Properties of Polyphenylene Sulfide Coatings

6

Properties of Polyphenylene Sulfide Coatings

H. WAYNE

H I L L , JR., and J. T. E D M O N D S , JR.

Downloaded by PENNSYLVANIA STATE UNIV on January 19, 2016 | http://pubs.acs.org Publication Date: June 1, 1973 | doi: 10.1021/ba-1973-0129.ch006

Phillips Petroleum Co., Bartlesville, Okla. 74004

Polyphenylene

sulfide is a unique material that combines

high thermal stability with outstanding chemical resistance. This combination of properties provides unusual utility as molding resins and as protective coatings for the chemical and petroleum industries, and as release coatings in the food industry.

The synthesis of phenylene sulfide polymers is

presented here.

Coatings of polyphenylene sulfide may be

applied to a variety of substrate metals by slurry spraying, fluidized-bed

techniques, and dry-powder

lease coatings based on polyphenylene obtained by adding a small amount of lene to the coating formulation.

spraying. sulfide may

Rebe

polytetrafluoroethy-

The performance of these

release coatings on household cookware is discussed.

" P o l y p h e n y l e n e sulfide is a n u n u s u a l m a t e r i a l , c o m b i n i n g some of t h e characteristics of b o t h thermoplastics a n d thermosets w i t h a n out standing balance sistance.

of h i g h - t e m p e r a t u r e p e r f o r m a n c e

a n d chemical re

A l t h o u g h the m a t e r i a l is a n excellent m o l d i n g r e s i n , there are

e q u a l l y i m p o r t a n t a p p l i c a t i o n s as p r o t e c t i v e coatings f o r t h e c h e m i c a l a n d p e t r o l e u m industries a n d as n o n s t i c k coatings for the f o o d a n d c o o k ware industry. I n early w o r k

o n organosulfur

compounds,

Duess

(1)

and H i l -

d i t c h (2) r e p o r t e d the p r e p a r a t i o n of various a r o m a t i c disulfides b y c o n d e n s a t i o n reactions o f t h i o p h e n o l o n treatment w i t h a l u m i n u m c h l o r i d e a n d s u l f u r i c a c i d , respectively. preparation of a phenylene the

reaction

sealed vessel.

M a c a l l u m (3) was the first to r e p o r t the

sulfide p o l y m e r .

of s u l f u r , s o d i u m

carbonate,

H i s procedure

involved

a n d dichlorobenzene

in a

P o l y m e r s m a d e b y this scheme g e n e r a l l y h a v e m o r e t h a n

one s u l f u r a t o m b e t w e e n

benzene

rings, as i n d i c a t e d b y t h e structure

— ( C H 4 S ^ ) —. 6

n

L e n z a n d coworkers

(4-6) h a v e d e s c r i b e d the p r e p a r a t i o n of p o l y

p h e n y l e n e sulfide b y a n u c l e o p h i l i c s u b s t i t u t i o n r e a c t i o n i n v o l v i n g self80 In Polymerization Reactions and New Polymers; Platzer, Norbert A. J.; Advances in Chemistry; American Chemical Society: Washington, DC, 1973.

6.

HILL,

JR. A N D E D M O N D S , JR.

Polyphenylene

Sulfide

81

Coatings

c o n d e n s a t i o n of m a t e r i a l s s u c h as c o p p e r p - b r o m o t h i o p h e n o x i d e .

These

s u b s t i t u t i o n reactions are c a r r i e d out at 200-250°C u n d e r n i t r o g e n i n t h e s o l i d state, or i n the presence of m a t e r i a l s s u c h as p y r i d i n e as r e a c t i o n media. T h e a b o v e t w o methods as w e l l as other methods of p o l y m e r i z a t i o n have been reviewed by Smith ( 7 ) .

W e h a v e d i s c o v e r e d a n e w process

for the p r e p a r a t i o n of a w i d e v a r i e t y of p o l y a r y l e n e sulfides ( 8 ) . example, polyphenylene

sulfide m a y b e p r e p a r e d b y the r e a c t i o n

For of


p - d i c h l o r o b e n z e n e a n d s o d i u m sulfide i n a p o l a r solvent.

Properties I n the P h i l l i p s process, p o l y p h e n y l e n e sulfide ( P P S )

is o b t a i n e d

f r o m the p o l y m e r i z a t i o n m i x t u r e i n the f o r m of a fine w h i t e

powder,

w h i c h , after p u r i f i c a t i o n , is d e s i g n a t e d R y t o n V P P S . C h a r a c t e r i z a t i o n of this p o l y m e r is c o m p l i c a t e d b y its extreme i n s o l u b i l i t y i n most s o l vents.

