority: GB
Original assignee: Firestone Tire and Rubber Co
Current assignee: Bridgestone Firestone Inc
Priority date: 1975-11-17
Filing date: 1976-11-16
Publication date: 1980-06-25
Also published as: DE2651840A1; JPS5263251A; NL7612569A; IT1123080B; CA1096527A; FR2332295B1; LU76201A1; FR2332295A1

Description

(54) SMOKE-RETARDANT CHLORINATED POLYMER COMPOSITIONS (71) We, THE FIRESTONE TIRE & BR< RUBBER COMPANY, a Corporation organized under the laws of the State of Ohio, United States of America, of 1200 Firestone Parkway, Akron, 44317 State of Ohio, United States of America, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: There is much art on flame-retardants, but little on smoke-retarders or suppressants.

A paper entitled SMOKE GENERATION FROM THE BURNING OF SOME POLY MERIC MATERIALS BY Brauman et al, given at the 32nd Annual Technical Conference of the Society of Plastic Engineers held in San Francisco in May 1974 discusses the problem and the effect of several smoke retarders, but does not suggest the invention.

Mitchell 3,821,151 suggests the use of molybdenum oxide in conjunction with iron powder and copper oxide as a smoke retardant in polyvinyl chloride, but no data are given. Miscellaneous patents on smoke retardants for vinyl chloride resins inciude, for example United States Patents Nos.

3,725,319; 3,746,664; 3,758,638; 3,819,577; 3,822,234 and 3,900,441; but these include no suggestion of the invention.

The present invention provides, in one aspect, a polymer composition having a reduced tendency to smoke under combustion conditions comprising (a) at least one polymer having a chlorine content of from 5 to- 70% based on the weight of the polymer and (b) from 1 to 10 parts by weight per 100 parts by weight of component (a) of at least one cobalt or manganese salt of an aliphatic C2 to C, dicarboxylic acid or an aliphatic C2 to cm hydroxy carboxylic acid.

The present invention, in a second aspect, provides a polymer composition having reduced flammability and reduced tendency to smoke under combustion conditions comprising (a) at least one polymer having a chlorine content of from 5 to 70% based on the weight of the polymer, (b) from 1 to 10 parts by weight per 100 parts by weight of component (a) of at least one cobalt or manganese salt of an aliphatic C2C,; dicarboxylic acid or an aliphatic C2-C6 hydroxy carboxylic acid and (c) from 10 to 150 parts by weight per 100 parts by weight of component (a) of aluminium hydroxide.

It has been found that cobalt, zinc, iron and manganese salts of dicarboxylic and hydroxycarboxylic acids containing 2 to 6 carbon atoms are very effective smoke suppressants when added to halogen-containing polymers or copolymers, including chlorinated polyethlene and propylene, chlorinated paraffins, oils and waxes, polyvinylidene chloride and preferably vinyl chloride polymers and chlorinated vinyl chloride polymers and blends of the foregoings polymers. The chlorine content of polyvinyl chloride is about 57 percent. If copolymers of vinyl chloride are used, the chlorine content is less if the comonomer (such as vinyl acetate) does not contain chlorine, and is higher if the comonomer contains chlorine, (such as vinylidene chloride).The chlorine content of chlorinated polyethylene, chlorinated polypropylene, or other chlorinated paraffins can vary over a wide range depending upon the physical properties desired in the polymer composition. Generally, a range of from about 5 to 70 percent chlorine is present.

The polyvinyl chloride composition can be rigid or flexible. The chlorine content of a flexible polyvinyl chloride composition will generally be less than 57 percent unless chlorinated plasticizer is present. Thus, the chlorine content of the polymer composition can range from 5 to 70 percent. The incorporation of the above-named salts retards and lessens the smoke generated by the burning polymer. One can use 1 to 10 parts by weight of the salts, or more, if desired, per 100 parts by weight of the polymer. Preferably there should be used 4 to -8 parts by weight of the salts per 100 parts by weight of the halogenated polymer.

The cobalt and manganese salts of hydroxyand dicarboxylic acids, besides being excellent smoke retardants when used alone, have a particularly excellent synergistic effect when used in combination with hydrated aluminum hydroxide. Not only does there result a degree of smoke suppression greater than is obtained with the use of the individual materials, but also there is a substantial reduction in flammability. This last is particularly surprising, since the use of the fire retardant salts of the present invention alone sometimes results in a slight increase in flammability.To obtain this synergistic effect, the hydrated aluminum oxide should be used in amounts of from 10 to as high as 150 and preferably from 20 to 75 parts by weight of aluminum hydroxide per 100 parts by weight of chlorine-containing polymer; the upper limit selected for said aluminum hydroxide is one based on practicality.

The acid moieties of the salts of cobalt or manganese can be those of any aliphatic organic hydroxy-carboxylic or dicarboxylic acid containing 24 carbon atoms; mixtures can be utilized. Examples of such acids include oxalic, malonic, succinic, glutaric, adipic and similar dicarboxylic acids; hydroxyacetic, tartaric, ascorbic, citric, hydroxypropionic and similar hydroxy acids.

