Practical Aspects of the Formulation of Fire-Retardant Paints

Practical Aspects of the Formulation of Fire-Retardant Paints T. M. MURRAY, FELIX LIBERTI, and AUSTIN O . ALLEN

Downloaded by UNIV OF ARIZONA on January 2, 2013 | http://pubs.acs.org Publication Date: January 1, 1954 | doi: 10.1021/ba-1954-0009.ch006

Vita-Var Corp., Newark, N.J.

An effective fire-retardant paint for use on burnable substrate must have the following properties: The dried film should be incombustible. It should liberate heavy inert or noncombustible gases, which tend to smother flame. The film should contain materials to give a glasslike flux by low-melting organic compounds which tend to seal the underlying surface from flame. A cellular mat should be formed, which serves to insulate the underlying surface. The paint film should be reasonably insoluble in water, so that interior paints will withstand washings and exterior paints withstand weather conditions. Vehicles and pigments have been selected to give these characteristics and at the same time produce practical protective and decorative coatings for interior and exterior use. Considerable thought was given to the evaluation of various formulations. Federal Specification TT-P-141 was adhered to as far as possible for test methods. The New York Production Club cabinet, with modifications by the Engineer Research and Development Laboratories, was utilized for the fire-retardant evaluations and a leaching test was introduced to determine the water solubility of the films.

Ihrough the past 50 to 75 years, considerable interest has been demonstrated i n paints or coatings that might be used as protection against fire. The methods of approach to the problem vary w i d e l y . However, Ware and Westgate (2) cover the fundamentals adequately with four principles: (1) replacement of combustible organic matter i n the v e h i c l e by less combustible or incombustible m a t e r i a l , (2) liberation of inert or noncombustible gases which tend to smother flames, (3) formation of glazes by l o w - m e l t i n g inorganic compounds which flux and tend to seal the underlying surface from flame, and (4) formation of thick c e l l u l a r mats which serve to insulate the underlying surface. A fifth function might very w e l l be i n c l u d e d , and that is the charring of a c e l l u losic surface by the action of corrosive acids such as sulfuric or phosphoric, which are released by decomposition of the f i l m . This latter function provides a surface very s i m i l a r to c h a r c o a l , which has the w e l l - k n o w n property of glowing without f l a m i n g . 35 In FIRE RETARDANT PAINTS; Advances in Chemistry; American Chemical Society: Washington, DC, 1954.

36

A D V A N C E S IN C H E M I S T R Y SERIES


At this point a differentiation should be made between a nonflammable and a fire-retardant f i l m . On the one hand, the coating is designed to be applied on a nonflammable substrate and, in this case, the f i l m itself should be as near nonflam mable as possible. On the other hand, a fire-retardant f i l m is designed to retard the spread of flame through a flammable substrate. Most c o m m e r c i a l paints are fire-re tardant to a degree; an unpainted wood or w a l l board surface w i l l burn much more freely i f unpainted than i f coated with an ordinary flat w a l l paint such as T T - P - 4 7 . There has been a widespread misconception that the dried paint f i l m is a fire hazard, when a c t u a l l y a wood or c e l l u l o s i c wallboard surface is cor^iderably more readily combustible uncoated than when coated with the average w a l l paint. The test apparatus used i n this work was the New York Production C l u b cabinet developed by the New York Paint and Varnish Production C l u b and modified by E n g i neer Research and Development Laboratories, Fort Bel voir, V a . It consisted essenti a l l y of two p a r a l l e l iron bars set 6 inches apart and extending upward at a 45* angle from the lower side of the cabinet, and an adjustable cross bar to support the test panel i n the desired position. T h e flame source consisted of absolute ethyl a l c o h o l contained i n a brass cup supported on a cork-insulated m e t a l pedestal. The test panel was placed i n position on the angular supports. Five m i l l i l i t e r s of absolute ethyl a l c o h o l was measured into the brass cup by means of a buret. The cup was then placed on the cork-insulated pedestal and placed i n a position exactly 1 inch from the face of the panel. The panel used was cut from selected poplar wood to the dimensions, 6 χ 12 χ 1/4 inches. Two coats of paint were applied to these panels to provide a dry f i l m t h i c k ness of 0.004 i n c h . Included i n the work was a leaching test consisting of complete immersion of the painted panels i n distilled water for 48 hours at 120* F. The panels were than re moved and'dried at 120* F. for 72 hours before being submitted to the burn test. This test was considered important i n the prediction of the effect of washing on an interior paint and it is obvious that the effect of r a i n f a l l should be predetermined on an exterior paint. T e n t y p i c a l pigments and /or extenders have been tested i n an alkyd v e h i c l e i n both the presence and absence of chlorinated paraffin. These results were determined at pigment loadings of 40% and 60% P V C . T a b l e I shows that, of a l l the pigments tested, z i n c borate showed the best fireretardant properties. C a l c i u m carbonate showed valuable retardant properties, its effectiveness increasing with increased concentration. This would indicate that it functions by decomposition with subsequent release of /carbon dioxide. In view of a l l of the references to be found i n the literature, results with antimony oxide seem disappointing. However, most of the data on this pigment have been de veloped on fiber or fabric and it is obvious that these data would not necessarily a p ply to fire-retardant performance of supported films. T e n different vehicles or v e h i c l e combinations have been studied for fire-retard ant properties. This study was conducted with a constant pigment combination and at a constant pigment volume concentration. The pigment loading concentration of 3 4 % was chosen because it was believed that this concentration would f a l l below the c r i t i c a l range indicated i n T a b l e I. T h e combination of pigments was chosen to pro vide adequate hiding which had been indicated up to this point i n the investigation.

