1. business and industrial
2. chemicals industry
3. plastics and polymers

Polyamide Technology
For the economical production
of a high-quality polymer
Uhde Inventa-Fischer
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Polyamide 6
The most important polyamide
In today’s synthetic fiber industry polyamide 6 is a key polymer.
Besides being used for the production of textile filaments, technical
yarn – especially tire cord – and carpet yarn, polyamide 6 resins
are also used for the production of engineering plastics and monofilaments as well as film and extrusion applications.
Uhde Inventa-Fischer’s know-how in the poly­amide 6 field covers a wide
range of processes for all applications. Constant process optimizations, new
process developments and innovative polymer modifications have allowed us
to become the market leader in polyamide 6 technology, offering a range of
state-of-the-art technology.
Uhde Inventa-Fischer offers you two processes for the production of
polyamide 6, both with minimal waste and almost 100% polymerization
of the caprolactam feed.
Polyamide 6 production plant with a capacity of 150 t/d
as design and as built
Reference Plants
Customer
Location
Capacity
Special Features
Zig Sheng
Taiwan
65,000 t/year of PA 6 for textiles, film applications, industrial
yarn and engineering plastics
Textile, full-dull or semi-dull, High-Performance
Polyamide (HPPA®), Virgin Lactam Process (VLP®),
Over-Proportional Refeeding Process (OPRP®),
Re-Polymerization Process (RPP®)
Huafon Group
P.R. China
40,000 t/year of PA 6.6
for all applications
Plant includes continuous AH salt preparation,
batch size 2.5 t
Grodno Khimvolokno
Belarus
91,000 t/year of PA 6 for
technical yarn and carpet yarn
Overproportional Refeeding OPRP®,
2x 130 t/d
FCFC - Formosa Chemicals
& Fibre Corporation
Vietnam
47,000 t/year of PA 6
for textiles applications
Textile, full-dull or semi-dull,
High-Performance Polyamide (HPPA®),
Virgin Lactam Process (VLP®),
Kuibyshev Azot
Russia
54,000 t/year of PA 6
for textiles applications
PA 6 Melt Conditioning
with titanium dioxide (MCPA®)
DSM
P.R. China
52,500 t/year of PA 6
for film applications
Direct Refeeding Process (DRP®)
Xinhui Meida Nylon
P.R. China
81,000 t/year of PA 6
for textiles and other
applications
World’s largest single-stage VK 160 t/d,
Virgin Lactam Process (VLP®),
Over-Proportional Refeeding Process (OPRP®)
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Polyamide 6 Polymerization Processes
PA 6 technologies for your applications
Whether you require a plant for the production of textile or film-grade chips,
or one for engineering plastics, Uhde Inventa-Fischer can offer the perfect solution
based on proven proprietary technologies. We offer the following processes:
Two-stage process
Single-stage process
The two-stage polymerization process is very well-suited for all
applications, especially high-viscosity applications such as the
production of engineering plastics and film, as well as for overproportional refeeding and for re-polymerization plants. Two-stage
polymerization can be used with DRP® and MCPA® technology to
produce textile polymers on a single production line.
Uhde Inventa-Fischer’s single-stage process has been used successfully for several applications since it produces a highly homogeneous polymer with a low level of cyclic dimer. It is especially
suited for textile applications and has been optimized to produce a
high-performance textile polymer.
Uhde Inventa-Fischer’s two-stage polymerization process consists
of a pre-polymerizer and a VK tube. The pre-polymerizer and the
VK tube are designed for optimum heat transfer. This, together with
other design features, leads to a high conversion of the caprolactam. The pre-polymerizer works at pressure and the VK tube under
vacuum or atmospheric pressure.
Our single-stage process has proven to be very reliable, easy to
operate, and economical.
We can offer the single-stage polymerization process with up to
160 t/d in one line.
We even built the world’s largest single-stage polymerizer with a
nominal capacity of 160 t/d for a client in China.
The process can be used for a wide range of applications; it is reliable, very flexible and economical. The product is highly homogeneous.
We offer single-line polymerization plant capacities of up to 500 t/d.
Uhde Inventa-Fischer’s two-stage PA 6 process
Uhde Inventa-Fischer’s single-stage PA 6 process
LC
LC
DRY CHIPS
WD
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DRY CHIPS
WD
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High-Performance Polyamide 6
Especially for high-speed spinning
High-Performance Polyamide (HPPA®)
Advantages
Improved performance in spinning,
high-speed spinning and
down­stream processing
• increased take-up speed
• higher full-bobbin rate
Deeper dyeing
• higher amount of amino end groups
for better dye affinity
Increased melt stability
• reduced viscosity increase in
the spinning line
Minimized caprolactam regeneration
• less monomer smoke
Excellent heat-set stability
Superior resistance to heat,
UV light and weathering
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High-Quality Textiles In Different Lusters
Innovative solutions
Advantages
Melt conditioning
A unique feature of our polyamide technology is melt
conditioning with titanium dioxide (TiO2) after the
polymerization reaction. This technology is used to produce textile yarn (dulled) in single lines or when different dulling grades have to be produced in one line.