Before referring to the results, it is nieces sary to know the meaning of the terms utilized. Details of the test methods employed and the definitions used are given below.

Evaluations for the density of visible smoke were made using a commercial smoke density chamber modelled after one developed at the National Bureau of Standards by the Fire Research Group (see D. Gross, J. J. Loftus and A. F. Robertson, ASTM Special Technical Publication 422 pages 166-204 (1969).) This chamber contains a radiant heater producing 2.5 W/cm2 of heat at the surface of a 3 > 'x3" 3" sample, a pro- pane-air pilot burner and a vertical beam of light with a photomultiplier tube detector and microphotometer to record the attenuation of light by smoke developing in the chamber. During smoke testing, the chamber is sealed to enclose the combustion products and smoke.The smoke developed is measured as Specific Optical Density, Ds, where V T, T, Ds= -- log,, 132 log10 - AL T T V - = volume of chamber A = area of test specimen L = Length of light path To = initial light transmittance through the chamber T = transmittance of light during test At the peak of smoke build-up Ds=D,n, and for purposes of the report, corrected maximum smoke is recorded as Dmo= D,--D, where D0 is the clear beam specific optical density occurring after the smoke test, when the chamber has been exhausted of smoke. Lower values of D indicates less obscuration of light due to smoke.

Several other quantities measured include the time in minutes to 90 percent of Dm (t.9 Dm) and the time (in minutes) to Ds= 16 (t D6), which are indicative of the rate of smoke development (higher numbers signify slower rates), as well as the smoke obscuration numbers for the first four minutes of test, SON4, where Ds (1 min.)+Ds (2 min.)+Ds (3 min.)+Ds (4 min.) SON4= 4 which also represents the early rate of smoke development (lower numbers mean less smoke). The definitions of terms are summarized below.

Dme = Specific optical density at maxi mum smoke intensity, corrected for fogging of lens seals. Dme < 25, light; 25-75, moderate; 100--400, dense; > 400 very dense.

t9 Dm = time (minutes) to reach 90 per cent of maximum optical den sity.

tDl" = time (minutes) to D= 16; cor responds to early visibility obs curation. tD10- < 1, very fast; 1-3 fast; W6 moderate; 7-10 slow; > 10, very slow smoker.

SON4 = Smoke obscuration number over first four minutes of test, indi cates amount of smoke vs. rate of build-up early in the test.

SON4 (3, very low; 4--10, low; 10-50, moderate; 50-100, high; > 200, very high.

LOI is the abbreviation for Limiting Oxygen Index which is defined as the minimum volume percent oxygen content required in an oxygen/nitrogen mixture to maintain combustion of a vertical, top lighted test specimen. The value is expressed in mathematical terms as follows: [O2j LOI= X100 [ 2] +,:2J where [021 is the volume of oxygen and .'[N2] is the volume of nitrogen. The LOI is considered to be an accurate, reproducible determination of the flammability of materials. From a practical standpoint, an LOI value of greater than 25 generally means that the test specimen will be selfextinguishing. For a more detailed discussion of the LOI and method of determination, C. P. Fenimore and F. R. Martin's article in COMBUSTION AND FLAME 10 No. 2, page 135 (1966), should be consulted.

Limiting Oxygen Indices were obtained using the Michigan Chemical LOI apparatus.

An Aminco--NBS smoke density chamber was used to obtain data on the rate of smoke generation as well as intensity of visible smoke.

EXPERIMENTAL RESULTS Polyvinyl Chloride Resin 100 grams ("FPC-965" a product of The Firestone Tire & BR< Rubber Company) Calcium Stearate 2 grams Dilauryl Tin Mercaptide 3.75 grams Smoke Suppressant 5 grams (per Table I) A series of plaques was prepared in accordance with the foregoing recipe, using different smoke suppressants in the several runs as set forth in Table I. In each case, the ingredients in the recipe were compounded, in the order in which they are listed, on a laboratory roll mill heated at 350"F. (177"C.). The compounded material was then pressed into sheets 0.030" (0.762 mm.) thick in a laboratory press, the platens of which were heated at 345 F. (174"C.).

Specimens from each sheet were submitted to NBS smoke density tests as described above.

Also, specimens were pressed out at 345 F.

(174"C.) with dimensions 0.25" X 5" X 1.0" (6.35 mrn.xl27 mm.x25.4 mm.) and subjected to oxygen index measurements as described above. Set fourth herewith in Table I are the results of these experiments.

TABLE I Smoke Color of TEST RESULTS Inhibitor Specimen Used LOI D,,, t.9Dm tDl6 SON4 Example None light 45.1 357 2.67 0.42 272 1 (Control) yellow Cobalt light 43.4 273 2.43 0.45 214 2 Oxalate blue Manganese light tan- 43.0 317 2.16 0.39 265 3 Tartrate yellow Barium light 39.9 432 3.16 0.37 342 4 Tartrate yellow (Control) Examples 1--4 show the different effects of the various compounds added. Thus cobalt oxalate and manganese tartrate of the present invention (Examples 2-3) decreased the smoke in relation to the control (Example 1). Barium tartrate increased the smoke.

