The document discusses differences in approaches to highly filled plastic applications between India and China, focusing on PVC pipes. India uses high calcium carbonate (CaCo3) fillers without impact modifiers or flow promoters, leading to breakage issues. China uses locally developed chlorinated polyethylene (CPE) and acrylic (ACR) additives to boost CaCo3 levels up to 200phr while maintaining performance. The document analyzes how additive selection impacts properties and processing of highly filled PVC pipes.

1. Plastic Applications with high CaCo3 loadings.
Worldwide Trends and Differences in Approach in India and
China.
In my previous article, I had described the many applications of CaCo3 in Plastics. In this
article I would like to explore those applications where the filler forms a substantial part
of the product. While addressing the minerals community through this esteemed
publication, I thought that out of the myriad plastics applications, it is the highly filled
ones that would attract maximum attention. Though this report was written 8 years ago, it
is still relevant.
There have been differences in approach to the style of plastic processing and
formulating in different regions of the world. There are some marked differences in the
way Plastic technology has evolved. We will have a closer look at a specific application
area, highly filled PVC pipes worldwide and the differences in approach in India and
China.
Let me elaborate on the differences in styles in PVC Pipe processing that I have observed
in various parts of the world. These are my personal impressions and are very broad
generalizations. There has been considerable convergence especially in the last two
decades of globalization, but the broad trends are still discernible.
Technology
Style
Approach Examples in PVC Pipe
technology
Countries following
German State of the art,
high precision,
Automation,
high cost,
Rugged and
robust
machinery.
Pioneered Twin screw
extrusion, Automation,
precision in extrusion, long
life machinery. Switching
from Lead Stabilisation to
Lead free systems. Grey is
the preferred colour. Wide
differences in Filler loading
styles country to country.
European countries,
U.K., Australia,
South Africa, India,
Gulf Countries.
American Strong in
manufacturing,
lags Germany
in Technology,
but catches up
when newer
innovations are
accepted.
Persisted with Single screw
extruders well into the 80s
while the world had
embraced Twin screws. Tin
Stabilised white pipe is the
norm. Conservative with
filler loading.
Most countries in
North and South
America.
Japanese Precision
instrumentation
and control
systems
Embraced Twin Screw
Technology early. Parallel
screw systems with excellent
controls competed with
Japan, Taiwan
South Korea.

2. compensate for
technological
gap with
German
technology.
Strong in
Automation.
German conical screw
technology. Comparable
Capital Costs and machinery
life. Lead based
stabilization, but shifting to
non lead. Grey preferred
colour. Conservative with
filler loading.
Chinese Low Cost
Manufacturing.
Machinery
derived from
German and
Japanese
technology, but
of lower cost
and shorter life.
Conical Twin screw
extrusion seems to be the
norm, though parallel screws
also used. Lead based
systems. Very high filler
loading in non pressure
pipes. White is the preferred
colour. Most aggressive in
filler loadings.
China, Vietnam,
Thailand, Malaysia,
Sri Lanka
Note on Pipe colours: The difference in the preferred pipe colour for PVC pipes in
different regions of the world has always intrigued me. PVC Pipes are mainly installed
underground, and apart from DWV (Drain Waste Vent) applications, are rarely used
exposed. Even in DWV lines in constructions the pipes are often painted over. So why is
the colour of pipe important when it gets hidden anyway?
I can provide some insight to the Indian scene where I was involved in PVC Pipe
development in the nascent stages. PVC pipes were made in white colour like the
American system, or black, like in PVC Conduits for electrical installation. Wavin India,
the pioneer stuck to the German grey. The white pipes needed 3-4 PHR TiO2, which was
quite an expensive pigment those days. Carbon Black was much cheaper, and all HDPE
pipes were black. However, there was a serious problem with black pipes in India. They
were deforming during storage in the Indian summer. Our investigations showed that the
Sun Radiation Temperature was the cause. This is the temperature that a black body
attains under direct exposure to sunlight. At the height of summer in many parts of India,
when ambient temperature was hitting the 45o
C mark (115 o
F, phew), the sun radiation
temperature could soar to 79-80 o
C. This is higher than the Vicat Softening point of
UPVC which is 72o
C. The black pipes were deforming under their own weight in the sun
or even in closed metal containers like railway wagons. Injection moulded fittings which
have lower Vicats were very badly affected.
It was noticed that under similar conditions, white pipes were unaffected. The sun
radiation temperatures were a good 10-12o
C lower than black pipes and, thus, below the
softening point. However the industry was reluctant to adopt white as the pigment cost
was high. A compromise was reached with about 1 PHR TiO2 and a pinch of Carbon
black to give a light Grey colour. The colour lowered the sun radiation temperatures to a
manageable level and was not too expensive pigment cost wise. It was necessary for the

