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8/17/2019 patent PTFE Us 3532782
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U n i t e d S t a t e s P a t e n t
0”
1
3 , 5 3 2 , 7 8 2
POLYTETRAFLUOROETHYLENE
GRANULAR
POWDER AND PROCESS FOR ITS
MANU
FACTURE
R o b e r t
H a r t w i m m e r , B n r g h a u s e n , S a l z a c h , G e r m a n y , a s
s i g n o r t o F a r b w e r k e
H o e c h s t A k t i e n g e s e l l s c h a f t ,
F r a n k
f u r t
am
a i n , Germany, a c o r p o r a t i o n o f G e r m a n y
No
r a w i n g . F i l e d D e c . 2 0 , 1 9 6 6 ,
S e r .
N o .
6 0 3 , 1 7 0
C l a i m s p r i o r i t y ,
a p p l i c F a t i g g g e r m a n y ,
D e c .
3 0 , 1 9 6 5 ,
3
I n t .
( : 1 . c é s f 4 7 / 0 2
US. C l . 264-117 8
C l a i m s
ABSTRACT
OF THE DISCLOSURE
A n e - s t e p p r o c e s s
f o r
p r e p a r i n g
g r a n u l a t e d p o l y t e t r a
? u o r o e t h y l e n e
f r o m
t h e
c o r r e s p o n d i n g
p u l v e r i z e d
m a t e
r i a l b y a d m i x i n g
a
d i s p e r s i n g a g e n t
c o m p r i s i n g
a n a l k a n e
c o n t a i n i n g h y d r o x y l o r
amino
g r o u p s o r c o u p l e d
p r o d u c t
t h e r e o f ,
t h e
r a t i o
o f p u l v e r i z e d m a t e r i a l - t o - d i s p e r s i n g
a g e n t
u t i l i z e d b e i n g a b o u t
1 : 1 - 1 0 ; m a i n t a i n i n g
t h e
m i x
t u r e
a t
a t e m p e r a t u r e
o f
a b o u t 20-300° C . and s e p a r a t i n g
t h e g r a n u l a t e d p o l y t e t r a ? u o r o e t h y l e n e f r o m d i s p e r s i n g
a g e n t .
The p o l y m e r i z a t i o n
o f
t e t r a ? u o r o e t h y l e n e
i n
a n a q u e
ous m e d i u m
under p r e s s u r e
a n d i n t h e p r e s e n c e
o f a
s u b s t a n c e f o r m i n g f r e e r a d i c a l s p r o v i d e p o l y m e r s w h i c h ,
p r i o r t o t h e i r
p r o c e s s i n g
i n t o b a n d s , ? l m s a n d f o i l s , p i p e s ,
s h a p e d
a r t i c l e s
a n d
i n t e r m e d i a t e p r o d u c t s , h a v e
t o
b e
a f t e r - t r e a t e d
c o r r e s p o n d i n g l y
t o
t h e i r
a p p l i c a t i o n s ,
on
a c c o u n t
o f t h e i r
non
u n i f o r m s h a p e
and s i z e o f p a r t i c l e s .
A c c o r d i n g t o US. P a t . N o . 2 , 9 3 6 , 3 0 1 , t h e
g r i n d i n g
o f
p o l y t e t r a ? u o r o e t h y l e n e (PTFE) exposed i n a w h i r l o f
a i r
o r g a s e s t o t h e s h e a r i n g f o r c e o f
a p u l v e r i z e r
a t
a
t e m p e r a t u r e
i n t h e
r a n g e o f from 1 9
t o
3 2 7 ° C .
l e a d s
t o
a
dow ny powder which
h a s a h i g h
p r o p o r t i o n o f
?
b r o u s
p a r t i c l e s
a n d
w h i c h i s
s a i d t o b e p a r t i c u l a r l y s u i t
a b l e f o r m a k i n g t h i n
s h e e t s , b a n d s a n d
f o i l s .
For making shaped a r t i c l e s i n
a r a m
o r
screw
e x t r u d e r ,
t h e
P T F E - p o w d e r s
u s u a l l y
o b t a i n e d
b y p o l y m e r i z a t i o n
a r e
n o t
s u i t a b l e s i n c e
t h e y t e n d
t o s t i c k and
t h e r e f o r e
a r e d i ? i c u l t t o
convey
and t o d o s e . A
r o c e s s i n g o f t h i s
k i n d r e q u i r e s a
m a t e r i a l
h a v i n g g o o d ?ow
p r o p e r t i e s
a n d
a v e r y
u n i f o r m
g r a i n s i z e . Such
p r o p e r t i e s
a r e p e c u l i a r
t o g r a n u l e s .
PTFE
c a n ,
h o w e v e r , n o t b e
g r a n u l a t e d
b y
u s u a l
m e t h o d s . A c c o r d i n g
t o
US. P a t s . N o s .
3 , 0 8 7 , 9 2 1
and
3 , 1 5 2 , 2 0 1 , g r a n u l e - l i k e P T F E - p r o d u c t s c a n b e o b
t a i n e d
by
h e a t i n g i n a ? r s t s t e p
normal
u n s i n t e r e d PTFE
t o
a
t e m p e r a t u r e
i n
t h e
range o f
from
50 t o 400°
C . ,
w i t h
o r
W i t h o u t
t h e a p p l i c a t i o n
o f
p r e s s u r e , whereby t h e
n o n uniform porous p a r t i c l e s a r e s i n t e r e d
or
baked t o
g e t h e r a n d t h u s t h e h i t h e r t o l o o s e p o w d e r
i s
a g g l o m
e r a t e d .
A f t e r
h a v i n g b e e n
c o o l e d , t h e p o l y t e t r a ? u o r o
e t h y l e n e t h u s t r e a t e d
i s t h e n
r e d u c e d ,
i n
a
s e c o n d
s t e p ,
t o
s m a l l
p a r t i c l e s
w h i l e a p p l y i n g s h e a r i n g f o r c e s . T h e
p r e s e n t
i n v e n t i o n
p r o v i d e s
a o n e ~ s t e p p r o c e s s f o r p r e p a r i n g g r a n
u l e s o f p o l y t e t r a ? u o r o e t h y l e n e , w h i c h c o m p r i s e s
h e a t i n g
a p o l y t e t r a ? u o r o e t h y l e n e p o w d e r , w i t h a g i t a t i o n f o r
a
c e r t a i n p e r i o d o f t i m e , t o t e m p e r a t u r e s i n t h e
r a n g e o f
from
r o o m
t e m p e r a t u r e
t o
t h e
s i n t e r i n g
t e m p e r a t u r e ,
p r e f e r a b l y f r o m
room
t e m p e r a t u r e
( 2 0 °
C . ) t o 1 5 0 ° C . ,
i n
t h e
p r e s e n c e
o f
a p p r o p r i a t e d i s p e r s i n g a g e n t s - p r e f e r
a b l y a l k a n e s
c a r r y i n g s e v e r a l
h y d r o x y a n d / o r a m i n o
g r o u p s , a n d / o r compounds which
c a n f o r m a l l y b e
d e
r i v e d f r o m t h e a f o r e m e n t i o n e d a l k a n e s b y c o u p l i n g
t h e m
by means
o f t h e
s u b s t i t u e n t s .
Compared
w i t h
t h e known p r o c e s s e s , t h e p r o c e s s o f
t h e p r e s e n t i n v e n t i o n h a s t h e a d v a n t a g e o f b e i n g a
o n e
s t e p p r o c e s s d i r e c t l y
p r o v i d i n g
g r a n u l e s
f r o m
PTFE
powder
a n d c a p a b l e o f b e i n g a l r e a d y c a r r i e d o u t
a t
s u r
20
30
40
60
65
7 0
3 , 5 3 2 , 7 8 2
P a t e n t e d O c t .
6 , 1970
C C
2
p r i s i n g l y l o w
t e m p e r a t u r e s .
The a r t i c l e s i z e c a n b e
v a r i e d
w i t h i n
w i d e
l i m i t s
b y
c h a n g i n g
t h e
s t i r r i n g
s p e e d ,
v a r y i n g
o r d i l u t i n g t h e
s u s p e n d i n g a g e n t .