A t elevated temperatures, h o w e v e r , R y t o n V P P S is soluble* to

a l i m i t e d extent i n some a r o m a t i c a n d c h l o r i n a t e d a r o m a t i c solvents a n d i n certain heterocyclic

compounds.

T h e i n h e r e n t viscosity, m e a s u r e d

at 2 0 6 ° C i n 1-chloronaphthalene, is g e n e r a l l y 0.16, i n d i c a t i n g o n l y m o d erate m o l e c u l a r w e i g h t .

T h e p o l y m e r is h i g h l y c r y s t a l l i n e , as s h o w n b y

x-ray d i f f r a c t i o n studies ( 9 ) .

T h e crystalline melting point determined

b y d i f f e r e n t i a l t h e r m a l analysis is a b o u t 2 8 5 ° C . W h e n d i e m o l t e n p o l y m e r is s u b j e c t e d to a d d i t i o n a l heat i n the presence of a i r , the m e l t darkens a n d , after a w h i l e , it gels a n d solidifies. T h e s o l i d p o l y m e r is b e l i e v e d to be c r o s s l i n k e d because i t is i n s o l u b l e i n a l l o r g a n i c solvents, even at e l e v a t e d t e m p e r a t u r e . T h e changes that o c c u r at h i g h temperatures c a n b e d e m o n s t r a t e d readily by conducted

d i f f e r e n t i a l t h e r m a l analysis ( D T A ) .

W h e n the D T A is

u n d e r n i t r o g e n to suppress c r o s s l i n k i n g , the s a m p l e c a n b e

m e l t e d , c o o l e d , a n d r e m e l t e d w i t h l i t t l e effect o n the t h e r m a l transitions. T h i s e x p e r i m e n t is i l l u s t r a t e d b y c u r v e A of F i g u r e 1, i n w h i c h b o t h the glass-transition t e m p e r a t u r e at 80 ° C p o i n t at 2 8 2 ° C are v i s i b l e .

a n d the c r y s t a l l i n e m e l t i n g

W h e n the D T A is r u n on a s a m p l e that has

b e e n h e a t e d i n a i r at 3 7 0 ° C for f o u r hours, the c r y s t a l l i n e m e l t i n g p o i n t is b a r e l y v i s i b l e i n the D T A trace.

T h e s h a r p exotherms at 125°-135°C

are i n d i c a t i v e of c r y s t a l l i z a t i o n temperatures.

In Polymerization Reactions and New Polymers; Platzer, Norbert A. J.; Advances in Chemistry; American Chemical Society: Washington, DC, 1973.

82

POLYMERIZATION

R E A C T I O N S A N D N E WP O L Y M E R S

W h i l e t h e l i n e a r p o l y p h e n y l e n e sulfide p o l y m e r possesses a m o d erate degree of m e c h a n i c a l strength as i t is p r o d u c e d i n t h e p o l y m e r i z a t i o n process, i t c a n b e c o n v e r t e d i n t o a m u c h tougher p r o d u c t b y t h e r m a l treatment.

A c c o r d i n g l y , w h e n t h e p o l y m e r is h e a t e d to a h i g h e n o u g h

t e m p e r a t u r e i n a i r , c h a i n extension a n d c r o s s l i n k i n g occur, p r o d u c i n g a


" c u r e d " p o l y m e r that is t o u g h , d u c t i l e , a n d v e r y i n s o l u b l e .

SAMPLE A-MELTED UNDER NITROGEN AND QUENCHED BEFORE DTA SAMPLE B-HEATED AT 370*C IN AIR 4 HOURS AND QUENCHED BEFORE DTA HEATING RATE, WC/MINUTE

SAMPLE A

A -

r

SAMPLE B

50 Figure

1.

100

Differential

_J_

_i_

150 200 250 TEMPERATURE, °C

300

thermal analysis of polyphenylene

350

400

sulfide in nitrogen

T h e c h e m i s t r y of this c u r i n g process involves several c o m p l e x reac tions.

I n a d d i t i o n , t h e v e r y l i m i t e d s o l u b i l i t y of t h e l i n e a r p o l y m e r a n d

the extreme

i n s o l u b i l i t y of t h e c u r e d p o l y m e r m a k e exact

assignments almost i m p o s s i b l e .

structural

It is possible to describe some of t h e

c o n t r i b u t i n g reactions i n q u a l i t a t i v e terms.