In FIRE RETARDANT PAINTS; Advances in Chemistry; American Chemical Society: Washington, DC, 1954.

MURRAY, ET AL — FORMULATION OF FIRE-RETARDANT PAINTS

37

T h e pigments were combined i n the following ratio: T i t a n i u m dioxide Z i n c borate C a l c i u m carbonate Asbestine

42.0% 38.0% 12.5% 7.5%


Examination of T a b l e II w i l l show that, of a l l the vehicles tested, the a l k y d resins produced the best fire-retardant properties. A l l these films were air-dried at room temperature i n the absence of any catalysts other than lead and cobalt where appropriate. As might be expected, pigment volume concentration is shown i n many instances to have definite effect on fire-retardant properties. This effect appears to be specific for each pigment. In general, this work shows better results at lower pigment volume concentration, but, as is shown i n T a b l e I, there is departure from this rule sufficient to indicate the probability of a c r i t i c a l pigment - - binder ratio for each pigment. When this ratio is exceeded, f i l m porosity is increased, thus detracting from the retardant effectiveness. Intumescent Agents Perhaps the most important single property for a fire-retardant f i l m is intumescence, the property of swelling or puffing when exposed to the heat of flame. Such swelling providing a thick c e l l u l a r insulating layer between the fire and the flammable substrate. During the course of this work, the following compounds were tested as intumescent agents i n various formulations and concentrations both alone and i n combination with each other. A m m o n i u m phosphate Vermiculite Casein Starch Benzene sulfonyl hydrazide Isano o i l Carbamide phosphoric a c i d Polyamide resin ( N o . 93, General M i l l s ) Urea Paraformaldehyde Aminoacetic acid V i c t a m i d e ( V i c t o r C h e m i c a l Works) Methylene d i s a l i c y l i c a c i d A l l these materials produced intumescence to some degree, but only a few showed enough to be of real value. The most effective was a combination of paraformaldehyde, urea, and a m m o n i u m phosphate. This confirms the work of Jones and S o l l ( l ) . The combination of isano o i l with polyamide resin gave best results i n exterior paint formulations. A m i n o acetic a c i d with starch and also with a m m o n i u m phosphate gave good results. The better intumescent agents are water-soluble and therefore produce paints having poor water and scrub resistance. The V i c t a m i d e is a r e l a t i v e l y new product and has not been c o m p l e t e l y evaluated as yet. It is less water-sensitive than most of the other compounds. A n effort has been made to decrease water sensitivity when using water-soluble In FIRE RETARDANT PAINTS; Advances in Chemistry; American Chemical Society: Washington, DC, 1954.

In FIRE RETARDANT PAINTS; Advances in Chemistry; American Chemical Society: Washington, DC, 1954.

VE 1 VE 2 VΕ 3 VE 4 VE 5 VE 6 VE 7 VE 8 VE 9 V E 10

II.*

14.7 14.55 25.8 23.1 20.4 18.0 31.9 26.0 20.2 21.0 19.9 38.5 29.3 28.2

Recapitulation

19.75 15.5 17.2 25.4 18.2 20.4 21.7 31.0 27.2 21.1 20.0 39.3 39.3 19.9

Average Wt. Loss Grams 60% P V C 4 0 % P V C

refined linseed o i l plus chlorinated paraffin alkyd resin plus chlorinated paraffin alkyd resin plus silicone resin alkyd resin plus chlorinated rubber v i n y l chloride acetate resin o i l - m o d i f i e d epichlorhydrin resin urea-formaldehyde resin alkyd resin plus ethyl silicate a c r y l i c resin plus chlorinated rubber polystyrene resin emulsion

Vehicle

Table

Z i n c borate, no C I Z i n c borate, plus C I C a l c i u m carbonate, | plus C I Lead silicate, no C I Lead silicate, plus C I Magnesium silicate, plus C I Blanc fixe, plus C I Z i n c oxide, no C I Z i n c oxide, plus C I Antimony oxide, no C I Antimony oxide, plus C I C a l c i u m pyrophosphate, plus C I Lead carbonate, plus C I Lithopone, plus C I