I t i s p o s s i b l e ,
a c c o r d i n g
t o
t h e
i n v e n t i o n , t o
o b t a i n g r a n u l e s
w i t h s u c h
a
v a r i e t y
o f p a r t i c l e
s i z e s a s ,
f o r
e x a m p l e ,
i n t h e
r a n g e
o f from
1 0 0 t o 4 0 0 p , 500 t o 1 , ' O 0 O , u .
o r 1 ,0 0 0
t o 3 , 0 0 0 / 1 . a s
t h e
main
p o r t i o n ,
b u t a l s o p a r t i c l e
s i z e s o f a d i a m e t e r r a n g
i n g
from
5 t o 1 0 mm. and more. I n t h e p r o c e s s
o f
t h e
i n v e n t i o n ,
n e i t h e r c o n s i d e r a b l e p r e s s u r e s nor g r e a t
s h e a r
i n g f o r c e s n o r
h i g h
t e m p e r a t u r e s a c t upon t h e p o l y m e r
i n ? u e n c e s
w h i c h ,
a s i s
known, m a y
a d v e r s e l y a f f e c t
t h e
?ne s t r u c t u r e o f
a
p o l y m e r .
The i n d i v i d u a l
p a r t i c l e s
o f a
g r a n u l a t e d
P T F E - m a t e r i a l
o b t a i n e d
a c c o r d i n g t o t h e i n v e n t i o n , p r e d o m i n a n t l y h a v e
a
g l o b u l a r
s h a p e and a smooth s o l i d , b u t n o t hard s u r
f a c e ,
which
i s r e l a t i v e l y n o n - p o r o u s .
I t
i s f o r t h i s r e a s o n
t h a t t h e
g r a n u l e s
o b t a i n e d h a v e
e x c e l l e n t
?ow
p r o p e r t i e s
and d o n o t t e n d
t o form
l u m p s ,
a
t e n d e n c y which
i s ,
t o
a
h i g h
e x t e n t , p e c u l i a r
t o u n t r e a t e d
P T F E - p o w d e r s . The
p r o d u c t o b t a i n a b l e
a c c o r d i n g t o t h e
p r o c e s s o f
t h e
p r e s e n t
i n v e n t i o n
can e a s i l y be
t r a n s p o r t e d on
c o n v e y o r bands
and c h u t e s ,
i t d o e s
n o t p i l e
up
i n f u n n e l s
a n d c h a r g i n g
t u b e s , t h u s
f a c i l i t a t i n g
d o s i n g a n d a c c u m u l a t i o n , p r o p e r
t i e s w h i c h
a r e e x t r e m e l y
i m p o r t a n t
f o r t h e
p r o c e s s i n g
o f
t h e p o l y t e t r a f l u o r o e t h y l e n e i n r a m or screw e x t r u d e r s .
N e e d i n g n o p r e l i m i n a r y
s i n t e r i n g ,
t h e p r o d u c t m a i n t a i n s ,
i n s p i t e o f
i t s
good f l o w p r o p e r t i e s
a n d i t s s m o o t h
a n d
hard s u r f a c e ,
a
c e r t a i n d u c t i b i l i t y and
a
s o f t ? o w under
e l e v a t e d
p r e s s u r e , which a r e
o f a d v a n t a g e t o
t h e t r a n s
p a r e n c y , smoothness and l a c k o f p o r e s o f t h e s h a p e d a r
t i c l e s
made
w i t h e x t r u d e r s . The a f t e r - t r e a t m e n t a c c o r d i n g
t o t h e
i n v e n t i o n
d o e s n o t
a t
a l l
a d v e r s e l y
a f f e c t
t h e
good
m e c h a n i c a l ,
t h e r m a l
a n d
e l e c t r i c a l p r o p e r t i e s
o f
t h e
p o l y
t e t r a f l u o r o e t h y l e n e .
A c c o r d i n g
t o t h e
p r o c e s s o f
t h e
i n v e n t i o n ,
a l l
PTFE
t y p e s can be g r a n u l a t e d , n o
matter Whether
i t i s
an u l t r a
? n e l y
g r o u n d
s u s p e n s i o n p o l y m e r ( l e s s
t h a n
5 0 p ) ,
a n
u n t r e a t e d s u s p e n s i o n
p o l y m e r ( 1 0 0 - 4 0 0 p ) o r
a r e l a t i v e l y
c o a r s e - g r a i n e d P T F E - p o w d e r ( 3 0 0 - 7 5 0 p )
o r
w h e t h e r t h e
s o f t
and d u c t i l e m a t e r i a l t h a t
c a n be
p r e c i p i t a t e d from
a P T F E - d i s p e r s i o n , i s
i n t e n d e d
t o be u s e d . U n s i n t e r e d
PTFE s p a r t i c u l a r l y u s e d
f o r
t h e p r o c e s s o f
t h e i n v e n
t i o n ,
a s
i s
o b t a i n e d
by
t h e
known p o l y m e r i z a t i o n p r o c
e s s e s ( c f . G e r m a n P a t e n t
No.
1 , 1 0 9 , 3 7 0 ) .
I n
a d d i t i o n
t h e r e ,
m i x t u r e s o f
t h e
s e v e r a l
p u l v e r u l e n t
P T F E - t y p e s
w i t h
e a c h o t h e r c a n a l s o
b e
g r a n u l a t e d ;
P T F E - p r o d u c t s w h i c h
a r e
m o d i ? e d
b y
i n c o r p o r a t i n g
b y
p o l y m e r i z a t i o n
s m a l l a m o u n t s o f o t h e r p e r ? u o r o - o l e ? n s ,
a r e a l s o s u i t a b l e f o r
g r a n u l a t i o n a c c o r d i n g
t o t h e p r o c e s s
o f
t h e
i n v e n t i o n .
F o r o b t a i n i n g t h e h i g h e s t p o s s i b l e p o w d e r d e n s i t y , i t
i s
a d v i s a b l e ,
i n m a n y
c a s e s , t o d e g a s t h e PTFE-powder by
e s t a b l i s h i n g a v a cuum f o r a
s h o r t p e r i o d
o f t i m e ,
p r i o r
t o t h e a d d i t i o n o f t h e d i s p e r s i n g a g e n t .
D i s p e r s i n g a g e n t s a c c o r d i n g t o t h e i n v e n t i o n a r e p r e f
e r a b l y a l k a n e s
c a r r y i n g
h y d r o x y a n d / o r a m i n o
g r o u p s ,
and/
r
c o m p o u n ds t h a t c a n b e
d e r i v e d
from t h e s e
a l k a n e s
by c o u p l i n g them b y means o f t h e h y d r o x y and/
r
amino
g r o u p s , o r m i x t u r e s
o f t h e s e
compounds,
f o r example
e t h
y l e n e g l y c o l ,
p r o p a n e - d i o l - ( L Z ) ,
p r o p a n e - d i o l - ( l . 3 ) ,
b u
t a n e - d i o l - ( 1 . 3 ) ,
b u t a n e - d i o l - ( 1 . 4 ) a s w e l l
a s p e n t a u e - d i o l s
a n d
- t r i o l s ,
m o r e o v e r
g l y c e r o l ,
d i e t h y l e n e
g l y c o l ,
t r i e t h y l
e n e g l y c o l , e t h a n o l a m i n e a n d d i e t h a n o l a m i n e ,
e t h y l e n e
d i
a m i n e , p r o p y l e n e
d i a m i n e . W h e n s u s p e n d e d i n t h e s e c o m
p o u n d s , t h e PTFE a r t i c l e s d i s t i n c t l y t e n d t o f o r m
l a r g e r
g r a i n s
b y a g g l o m e r a t i o n ,
a f t e r a
s l i g h t i n c r e a s e i n t e m p e r
a t u r e . T h i s
t y p i c a l e f f e c t p r o d u c e d b y t h e d i s p e r s i n g a g e n t s
i s i n t e n s i ? e d by
s t i r r i n g , s o t h a t u n i f o r m ,
p r e d o m i n a n t l y
g l o b u l a r p a r t i c l e s h a v i n g a s m o o t h r e l a t i v e l y
n o n - p o r o u s
s u r f a c e i s f o r m e d .