3. industry to standardize the colour as it would allow long runs during production without
the need to change colours frequently,
The light grey colour standardized in India had a remarkable and positive side effect.
HDPE pipe was the main competition, and it had to be coloured black as Carbon Black is
the preferred UV Protection agent in Polyolefins. Unscrupulous manufacturers started
adding recycle and scrap which went undetected by the customer because of the black
colour. On the other hand, the light grey of PVC did not allow excessive scrap addition to
go undetected.
HDPE Pipe quality plummeted; there were large scale failures in the field and the HDPE
Pipe market imploded. PVC Pipes took off in this phase and has left HDPE Pipes far
behind ever since. All because of Colour??? Food for thought.
I am disappointed at the Indian PVC Pipe industries choice of colour for SWR pipes. In
Europe and most parts of the world, a reddish brown colour is prevalent (in line with red
mud, a by product of bauxite processing?). In India a very dark grey was chosen. Perhaps
it was felt that that the Red- Brown pigments were unaffordable. Unfortunately the Dark
grey has opened the door to extensive scrap addition.
China, for some reason, has stuck to white pipes. Their colour is not as white as the
American pipes, perhaps because TiO2 levels are lower. Perhaps in China, the drive to
use more and more fillers has something to do with enhancing the white colour.
I would invite insights from readers on this subject.
The major highly filled applications in Thermoplastics are in the following fields.
Application Area Product Typical Filler
Loading
HDPE and PP Raffia
Tape, Blow Mouldings,
HMHDPE Shopping
bags
Filler Masterbatch Upto 70% CaCo3.
PVC Wires and Cables
Insulation
Inner Sheating
Outer Seathing,
PHR
10
50
100
%
6%
25%
35%
PVC Leathercloth
Top coat
Base Coat
PHR
10
150
%
5%
45%
Extruded Floor Tiles
Soft
Hard
PHR
300
400
%
65%
70%

4. PVC Pipes
Pressure
DWV
Highly Filled-1
Highly filled 2
PHR
8
40
100
200
%
7%
27%
48%
65%
In my estimate, these applications alone account for 80-85% of CaCo3 usage in plastics.
Considering that PVC Pipes along with Wires and Cables, Calendering is 85% of the 2
MTA PVC market in India, CaCo3 in PVC is a significant market, and of considerable
interest to the Minerals community.
The development of filler masterbatches as a tool to spread out the compounding costs
over a larger quantity of Polyolefins has been described in my previous publication, and
the trends are similar worldwide. Automotive, White goods and custom mouldings use
filled compounds, while the more competitive moulded furniture market exclusively use
filler masterbatches. There is not much difference in the pattern of CaCO3 usage in Wire
and Cables, Leathercloth, Calendered films and sheets worldwide. Individual processors
2010-11
73%
7%
6%
5%
2%
3%
4%
Pipes& Fitting
Calendering
Films & Sheets
Wires & Cables
Footw ear
Profiles
Others