F o r example, a chain-exten

sion r e a c t i o n i n v o l v i n g t h e r m a l scission of c a r b o n - s u l f u r b o n d s n e a r t h e e n d of a p o l y m e r c h a i n , f o l l o w e d b y f o r m a t i o n of a n e w c a r b o n - s u l f u r b o n d b e t w e e n t w o large p o l y m e r residues a n d b e t w e e n t w o s m a l l p o l y m e r residues, c a n l e a d to a n o v e r a l l increase i n m o l e c u l a r w e i g h t w h e n the s m a l l molecules f o r m e d are lost b y v a p o r i z a t i o n .

T h i s process is

essentially a n exchange r e a c t i o n , as i n d i c a t e d i n this structure, w h e r e m is s i g n i f i c a n t l y l a r g e r t h a n n :


6.

HILL,

Polyphenylene


Sulfide

83

Coatings

I

II

T h u s , II is lost at the h i g h temperatures i n v o l v e d i n the c u r i n g p r o c ess.

O t h e r possible reactions also occur.

F o r example, o x i d a t i v e c o u


p l i n g b e t w e e n a r o m a t i c rings ( b i p h e n y l r e a c t i o n ) ; n u c l e o p h i l i c attack o n a n a r o m a t i c r i n g of one p o l y m e r c h a i n b y a n e n d - g r o u p f u n c t i o n of a n other p o l y m e r c h a i n , or b y a c l e a v e d segment

derived from

another

p o l y m e r c h a i n ; s u l f o n i u m i o n f o r m a t i o n i n v o l v i n g a sulfide l i n k a n d a sulfur-containing end group.

Reactions of this t y p e p r o d u c e an increase

in molecular weight and crosslinking.

It is l i k e l y that several of these

reactions o c c u r s i m u l t a n e o u s l y d u r i n g the c u r i n g process. T h e r m o g r a v i m e t r i c analysis of p o l y p h e n y l e n e sulfide i n n i t r o g e n or i n a i r indicates no a p p r e c i a b l e w e i g h t loss b e l o w a b o u t 500° C .

Deg

r a d a t i o n is essentially c o m p l e t e i n air at 7 0 0 ° C , b u t i n a n inert atmos phere, about 40% of the p o l y m e r w e i g h t remains at 1000°.

In addition,

p o l y p h e n y l e n e sulfide p r e p a r e d b y the P h i l l i p s process is m o r e stable t h a n that p r e p a r e d b y the L e n z process

(6).

Comparative thermo

g r a v i m e t r i c d a t a , s h o w n i n F i g u r e 2, demonstrate that p o l y p h e n y l e n e sulfide d i s p l a y s a m u c h greater resistance to w e i g h t loss at e l e v a t e d temperatures t h a n do

either the c o n v e n t i o n a l thermoplastics or s u c h

s p e c i a l t y heat-resistant p o l y m e r s as polytetrafluoroethylene.

Mechanical

properties of m o l d e d specimens are essentially unaffected after exposure at 4 5 0 ° F i n air for four months. P o l y p h e n y l e n e sulfide also possesses u n u s u a l c h e m i c a l resistance. T o demonstrate this resistance, i n j e c t i o n - m o l d e d tensile bars of c u r e d p o l y m e r w e r e exposed to a representative groups of reagents at 2 0 0 ° F for 24 hours.

A f t e r exposure, the bars w e r e w e i g h e d to d e t e r m i n e w e i g h t

g a i n or loss, a n d the tensile strength d e t e r m i n e d .

T h e results of these

experiments are g i v e n i n T a b l e I. T h e tensile strength of the u n e x p o s e d

bars a v e r a g e d

11,000 p s i .

T h e s e tensile bars are unaffected b y gasoline, m o t o r o i l , h y d r o c a r b o n s , a n d c a r b o n t e t r a c h l o r i d e , w h i l e exposure to t r i c h l o r o e t h y l e n e results i n a s m a l l w e i g h t g a i n a n d loss i n tensile strength.

Alcohols,

esters, a n d o r g a n i c acids d o not affect the p o l y m e r .

Some nitrogenous

organic compounds—such

ketones,

as b u t y l a m i n e , p y r i d i n e , a n d a c e t o n i t r i l e —

cause a modest loss i n tensile strength.

O t h e r c h e m i c a l s , s u c h as d i -

m e t h y l a n i l i n e , e t h a n o l a m i n e , a n d n i t r o b e n z e n e , h a v e v i r t u a l l y no effect o n tensile strength or w e i g h t change.