T h i s e f f e c t i s v e r y s u r p r i s i n g
s i n c e
PTFE-powders
w h i c h
a r e t r e a t e d under t h e s a m e c o n d i t i o n s a n d a t t h e s a m e
8/17/2019 patent PTFE Us 3532782
http://slidepdf.com/reader/full/patent-ptfe-us-3532782 2/6
3 , 5 3 2 , 7 8 2
3
t e m p e r a t u r e s
w i t h s o l v e n t s o r d i s p e r s i n g a g e n t s o t h e r t h a n
t h e
a f o r e m e n t i o n e d ones—for e x a m p l e
a r o m a t i c h y d r o
c a r b o n s , h i g h e r h y d r o c a r b o n s , e s t e r s o f h i g h e r - b o i l i n g
p r i
m a r y alcohols—are
n o t a t a l l
changed
a s t o
t h e i r
p a r t i c l e
size.
The
d i s p e r s i n g
a g e n t
u s e d a c c o r d i n g
t o
t h e i n v e n t i o n
m a y b e
d i l u t e d
by
o t h e r
l i q u i d s which a r e i n e r t i n t h e
p r o c e s s o f t h e i n v e n t i o n , f o r e x a m p l e a l c o h o l s , e s t e r s , n i
t r i l e s ,
k e t o n e s , a r o m a t i c o r
a l i p h a t i c
h y d r o c a r b o n s o r
wa
t e r . When water i s
used a s
t h e d i l u e n t , i t i s a d v i s a b l e , o n
a c c o u n t o f
t h e h y d r o p h o b i a
o f t h e
p o l y t e t r a ? u o r o e t h y l
e n e , t o a d d
simultaneously a s m a l l a m o u n t o f
a usual
w e t t i n g
a g e n t , s u c h
a s p - n o n y l p h e n o l - p o l y e t h y l e n e g l y c o l
e t h e r , t r i b u t y l p h e n o h p o l y e t h y l e n e g l y c o l e t h e r o r p e r
? u o r o - o c t a n o i c a c i d . The r a t i o
o f
PTFE-powder
t o
d i s
p e r s i n g r a g e n t i s n o t
c r i t i c a l
and can be v a r i e d w i t h i n
wide
l i m i t s . S i n c e , h o w e v e r , t o o t h i c k a s u s p e n s i o n
m a y
l e a d
t o
t h e
formation of lumps,
o n
t h e o ne hand, a n d
t o o
low a
c o n c e n t r a t i o n o f PTFE weakens
t h e
g r a n u l a t i n g e f f e c t , on
t h e
o t h e r
hand,
i t i s advantageous t o choose
a
r a t i o
g e n e r -
.
a l l y
r a n g i n g
from
1 : 1
t o
1 : 1 0 .
For
a c o a r s e - g r a i n e d ma
t e r i a l ,
t h e
r a t i o
a d v a n t a g e o u s l y
r a n g e s
from 1 : 3
t o 1 : 5 ,
f o r
? n e r p o w d e r s ,
i t p r e f e r a b l y
r a n g e s from
1 : 4
t o
1 : 7 .
The s t i r r i n g s p e e d
e x e r t s
i t s i n ? u e n c e on
t h e
p a r t i c l e
s i z e
o f
t h e
g r a n u l e s
t o
b e f o r m e d .
A
i g h
s t i r r i n g s p e e d
g e n e r a l l y f a v o u r s
t h e
f o r m a t i o n
o f
? n e - g r a i n e d
g r a n u l e s , a
moderate
n u m b e r
o f
r o t a t i o n s o f t h e
s t i r r e r
r e s u l t s
i n
t h e
f o r m a t i o n
o f c o a r s e r
g r a n u l e p a r t i c l e s . The s t i r r i n g s p e e d
t o
b e
a p p l i e d i n e a c h c a s e d e p e n d s on t h e
p a r t i c l e s i z e
wanted
a s w e l l
a s o n t h e
dimensions
and s h a p e s o f
s t i r r i n g
v e s s e l and
s t i r r e r .
Th e m i n i m u m t e m p e r a t u r e n e c e s s a r y f o r o b t a i n i n g a
d i s t i n c t g r a n u l a t i n g e f f e c t d e p e n d s on t h e k i n d o f
t h e d i s
p e r s i n g
a g e n t
u s e d a n d ,
t o
a s m a l l d e g r e e ,
o n t h e
i n i t i a l
0
10
4
a d r y i n g c a b i n e t a n d , i f
r e q u i r e d, c l a s s i ? e d
i n t o d i f f e r e n t
g r a i n
s i z e s
b y m e a n s o f a s c r e e n
o r a n o t h e r
a p p r o p r i a t e
d e v i c e . The s u s p e n d i n g a g e n t c a n b e a g a i n u s e d w i t h o u t
f u r t h e r
t r e a t m e n t .
Only
a f t e r h a v i n g been u s e d f o r a l o n g
p e r i o d
o f t i m e ,
i t
h a s t o b e
p u r i ? e d b y
d i s t i l l a t i o n .
The
f o l l o w i n g
e x a m p l e s
i l l u s t r a t e
t h e
p r e s e n t
i n v e n t i o n ,
b u t t h e y
a r e
n o t i n t e n d e d
0 t
l i m i t
i t
t h e r e t o .
EXAMPLE
A o u r - n e c k e d
? a s k
o f a c a p a c i t y o f 4
l i t e r s ,
p r o v i d e d
with a
s t i r r e r ,
a
t h ermo met er a n d
a c o o l e r , was ? l l e d
with
2 . 8 l i t e r s
o f e t h y l e n e g l y c o l a n d , w h i l e s t i r r i n g
a t 7 0 0
r . p . m . w i t h a
? a t
p a d d l e mixer h a v i n g
a s t i r r i n g s u r f a c e
o f 4 - 5 c m . 2 , 5 0 0
grams
o f s c r e e n e d
PTFE-powder
( p r e
p a r e d by
p o l y m e r i z a t i o n o f
t e t r a ? u o r o e t h y l e n e i n a n a q u e
o u s m e d i u m
( s u s p e n s i o n ) ,
f o r
example a c c o r d i n g
t o
Ger
m a n P a t .
No. 1 , 1 0 9 , 3 7 0 , m e d i u m
g r a i n s i z e : 2 3 0 , “ )
were
i n t r o d u c e d . Th e m i x t u r e
was
s t i r r e d f o r a s h o r t
p e r i o d
o f
t i m e
u n t i l
a
homogeneous
d i s t r i b u t i o n was
o b t a i n e d , t h e
s u s p e n s i o n was
then heated
t o a
temperature
of
150°
C.
which was
m a i n t a i n e d
f o r
45
m i n u t e s .
S u b s e q u e n t l y ,
t h e
s u b s t a n c e
was
q u i c k l y
c o o l e d t o
r o o m t e m p e r a t u r e ,
t h e
c o n t e n t s o f t h e
?ask
was p ou r e d
onto a
v a c u u m ? l t e r , t h e
g l y c o l was
c a r e f u l l y
? l t e r e d w i t h s u c t i o n ,
t h e g r a n u l e s
on
t h e
v a c u u m
? l t e r were
washe d with a
l a r g e
a m o u n t of
w a t e r
( f r e e
from
s a l t ) a n d
t h e n
d r i e d i n t h e d r y i n g c a b i n e t
a t
l40-l50° C . f o r
1 2 t o
24 h o u r s .
There were
o b t a i n e d
i n t h i s
m a n n e r
g r a n u l e s h a v i n g
e x c e l l e n t ? ow p r o p e r t i e s
a n d
a
powder d e n s i t y i n t h e
r a n g e o f
from 500 t o 650 grams p e r l i t e r . The predomi
n a n t l y g l o b u l a r p a r t i c l e s showed a smooth
d e n s e
s u r f a c e .
The p r o d u c t s d i d n o t any l o n g e r s t i c k o r
form
l u m p s .
- B y means o f a s i e v e a n a l y s i s , t h e g r a i n s i z e s o f s e v e r a l
g r a n u l e s
( A ,
B , C) t h u s p r e p a r e d w e r e d e t e r m i n e d :
P a r t i c l e
s i z e
Mo re Less
than
1 , 2 0 0 - 6 0 0 — 3 0 0 - than
2 , 0 0 0 } ;
2 , 0 0 0 ; L 1 , 2 0 0 } : 6 0 0 ; ] . 3 0 0 1 . ;
P r o p o r t i o n s i n :
Granule
A, p e r c e n t _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
_ _
Aligut
1 1
3 5
3 4
1 0
Granule B,
percent _ _ _ _ _ _ _ _ _ _ _ _ _ _
_
A b o u t 2 3 2 6 2 7
8
1 6 .