5. have their preference for PCC or GCC and the micron sizes as per their equipment and
processes.
Extruded floor tiles seem to be exclusively on GCC and cost considerations have forced
use of coarser particle sizes (10-20 microns). Extruded Floor tiles are very well
developed in China and the Far East, while Calendered floorings are well entrenched in
the West, US and India. Cushion Vinyl floorings has seen amazing effects being offered
and is a major Paste grade PVC resin outlet.
It is in the area of PVC pipes that there has been a divergence of approach, I will examine
the path followed in India and China.
PVC Piping systems can be broadly classified under two groups:
Pressure Pipes:
They are designed to convey many different fluids under pressure. Ratings are according
to the pressures to be withstood and range from 2.5 bar right up to 16 and even 20 bar.
The wall thickness progressively increases as the pressure ratings increase.
The stringent specifications restrict CaCo3 levels to 8-10 PHR. Good quality, fine
particle size GCC and PCC actually improve impact strength and processability at these
levels. Top of the line GCCs like the offerings from Omya, or the Ultrafine PCCs offered
by firms like Solvay actually improve the impact strength at even higher levels (15-20%),
but Burst pressures could be affected adversely over 10 PHR.
As Pressure pipes are a critical application, mature producers worldwide self control the
Filler levels to 8-10 PHR. Some specifications like the Indian BIS 4985 for pressure
pipes specify a Sulphated ash content limits which would not permit higher dosages of
mineral fillers.
Worldwide, PVC pressure pipes form approximately 30% of the total PVC Pipe market.
In India it is a bit different. There is a huge irrigation sector using many thousands of
kilometers of PVC pipes annually. These are normally the lower pressure rating pipes
like 2.5 bar and 4 bar and some 6 bar rated pipes. This skews the pressure pipe market
share right up to about 70% in the Indian Market.
In India, it is in the Agri Pipe area that competitive pressures have pushed up Filler
loadings to what I consider as unhealthy levels. We will examine the ramifacations
closely a bit later.
Non Pressure Pipes:
The bulk of PVC pipes are used in construction related applications like DWV (Drain,
Waste and Vent), SWR (Sewage, Waste, Rainwater) conduits and Tube Well casings,
Rain water harvesting systems etc. Usually these represent nearly 70% of the PVC pipe
market and are a major contributor to Filler tonnage consumed in pipes.
These pipes competed with Asbestos Cement pipes and have rapidly replaced them,
especially after the awareness of Asbestos’s link with cancer grew worldwide. PVC pipes
offered a much lighter and safer systems, which were easy to install.

6. PVC Pipes need to be protected against UV degradation as many of them are exposed to
sunlight unlike pressure pipes which are normally buried or concealed. However, because
of competitive pressures an unhealthy trend of doing away with expensive UV stabilizers
seems to have permeated the Indian SWR Industry. I am not sure whether this is the case
in other countries also.
In many buildings the exposed PVC pipes are painted to match the Building exterior. The
paint layer offers some protection from UV attack.
The success of PVC pipes in the SWR and related DWV sectors owes a lot to
development of a wide range of Injection Moulded Fittings. These fittings either have
Rubber ring in groove jointing systems or are threaded (Casing Pipes and Plumbing)
The main effects on PVC Pipe Properties as CaCO3 loadings increase can be summarized
thus:
Property 0- 8 PHR 10-50 PHR 50-100 PHR
Density Gms/cc 1.38-1.44 1.45-1.66 1.66-1.84
Formulation Cost, Rs/Kg `50.08 to `47.19 `46.53 to `37.39 `37.39 to `30.67
Volume Cost Rs/Kg
`69.99 to `68.33 `67.94 to `62.05 `62.05 to `56.21
Impact Strength, Falling
Dart.
Breakage in
Transportation/Installation
Unaffected
Tensile Modulus. Unaffected
Burst Pressure (Hoop
Stress_
Unaffected
Rigidity (Flexural
Modulus)
Unaffected
Processing Ease Unaffected
It is self evident that it is unwise to use more that 10 PHR Filler for pressure pipes. In non
pressure pipes a balance has to be made between the reduction in cost with the
deterioration in Impact properties which directly translates to losses due to pipe breakage
during transportation and installation.
It is evident that to improve the performance of highly filled PVC pipes. The impact
properties need to be modified. It is in this area that the practices followed in India are
widely different from China.
There are two important additives which enhance Unplasticised PVC (UPVC) processing
and performance. These need to be studied in some detail.