TABLE II Smoke Color of TEST RESULTS Inhibitor Specimen Used LOI D t.9Dm tDlG SON4 Example None cream 49.0 284 3.20 0.48 206 5 (Control) Cobalt light 57.4 216 3.34 0.56 145 6 Oxalate blue Examples 5-6 of Table II illustrate the synergistic effect of the smoke suppressants of the present invention when used in connection with aluminum hydroxide, which itself is used as a flame retardant and smoke suppressant for a variety of resins.

The compositions of Table II contained, in addition to the ingredients of the foregoing recipe and the indicated smoke inhibitors, 30 grams of hydrated aluminum oxide (aluminum hydroxide, Al(OH2)).

Comparing the control Example 1 of Table I with the other runs, in Example 5 of Table IT, the aluminum hydroxide alone cuts down the visible smoke (dog) by 20%, and at the same time, increases LOI by 9% (decreased flammability). In contrast, cobalt oxalate alone (Example 2) cuts down visible smoke (doc) but decreases LOI (increased flammability). However, when both are used together (Example 6) the visible smoke (doc) is reduced and the LOI (inverse to flammability) is increased.

WHAT WE CLAIM IS:- 1. A polymer composition having a reduced tendency to smoke under combustion conditions comprising (a) at least one polymer having a chlorine content of from 5 to 70% based on the weight of the polymer and (b) from 1 to 10 parts by weight of at least one cobalt or manganese salt of an aliphatic C2 to C6 dicarboxylic acid or an aliphatic C2 to C6 hydroxy carboxylic acid per 100 parts by weight of component (a).

2. A polymer composition having reduced flammability and reduced tendency to smoke under combustion conditions comprising (a) at least one polymer having a chlorine content of from 5 to 70% based on the weight of the polymer, (b) from 1 to 10 parts by weight of at least one cobalt or manganese salt of an aliphatic C2-C6 dicarboxylic acid or an aliphatic C2-, hydroxycar boxylic acid per 100 parts by weight of component (a) and (c) from 10 to 150 parts by weight of aluminum hydroxide per 100 parts by weight of component (a).

3. A composition as claimed in either claim 1 or claim 2 wherein the salt is present in an amount of from 4 to 8 parts by weight per 100 parts by weight of component (a).

4. A composition as claimed in either claim 2 or claim 3 wherein the aluminium hydroxide is present in an amount of from 20 to 75 parts by weight per 100 parts by weight of component (a).

5. A composition as claimed in any one of claims 1 to 4 wherein the polymer is polyvinyl chloride.

6. A composition as claimed in claim 5, which composition is rigid.

7. A composition as claimed in any one of claims 1 to 4 wherein the polymer is chlorinated polyethylene.

8. A composition as claimed in any one of claims 1 to 7 wherein the salt is a salt of oxalic acid.

9. A composition as claimed in any one of claims 1 to 7 wherein the salt is a salt of tartaric acid.

10. A composition as claimed in any one of claims 1 to 9 wherein the salt is a salt of cobalt.

11. A composition as claimed in any one of claims 1 to 9 wherein the salt is a salt of manganese.

12. A composition as claimed in any of claims 1 to 7 wherein - the salt is cobalt oxalate.

13. A composition as claimed in any one of claims 1 to 7 wherein the salt is manganese tartrate.

14. A composition as claimed in claim 1 and substantially as hereinbefore described in any one of Examples 2 to 3.

15. A composition as claimed in claim 2 and substantially as hereinbefore described in Example 6.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. Examples 5-6 of Table II illustrate the synergistic effect of the smoke suppressants of the present invention when used in connection with aluminum hydroxide, which itself is used as a flame retardant and smoke suppressant for a variety of resins. The compositions of Table II contained, in addition to the ingredients of the foregoing recipe and the indicated smoke inhibitors, 30 grams of hydrated aluminum oxide (aluminum hydroxide, Al(OH2)). Comparing the control Example 1 of Table I with the other runs, in Example 5 of Table IT, the aluminum hydroxide alone cuts down the visible smoke (dog) by 20%, and at the same time, increases LOI by 9% (decreased flammability). In contrast, cobalt oxalate alone (Example 2) cuts down visible smoke (doc) but decreases LOI (increased flammability). However, when both are used together (Example 6) the visible smoke (doc) is reduced and the LOI (inverse to flammability) is increased. WHAT WE CLAIM IS:-

1. A polymer composition having a reduced tendency to smoke under combustion conditions comprising (a) at least one polymer having a chlorine content of from 5 to 70% based on the weight of the polymer and (b) from 1 to 10 parts by weight of at least one cobalt or manganese salt of an aliphatic C2 to C6 dicarboxylic acid or an aliphatic C2 to C6 hydroxy carboxylic acid per 100 parts by weight of component (a).

6. A composition as claimed in claim 5, which composition is rigid.