Granule 0 percent __
________
_
14__
_
_ 21 2G 32 7
Starting material, per c ent _______________________________ _
10 25
65
N o r m - M e d i u m g r a i n
s i z e :
a b o u t
6 0 0 , “
( s t a r t i n g
m a t e r i a l : 2 3 0 , “ ) .
g r a i n
s i z e o f t h e PTFE-powder. T h i s t e m p e r a t u r e r a n g e s
from
room
t e m p e r a t u r e ( 2 0 ° C . ) t o 3 0 0 ° C . , p r e f e r a b l y
from 50 t o
1 5 0 ° C .
The p r o c e s s i s g e n e r a l l y
c a r r i e d
o u t u n d e r a t m o s p h e r i c
p r e s s u r e
which
s ,
h o w e v e r , n o t
a
p r e - r e q u i s i t e ; t h e g r a n u
l a t i o n
m a y — p h y s i c a l
c o n s t a n t s
a n d
a p p a r a t u s p e r m i t t i n g
— a l s o
be
c a r r i e d
out
under
e l e v a t e d o r
reduced p r e s s u r e .
A f t e r h a v i n g
r e a c h e d
t h e
n e c e s s a r y t e m p e r a t u r e ,
t h e
P T F E - p a r t i c l e s
a r e
u s u a l l y a g g l o m e r a t e d
r a t h e r
q u i c k l y t o
form
l a r g e r
p a r t i c l e s
o f a g l o b u l a r s h a p e and a d e n s e
s u r
f a c e .
T h i s
t e m p e r a t u r e which
i s
i n t h e r a n g e mentioned
a b o v e and d e p e n d i n g on
t h e t y p e
o f
t h e
s u s p e n d i n g
a g e n t
and t h e
g r a i n s i z e
o f t h e s t a r t i n g m a t e r i a l i s
t h e n
main
t a i n e d
f o r
a n o t h e r 1 5 t o
6 0
m i n u t e s .
The
s u s p e n s i o n o f g r a n u l e s o b t a i n e d
i n t h i s manner
i s
worked up a s f o l l o w s :
t h e
g r a n u l e s
and
t h e s u s p e n d i n g
a g e n t a r e s e p a r a t e d from
e a c h
o t h e r by known methods
and t h e
g r a n u l e s
a r e l i b e r a t e d from t h e a d h e r i n g
rem—
n a n t s o f s u s p e n d i n g
a g e n t ,
f o r e x a m p l e , by a r e p e a t e d s t i r
r i n g o f
t h e
p r o d u c t
u n d e r w a t e r
o r by
a s u b s e q u e n t d i s
t i l l a t i o n
w i t h
s t e a m .
The
g r a n u l e s
f r e e
from
t h e
s u s p e n d i n g
a g e n t
a r e
t h e n
d r i e d i n a
p n e u m a t i c c o n v e y i n g d r y e r o r i n
50
EXAMPLE
2
A o u r - n e c k e d ? a s k o f
a
c a p a c i t y o f 6 l i t e r s ,
p r o v i d e d
w i t h s t i r r e r , c o o l e r and
sum p
t h e r m o m e t e r , was ? l l e d
w i t h
4 . 5
l i t e r s
o f
g l y c o l
a n d , w h i l e v i g o r o u s l y
s t i r r i n g
a t
6 0 0
700 rpm. w i t h a ? a t paddle
mixer
o f a s t i r r i n g s u r f a c e
o f 5 — 6 c m . ~ ’ , 1 k i l o g r a m o f s c r e e n e d
PTFE-powder
( s u s
p e n s i o n
p r o d u c t - m e d i u m
p a r t i c l e s i z e : 2 3 0 , 1 1 . ) was
a d d e d
t h e r e t o i n p o r t i o n s .
A s soon
a s
a
homogeneous s u s p e n s i o n
was
o b t a i n e d , i t
was
heated t o a temperature
o f
135° C.
a n d
t h e
mixture was maintained
a t
t h i s temperature
f o r
1
h o u r . T h e s u b s t a n c e was t h e n
cooled
t o
r o o m
t e m p e r a t u r e .
O n a W a s h i n g va c u u m
? l t e r ,
t h e g l y c o l
and
t h e g r a n u l e s
were
s e p a r a t e d
from each
o t h e r
and t h e
g r a n u l e s
were
c a r e f u l l y washed w i t h 1 0
t o
20 t i m e s t h e a m o u n t o f w a t e r
( f r e e from s a l t ) . F i n a l l y , t h e p r o d u c t was d r i e d i n t h e
d r y i n g c a b i n e t a t
140—150°
C .
f o r
1 2
t o
24 h o u r s .
T he
product
t r e a t e d
i n t h i s m a n n e r c o n s i s t e d i n
g r a n u l e s o f a
p r e d o m i n a n t l y
g l o b u l a r s h a p e and
had
e x
c e l l e n t
?ow
p r o p e r t i e s .
The
s i e v e
a n a l y s i s
showed
t h e
f o l l o w i n g
d i s t r i b u t i o n
o f g r a i n s i z e s :
P a r t i c l e s i z e
Mor e
Less
than
1 , 2 0 0 —
6 0 0 - 3 0 0 - than
2 , 0 0 0 “ 2 , 0 0 0 ” 1 , 2 0 0 ”
6 0 0 ; ] .
3 0 0 p
P r o p o r t i o n s i n :
The
granules, per c ent _____________ _ 19 13 18
3 5
15
S t a r t i n g
m a t e r i a l , percent ______________________________ 1 10 25
G 5
8/17/2019 patent PTFE Us 3532782
http://slidepdf.com/reader/full/patent-ptfe-us-3532782 3/6
3 , 5 3 2 , 7 8 2
5 6
EXAMPLE w i t h 4 . 3
l i t e r s
o f
d i e t h y l e n e
g l y c o l a n d , w h i l e s t i r r i n g , 1 . 2
An
e n a m e l e d
t a n k o f a c a p a c i t y o f 5 0 l i t e r s , p r o v i d e d k l l o g r a n e s o f s e f e e n e d P T F E ' p e w d e r
( s u s p e l i s i e n
P r o d ‘
w i t h
s t i r r i n g , h e a t i n g
a n d
c o o l i n g f a c i l i t i e s , w a s ? l l e d
uet‘medmm gram
d l a m e t e r :
2 3 0 / ‘ w e r e t h e n 1 n F r ° ‘ ? “ ° e d ~
w i t h 3 0 l i t e r s o f g l y c o l
a n d
5 k i l o g r a m s o f
a
p o l y t e t r a - { e s s o o n , a s , t h e p o w e e r w a s
h o m o g e n e o u s l y
d l s t n l f ’ u i e d
? u o r o e t h y l e n e
d i s p e r s i o n
p o l y m e r m o d i ? e d
w i t h
a b o u t 5 m h e
h q u l d ’
t h e
m 1 x t u r e _ w a s
h e e t e d
a n ‘ ?
t h e
Smrmg
005
t o
Q1 %of p e r ? u o r o p r o p e n e
( i n
p u l v e r u l e n t f o r m ) _ s p e e d o f t h z e ? a t p a d d l e m i x e r
h a v l n g
a s t i r r i n g s u r f a c e
The m i x t u r e was v i g o r o u s l y s t i r r e d u n t i l t h e p a r t i c l e s w e r e o f 5 - 6
e e l ‘
’ w a s
I n c r e a s e d
t _ ° 6 9 0 - 7 0 0
r ' p ' m '
T o h e t e m '
homogeneously d i s t r i b u t e d and
no
lumps c o u l d b e O b _
p e r a t u r e 1 n
t h e
f l a s k
was m a i n t a l n e d
a t
130-140
C . f o r
1
h o u r , t h e
s u b s t a n c e was t h e n q u i c k l y c o o l e d t o r o o m
t e m p e r a t u r e
and
t h e
c o n t e n t s
o f t h e
? a s k
was
p o u r e d o n t o
a v a c u u m
? l t e r .
The
d i e t h y l e n e
g l y c o l was c a r e f u l l y
? l t e r e d
with
s u c t i o n , t h e g r a n u l e s were washed
with
a
l a r g e
amount
o f w a t e r ( f r e e from
s a l t )
a n d ? n a l l y d r i e d
i n t h e
d r y i n g
c a b i n e t a t 1 5 0 °
C .
f o r
1 2
t o
24
h o u r s .