7. 1. Impact Modifiers: These introduce a rubbery element in the brittle filled PVC
matrix. They act as shock absorbers and improve the impact strength of PVC,
sometimes dramatically.
a. Acrylic, MBS and ABS types
b. Chlorinated Polyethylene (CPE)
2. Flow Promoters: They smoothen the flow of the UPVC melt allowing it to
encapsulate and homogenize the filler particles. The extrusion of the filled PVC
melt improves and the Pipe surface finish is enhanced.
a. Predominantly Acrylic (ACR)
In India, Such Impact Modifiers and Flow Promoters are extensively used in Critical
PVC applications like Pharmaceutical Blister Film. Blown Bottles, Industrial Sheeting,
and in Pipes in the niche market of Column Pipes.
Impact modifiers like the ones developed by Rohm & Haas (KM 323B) and Flow
Promoters like K-120ND & K-175 are very well known and are manufactured locally.
Products from Kane Ace are also popular. However these are very costly additives and
their use is restricted to Critical applications.
The Indian PVC pipe industry has tended to steer clear of these additives because costs
will increase. In fact many producers take pride that they are able to produce saleable
pipe without the use of these expensive additives. It should be noted that smaller
producers who employ single screw extruders for PVC are forced to use at least the Flow
Promoter to make acceptable pipes. They were forced to use single screw extruders as
they could not afford the costlier twin screw technology. Hence they compromise with a
costlier formulation.
Column Pipes which have to support heavy submersible pumps in deep tubewells, is
about the only application where Impact modification is resorted to, that too with nominal
filler levels < 10PHR. The starting torque of the submersible pumps has to be resisted by
a tough pipe, especially as they are attached by threading, which anyway weakens the
joint as PVC is inherently notch sensitive.
Thus highly filled PVC pipes are processed in India without any Impact modifiers and
flow promoters. Even Agri pipe mentioned earlier which is a pressure application, albeit
relatively low pressures, have seen high filler loadings. However it becomes increasingly
difficult to make acceptable pipe at filler loadings higher than 40PHR, which seems to be
the norm in non branded SWR Pipes.
The dangers of such “mindless filler loadings” have been explained in my article
‘Volume cost in plastics applications’ published in July 2011.
In China, the approach has been quite different and has spawned its own industrial sector.
PVC processors in China realized the problems of using expensive Impact Modifiers and
flow promoters which were the norm in Western and Japanese Industries. They started
investigating CPE and results were good. At 3-4 PHR CPE levels, Filler loadings could
be boosted substantially and still yield a workable Pipe.

8. The CPE grades available from Du Pont and Dow were found to be too expensive, and
CPE from local technology gradually found good acceptance with the Pipe
Manufacturers in China. Concurrently, flow modifiers were developed to replace the
more expensive Western counterparts. The locally developed Acrylic Flow modifiers
were generically known as ACR. It was quite effective at 1-1.5 PHR Level.
The Chinese PVC Pipe industry has progressively increased the Filler levels from 40PHR
to 75 PHR using 3-4 PHR of CPE and 1-1.5PHR of ACR. The results were acceptable to
the non pressure pipe consumers, and filler levels were boosted to 100PHR, and there are
reports of even 200PHR being used. What is lesser known is that it is CPE and ACR
which are making such staggeringly high Filler Loadings possible. A lot of research has
gone into this activity and I am not privy to all the techniques used, but use of Impact
modifiers and Flow promoters seem to be the cornerstone of the success.
The Chinese PVC Pipe industry is huge. Add to this the Profile and Ceiling Tile markets,
the CPE and ACR consumption must be impressive. So much so that I have noticed on
the websites of many PVC Resin Manufacturers that they produce CPE and sometimes
ACR also. Chlorinated PVC needs Chlorine which is a major raw material in PVC Plants,
so it makes sense for such Plants to put up an auxiliary Polyethylene Chlorination plant to
support their PVC sales.
Non Pressure PVC pipes are not only solid wall, Corrugated, 2 layer Corrugated, Foam
Core PVC pipes and other variants have been developed where the pipe is lighter than the
equivalent Solid Walled Pipes. The key feature in the design of such lightweight pipes is
resistance to crushing from external loads rather than any internal pressure resistance.
Filler levels are not very high in such applications.
I would like to wind up this article comparing production philosophies in China and India
by discussing something which has a different connect with Minerals. The way PVC
Resin is made seems to be different.
Suspension Grade PVC resin can be manufactured from the petrochemicals and also a
non petrochemical route.
Ethylene obtained by cracking of petroleum fractions like Naphtha, Heavy ends and light
ends like c4 gases is the key input. The process is:
C2H2+Cl2 EDC (Ethylene Dichloride) VC(Vinyl Chloride) PVC
Chlorination De Hydro Chlorination Polymerisation
PVC made by this route is termed ePVC (Ethylene or Petrobased PVC).
PVC is a major Plastic which can be and is manufactured from non petrochemical
sources. Key inputs are two minerals, Coal and Limestone and cheap electricity. The
Carbon in Coal is reacted with the Calcium Carbonate in Limestone in an Electric
Furnace. The Calcium Carbide then formed is treated with water to release Acetylene,
which is then converted to Vinyl Chloride by combining with HCl and polymerized to
PVC:
PVC made by this route is termed as Carbide based PVC.
The availability of cheap electricity and abundant Coal and Limestone is crucial to the
economic viability of Carbide based PVC. It seems China has these inputs in abundance.

