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It is a translation based on the content of corporate PR magazine“Sanyo Chemical News” issued in Autumn 2018.

erformance

Successful Performance Chemicals of Sanyo Chemical Group
hemicals134

Research & Application
No. 2 Division
Unit Chief, Functional
Resin Research Section

Low-molecular-weight Yosuke
Polyolefins
NakataPolyolefin is the collective term
for simple olefin based polymers,
including polyethylene andpolypropylene, which are used infilms, containers, etc., that are
essential in daily life. Polyolefinsthat are used as plastic in generalinclude those with high molecularweights ranging from tens of
thousands to hundreds ofthousands. Meanwhile,
low-molecular-weight polyolefins,with molecular weights less thantens of thousands, are types ofwax, and show physical andchemical properties that are
different from those ofhigh-molecular-weight polymers.
This article introduces featuresand examples of the applicationof our low-molecular-weight
polyethylene ‘SANWAX’ Series
and the low-molecular-weight
polypropylene ‘VISCOL’ Series.

What is a wax?
While hair wax and car wax are
the most familiar waxes to us,
wax is a collective term for
wax-like substances, and there
are various different types. Its
definition is “a substance [1] thatis solid or semisolid at ordinary
temperature with melting pointat 40°C or higher, and [2] whichmelts without decomposing andhas low viscosity when heated.”
The origin of the word wax is
said to be “weax,” which is
Anglo-Saxon for beeswax, andits history goes back to 4000 B.C.
Natural types of matter that had
similar properties to beeswax
were later found one after
another, and paraffin wax andmicrocrystalline wax, whichwere purified from crude oil, andwaxes synthesized from ethylene
and propylene (synthetic waxes)
came to be manufactured anddistributed in the 20th century1).
Waxes are made from various
raw materials, and can beroughly classified into natural
waxes, semisynthetic waxes, andsynthetic waxes (Table 1).
Natural waxes include beeswax
and carnauba wax, which arederived from biological sources,
and montan wax, paraffin wax
and microcrystalline wax, which
are derived from fossils (brown
coal, crude oil). Since they arederived from natural sources,
they have a wide range ofcompositional distributions,
including molecular weight
distribution, and require
purification. Semisynthetic
waxes are produced throughsynthesis while using natural
substances as the raw materials.
For example, amide wax ismanufactured by a condensation
reaction between fatty acid andamine. Synthetic waxes include
polyethylene and polypropylene
waxes, and they are
manufactured by synthesis ofpetroleum raw materials(ethylene, propylene, and othermonomers) or decomposition of
Table 1

Classification of waxes
Natural wax

Derived from
biological sources
Animals

Beeswax

polymers to reduce theirmolecular weight.
Applications of waxes arediverse, and they are used as
raw materials or additives tomany industrial products anddaily commodities such as
cosmetic products, printing inks,
chemical paper, tires, flooring,
and adhesives.
Synthetic waxes, in particular,
possess physical properties thatare easy to control, such as melt
viscosity, since it is relatively
easy to control their composition,even though they have similar
properties to natural waxes.
Since they can meet diverse
needs, they are used quite often
as industrial raw materials forpaints, inks, adhesives, etc., forwhich application is actively
developed.
Synthetic waxes can be classified
into polymerization types andthermal decomposition types
based on the manufacturingmethod. Polymerization types
include single polymerization
product of ethylene monomer andmodified low-molecular-weight
polyethylene prepared bycopolymerization of ethylene
and other polar monomers.
Thermal decomposition types
are the low-molecular-weight