1 5
The f o l l o w i n g
t a b l e s h o w s
t h e d i s t r i b u t i o n o f
g r a i n
s i z e s o f 6 g r a n u l e s
( A - F ) p r e p a r e d a c c o r d i n g t o
t h e s e
s e r v e d . U n d e r s l o w a g i t a t i o n ( a b o u t
4 0 0 r . p . m . ) , t h e
s u s p e n s i o n was
h e a t e d
u p . The
g r a n u l a t i o n a l r e a d y
s t a r t e d
1 0
a t a temperature s l i g h t l y above 50° C .
T h e
mixture
was
maintained a t a temperature i n t h e range of from 80
t o
9 0 ° C .
f o r
30
m i n u t e s , t h e n c o o l e d
w h i l e
s t i r r i n g
u n t i l
t h e s u s p e n s i o n o f g r a n u l e s a g a i n r e a c h e d
room
t e m p e r a
t u r e . By
means
o f a
v a c u u m ? l t e r , t h e
s u s p e n d i n g a g e n t
a n d
t h e g r a n u l e s
w e r e
s e p a r a t e d from e a c h o t h e r ,
t h e
g r a n u l e s
w e r e
removed
from
t h e
v a cuum
? l t e r ,
s u s p e n d e d
m d l c a t l o n s :
P a r t i c l e
s i z e
Mo re
Less
than
1 , 2 0 0 - 6 0 0 - 3 0 0 -
than
2 , 0 0 0 , ‘
2 , 0 0 0 a
1 , 2 0 0 , ‘
6 0 0 a
3 0 0 p .
P r o p o r t i o n s i n :
G r a n u l e A , percent
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
- _ 1 .
7 3 5 .
5
6 2 . 0
0 .
8
Granule B, percent.-. _
2 . 0 3 4 . 0 6 3 . 0
1 . 0
Granule C, pe r cent-“
_ l . 0 3 0 . 0 6 8 . 0 1 . 0
Granule
D, p e r c e n t . . .
_ _
1 . 5 5 3 . 0 4 4 . 5 1 . 0
GranuleE percent _
_ .
_
_ _ . _ _ _ _ _ _ _ . _
51 48 4 O 6
G r a n u l e F, p e r c e n t __________ _ _ _ _ 1 .
2 52 46
0 .
8
Starting material
p e r c e n t
_______________________________ . 10 25 6
b
i n 2 0
l i t e r s o f w a t e r and v i g o r o u s l y s t i r r e d . The
w a s h i n g
w a t e r was l e t o ? a f t e r 3 m i n u t e s and
t h e
whole washing The
? n e - g r a i n e d p r o d u c t s
h a v i n g e x c e l l e n t ? ow p r o p
p r o c e d u r e w a s r e p e a t e d
s e v e r a l
t i m e s w i t h f r e s h w a t e r . e r t i e s (medium p a r t i c l e s i z e : 5 0 0 — 7 0 0 p . ) c o u l d b e e x c e l
Th e
washed
g r a n u l e s
were d r i e d
on
s h e l v e s i n t h e
d r y i n g l e n t p r o c e s s e d b y
means
o f r a m o r s c r e w e x t r u d e r s . Th e
c a b i n e t
a t 1 4 0 ° C .
f o r
2 0 - h o u r s a n d
? n a l l y c l a s s i ? e d b y
3 5 p o w d e r d e n s i t y
o f t h e c o a r s e - g r a i n e d
p r o p o r t i o n s
s c r e e n i n g :
P a r t i c l e s i z e
Mor e
L e s s
T h a n 2 , 0 0 0 — 1 , 2 0 0 — 6 0 0 - 3 0 0 -
2 0 0 -
T h a n
3 , 0 0 0 “ 3 , 0 0 0 u 2 , 0 0 0 u 1 , 2 0 0 ”
6 0 0 ; ] .
3 0 0 p
1 5 0 1 ; 1 5 0 ; :
P r o p o r t i o n s i n t h e g r a n u l e s ,
p e r c e n t _________________
__
1 . 6
6 .
0
2 3 .
4 5 3 . 5
1 5 . 5
______________________
__
P r o p o r t i o n s
i n
t h e
s t a r t i n g
material, per c ent- __________________________________________ -
1 3 . 4 2 6 .
1
2 7 .
1
1 7 .
0 1 6 .
4
b N o ' i ‘ r * . 3 . 0 — G r a n u l e s o f a r a t h e r
u n i f o r m
g r a i n s i z e , m e d i u m i z e : a b o u t
1 , 0 0 0 “ ;
s t a r t i n g m a t e r i a l : m e d i u m i z e :
a
o ut
3
[ 1 .
EXAMPLE
4 amounted t o a b o u t 4 0 0 - 5 0 0 , t h a t o f t h e ? n e r p r o p o r t i o n s
In an a p p a r a t u s a s d e s c r i b e d i n E x a m p l e
3 ,
9 0 0
grams 50 a m o u n t e d
t o 500—650.
~
o f a p u l v e r u l e n t
P T E E - d i s p e r s i o n
p o l y m e r
a n d
2 , 6 0 0 ‘
grams o f
a s c r e e n e d PTFE-suspension polymer
were
added w h i l e s t i r r i n g
t o
1 8
l i t e r s
o f
g l y c o l
and t h e m i x t u r e
was s t i r r e d t o for m
an
i n t i m a t e s u s p e n s i o n .
The m i x t u r e was
t h e n
h e a t e d , w h i l e s t i r r i n g a t
400-
5 5
A
o u r - n e c k e d ? a s k o f a c a p a c i t y o f 4 l i t e r s , p r o v i d e d
EXAMPLE 6
500 r . p . m . , t o a
t e m p e r a t u r e r a n g i n g
between
120
and
W i t h
8 -
s t i r r e r , a 6 0 0 1 6 1 ‘ and
a
S u m p
thermometer
and
1 3 0 °
C .
f o r
a
s h o r t
p e r i o d o f
t i m e
a n d t h e n c o o l e d
q u i c k - ? l l e d
w i t h
2 . 7 5 l i t e r s o f f r e s h l y
d i s t i l l e d b u t a n e - d i o l - ( 1 . 4 ) ,
l y
t o
r oom t e m p e r a t u r e . G l y c o l and g r a n u l e s
were
s e p a - was c h a r g e d , w h i l e s t i r r i n g , w i t h 750
grams
o f s c r e e n e d
r a t e d i n
known
manner and t h e
g r a n u l e s w e r e a f t e r - PTFE-powder ( s u s p e n s i o n p r o d u c t ) . The number o f
r o t a
t r e a t e d
i n t h e
manner d e s c r i b e d
i n Example 3 . The g r a i n
6 O
t i o n s o f t h e s t i r r i n g
p a d d l e
t h e s u r f a c e
o f
which
was
4
t o
s i z e s
o f
t h e p r o d u c t were a s f o l l o w s : 5 c m . 2 , amounted t o 600-700
r . p . m .
The c o n t e n t s
o f
t h e
P a r t i c l e s i z e
Mo re Less
than
3 0 0 -
than
3 , 0 0 0 , ; 2 , 0 0 0 — 3 , 0 0 0 p 1 , 2 0 0 — 2 , 0 0 0 G O O - 1 , 2 0 0 ” 6 0 0 a 3 0 0 a
Proportions i n the g r a n u l e s , percent _ _ _ _ _ _ _ _ _ _ 0 . 4 4 .
3
9 . 5
2 9
5 0 6 .
8
P r o p o r t i o n s i n t h e s t a r t i n g m a t e r i a l d i s p e r s i o n - S e e Example 3
P r o p o r t i o n s i n t h e s t a r t i n g m a t e r i a l s u s p e n
sion ______________________________________ __ See Example
2
EXAMPLE
5
?ask
was then heated t o a temperature i n t h e range
o f
A
o u r - n e c k e d
? a s k
o f a c a p a c i t y o f 6 l i t e r s , p r o v i d e d from 1 4 0
t o
1 5 0 ° C . f o r 3 0
t o
5 0 m i n u t e s
and
s u b s e
w i t h a s u m p t h e r m o m e t e r , a s t i r r e r and a
c o o l e r , was
? l l e d q u e n t l y q ui c k l y c o o l e d a g a i n . The b u t a n e - d i o l - ( 1 . 4 ) was
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3 , 5 8 2 , 7 8 2
? l t e r e d
f r o m
t h e
g r a n u l e s w i t h
s u c t i o n a n d t h e
g r a n u l e s
were c a r e f u l l y washed
w i t h
20
t o
25 t i m e s t h e a m o u n t o f
The
g r a n u l e s
o b t a i n e d w i t h
a
l i t t l e
c o a r s e r g r a i n s had
t h e f o l l o w i n g c o m p o s i t i o n :
P a r t i c l e
s i z e
Mor e
Less
than 1 , 2 0 0 - 6 0 0 -
3 0 0 -
than
2 , 0 0 0 “
2 , 0 0 0 p
1 , 2 0 0 1 , ‘
G O O / p 3 0 0 p .