I n general, o x i d i z i n g agents s u c h

as b r o m i n e w a t e r , a q u a r e g i a , a n d 50% c h r o m i c a c i d cause a severe loss



84

POLYMERIZATION

0

200

400

REACTIONS AND N E W

600

600

POLYMERS

1000

TEMPERATURE, °C KEY:1-P0LYVINYLCHL0RIDE;2-P0LYMETHYLMETHACRYLATE 3-POLYSTYRENE; 4-POLYETHYLENE;5-P0LYTETRAFLU0R0ETHYLENE; 6-P0LYPHENYLENESULFIDE IN AIR ATMOSPHERE; 7-POLYPHENYLENE SULFIDE; 8-P0LYPHENYLENE SULFIDE (LENZ4C)|N AIR. ;

Figure

i n strength.

2.

Comparative

thermo gravimetric atmosphere )

analysis

(nitrogen

H o w e v e r , aqueous p o t a s s i u m d i c h r o m a t e does not.

S t r o n g acids, s u c h as 96% s u l f u r i c a c i d , attack the p o l y m e r rather severely; w e a k e r acids a n d a v a r i e t y o f i n o r g a n i c bases are not d e t r i mental.

T h e p o l y m e r is inert to a w i d e v a r i e t y of i n o r g a n i c salt s o l u

tions, w i t h some samples o f c o a t e d metals h a v i n g b e e n exposed i n salt w a t e r i n the G u l f of M e x i c o for one y e a r w i t h o u t d e t e r i o r a t i o n . I n fact, e v e n the u n c u r e d p o l y m e r is r e m a r k a b l y resistant to a b r o a d g r o u p o f chemicals.

Applications I n j e c t i o n - M o l d i n g R e s i n s . A h i g h m e l t viscosity r e s i n is r e c o m mended for use i n injection-molding applications. T h e mechanical


6.

HILL,

Polyphenylene


T a b l e I.

Sulfide

C h e m i c a l Resistance of P P S T e n s i l e B a r s Exposure:

200°F for

hours Weight


Test

85

Coatings

Chemical

Change

(%)

Tensile (psi)

Hydrocarbons and Chlorinated H y d r o carbons Kerosene Motor Oil Carbon Tetrachloride Cyclohexane Gasoline Trichloroethylene

-0.05 -0.02 1.7 0.05 0.07 6.52

11,700 11,900 11,100 12,000 10,300 7,400

Alcohols, Ketones, Esters, and Ethers B u t y l Alcohol M e t h y l E t h y l Ketone A m y l Acetate Dioctyl Phthalate Dibutyl Ether

0.05 1.02 0.14 -0.07 0

10,500 11,200 13,300 13,100 11,400

Organic Acids Glacial Acetic Trichloroacetic F o r m i c (88%) Benzenesulfonic

0.09 0.45 0.18 -0.05

12,400 12,000 10,900 11,400

1.52 2.32 0 3.84 0.59 2.43

7,100 10,200 12,600 8,900 9,000 11,000

Nitrogenous Organic Compounds Butylamine Dimethylaniline Ethanolamine Pyridine Acetonitrile Nitrobenzene Oxidizing Agents Bromine Water A q u a Regia (Room Temperature Exposure) 5 0 % Chromic Acid 1 0 % Potassium Dichromate S o d i u m H y p o c h l o r i t e (Clorox) Inorganic A c i d s a n d Bases 10% Nitric Acid 3 7 % Hydrochloric A c i d 3 0 % Sulfuric A c i d 9 6 % Sulfuric A c i d 8 5 % Phosphoric A c i d 1 0 % Sodium Bicarbonate

a

4.34

Severe atts

18.64 0.84 0.36 0.50

Severe atta 3,300 12,300 5,400

0.32 0.57 0.14 Severe a t t a c k -0.05 0.36

12,000 10,900 11,700 Severe a t t a c k 12,500 11,600


86

POLYMERIZATION

T a b l e I.

REACTIONS A N D N E W POLYMERS

Continued

Tensile (psi)

Test Chemical


1 0 % Sodium Carbonate 3 0 % Sodium Hydroxide 7 8 % Ammonium Hydroxide Inorganic S a l t S o l u t i o n s Saturated Sodium Chloride 1 0 % Sodium Acetate 10% Sodium Nitrate 1 0 % Sodium Sulfate Trisodium Phosphate 1 0 % Calcium Chloride

a

0.32 0.07 0.73

9,600 10,000 11,400

0.16 0.32 0.32 0.36 0.36 0.36

10,400 13,800 11,100 10,100 11,200 12,700

Tensile of unexposed specimen was 11,000 psi

a

properties

of

unfilled

a n d glass-filled i n j e c t i o n - m o l d e d

summarized in Table II.

specimens

are

T h e u n f i l l e d r e s i n is c h a r a c t e r i z e d b y h i g h

tensile strength, h i g h flexural m o d u l u s , h i g h heat-deflection t e m p e r a t u r e , a n d modest i m p a c t strength.