PlantsSemisynthetic
wax

Synthetic wax

Amide wax

Low-molecular-weight
polyethylene
Low-molecular-weight
polypropylene

Derived from fossils
Brown
coal

Carnauba Montan
wax
wax

Crude oilParaffin wax,
microcrystalline
wax

Sanyo Chemical News 2018 Autumn No. 510

1

Polymerization type (mainly ethylene types)

experienced at the time2).
The ‘SANWAX’ and ‘VISCOL’
Series are thermal decomposition
types, and have characteristicsof [1] high softening points andhigh crystallinity compared tonatural waxes, [2] excellent
compatibility with polyolefin
resins, [3] a wide range ofmolecular weight distribution
due to being thermal
decomposition types, and [4]relatively high compatibility
with non-polyolefin resins (Fig.
2, Table 4). Furthermore, theindustrial processes of thermal
decomposition are suited tosmall-quantity production
compared to the industrial
processes of the polymerization
types, and can be minutely
adjusted to meet various
different needs.

Synthetic wax
Low-density polyethylene

Ethylene

Polymerization
High-density polyethylene
Oxidized polyethylene
Modification

Polyethylene copolymer(acid monomer, unique monomer)

Thermal decomposition type
Polyethylene

Thermaldecomposition

Low-density polyethylene thermal
decomposition product

Polypropylene

Thermaldecomposition

Polypropylene thermal
decomposition productFig. 1 Classification of synthetic waxes by method of manufacture

products of the decomposition ofhigh-molecular-weight
polyethylene resin or
polypropylene resin with radicals(Fig. 1).

Japan, and the low-molecularweight polypropylene ‘VISCOL’
Series, which was developed byapplying our technology (Tables
2 and 3)1). Both series havelong-running products that are ahalf a century old since
manufacture and release andthat are still being utilized fortheir features. Please see thereference for the history ofdevelopment and stories of thehardships the developers‘SANWAX’ and ‘VISCOL’
SeriesOur company manufactures anddistributes the low-molecularweight polyethylene ‘SANWAX’
Series, which was the firstindustrialized synthetic wax inTable 2 Typical properties of low-molecular-weight
polyethylene ‘SANWAX’ Series
SANWAX
131-P

SANWAX
151-P

Table 3

Product name

SANWAX
161-P

SANWAX
171-P

Appearance

White powder White powder White powder White powder

Application examples of‘SANWAX’ and ‘VISCOL’
Series
1. Pigment dispersing agent forplastic
While there is an extremely

Typical properties of low-molecular-weight
polypropylene ‘VISCOL’ Series

Product nameAppearance

VISCOL
330-P

VISCOL
550-P

VISCOL
660-P

White powder White powder White powder White powder

Color number

30

30

30

30

Color number

200

200

200

1 (Gardner)

Softening point (°C)

111

108

107

107

Softening point (°C)

153

153

152

145

Penetration

2

3.5

4

4.5

Penetration

1 or lower

1 or lower

1 or lower

1.5

180

Melt viscosity(mPa·s)

4,000

1,800

200

70

9,500

Weight averagemolecular weight

40,00030,00015,0008,000Melt viscosity(mPa·s)

4,200

Weight averagemolecular weight

1,000

30,000290

20,00012,500Color number: Hazen method, melting point: DSC method,
melt viscosity: measured with a BL type viscometer at 160°C
Molecular weight: High-temperature GPC method

Color number: Hazen method, melting point: DSC method,
melt viscosity: measured with a BL type viscometer at 140°C
Molecular weight: High-temperature GPC method

Table 4Polyethylene

Carnauba wax
Montan wax

Paraffin wax

40

50

60

70

80

90

Polypropylene

100

110

120

Softening point

Fig. 2

Characteristics of synthetic waxes

130

140

150

160

Structural characteristics of polymerization type
and thermal decomposition type synthetic waxes

Manufacture
methodSynthetic wax (polymerization type,thermal decomposition type)

Microcrystalline wax

2

VISCOL
440-P

170
(°C)

ThermalPolymerization Polymerization
decomposition
type
type
type (method(high pressure) (low pressure)by our company)

Molecular
weightdistribution(Mw/Mn)Wide(3 to 5)

Narrow(around 2)

Narrow(around 2)

Threedimensional
structure

Long-chain
branchingcontained

Short-chain
branchingcontained(normalmethyl group)Long-chain
branchingcontained

Sanyo Chemical News 2018 Autumn No. 510

It is a translation based on the content of corporate PR magazine“Sanyo Chemical News” issued in Autumn 2018.