P r o p o r t i o n s i n :
Granules
A percent ___
_ ,
_______________ __
7 54 30 9
Granules
B
percent
__
_ _ __ 9 .
3 49 28
13. 7
S t a r t i n g material _______________________________________
10 25 65
EXAMPLE
w a t e r
( f r e e
from s a l t ) . The p r o d u c t was ? n a l l y d r i e d i n
t h e d r y i n g c a b i n e t a t
1 4 0 - 1 5 0 “
C . f o r
1 2
t o
2 0
h o u r s .
There was
o b t a i n e d
a ? n e l y - d i v i d e d PTFE-granulate
h a v i n g
g o o d
?ow p r o p e r t i e s , no t e n d e n c y
o f
f o r m i n g
lumps and a powder d e n s i t y o f
5 6 0 .
T he s i e v e
o f s o m e
g r a n u l e s (A-C) t h u s
p r e p a r e d
a r e
i n d i c a t e d
i n t h e f o l
l o w i n g
t a b l e :
1 5
20
A n e n a m e l e d
s t i r r i n g v e s s e l o f a c a p a c i t y o f
1 0 0
l i t e r s
was ? l l e d w i t h
6 0
l i t e r s
o f
g l y c o l and 1 5 k i l o g r a m s o f
PTFE-powder
( s u s p e n s i o n
p r o d u c t ) w e r e
a d d e d
t h e r e
t o . A homogeneous s u s p e n s i o n was p r e p a r e d by
m e a n s
o f a t u r b i n e s t i r r e r ( 4 0 0 — - 6 0 0 r . p . m . ) and
t h e n
t h e con
t e n t s
o f t h e
v e s s e l
was
heated
t o
a
temperature
o f
150°
P a r t i c l e s i z e
Mo re Less
than 1 , 2 0 0 - 6 0 0 - 3 0 0 -
than
2 , 0 0 0 2 , 0 0 0 } ; 1 , 2 0 0 6 0 0 ; » 3 0 0 , 1
P r o p o r t i o n s i n :
G r a n u l e s A , per c ent ________ _ 3 4 63.8
2 . 2
Granules
B,
p e r e e n t _ 4 0 . 8
5 8 1 . 2
Granules C , percent .--
4 3 5 4
3
S t a r t i n g m a t e r i a l , p e r c e n t 1 0 2 5 6 5
f o r 1
h o u r .
After t h i s e r i o d
o f
time t h e s u b s t a n c e
EXAMPLE
3 -
C
. P ’
a was q u i c k l y c o o l e d t o r o o m temperature and t h e v e s s e l
I n
t h e
a p p a r a t u s
d e s c r i b e d i n
Example
6 ,
8 0 0
grams
o f s c r e e n e d p o l y t e t ra ? u o r o e t h y l e n e ( s u s p e n s i o n p r o d u c t )
were
s u s p e n d e d i n 2 . 7 l i t e r s o f b u t a n e - d i o l - ( 1 . 3 ) and
t r e a t e d f u r t h e r a s
d e s c r i b e d i n
Ex a m p l e 6 .
There
were
o b t a i n e d ? n e - g r a i n e d g r a n u l e s h a v i n g g o o d f l o w p r o p e r
t i e s
a n d
s h o w i n g
t h e f o l l o w i n g d i s t r i b u t i o n
o f g r a i n
s i z e s .
40
w a s then e m p tie d over a
v a c u u m
? l t e r . T h e g l y c o l was
r e c y c l e d i n t o t h e
v e s s e l ,
t h e g r a n u l e s w e r e b r i e ? y w a s h e d ,
removed from t h e
? l t e r ,
immersed i n t o
water and once
m o r e c a r e f u l l y washed
with a
l a r g e a m o u n t o f w a t e r .
A f t e r h a v i n g
been
o n c e mo re s q u e e z e d o f f , t h e y were
d r i e d
i n
t h e
d r y i n g
c a b i n e t
a t
1 5 0 ° C . f o r
20
h o u r s .
There
P a r t i c l e
s i z e
Mo re Less
than 1 , 2 0 0 - 6 0 0 - 3 0 0 - than
2 , 0 0 0 #
2 , 0 0 0 ”
1 , 2 0 0 , “ 6 0 0 a 3 0 0 a
P r o p o r t i o n s i n t h e
g r a n u l e s ,
p e r c e n t _ _ _ 1 3 . 3 7 8 . 0
8 .
7
Starting
material,
p e r c e n t
___________
_ 1O 25 65
EXAMPLE
I n t h e a p p a r a t u s d e s c r i b e d i n Example 6 , 8 0 0 g r a m s
w e r e
o b t a i n e d g r a n u l e s
h a v i n g e x c e l l e n t
f l o w p r o p e r t i e s
a n d
t h e
f o l l o w i n g d i s t r i b u t i o n o f
g r a i n
s i z e s :
P a r t i c l e
s i z e
L e s s
than
1 5 0 - 2 0 0 — 2 5 0 - 3 0 0 - 4 0 0 - 5 0 0 - 6 0 0 - 7 5 0 - 1 ,
( J 0 0
1 5 0 / . t
2 0 0 p 2 5 0 1 ; 3 0 0 p . 4 0 0 / 1
5 0 0 1 , :
6 0 0 p 7 5 0 p . 1 , 0 0 0 g . 1 , 5 0 0 p .
Proportions
i n
the
granules, percent ________________________________________________________
_ 1 .
5
5 .
7 1 5 . 6
5 0 .
7
2 0 . 5
Starting m a te r i a l ,
p e r c e n t
___________________
_ 4 2 .
5 1 6 . 7 22 12
5 .
7 0 . 6 0 . 2
0 .
2 ______________________
_
o f
s c r e e n e d
PTFE-powder
were s u s p e n d e d
i n 2 . 5
l i t e r s
EXAMPLE 0
o f e t h a n o l a m i n e
and v i g o r o u s l y
s t i r r e d . A f t e r so me t i m e ,
t h e
mixture
was heated u p t o a
temperature
i n t h e range
o f from
90
t o 110° C .
and
t h i s
t e m p e r a t u r e was m a i n
t a i n e d
f o r 30-60 m i n u t e s ,
t h e
s u b s t a n c e
Was c o o l e d ,
w h i l e
s t i l l
s t i r r i n g , and ? n a l l y
t h e
g r a n u l e s
w e r e
s e p a r a t e d
from
t h e e t h a n o l a m i n e by ? l t r a t i o n . The g r a n u l e s
were
washed
with
20 t o 25
t i m e s
t h e a m o u n t
o f
water f r e e from
s a l t
and
t h e n d r i e d
i n
t h e d r y i n g c a b i n e t
a t 1 5 0 °
C . f o r 20
h o u r s .
7 0
7 5
I n an
enameled
s t i r r i n g v e s s e l o f a
c a p a c i t y
o f 1 0 0
l i t e r s ,
6 0
l i t e r s o f g l y c o l and 1 5
k i l o g r a m s
o f a
PTFE
powder ( s u s p e n s i o n p r o d u c t )
were
s t i r r e d by means
o f
a t u r b i n e s t i r r e r a t 600-700 r . p . m . t o y i e l d a h o m o g e n e
ous
suspension a n d t h e
mixture was heated t o a t empera
t u r e o f 1 3 0 ° C .
f o r
50 m i n u t e s .