T h e glass-filled resin has s u p e r i o r p r o p e r

ties a n d is g e n e r a l l y

greater p r a c t i c a l a p p l i c a t i o n s t h a n is the

unfilled material.

finding

F o r e x a m p l e , the 40% glass-filled r e s i n has a tensile

strength of 21,000 p s i at r o o m t e m p e r a t u r e , a n d 4700 p s i at 4 0 0 ° F .

Its

tensile strength at 4 0 0 ° F is greater t h a n that of p o l y e t h y l e n e at r o o m temperature.

T h e flexural m o d u l u s is 2.2 X 10° p s i at r o o m t e m p e r a t u r e ,

d e c r e a s i n g g r a d u a l l y to 600,000 p s i at 4 5 0 ° F .

The

flexural

modulus

at 450° F is greater t h a n the r o o m - t e m p e r a t u r e flexural m o d u l u s of m a n y established plastics, s u c h as A B S resins, polyacetals, n y l o n s , a n d p o l y carbonates. A s a f u r t h e r c o m p a r i s o n , the

flexural

m o d u l u s of glass-filled p o l y

p h e n y l e n e sulfide at 450° F is a b o u t 10 times that of u n f i l l e d p o l y t e t r a fluoroethylene

at r o o m t e m p e r a t u r e .

T h e s e d a t a illustrate the o u t s t a n d

i n g r e t e n t i o n of stiffness of this m a t e r i a l at elevated temperatures.

The

heat-deflection t e m p e r a t u r e of p o l y p h e n y l e n e sulfide c o n t a i n i n g 40% glass fibers

is greater t h a n 425°F, a c c o u n t i n g for the excellent r e t e n t i o n of

m e c h a n i c a l properties at elevated temperatures. E l e c t r i c a l properties of p o l y p h e n y l e n e sulfide c o m p o u n d s are s u m marized in Table III.

T h e d i e l e c t r i c constant of 3.1 is l o w i n c o m p a r i s o n

w i t h m a n y other p l a s t i c materials. very low.

S i m i l a r l y , the d i s s i p a t i o n factor is

D i e l e c t r i c strength ranges f r o m a b o u t 500-600 volts p e r m i l

for the various c o m p o u n d s ;

these values are q u i t e h i g h .

Thus, both


6.

HILL,

filled


Polyphenylene

87

Sulfide Coatings

a n d u n f i l l e d p o l y p h e n y l e n e sulfide materials are excellent e l e c t r i c a l

insulators. L i m i t i n g o x y g e n i n d e x values ( L O I )

of a n u m b e r of plastics are

shown in Table I V .

T h e L O I is the c o n c e n t r a t i o n of o x y g e n r e q u i r e d

to m a i n t a i n b u r n i n g .

P o l y p h e n y l e n e sulfide has a v a l u e of 44, a n d falls

a m o n g the least flammable types of plastics.


Table II.

M e c h a n i c a l P r o p e r t i e s of I n j e c t i o n - M o l d i n g C o m p o s i t i o n s Ryton PPS Glass-Filled Ryton PPS

(60/40) 1.64

1.34

Density Tensile, psi A t 70°F A t 400°F

11,000 4,700

E l o n g a t i o n (70°F),

21,000 4,700

%

3

Flexural M o d u l u s , psi A t 70°F A t 450°F

600,000

2,200,000 600,000

Flexural Strength, psi

20,000

37,000

86

92

H a r d n e s s , Shore D N o t c h e d I z o d I m p a c t , ft l b / i n A t 75°F A t 300°F H e a t Deflection Temperature @ p s i , °F

264

M a x i m u m Recommended Service T e m p e r a t u r e , °F

T a b l e III.

0.8 1.8

0.3 1.0 280

>425

500

500

E l e c t r i c a l P r o p e r t i e s of P o l y p h e n y l e n e S u l f i d e C o m p o u n d s Unfilkd PPS

40% GlassFilled PPS

Dielectric Constant 10 H e r t z 10 H e r t z

3.1 3.1

3.8 3.8

Dissipation Factor 10 H e r t z 10 H e r t z

0.0004 0.0007

0.0037 0.0066

3

6

3

6

Dielectric Strength, V o l t s / M i l

585

490


88

POLYMERIZATION

Table IV.

