Engineering flow diagram of the production of polyamide from adipic acid with hexamethylenediamine

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ENGINEERING FLOW DIAGRAM OF THE PRODUCTION OF POLYAMIDE FROM

ADIPIC ACID WITH HEXA~lliTHYLENEDIAMINE

by J. C. KIM Oude Delft 89

Delft

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1. Introduction

In Oc t ob er ,1 938 , ann ounc emen t was made of a group

of new synthetic materials resembling silk and wool both in appe a r ance

and in chemical composition. This group, a member of the polyamide

family, was given the generic name Nylon.

Carothers has shown that the material with bifunc

-tional gr oup has the possibility to form a linear polymere In the

ca s e of the polyamides , the fun c tàon a l greup s are amino and carboxyl

groups , which may be distributed so that the molecule con t a i nin g

on e amine and one carboxyl gr oup, or that, of two molecules , one would con t a i n two amine groups and the other two car bo xy l groups.

In 1939, the Du Pont company set up a plant for

the manufacture of Nylon product. Nylon ~ first appeared on the

market as bristles on 11 Dr.West 's Ivliracle Tuft Toothbrushesll and

during the first year, 64 ,000 ,000 pairs of woman's nylon stockings

were sold .

In 1941, the Ny l on mo.lding powder appeared on

the world market . At moment Nylon is produced at several different

connt r i e s and sold under qwn trade name.

The following table shows the trade name and its

pr oduc er . AKULON Zyte l Rilsan Tynex Versamid Perlon-L Nylenka lPl a s kon" Ny lon: Grilon

Polycaprolactam polymer of Algemene Kunstzi jde

Unie in Holland

Aseri es of

nu

Pont Nylon mo.lding powders from

r eaction of diamines and dibasic acide s .

Polyamide-l ,l from l ,l-aminoundecanoic acide

made by Organico in Franc e

Filaments of

nu

Pont Nylon from dibasic acids

and diamines.(U .S JA . )

Aseries of polymers made by General Mills from

di mer i z e d linoleic acid and polyamid es.(U.S.A.)

German version of nylon -6 from e-capr ol ac t am

polycaprolactam polyamides of American Enka

Corporation.(U .S .A .)

Nylon-6 made by Barrett Division of Allied

Chemical and Dye

~ There are several types of polyamid es and their

proper t ie s ;prre dependy' on the( a t ar- t rng' raw materials , reac ti on

con dit ion and the modiification with other materials.

After 1939, although the pric e of the polyamid e

higher than most of other synthetic polYmers , the production of

th e polyamides in cr ea s e d remarkably , because of their superi ori ty

in the properties. In the Netherlands, the A.K .U .produced 430 t ons

of polyamide plastics and 2000 tons of polyamide synthetic fibers

in the year of 1954. Meanwhile the total import of the plas~ics

1

in this country was ~,8300 tons with !32.1 million guilders and

the total èxpo r t wasl 11800 tons with 32.1 million guilders in

the same year. In United State of America the total producti on

of the polyamide(textile , bristles, other fibre forms ,gears ,

other molded products, adhesives and coatings) was about 300 , 000 , 000

pounds in 1955.

2. Chemistry of Nylon-6 ,6

Raw materials

aJ Adipic acid

This was produced by the normal method of nitric

acid oxidation of cyclo-hexanol obtained by hydrogenation of phenol.

However, we can obtaine this compound in the following way fr om

petroleum.

Petroleum~yclohexane~cyclohexanol

~

adipic adid

Coke_{l' ht}oven_{'1--+ Benzene}

t:

>

_{Tetrahydrofuran}

'l

'\.

_{Nylon-6 ,6}

19 Ol

Furan

->

t

.t\dip.' " trile

I

Corn cobs

t

.

+

\

.

.

Oat hulls-- -Furfural Dlchlorobutane Hexamethylenedlamlne

Petroleum ~ne~But ad i en e

~

~

t

Dicyanobutene

Natural gas

~

Ethylene

Dichlorobutene

;:-Molasses

r

-

- -- -- - - - -- - -

-J

b) Hexamethylenediamine

We can obtainJ this compound from adipic

acid. ( see the above sbbeme)

Polyamide formation

The formation of the polyamide from adipic

acid with hexamethylenediamine is done in the following steps:

1) Nylon salt formation

Adipic acid and the hexamethylenediamine form

hexamethylenediammoniumadipate(usually in aqueous solution) ,

so called Nylon salt. This neutralization is~6xothermic

r-eaot i.onand the equivalent point is PH 7.63+0. 3 •

The control of the P of the formed nylon salt solution

is very impoDtant ,

~ecause

this dominates the properties

of the final polyamide.