PA 6-dulling from a single polymerization line, with proven DRP®
process. No second line for treatment of extracts required.
Maximum flexibility in operation. Different dulling types and
bright material can be produced at the same time in the
same plant.
Optimal efficiency with respect to energy consumption,
raw material price and plant capacity.
Extremely suitable for use in the production of
high-performance polyamide.
The process is as follows: A side-stream of the melt
from the VK tube is fed into a specially designed
dynamic mixer, where it is mixed with the TiO2 powder.
This “internal masterbatch” is then re-fed into one or
several polymer streams. Both the melt-conditioned
polymer and the raw polymer are mixed by a static
mixer.
The homogeneity obtained is fully comparable to topof-the-market slurry technologies where the TiO2 is
added to the caprolactam upstream of the VK tube.
TiO2
big bag
M
N
Degassing
M
N
M
Dynamic mixer
G
Polymer pumps
Polymer pump
WCL
PA 6 polymer
full-dull
PA 6 polymer
semi-dull
PA 6 polymer
from VK tube
PA 6 polymer
bright
Polymer pump
Static mixer
Polymer filters
Uhde Inventa-Fischer’s Melt Conditioning Process
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Refeeding Technologies For Polyamide 6
Improved raw material yield
Direct recycling in the continuous polymerization process
In the production of polyamide 6 the
feedstock caprolactam accounts for
approximately 80% of all costs. It is therefore essential that all of the feedstock is
converted. Caprolactam and its oligomers,
which are removed from the polyamide 6
raw polymer by hot water extraction, need
to be recycled in an economical and ecological process.
In the past, the standard process for recycling the ex­tractables was mainly distillation
and depolymerization. This process has
obvious disadvantages regarding raw material conversion, energy consumption and
environmental issues.
Uhde Inventa-Fischer applies modern
technologies for direct extract recycling
in the polymerization process, such as
the Direct Refeeding Process DRP®, the
Overproportional Refeeding Process OPRP®
and the Repolymerization Process RPP®.
VLP® - In the Virgin Lactam
Process 100% virgin capro­
lactam is fed into the polymer­
ization process to ensure the
product meets highest quality
demands in textile applications.
virgin caprolactam
polymerization
extract concentrate
extraction
drying
DRP® - In the Direct Refeeding
Process the concentrated
extract from a polymerization
line is mixed with virgin caprolactam and re-fed directly back
to the same polymerization line.
It is especially suited for singleline production.
final product
evaporation of extract water
condensate (wash water)
additional virgin caprolactam
polymerization line 1
extraction line 1
drying line 1
final product 1
extraction line 2
drying line 2
final product 2
extraction line n
drying line n
final product n
virgin caprolactam
polymerization line 2
OPRP® - Overproportional
Refeeding is achieved when
the extracts from two or more
production lines are directly refed into a single polymerization
line (up to 75% of the total
caprolactam consumption). It is
especially suited for multi-line
plants.
virgin caprolactam
polymerization line n
evaporation of extract water
extract concentrate
RPP® - Repolymerization is
performed by polymerizing
the concentrated extractables
from several production lines in
one recovery line while adding
a minimal amount of capro­
lactam.
condensate (wash water)
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Polyamide 6.6
A flexible batch process
AH salt
Uhde Inventa-Fischer's high-performance autoclave
batch process is the ideal solution for your polyamide 6.6 production needs.
M
M
M
Highlights of the batch operation are:
Quick product change
Batch sizes up to 2,500 kg
Batch time of 3 hours, i.e. 8 batches per day
Streamlined pre-concentration of AH salt
Optimized design, minimal residues and
contamination
Custom-made heating elements and agitators
for superior product homogeneity
Melt modifying
Continuous solid-state polymerization (SSP) for
higher viscosities available
PA 6.6
PA 6.6 polymerization process with a capacity of 60 t/d
Our polyamide 6.6 autoclave is available in
smaller sizes, e.g. 1,000 kg or 1,500 kg. The
autoclave is also the perfect choice for the production of other polyamides, such as PA 11,
PA 12, PA 6.10 or PA 6.12, as well as for the
production of co-polyamides.
AH salt preparation
- Continous operation
AH salt - precondensation
- Natural circulation process
Polymerization
- Autoclave process
(1 tonne/batch)
- Autoclave process
(2.5 tonnes/batch)
Chips production
- Underwater strand granulator
Conditioning
- Drying only
- Drying with SSPC
Specialities
- Dry blending for film
& engineering plastics
- Cont. additive blending
for technical yarn
Recovery
- Process water recirculation
- Nitrogen washing and re-use
High-performance heat exchanger of a polyamide 6.6 autoclave
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Uhde Inventa-Fischer GmbH
Holzhauser Strasse 157–159 · 13509 Berlin · Germany
Phone +49 30 43 567 5 · Fax +49 30 43 567 699
www.uhde-inventa-fischer.com · [email protected]
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Uhde Inventa-Fischer AG
Via Innovativa 31 · 7013 Domat/Ems · Switzerland
Phone +41 81 632 63 11 · Fax +41 81 632 74 03
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