REACTIONS AND N E W

Flammability Limiting Oxygen Index, %

M aterial


P o l y v i n y l chloride P o l y p h e n y l e n e sulfide N y l o n 6-6 Polycarbonate Polystyrene Polyolefins Polyacetal Coatings.

POLYMERS

47 44 28.7 25 18.3 17.4 16.2

P o l y p h e n y l e n e sulfide coatings are c h a r a c t e r i z e d b y a n

u n u s u a l c o m b i n a t i o n of t h e r m a l s t a b i l i t y a n d c h e m i c a l resistance. are

finding

They

a c c e p t a n c e as corrosion-resistant coatings for metals i n the

c h e m i c a l a n d p e t r o l e u m industries.

P o l y p h e n y l e n e sulfide coatings m a y

be a p p l i e d b y m a n y different solventless c o a t i n g systems s u c h as s l u r r y spraying,

fiuidized-bed

coating, and

flocking.

A l l of these

techniques

r e q u i r e a b a k e c y c l e to cure the p o l y m e r to o b t a i n t o u g h , coalesced coatings.

T y p i c a l b a k e cycles of 45 minutes at 7 0 0 ° F or 15 m i n u t e s

at 8 0 0 ° F i n a c i r c u l a t i n g air o v e n are u s u a l l y e n o u g h to cure of

a b o u t 5 - m i l thickness or less.

baking

to

achieve

mechanical

a sufficient

coatings

T h i c k e r coatings r e q u i r e a d d i t i o n a l

l e v e l of

c u r i n g to

provide

optimum

toughness.

Best a d h e s i o n is o b t a i n e d w h e n the m e t a l surface is g r i t - b l a s t e d before c o a t i n g .

A l u m i n u m surfaces do not r e q u i r e a n y a d d i t i o n a l s u r

face treatment for g o o d adhesion.

F o r adequate

adhesion, iron sur

faces s h o u l d be heat-treated at 7 0 0 ° F i n a i r before s l u r r y c o a t i n g , or p r i m e d w i t h a m i x t u r e of p o l y p h e n y l e n e

sulfide a n d cobalt o x i d e i n

s l u r r y f o r m before a p p l i c a t i o n of a c o a t i n g b y

fluidized-bed

techniques.

U n c u r e d p o l y m e r s h o u l d b e u s e d for a p p l i c a t i o n of t h i n coatings

(1-2

m i l s per c o a t ) b y slurry t e c h n i q u e s ; the c u r e d resins are p r e f e r r e d for a p p l i c a t i o n of t h i c k e r coatings b y

fluidized-bed

or

flocking

techniques

to a v o i d p r o b l e m s of d r i p p i n g a n d s a g g i n g d u r i n g the o p e r a t i o n .

Pig

ments s u c h as t i t a n i u m d i o x i d e , c h a n n e l b l a c k , a n d a v a r i e t y of i r o n oxide compositions m a y be used w h e n d e s i r e d . Two

typical slurry coating

f o r m u l a t i o n s are s h o w n i n T a b l e

V.

F o r m u l a t i o n A , w h i c h consists of P P S , TiO >, w a t e r , a n d a d i s p e r s i n g L

agent, is s u i t a b l e for the p r o d u c t i o n of m u l t i p l e coats a n d for a v a r i e t y of other a p p l i c a t i o n s .

F o r m u l a t i o n B contains

polytetrafluoroethylene,

a n d c a n be used to p r o d u c e single coat nonstick surface coatings, or it c a n b e a p p l i e d as a top coat to a surface a l r e a d y c o a t e d w i t h F o r m u l a tion A . R y t o n P P S coatings that are p i n h o l e free at 2-4 m i l s m a y b e t a i n e d easily b y s l u r r y - c o a t i n g procedures. are i n d i c a t e d i n T a b l e V I .

ob

Properties of these coatings

T h e s e coatings are q u i t e h a r d , w i t h a p e n c i l


6.

HILL,

Polyphenylene


hardness of 2 H at r o o m t e m p e r a t u r e .

Sulfide

89

Coatings

T h i s hardness is m a i n t a i n e d at

temperatures u p to 300°F, a n d the c o a t i n g s t i l l has a p e n c i l hardness of 2 B at 500°F. measured

on

H a r d n e s s a n d a d h e s i o n to g r i t - b l a s t e d a l u m i n u m , as

the A r c o

respectively, for

M i c r o k n i f e , are 450-600

a coating

grams

a n d 4-5

mils,

c o n t a i n i n g 3 parts P P S a n d 1 p a r t T i O o

T h e s e coatings w i l l w i t h s t a n d f o r w a r d a n d reverse i m p a c t tests of i n c h - p o u n d s , a n d a 3 / 1 6 i n c h m a n d r e l b e n d of 180°.