2) Dehydration of the nylon salt

Nylon aa l t is dehydrated by heating to 2250C in a closed

vessel in the presence of nitrogen gas and forms half

polymer.

3) Formation of the final polyamide

The half polymer is heated to the melting point of the

final polyamide to proceed the polymerization by remov

-ing the water ~n °t h e system and the condensation water .

The removing of the water contro~the quality of the

final product, because ~he trace~of the water in the

system avoid the further progress of the polymerization

( by the reversible reaction) .

An inert atmosp here of nitrogen is usually

provided in order to avoid the oxidation and decomposi

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The polymerization reaction must b~ so arranged that

the t erminal groups cannot condense from each en d of the moleale

to form a cyclic substance thus »:

CO-NH"".

I

I;~~

~~

~~~~~~-.~o~~II~\C-~~)'1.-

C

~~~[l

-

~>

C

e.-

J·h.)~Á/H_

c..()/(CHo/,.

-t- I-J,.

0

Carothers had found that if a diamine and a dicar oxyli c

acid of formula

NH2

- (CH2

~-

NH2

and HOOC-(CH )m-COOH respectively were

induced to condense , then cyclization

woul~

not take place if n

were equa l to or gr e a t er than 4 and if m were not less than 3.

Th e radical length of the polymer is the swn of n

+

mand for

successful superpolymerization this length should not be l ess

than 8 and preferably

9

.

3. Properties of Nylon-6 ,6

The adipic and the hexamethylenedi

-amine was the given raw material in my case and the Nylon-6 ,6

is the polyamide from the above compounds which is produc ed by

Du Pont cê mp an y in U.S .A . The number 6,6 in the Nylon-6 ,6 means

this polyamide is produc e d by the condensation of the diamine

with 6 ca r b on atoms and the dibasic acid with 6 ca r bon atoms.

11 :16, 000- 32, 000 :265

°

c

:1. 14 10 ,500 1b/in2 7,600 go % 320 11 :400, 000 lb/in2 :Rl 1 8

:

>

4800F

-

5

: 5.5 10 2 :1. 7 BTU/hr/ft loF/in :0. 4 :4 . 0 :1. 5

.%

:s e l f extinguishing

:wea k acids,weak alkalis

strong alkalis,alcohols

esters ,aliphati c hydr ocar b on s

aromatic hydrocarbons

: strong acids

The Nylon-6 ,6 is attacked by

According to the literature , The Nylon

-6,6 has the following properties:

-,. Molecular weight Melting point Density Tehsile strength, at 73°F at 170°F Elongation at 730F at 1700F

Modulus of elasticity,at 73°F

Rockwell hardness

? Flow temperature

Coeffici ent of linear thermal

expansJ..on

.Th er ma l con duc t i v i t y

Specific heat

Dielectric constant, at 103cycles

Water absorption Flammability

The Nylon-6 ,6 can resist against

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-4.Use

As I described previously,the nylon-6 ,6 possess es some

excellent properties . The polyamide fr ome adi p i c acid with

hexamethylenediamine (so called Ny l on-6,6 ) applied as synthetic

fibre or molding powder. However , I prepared the polyamide which

is more suitable for the application other than the synthetic fibre .

This is done ~o k~~~ the molecular weight of the final product

a~ l ow as possible , that is to say to give a low intrinsic vi scosi ty

t o the final product, without losin g its excellent mechani cal

and ot h er properties ,b ec au s e the ny l on with very high mole cular

weight is very difficult to molde

I admi re the following articles as

the maior uses of my pr~. oduct •

a, ) Filament

Nylon filament ha s exce ptionally good r e s i s t ance t o

abrasion. This toughness is on e of the out s t an di n g characteristic s

which is illustrated int the leading applications in the form of

mon ofilament for bristles. These are not only used for personal

use as tooth-brushes and hair brushes, but also for industrial

brushes, because it is i~flamable and ha s good solvent resist~ncy .

The leading industrial uses of the Ny l on bristles are bottIe wash

-ing , textile printing, dry cleanin 6 and salvage di s po s a l.

b.) Coating

The nylon has excellent electrical charact eristics

and used for coating wires usedt in electrical equipment.

, ';

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'\1.\.,1'" C. Molding powder

C ,

~,t\ \,1'" The molded articles have the ua .Iu ebLe comb i n

a-t "

"'\ ,> "...,' ,: tion of properties , namely, high temperature resistance together

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<\ :(Wi th great toughness. The leading mol de d artieles are bobbines ,

\"", .-' ,'0-,", comb s, beakers,flexible spools and coil formers

J' L';' ':,.~ I have shown her e the consumption of the nylon

\ ~<' '~-". .r- molding powder by industry in Arnerica during last few years for

<, ' ; ' " '"" ~ referenc e.

'-.-- \ .'.\~.., ,....