Photo 1

Colorfully colored plastic

600

Shear viscosity (Pa·s)

large number of colorful plastic
products that we see on a daily
basis, the number of resin types
that are used as the raw materials
is actually small, and theymainly consist of polyethylene,
polypropylene, ABS, etc.
When coloring plastic withpigments, etc., the dispersion of
the pigment has a large effect on
the quality of the molded
product. However, simply
putting pigments and resin
together does not mix them well,
but tends to generate unevencoloring3). Thus, the general
method is to first prepare amaster batch in which thepigments are dispersed at a highconcentration, and add this to
the resin as the coloring agent tomechanically knead by heating
and melting (melting andkneading).
Use of the ‘SANWAX’ and‘VISCOL’ Series can [1] preparea high-concentration masterbatch with excellent pigment
dispersion, as they have lower
melt viscosity than the resins tobe kneaded with and relatively
high compatibility with pigments
and resins. They also [2] havelittle effect on the mechanicalproperties of the resin as they
have adequate molecularweights, and [3] excel incompatibility with the resin tobe kneaded with. [4] Being
nonpolar, they do not inhibit thecolor development of pigments
and show stability in coloring.
Thanks to such features, they
are well-suited as pigment
dispersing agents for plastic.

Fluidity improvement by 15%

Shear viscosity was measured(temperature: 240°C, shear rate:
608/sec) after kneading polybutylene
terephthalate (PBT) resin and
SANWAX 161-P (0.5% by weight),
which were dried in advance at
130°C for 3 hours, in a twin screw
extruder (temperature: 250°C).

500
400
300
200

0

0.5

SANWAX 161-P addition amount (% by weight)

Fig. 3

Table 5

Formability (fluidity)

Effects of ‘SANWAX’ addition on mechanical properties

Test item

No addition

SANWAX 161-P(addition of 0.5% byweight)Shear viscosity (Pa·s)

533

458

Tensile strength (MPa)

54.7

54.1

Bending strength (MPa)

81.8

80.1

2. Machinability improver forplastic
Molded products of polyethylene,
polypropylene, vinyl chloride(PVC), ABS, polybutylene
terephthalate, etc., are normallymanufactured by melting andkneading the resin as powder orpellets with additives such asstabilizers and fillers, extruding
the mixture into the die and thencooling. The formability may
deteriorate, e.g., if the fluidity is
reduced because of frictional
resistance between the melted
resin and metal or the high melt
viscosity of the resin during themelting and kneading process.
There are issues such as adecrease in molding cycle(decrease in productivity) andfailure to produce molding
products with complex shapes if
we try to improve the formability
by adjustment of the dietemperature or injection molding
pressure.
Since ‘SANWAX’ and ‘VISCOL’
are low in viscosity, the additionof these during the molding
process can improve the fluidityof the resin as they enter theinterface between die and resinor the gaps in polymeric chains.
As they deliver effects with theaddition of a small quantity,
they improve formability without
reducing the mechanical
Sanyo Chemical News 2018 Autumn No. 510

Measured according totensile test: ASTM D638,
and bending test: ASTM
D790 after kneading in asimilar fashion to Fig. 3and molding in an injection
molding machine (nozzle
temperature: 250°C, dietemperature: 50°C).