Pigment

Pigment

20.3 16.0 16.8 24.6 25.8 28.1 33.4 23.64 28.8 33.7

24.3 25.1 22.5 45.7 39.1 36.6 39.8 42.7 46.2 41.9 39.0 55.8 50.8 38.0

12.2 9.63 9.8 14.6 14.93 16.54 19.98 14.4 18.9 22

A v . Wt. Loss, %

Vehicles

4.27 3.8 4.22 7.33 7.4 6.91 8.16 7.98 8.0 7.8 7.34 10.9 10.2 7.11

39.0 32.6 28.1 47.5 48.3 45 53 42.8 52 53

7.36 6.2 5.44 8.94 9.0 9.04 12.18 7.96 9.7 12.18

A v . Char V o l . , C u . Inches

4.56 6.82 6.65 6.83 7.4 5.95 9.15 6.53 6.82 7.78 6.0 9.23 8.31 8.31

Average Char V o l u m e C u . Inches 60% PVC 40% PVC

A v . Char Area, Sq. Inches

on

25.5 36.3 38.1 39.3 39.3 31.5 45.0 34.5 36.3 41.3 31.8 49.0 50.4 58.0

Average Char Area _ _Sq._ Inches _ _ _ _ 60% PVC 40% PVC

Burn T e s t D a t a

9.1 8.4 15.3 13.67 11.5 10.8 17.6 15.5 11.5 11.53 10.54 22.7 16.2 16.5

40% PVC

Averag

11.4 8.96 9.9 14.0 10.4 12.1 12.5 17.1 13.5 11.45 11.1 21.2 19.6 14.6

60% PVC

of

Study

Average Wt. Loss

I.

A v . Wt. Loss, Grams

Table


>

3 ο S H

H

g 5 w

α

Q ^ 2

α >

39

M U R R A Y , ET A L . — F O R M U L A T I O N OF FIRE-RETARDANT PAINTS

intumescent agents. To accomplish this, relatively low concentrations of silicone resin were used. The result is demonstrated by reference to the washability values for formulations for interior paints 1,2, and 3. Interior paint 1 containing no silicone withstood 600 scrubbing strokes on the Gardner instrument; interior paint 3 containing 2.5% s i l icone withstood 1436 strokes; interior paint 2 with 30% silicone took 2275 strokes. Interior Paint Formulations Interior Paint 1

Interior Paint 3

P V C , 7 2 % . Wt./gal., 11.3 l b . Viscosity, 110 K U

P V C , 6 7 % . Wt./gal., 11.2 l b . Viscosity, 112 K U Pounds


Pounds T i t a n i u m dioxide Starch A m m o n i u m phosphate Chlorinated paraffin 70% A l u m i n u m stéarate Aminoacetic acid 10 cps. chlorinated rubber 5 0 % alkyd resin solution H i Flash naphtha

H i Flash naphtha

125.0 167.0 250.0 50.0 2.0 200.0 121.0 104.0 204.0

83.5

T i t a n i u m dioxide Starch A m m o n i u m phosphate Aminoacetic acid 10 cps. chlorinated rubber 5 0 % alkyd resin solution H i Flash naphtha 6 0 % silicone resin solution

H i Flash naphtha

P V C , 6 4 % . Wt./gal., 11.7 l b . Viscosity, 99 K U

P V C , 6 7 % . Wt./gal., 12.2 l b . Viscosity, 110 K U Pounds

Pounds

M i n e r a l spirits 2 % cobalt

82.5

Interior Paint 4

Interior Paint 2

T i t a n i u m dioxide Starch A m m o n i u m phosphate Aminoacetic acid 5 0 % alkyd resin solution 6 0 % silicone resin solution

144.0 57.5 330.0 61.5 119.0 115.0 206.0 8.2

200.0 65.0 380.0 100.0 280.0 104.0

70.0 7.0

T i t a n i u m dioxide Paraformaldehyde Neutralized a m m o n i u m phosphate (Fyrex, Victor C h e m i c a l Works) Urea Starch Chlorinated paraffin 7 0 % 10 cps. chlorinated rubber 5 0 % alkyd resin solution H i Flash naphtha

H i Flash naphtha

175.0 51.0 64.0 40.0 55.0 145.0 125.0 250.0

90.0

For the evaluation of paints for interior exposure, J A N - P - 7 0 2 was taken as a reference standard. During the course of this work, 27 interior fire-retardant paints have been developed and evaluated. Formulations and test results are shown for two of the best of these ( T a b l e s III and I V ) , together with the results obtained for J A N - P - 7 0 2 ( T a b l e VII). Formulation and fire-retardance test results are shown i n T a b l e V for interior paint 3, while data for interior paint 4 are given i n T a b l e V I . In FIRE RETARDANT PAINTS; Advances in Chemistry; American Chemical Society: Washington, DC, 1954.

40

ADVANCES m CHEMISTRY SERIES

S « «

ι Ο 00 CM C - i O 00 t^j 00 00

g c

Practical Aspects of the Formulation of Fire-Retardant Paints

Recommend Documents