9. I understand about 80% of the PVC capacity in China is Carbide based. This translates to
about 9 Million Metric Tonnes/Annum of the 11 MTA of China’s installed PVC
Capacity. Thus huge quantities of Coal and limestone are consumed.
There are many such producers which are located close to major Chlor Alkali projects
and also near Coal, Limestone and Hydel power units in the interior of China. Many such
units have their captive Coal fed power units if Hydel power is not conveniently
available. The electricity generated is used for the Carbide Furnaces as well as the Chlor
Alkali plants which produce Caustic Soda and the Hydrochloric Acid gas needed for
converting Acetylene to Vinyl Chloride.
In India, out of the six PVC plants in operation, only one is based on the Carbide Process.
Here also there is a major difference. The Chinese Carbide based PVC is considered
inferior in quality to ePVC and fetches lower prices. ePVC is found suitable for all PVC
applications including stringent applications like clear film, medical tubing and highly
plasticized applications. The Chinese Carbide route PVC apparently is deficient for such
applications. Fortunately Carbide based PVC is OK for opaque low plasticiser
applications PVC Pipes and Profiles which anyway is 70-80% of the PVC market.
In India, the scene is quite different. The Carbide based plant produces a quality of PVC
resin universally accepted in India as the best quality PVC and in many cases fetches a
premium. This I know first hand because I started my career in PVC in this very plant.
I am puzzled by this contradiction. My guess is that the Indian plant uses superior
technology in purifying the Vinyl Chloride and world-class polymerization technology to
convert it to PVC (They had started off 1n 1965 with Japanese collaboration and
continued with their in-house technology when the collaboration expired several decades
ago.
Perhaps the Chinese Carbide PVC plants could follow the technologies implemented by
the Indian unit to upgrade their quality. Even with their huge PVC capacity, China is a
net importer of ePVC for critical applications. With the slowing down of Construction
and Infrastructure projects in China which were huge consumers of PVC products, there
is a currently a severe PVC overcapacity in China. If they are able to upgrade the Carbide
based PVC quality, not only can ePVC imports stop, but also they would be able to
export to wider PVC markets overseas to tide over the hopeful;;y temporary overcapacity
situation.
I do not see any reason why this can be done. If an Indian plant can produce PVC from
Carbide which is superior to ePVC, the Chinese PVC plants should be able to do the
same if they employ similar technologies.
Siddhartha Roy
Mr. Siddhartha Roy is a Chemical Engineer from IIT Kharagpur (1968). He has worked with plastics all
throughout his career. He was actively involved in development of PVC markets and applications,
especially Pipes and Fittings. He worked with Shriram Vinyls, PRC (now DCW) and Chemplast,
manufacturers of PVC Resin & Compounds. He has managed a PVC Pipes & Fittings factory in Kuwait
and helped Jain Pipes (now Jain Irrigation) set up their Pipe production facilities.
He headed R&D at VIP Industries, Nasik, and is well versed in the processing of Polyolefins, Styrenics,
Polyamides and PC.
He has been active in IPI activities and has delivered several Endowment lectures. He was recently
awarded the Fellowship by the Governing council of IPI for his contribution to the Plastic Industry.
He is currently a consultant and can be contacted at royplastech@rediffmail.com (Mobile +919890366632)