160

E l o n g a t i o n of the


c o a t i n g is greater t h a n 32% ( l i m i t of t e s t ) , as d e t e r m i n e d o n a c o n i c a l Table V .

P o l y p h e n y l e n e S u l f i d e F o r m u l a t i o n s for Spray C o a t i n g Applications Parts by Weight

Ryton V PPS Titanium Dioxide Polytetrafluoroethylene Water Triton X-100

A

B

100 33 300 3

100 33 10 300 3

700 45

700 45

—

Cure Conditions T e m p e r a t u r e , °F Time, Minutes Table V I .

P r o p e r t i e s of P o l y p h e n y l e n e Sulfide C o a t i n g s PPS/Ti0 Coating (3/1) 2

Property Hardness, Pencil Hardness, Arco Microknife , g Adhesion, Arco Microknife , mils M a n d r e l B e n d , 180°, 3 / 1 6 " E l o n g a t i o n ( A S T M D 522), % Reverse Impact, inch-pounds A b r a s i o n Resistance, T a b e r m g loss/1000 rev., C S - 1 7 W h e e l C o n t a c t A n g l e % w a t e r , degrees C o n t a c t A n g l e , Wesson o i l , degrees Chemical Resistance Thermal Stability Color a

6

c

PPS/Ti0 / PTFE Coating (3/1/0.3) 2

2H 500 5 Pass >32 160

2H 350 4-6 Pass >32 160

50 82 41 Excellent Excellent Light T a n

57 110 68 Excellent Excellent Light T a n

A S T M 2197; measured on 1-mill coatings A S T M 2197; measured on a l u m i n u m coupons t h a t h a d been g r i t - b l a s t e d c o a t i n g (coating thickness, 1 m i l ) . M e a s u r e d w i t h a R a m e - H a r t M o d e l A - 1 0 0 goniometer a

b

c


before

90

POLYMERIZATION

m a n d r e l test apparatus.

REACTIONS AND N E W

POLYMERS

T h u s hardness, toughness, a n d e x t e n s i b i l i t y are

excellent. E x c e l l e n t release coatings based o n p o l y p h e n y l e n e sulfide m a y

be

p r e p a r e d b y i n c o r p o r a t i n g a s m a l l a m o u n t of polytetrafluoroethylene i n the c o a t i n g f o r m u l a t i o n .

F o r example, a f o r m u l a t i o n of 100 parts of

R y t o n V - l , 33 parts of t i t a n i u m d i o x i d e , a n d 10 parts of polytetrafluoro ethylene i n aqueous s l u r r y p r o v i d e s a c o a t i n g that v e r y r e a d i l y releases food i n a cooking operation.


Hart model

C o n t a c t angle, as m e a s u r e d w i t h a R a m e -

A - 1 0 0 goniometer,

is 68°

for

w a t e r on a c o a t i n g surface of this type.

Wesson

o i l a n d 110°

for

A v a r i e t y of colors m a y be o b

t a i n e d i n release coatings b y a p p r o p r i a t e c h o i c e of p i g m e n t .

The hard

ness of these coatings is s o m e w h a t greater t h a n that of the c o n v e n t i o n a l polytetrafluoroethylene

cookware

coatings

( p e n c i l hardness of 2 H

for

the P P S coatings vs. H for polytetrafluoroethylene c o a t i n g ) . One coating

very

interesting a p p l i c a t i o n for p o l y p h e n y l e n e

cookware

n o n s t i c k coatings

for

nonstick use

are o b t a i n e d

20% polytetrafluoroethylene

(10).

when

is used.

sulfide is i n

E x c e l l e n t , scratch-resistant,

a f o r m u l a t i o n c o n t a i n i n g 10

to

R y t o n P P S coatings are v e r y i n

s o l u b l e a n d nontoxic, a n i m a l f e e d i n g studies i n d i c a t e . T a b l e V I I shows the effect of l o n g - t e r m a g i n g of coatings at 5 0 0 ° F i n air.

T h e w e i g h t loss after 10 weeks exposure is less t h a n 1% i n the

f o r m u l a t i o n c o n t a i n i n g a s m a l l a m o u n t of Table VII.

polytetrafluoroethylene.