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,

[ 'Lln . '· V \. ' 6 1950 1951 1952 1953 1954 1955 Au tomo t i ve 350 940 1,672 253 3,380 3,940 Electrical 90 220 350 550 750 730 Ge ~r~ü~a~ingsl , 050 1,800 3,380 4,95 0 6,3 00 6,6 00 an .mgs medical 430 400 700 970 1, 00 0 1,5 00 t extile 90 220 350 550 620 2,100 ot he r 90 220 350 550 750 730 total 2,100 3,800 6,800 10,100 12,800 15,6 00 ( all figures in ~ 1000 pounds )

5. Manufacturing process

I designed a ehgin e er i n g flow diagram for the production of the polyamide from adipic acid with

hexamethylenediamine with 90 tons of annua1 producti~~ capacity.

There are number of patents which are con cer n e d with the production of the polyamide from the abov e 2

men t i on e d comp ounds. However, I ha v e chos en the following method, )

there are no 1iquid (ex cep t water) in the system and we can pr oc e s s

the last po1Ymerizati on under the atmospheric pressure . Theref or e

we can simplify the qu i pmen t for the production.

Unfortunately I could not find any

publication on the factory scale manufacturing met h od of the p

oly-amide and I dont knoweven the production of the abov e product

is don e cont i n e ou s l y or not in practice . However , I hav e se en

some polyester resin makers in the Netherlands and the Bayer

fa ct ory in K~efeld in W. -Germany and all gf them are using

ba t ch proc es s . More ov er , it is very difficult to produce p

oly-amide con t i neous 1y because of the l ong polYmerization time(6 hours )

in the polYmer ization kett1e .

From these reasons, I have designed

semi c ontineous flow diagram with 100kg/6hours of producti on

ca pac i t y.

(V

l ) : In this tank the adipic acid water solution is ma de

discontineously .

Tank capa c i ty ;::::: 4500 li tre Material ba1ance: In: acid~66 .4 kg = 3 ,3 30 kg Adipic water out: . Adipic Water acid _{66 .5 kg}

J

3,330 kg Solution

7.

J -A .',(.. 1\ , ,. •• \"( ; '1- -Temperat~e operation time Room temperature 1 hour I

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In this tank the adipic acid water solution is neutralized by the gradual addition of the Hexamethylenediamine(in solid form) and obtaine so called Nylon salt( h

_21ameth

Ylenediammo-niumadipate). According to the literature , the equivalent point of the neutralization is P

7.63t

0.3. The tankV₂ has a cooling spiral(cooling with

wa~er),

because the neutraliza-tion evolves the heat.

Tank capacity same as the tank(V l) Material balance In Adipic acid 66.4 kg _{so u}1 t' ~on

Hexamet~~1~ftediamine3,3~~.~~g/hour

", Out :

Nylon salt wi th impuri ty .)120kg/hour

water 3,330kg/hour

Temperature : In 200C Out 200C

Amount of heat (removed) 16,000kcal/hQur Size of the cooling ppiraJ;: " ,,\..'.\ .l

t~~l àt~~~~f 56~6~1

" .'."\>.\"" I , I \.,

Number of coil 14 (Filter)

This is the horizontal plate filter(M~ker:SparklerCo.) Capacity 5,000 l/hour

Size: "

Hr~~~er~~"

Material balance In:

Nylon salt water solution with impurity 3450 kg/hour Out: Nylon salt water impurity anä loss 108kg/hour 3,320 kg/hour 22 kg /hour Solution

- - - -

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Storage tank :

I pla ced two storage tanks be twe en the filter and

the heat exc hanger,to proc e ed the further pr oc e s s contineously.

(Heat exchanger):

Th i s heat exc hange r

o

the ny l on salt solution fr orn 20 C t o

(180°C)

Size:

Pi pe 1eng;l:ïh=2 m

Pipe ài ame t er

==

t

"/

5/ 8"

Number of pipel -:::::12

Diameter of exc hanger -::0.2 In

Len gth of exc hanger ::2.2 m

incre a s es the temperature of

1500C by he a t ing with stearn

r: t-.. j ti \'/~/ / / Ma t er i a l ba l anc e : as the inc oming he a t ==445900/ 6 kcal/hoUT sa lt

==

108 kg/6 hour s } Solution

==

3,320 kg/ 6 hour s In: Nylon wa te r Out: Same

°

In-:::20 C o Out = 150 C of the intro duce d Quantity Temp erat ur e (Evaporater) :

In thi s evapo ra tor the di l u t

₂

wate r sol u t i on of the

nylon salt is concentrated to 60%, solution ( by heat i n g

(t.

t

1500C

with steam(1800C).

~

. .

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.