A f t e r t h i s
p e r i o d
o f
t i m e ,
t h e substance was
q u i c k l y
cooled t o r o o m temperature
a n d
t h e c o n t e n t s of the
v e s s e l
was po ured over a
v a c u u m
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3 , 5 3 2 , 7 8 2
? l t e r . The g l y c o l was r e c y c l e d i n t o t h e v e s s e l a n d t h e
PTFE-granules were
immersed i n t o w a t e r
i n
a Washing
c o n t a i n e r
a n d
w a s h e d ,
w h i l e s l o w l y
s t i r r i n g ,
w i t h
a
l a r g e
10
T h e r e w e r e o b t a i n e d r e l a t i v e l y c o a r s e - g r a i n e d g r a n u l e s
h a v i n g
g o o d
?ow p r o p e r t i e s
a n d t h e
f o l l o w i n g d i s t r i b u
t i o n o f g r a i n s i z e s :
P a r t i c l e s i z e
L e s s
1 , 5 0 0 - 1 , 0 0 0 - 7 5 0 ~ 6 0 0 - 5 0 0 - 4 0 0 - 5 0 0 - 2 5 0 - 2 0 0 - than
2 ,
0 0 0 ; ;
1 ,
5 0 0 ; ;
1 , 0 0 0 ; ;
7 5 0 ; ; 6 0 0 ; ;
5 0 0 ; ;
4 0 0 ; ; 3 0 0 ; ;
2 5 0 ; ; 2 0 0 ; ;
P r o p o r t i o n s
i n
t h e
g r a n u l e s ,
p e r c e n t - _ . . _ 4 . 9 4 0 . 3 1 2 . 7 1 3 . 1 7 8 . 4 6 .
5
3 . 8
1 .
7 1 . 6
S t a r t i n g m a t e r i a l ,
per c ent
_________________________________________________________________________
_ 1 . 1 1 2 . 9 1 5 . 2
4 .
7
5 6 .
1
a m o u n t
o f
w a t e r . Th e washed g r a n u l e s were ? l t e r e d
i n
vacuo and
t h e n d r i e d i n a d r y i n g c a b i n e t a t 1 5 0 ° C . f o r
20 h o u r s .
T h e
s i e v e - a n a l y s i s s h o w e d t h e f o l l o w i n g
d i s t r i b u t i o n
o f
g r a i n s i z e s :
15
A
o u r - n e c k e d
? a s k o f a
c a p a c i t y
o f 4 l i t e r s , p r o v i d e d
with a s t i r r e r ,
a cooler
a n d a s u m p the r m om e te r w a s
? l l e d
w i t h
2 l i t e r s
o f g l y c o l , a t ? r s t
1 5 0 m i l l i l i t e r s
o f an
a q u e o u s P T F E - d i s p e r s i o n
o f
2 0%
s t r e n g t h
a n d t h e n 3 6 0
g r a m s
o f s c r e e n e d
P T F E - s u s p e n s i o n p o l y m e r
p o w d e r
I n
t h e same
a p p a r a t u s
and
under
t h e same c o n d i t i o n s
a s d e s c r i b e d i n Example ‘ 9 , 20
k i l o g r a m s o f a
PTFE
p o w d e r
( s u s p e n s i o n
p r o d u c t ) w e r e s u s p e n d e d
i n
8 0 l i t e r s
o f
d i e t h y l e n e
g l y c o l .
The number o f r o t a t i o n s o f t h e
t u r b i n e s t i r r e r was a d j u s t e d t o 300
r . p . m . ,
t h e v e s s e l was
h e a t e d
up t o a
t e m p e r a t u r e o f 1 4 0 ° C . f o r
70 m i n u t e s
and t h e n a g a i n c o o l e d t o r o o m t e m p e r a t u r e . The c o n t e n t s
o f t h e v e s s e l was worked up i n t h e m a n n e r d e s c r i b e d i n
t h e p r e c e d i n g e x a m p l e s .
T he g r a n u l e s o b t a i n e d were p e r f e c t l y
s u i t a b l e
f o r a
35
P a r t i c l e
s i z e
Less
than
1 5 0 - 2 0 0 - 2 5 0 —
3 0 0 —
4 0 0 - 5 0 0 - 6 0 0 - 7 5 0 -
1 ,
0 0 0
1 5 0 ; ; 2 0 0 ; ; 2 5 0 ; ; 3 0 0 ; ; 4 0 0 ; ; 5 0 0 ; ; 6 0 0 ; ; 7 5 0 ; ; 1 , 0 0 0 ; ; 1 , 5 0 0 ; ;
P r o p o r t i o n s
i n
t h e g r a n
u l e s , perc ent
_ _ _ _ _ _ _ _ _
_ _ 0 . 2 1 .
2
1 . 5 3 . 7 9 . 6 1 9 . 8 2 2 .
8
2 3 . 0 1 7 . 2 1 . 0
S t a r t i n g m a t e r i a l , percent;
4 3 .
4 1 6 . 2 1 2 . 6 1 4 . 4 1 1 . 8 1 . 0 0 . 2 0 . 2 0 . 2 _ _ _ _ _ _ _ _ _ _ _ _
3 0 were added t h e r e t o ,
w h i l e m o d e r a t e l y s t i r r i n g . The nu
EXAMPLE 1 h e r o f
r o t a t i o n s was
t h e n i n c r e a s e d t o
300-400
r . p . m .
and
t h e m i x t u r e
was
s l o w l y h e a t e d u p . Already a f t e r a
s h o r t
p e r i o d o f t i m e and a t a
t e m p e r a t u r e
s l i g h t l y a b o v e 3 0 ° C . ,
a n
a g g l o m e r a t i o n o f
t h e p a r t i c l e s
c o u l d b e d i s t i n c t l y
o b
s e r v e d .
At t h e same
t i m e , t h e
d i s p e r s i o n
d i s i n t e g r a t e d
a n d
i t s s o l i d s
p r o p o r t i o n
a l s o
p r e c i p i t a t e d o n
t h e s u s p e n d e d
P T F E - p a r t i c l e s ,
t h u s
a l s o f a v o u r i n g t h e a g g l o m e r a t i o n .
T h e
mixture
was
heated
t o a
t e m p e r a t u r e
i n t h e
r a n g e o f
from
4 0 t o
5 0 °
C . f o r 1
h o u r , t h e n c o o l e d a n d ? n a l l y
t h e
P T F E - g r a n u l e s o b t a i n e d
w e r e
s e p a r a t e d ,
washed and
d r i e d
i n t h e m a n n e r d e s c r i b e d
a b o v e .
S i e v e - a n a l y s i s
o f t h i s p r o d u c t :
P a r t i c l e s i z e
L e s s
1 , 0 0 0 - 7 5 0 - 6 0 0 - 5 0 0 - 4 0 0 - 3 0 0 - 2 5 0 - 2 0 0 - 1 5 0 - t h an
1 , 5 0 0 ; ; 1 , 0 0 0 ; ; 7 5 0 ; ; 6 0 0 ; ; 5 0 0 ; ; 4 0 0 ; ; 3 0 0 ; ; 2 5 0 ; ; 2 0 0 ; ; 1 5 0 ; ;
P r o p o r t i o n s i n
t h e g r a n u l e s ,
p e r c e n t _________________ _
48 2 7 .
6
1 2 .
4
4.
8
4.
2 1 . 4 1 . 0 0 . 6 ______________ _
Starting material, p e r c e n t __________ ' _
________________________
_ 1 . 0 6 . 0 1 4 . 2 1 3 . 2 1 4 . 8 1 4 . 6 3 6 . 2
r a m - e x t r u s i o n a n d
had t h e
f o l l o w i n g d i s t r i b u t i o n o f
g r a i n
s i z e s :
P a r t i c l e s i z e
L e s s
than 1 5 0 - 2 0 0 - 2 5 0 - 3 0 0 - 4 0 0 - 5 0 0 - 6 0 0 ~ 7 5 0 - 1 , 0 0 0 - 1 , 5 0 0
1 5 0 ; ;
2 0 0 ; ;
2 5 0 ; ;
3 0 0 ; ; 4 0 0 ; ; 5 0 0 ; ; 6 0 0 ; ; 7 5 0 ; ;
1 , 0 0 0 ; ; 1 ,
5 0 0 ; ; 2 , 0 0 0 ; ;
Proportions in the r a n u l e s , p e r - _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 2 . 0 9 . 3 1 4 .
3
1 6 . 9 2 0 .
5
3 1 . 8 5 .
2
can
Starting material, p e r c e n t
_ _ _ _
_ _ 3 8 .
7
1 7 . 4 1 4 .
7
1 5 .
2
1 2 . 9 ‘ 0 .
9
0 .