L o n g - T e r m T h e r m a l S t a b i l i t y i n A i r at 500° F . Weight Loss, % PPS/Ti0 Coating (8/1)

PPS/TiOt/PTFE Coating (8/1/0.8)

2

Exposure Time, Days 1 4 7 9 21 30 42 49 70

0.003 0.06 0.13 0.12 0.18 0.24 0.50 0 . 4 7 (Cracked)

0.02 0.07 0.15 0.16 0.21 0.29 0.34 0.31 0.95 (Cracked)

I n other h i g h - t e m p e r a t u r e tests, R y t o n p o l y p h e n y l e n e sulfide coat ings o n a l u m i n u m w i l l pass a n 80 i n c h - p o u n d reverse i m p a c t test after exposure i n air at 6 0 0 ° F for eight days, or at 7 0 0 ° F for t w o days

(Table

VIII). R y t o n p o l y p h e n y l e n e sulfide coatings are

finding

excellent

accept

ance as corrosion-resistant, p r o t e c t i v e coatings for o i l - f i e l d p i p e , valves,


6.

HILL,


Table V I I .

Polyphenylene

91

Sulfide Coatings

T h e r m a l S t a b i l i t y of P o l y p h e n y l e n e

Sulfide C o a t i n g s

f t

Evaluation

b

PPS/Ti0 Coating (3/1)

PPS/TiOt/PTFE Coating (3/1/0.3)

2

Exposure Conditions in Air 600°F—8 days 700°F—2 days

Pass Pass

Pass Pass

° One-mil coatings on aluminum As measured by 80 inch-pound reverse impact test


b

fittings,

c o u p l i n g s , t h e r m o c o u p l e w e l l s , probes, a n d other e q u i p m e n t i n

b o t h p e t r o l e u m a n d c h e m i c a l processing.

Parts of this t y p e h a v e b e e n

o p e r a t i n g satisfactorily f o r e x t e n d e d periods of t i m e i n m e d i a s u c h as l i q u i d a m m o n i a , c r u d e o i l , refined h y d r o c a r b o n s , m o t o r o i l , b r i n e , d i l u t e h y d r o c h l o r i c a n d s u l f u r i c acids, d i l u t e s o d i u m h y d r o x i d e , b u t y l acetate, chlorobenzene,

etc. I n p a r t i c u l a r , p o l y p h e n y l e n e b o t h corrosive

sulfide is p r o v i d i n g

protection

when

materials a n d h i g h temperatures a r e

involved.

T h u s , parts of c a r b o n steel c o a t e d w i t h various p o l y p h e n y l

ene sulfide resins a r e r e p l a c i n g parts f a b r i c a t e d f r o m expensive metals.

I n many

fluidized-bed ily.

cases,

corrosion-resistant

coatings

alloy

are applied b y

techniques to o b t a i n c o a t i n g thicknesses of 10-25 m i l s r e a d

H o w e v e r , w h e n t h e mass of t h e substrate m e t a l is sufficient t o

h o l d t h e heat w e l l , t h i c k coatings

may be obtained b y spraying the

hot (ca. 7 0 0 ° F ) m e t a l p a r t w i t h a n aqueous c o a t i n g s l u r r y f o r m u l a t i o n , f o l l o w e d b y a b a k e cycle.

B o t h a p p l i c a t i o n methods are b e i n g u s e d f o r

corrosion protection.

Literature

Cited

1. Duess, J. J. B., Rec. Trav. Chim., (1908) 27, 145. 2. Hilditch, T. P., J. Chem. Soc., (1910) 47, 2579. 3. Macallum, A. D . , J. Org. Chem. (1948) 13, 154; U.S. Patents 2,513,188 (June 27, 1950) and 2,538,941 (Jan. 23, 1951). 4. Lentz, R. W., and Carrington, W . K., J. Polym Sci., (1959) 41, 333. 5. Lenz, R. W., and Handlovits, C . E . , J. Polym. Sci., (1960) 43, 167. 6. Lenz, R. W., Handlovits, C. E., Smith, H . A., J. Polym Sci., (1962) 58, 351. 7. Smith, H . A., Encycl. Polymer Sci. Technol., (1969) 10, 653. 8. Edmonds, Jr., J. T., Hill, Jr., H . W., U.S. Patent 3,354,129 (Nov. 21, 1967.) 9. Tabor, B. J., Magre, E . P., Boon, J., Eur. Polym. J., (1971) 7, 1127. 10. Ray, G. C., U.S. Patent 3,492,125 (Jan. 27, 1970). R E C E I V E D April 14, 1972.


Properties of Polyphenylene Sulfide Coatings

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