" " \ :.,: Size Pipe diamet er _ 1" Len gt h of pipe _ 1 rn Numb er of pipe

=

40 Diamet er of evaporator=0.3 m Lengt h of evaporator =1.2 rn

,

Material balance: / \' In: Nylon salt

-Out:water

=-Nylon salt

₌₌

water

-water -:::: Temperature: o In

=

150 C o Out :: 150 C 18 kgjhr} solution 554 kgjhr 18 kg/hrl solution 12 kg/hrJ ₀

542 kg/hr(removed as steam I,-Iv ...(çc.

C

to outdoor) Cc' r. lr. /.'-1 1f

M

q 1'\ I'\\'f;\ (Au t oc l a v e ):

The concentrated nylon salt solution(60Z) flows into

the autoclave contineously with the mass flow of 30 kgjhr at 1500C.

During this period(6 hours) , the autoglave was operated_to _~e ep

the temperature of the contents to 150 C. Meanwhile calculatedlJ

amount of hexamethylenediammoniumacetate and adipic acid are added

to the autoclave to control the molecular weight of the final

product. 2 3)

(j According to the li terature ' , we can control the

molecular weight of the final polymer by addition of the diamine

-- --

--monobasic acid salt, monoaminedibasic aslt; or monoaminemonobasic

acid salt. The required amount of the above salts to give a

certain viscosity to the final product, is calculateÈ with the

following relation, ' ,'1_

'I... • J

Moles of stabilizer _ Mol.Wt. of salt moles of salt

required ( 16 ,000) (

1

)

~" '...'

,

" ',' , t.; ,' where C . t · . . .t

ln

~~

r.n r-a.nsi c V1SCOS1- J!

=

C

viscosity of a dilute solution of the polymer divided by the viscosity of the solvent

in the same unit and at the same temperature .

Concentr~tion in grams of polymer/lOOcc solu.

The relation between the !)trinsic viscosity and

the mmlecular weight is ,

(''1

J = K Ma

where

K and a are constant determined, respectively by

10

Th e K and a value for t~J poly-e-cap~~amine

at 250C with sulfuric acid as the solv en t are

2

.9

x

10 and

0.78,respectively, .

When 30 kg of 60~nyl on salt solution was collected

in the autoclave (~~ring 6 hours ) , the po lymer i s a t i on was done in. 1\.(1.

the following way, 0

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f l""

whole ma

₂

B was he a t e d 2 hours at 225 C(the

maximum pressure 225 lbAin ) under N

2g a s atomosphere , then increase

the temperature to 264°C~nd ke ep at hhis temperature for 4 hours

under 1 atmos phere N

2g a s and removed watef(include t he condensation

water) . _ .

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Mat er i a~ balance

In:

Nylon salt ~108 kg/6 hourSJ 1 t'

water ,

=

72 kg/ 6 hours so u aon aui pi.c aci de 0.30 kg } th' -l- th t Hexamethy1e- lS ,~sd t e amoun' d" requlre 0 gl v e ne lammon lU-t t 0 4 k 18,000 of mol .wt . to mace a e

=

.

g , t he flnal product ( I: J\ v I I. ': ',.' ,, -,

.

..

<. Out: Ny l on Water

=

100 kg/ 6 hour s 80 kg/ 4 hours(include 8 kg condensa

-tion water} removed

as waste

j;.VI\V\'

(Cooling wheel):

In practice the wheel is external coolin g

aluminigm whee l . I h~y'~ c9~led the wheel ~rrternally

with 15 C water spray and the used water is sucked

away. The ny l on i s coole d on the wheel in the form

of 10 cm wide rib bon wi t h with 1 mm thick.

The wheel i s mov ing with 5 cm/sec of the speed to

/...- . .. 0 0

decrease the initia l temperature( 260 C) to 30 C

Size of the wheel:

•

11

(Crusher) :

The cool e d nylon ribbon is crushed into the nyl on flakes .

Li teratures \. l)~arothers: U.S .P .2 ,130 ,947(September,2 0 ,1938) ti U.S .P .2 ,130 ,948( 11 11 ti) Flory U.S .P .2,172 ,374 (Spt . ,12,1939) Car ot her s: U.S .P .2 ,130 ,523(Spt . ,20 ,1938 ) Peterson :U. S.P .2 ,174 ,527 ( Oct . ,3 ,1939 ) Carothers U.S .P .2 ,163 ,584(June,27 ,1939) Spanagel U.S .P.2,163 ,636(June ,27 ,1939 ) 2) Flory U.S .P.2,i72,374 (Spt . ,12 ,1939) 3)Peterson U.S .P .2 ,174 ,527 (Oct . ,3 , 1939)

4)F1ory J.Am .Chern.S oc . ,70 ,2709 (1948 )

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