2
________________________________________________ . _
EXAMPLE 2
A f o u r - n e c k e d
? a s k
o f a c a p a c i t y o f
4
l i t e r s was ? l l e d EXAMPLE 1 4
w i t h
a m i x t u r e
o f l ' l i t e r
o f
g l y c o l , 1
l i t e r
o f w a t e r and
1 . 5 m i l l i l i t e r s
o f p - n o n y l p h e n o l - p o l y e t h y l e n e
g l y o l
e t h e r .
7 0 0 g r a m s o f s c r e e n e d
PTFE-powder
( s u s p e n s i o n p o l y
mer)
w e r e i n t r o d u c e d , w h i l e s t i r r i n g a t 700 r . p . m . , and
t h e r e a c t i o n mixture
was
then heated t o a temperature o f
9 0 ° C . f o r 60
m i n u t e s . The s u b s e q u e n t
work up
o f
t h e
b a t c h was c a r r i e d o u t i n know n
m a n n e r
by
? l t e r i n g
t h e
s u s p e n d i n g
a g e n t w i t h s u t i o n
a n d c a r e f u l l y w a s h i n g
t h e
remaining g r a n u l e s
o n t h e
v a c u u m ? l t e r w i t h water
f r e e
from s a l t . The s t i l l m o i s t p r o d u c t
was
? n a l l y removed
from t h e
v a cuum ? l t e r and
d r i e d i n t h e d r y i n g
c a b i n e t
a t 1 4 0 ° C . f o r 1 5 h o u r s .
65
7 0
7 5
1 , 0 0 0
m i l l i l i t e r s
o f
e t h y l e n e
d i a m i n e
h y d r a t e
w e r e
i n
t r o d u c e d
i n t o a f o u r - n e c k e d
?ask
o f a
c a p a c i t y
o f 2
l i t e r s
and 250
grams
o f a PTFE-powder t h e m e d i u m g r a i n s i z e
o f
which
h a r d l y e x c e e d e d 5 0 ; ; , w e r e a d d e d
t h e r e t o
w h i l e
s t i r r i n g . The s u s p e n s i o n was h e a t e d
t o
a
t e m p e r a t u r e
o f
8 0 ° C .
and
t h i s t e m p e r a t u r e
was
m a i n t a i n e d
f o r
45 m i n
u t e s . Th e s u b s t a n c e was t h e n a l l o w e d t o
c o o l
w h i l e s t i r
r i n g ,
t h e
P T F E - g r a n u l e s w e r e s e p a r a t e d
a n d ,
a f t e r h a v i n g
b e e n c a r e f u l l y washed s e v e r a l t i m e s w i t h w a t e r f r e e from
s a l t ,
t h e y
were
d r i e d
i n a
d r y i n g c a b i n e t
a t
1 4 0 °
C . f o r
2 0
h o u r s .
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3 , 5 3 2 , 7 8 2
The
g r a n u l e s
h a d
t h e f o l l o w i n g
c o m p o s i t i o n : 6 . The
p r o c e s s
o f c l a i m
1
w h e r e i n
t h e d i s p e r s i n g
a g e n t
P a r t i c l e s i z e
L e s s
7 5 0 -
6 0 0 - 5 0 0 - 4 0 0 —
3 0 0 -
2 0 0 - 1 0 0 - 7 5 — 5 0 — than
1 ,
0 0 0 , , 7 0 0 , , 6 0 0 , , 5 0 0 , , 4 0 0 , , 3 0 0 , , 2 0 0 , , 1 0 0 , ,
7 5 , , 5 0 , ,
P r o p o r t i o n s i n
t h e
g r a n u l e s , p e r ~
c e n t ___________________________ _ 0. 6
2 4 .
8
3 7 . 6
1 2 .
0
1 0 . 0 5 .
6 9 .
4 ______________________ _
Starting material, percent _ _ _ _ _ 0 .
8
5 .
8
l 6 .
4
2 9 .
4
4 7 .
6
I c l a i m :
1 .
A
r o c e s s f o r
p r e p a r i n g g r a n u l a t e d p o l y t e t ra ? u o r o
e t h y l e n e f r o m t h e p o w d e r e d f e e d c o n s i s t i n g
i n
t h o r o u g h l y
a d m i x i n g :
(A)
s a i d
f e e d w i t h
( B ) a d i s p e r s i n g a g e n t c o m p r i s i n g amino o r
hydroxy
g r o u p s
c o n t a i n i n g
a l i p h a t i c hydrocarbon
o r
c o r r e
s p o n d i n g
c o u p l e d
p r o d u c t s t h e r e o f
a t
a p r o p o r t i o n o f
(A) t o ( B ) o f a b o u t
1:1-10 and a t e m p e r a t u r e o f
a b o u t
2 0 - 3 0 0 ” ;
and
t h e r e a f t e r s e p a r a t i n g and r e c o v
e r i n g t h e
g r a n u l a t e d p r o d u c t
a n d
d i s p e r s i n g a g e n t .
2 . T he
p r o c e s s o f c l a i m 1
wherein t h e s t i r r i n g i s
c a r
r i e d out
a t
a
temperature
i n t h e
range
o f f r o m 40 t o
1 5 0 °
C .
3 . The p r o c e s s o f c l a i m 1 w h e r e i n t h e p o l y t e t r a ? u o r o
e t h y l e n e i s
an
u n s i n t e r e d
p o l y t e t r a ? u o r o e t h y l e n e which
i s
o b t a i n e d b y p o l y m e r i z a t i o n
o f t e t r a ? u o r o e t h yl e n e i n
a n
a q u e o u s
d i s p e r s i o n .
4 . The p r o c e s s o f c l a i m
1
w h e r e i n
t h e p o l y t e t r a ? u o r o
e t h y l e n e
i s
an u n s i n t e r e d
p o l y t e t r a ? u o r o e t h y l e n e which
i s
o b t a i n e d by p o l y m e r i z a t i o n o f
t e t r a ? u o r o e t h y l e n e
i n a n
a q u e o u s d i s p e r s i o n a n d
p u l v e r i z i n g t h e
p o l y m e r i z a t i o n
p r o d u c t .
5 .
The p r o c e s s
o f
c l a i m 1 ,
w h e r e i n
t h e
p o l y t e t r a ? u o r o
e t h y l e n e i s
a
p o l y t e t r a ? u o r o e t h y l e n e o b t a i n e d b y p o l y m
e r i z a t i o n o f
t e t r a ? u o r o e t h y l e n e
i n
t h e
p r e s e n c e o f
a s m a l l
q u a n t i t y o f a
p e r ? u o r o o l e ? n .
10
15
20
25
3 0
35
i s a t l e a s t one m e m b e r
o f
t h e group
c o n s i s t i n g o f e t h y l e n e
g l y c o l ,
p r op a n e -
d i o l
- ( 1 . 2 ) , propane-diol-(l.3),
butane
d i o l
-
( 1 . 3 ) , b u t a n e - d i o l - ( 1 . 4 ) ,
p e n t a n e - d i o l ,
g l y c e r o l , d i
e t h y l e n e g l y c o l , t r i e t h y l e n e
g l y c o l ,
e t h a n o l a m i n e ,
p r o p a
n o l a m i n e , d i e t h a n o l a m i n e ,
e t h y l e n e d i a m i n e ,
a n d
p r o p y l
e n e d i a m i n e .
7 .
The
p r o c e s s
o f
c l a i m
1
w h e r e i n t h e s t i r r i n g i s
c a r
r i e d o u t
i n
t h e f u r t h e r p r e s e n c e
o f
a s o l v e n t which
i s
i n e r t
u n d e r
t h e r e a c t i o n c o n d i t i o n s .
8 .
The
p r o c e s s o f c l a i m 1
w h e r e i n t h e p r o p o r t i o n
b e
t w e e n
p o l y t e t r a ? u o r o e t h y l e n e
a n d
t h e d i s p e r s i n g a g e n t
i s
i n t h e
r a n g e
o f 1 : 2
and
1 : 6 .
R e f e r e n c e s C i t e d
UNITED
S T A T E S
PATENTS
3,265,679
8 /1 96 6 Black e t a 1 .
______ __ 260—92.1
FOREIGN
PATENTS
1 , 1 0 0 , 3 8 8
1 / 1 9 6 8 G r e a t B r i t a i n .
JOSEPH L . SCHOFER, P r i m a r y E x a m i n e r
JOHN . DONAHUE R . , A s s i s t a n t Examiner
US.
C l .
X.R.
2 6 0 - 8 7 5 ,
9 2 . 1
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