properties of the resin (Fig. 3,
Table 5). Besides the performancedescribed above, they are also
used to improve the moldrelease characteristic of themolded products or add alubricating property to PVC by
utilizing their low polarity.
In recent years, manufacturersof transport machines, mainly inthe automotive field, areshowing the trend of replacing
metallic components with resin
components. Also, engineering
plastics, which excel in heat
resistance, mechanical strength,etc., are being used. In order tofurther improve the mechanicalproperties of engineering plastic,
which by nature has poor
fluidity and formability in themelted state, in more and morecases, composite materials arebeing applied with fillers thathave high aspect ratios such as
glass fiber and carbon fiber.
While needs are currently
growing for high- concentration
filling with these fillers, highfilling with the filler material
increases the overall viscosity of
the composite material, and may
cause productivity decrease orappearance defects.
‘SANWAX’ and ‘VISCOL’ are also
effective in engineering plastic
filled with high-concentration
fillers, and can improve3

Photo 2

In molded plastic products

productivity without reducing
the mechanical properties of thecomposite material by improving
fluidity with the addition of asmall quantity.
3. Modifier for paints andprinting inks
The design properties have large
effects not only on the functions
but also on the manner ofconsumption in the field of paints
and printing inks. A matted
appearance with delustering isoften demanded. Luster isdetermined by surface evenness,and becomes matted once acertain level of unevenness ispresent.
When ‘SANWAX’ and ‘VISCOL’
polyolefin waxes are used inpaints, the wax particles form
unevenness on the surface of thecoating film and diffuse the lightto give the delustering effect.
They also provide a uniform
delustering effect when combinedwith delustering agents such as
silica by preventing the
precipitation of the agents andkeeping them on the surface. In
addition, improvement in coating
film durability can be expected,
as polyolefin waxes arehydrophobic, and the wax
components oriented on thesurface waterproof the paintsurface, adding mold prevention
and antifouling.
Paints and inks normally havepoor sealing properties with
nonpolar molded products,
sheets, films, etc., typical ofwhich is the OPP film. However,‘SANWAX’ and ‘VISCOL’ have4

Photo 3As matting agent/water resistance-imparting
agent in gravure ink raw materials for foodpackaging films and molded components

high affinities to such nonpolarmaterials and can add afavorable sealing property tosuch films and sheets by using
them as components of paint orink.
4. Additive for hot melt adhesives
Although hot melt adhesives areenvironment-friendly adhesives
which can reduce volatileorganic compounds as they do
not contain solvents, they havethe disadvantage of decreasing
in adhesive strength when theenvironmental temperature(ambient temperature) increases
after adhesion, as they have low
melting points and arethermoplastic. ‘SANWAX’ and‘VISCOL’ have higher melting
points than hot melt adhesives
and thus can mitigate the effects
of adhesive strength
deterioration under hightemperatures when used asadditives. Since they are also low
in viscosity, they can be used toeasily adjust the viscosity of theadhesive, making them easy tohandle like other normal
adhesives.

Future prospects
Even though low-molecular-weightpolyolefins are already used indiverse applications, we believethat they still have enoughpotential for further application
developments. In the recent
years, resin replacement ofmetallic components is being
advanced mainly in theautomotive industry, and theirimportance as molding aids to
Sanyo Chemical News 2018 Autumn No. 510

Photo 4In hot melt
adhesives

improve the production speed,
yield, and formability of molded
products has also increased. We
will continue to devote ourefforts to providing anddeveloping products that meetsuch needs.
Reference
1) Toru Tomoshige, Hiroyasu Fujii:
Synthetic Waxes. High Polymes,
Japan, 26, 637-642 (1977)
2) “Story on Development of
Performance Chemicals – Kono
omoshirokumo nangina shigoto norekisi –,” Sanyo Chemical
Industries, Ltd. (1989)
3) Noboru Moriyama: “Chemistry of
Dispersion and Aggregation,”
Sangyo Tosho Publishing Co., Ltd.
(1995)[Contact (about the product)]
In Japan
Sales & Marketing Dept. of Transport &Polyurethane Foam Industry
https://www.sanyo-chemical.co.jp/eng/
In U.S.A
SANAM Corporation
State Highway 837
P. O. Box 567
West Elizabeth, PA 15088-0567
https://www.sanamcorp.com/