Millable polyurethane for shoes

1. Millable
Polyurethane for
Shoes
Luis Antonio Tormento
LT Químicos/TSE Industries
18/08/2016

2. Introduction
 Polyurethanes are based on polyols of the
polyether or polyester types, including
polycaprolactone and aromatic
diisocyanates MDI and TDI. Aliphatic
diisocyanates produce transparent
polymers having excellent ultraviolet light
resistance. There are special types with
FDA approval.
 Types based on polycarbonate polyols are
used in medical applications and have
exceptional transparency.

3. Types of Polyurethane
Polyurethane polymers used on
shoe manufacturing can be divided
into three (3) main groups:

4. Tipos de Poliuretano
 Thermoplastics: processed like any other
thermoplastic, using typical equipment such as
extruders and plastic injection molding.
 The thermosetting bicomponent: processed by
casting, pre-cured and then demoulded and post-
cured in an oven. In its production specific
equipment are needed.
 Thermosets: processed like any other elastomer in
typical equipments of rubber industry.

5. Comparison of Polymers
Properties Polyurethane Polychlooprene NBR NATURAL EPDM
Tensile Strength E B-E R B-E R
Hardness, Shore A 10-95 10-95 20-100 30-100 25-90
Max Temperature (ºC) 100 120 120 100 175
Ozone Resistance E R-B P P E
Cut Resistance E B R B R
Tear Strength E B R B R
Compression Set R-B B R-B R B
Abrasion Resistance E B-E R B R
Heat Generation E E P R-B R-B
E - Excelent, B - Good, R - Regular, P - Fair

6. Disadvantages
 Among its disadvantages include:
 Poor resistance to hydrolysis,
especially in polyester types (AU);
polyether types (PAUR) resist very
well to water.
 Poor resistance to ketones,
concentrated acids and bases

7. Typical Applications
Among the typical applications of
polyurethane shoes include:
 Insoles
 Absorbing Impact
 Soles

8. Typical Applications
1 – Insole to absorb impacts

9. Insoles

10. Insoles
 They are produced in two distinct ways:
 1 - From a foamed polyurethane latex over
a woven - polyester, cotton, nylon, etc-
insoles can be manufactured of different
densities and thicknesses
 2 - from an extrusion / calendering, a gas is
entrapped between layers of the material
which encourages the creation of an area
with the function of a shock absorber

11. Insoles
Advantage
 Absorbs shock
 Reduces fatigue in the feet, legs and
ankles
 Make the most comfortable shoes
 Provide lasting support
 It remains in place and maintains its
resilience
 Prevents proliferation of bacteria
 Gives no odor

12. Typical Applications
4 – Sole – Polyuretane Millable

13. Millathane 97
 Millathane 97 is a polyether based
polyurethane rubber which produces parts
with outstanding durability, high coefficient
of friction and good stability to UV. This
polyurethane rubber is for applications in
shoe soles / inserts, roll coating and other
applications where necessary
transparency, light brightness or artifact
pieces of decoration.

14. Millathane 97

15. Millathane 97

16. Millathane 97

17. Millathane 5004
 MILLATHANE 5004 is a polyester based polyurethane
elastomer, which has excellent processing characteristics.
MILLATHANE 5004 Compounds can be rapidly processed in
conventional rubber equipment. The vulcanization can be done
by using dicumyl peroxide or Varox.
 Compounds of MILLATHANE 5004 press-cured, achieve
optimum vulcanization within 15 minutes at 160°C, or 30 to 45
minutes at 152 ° C . The vulcanization can be accelerated to 3 to
4 minutes at higher temperatures, 177-204°C. The rubber
compound is of high quality, has good performance at low
temperatures and good resistance to hot air. The vulcanized has
also excellent abrasion resistance and tear strength at high
temperatures and excellent resistance to oxygen, ozone, fuel
and oils

18. Millathane E34
 Millathane E34 is a rubber based on polyether
polyurethane, high performance, designed for
applications that require high abrasion resistance, low
temperature flexibility, ozone resistance, resistance to oil
and fuel, hydrolytic stability and improved handling.
 Millathane E34 may be composed and processed with
conventional equipment for rubber. For example,
Millathane E34 can be mixed in an open mixer or internal
mixer. The compounds can be calendered, extruded,
injected, transferred or compressed, to produce finished
polyurethane parts.
 Millathane E34 is vulcanized using organic peroxides or
using sulfur and thiazoles accelerators.

19. Soles with MIllathane

20. Soles with Millathane
 Polyurethanes polyester and
polyether types may be used in
blends with other rubbers, in order to
give them better abrasion resistance,
tear resistance and penetration
resistance.

21. Soles with Millathane
Posible blends are:
 With NBR and NBR/PVC
 With SBR
 With BR
 With EPDM
 With HNBR

22. Millable Polyurethane
 The millable elastomer - commonly
called gum - was one of the first forms of
polyurethane.
 When the urethane was invented, the
standard process used to convert
elastomers to finished products
employed the same techniques of
rubbers.

23. Millable Polyurethane
 They differ from other polyurethanes in
the methods used in their healing, the
intense composition and processing. The
millable polyurethane rubbers are
processed on rubber conventional
equipment at temperatures of 120 -
130oC.
 Molded polyurethane liquid, but with
properties similar to polyurethane
millable require specific procedure sized
equipment, greenhouses and other
machinery.

24. Millable Polyurethane
Specifically, these properties are:
- Superior resistance to abrasion;
- Excellent resistance to cutting;
- Excellent resistance to ozone, fuels and
oils;
- High flexibility compression (load bearing);
- Great flexibility at low temperatures.
These are the joint properties that distinguish
them from other polymers polyurethanes.

25. Main Properties
 The abrasion resistance and durability of the
polyurethanes are the key properties which lead to
choose polyurethanes from other polymeric systems,
factors up to 10 to 1.
 The long durability of polyurethanes is reversed in cost
reduction. The hardness of the urethane elastomer
makes it an ideal elastomer for shoe soles in
applications such as: sports shoes for use in sandy or
abrasive ground, such as tennis courts, not to slip on
wet or dry ground; They are used in shoes for
basketball practice, and jogging. By having a strong
puncture resistance and flexibility at low temperature, it
is used in soles for climbing boots.

26. POLYETHER and POLYESTER
 The polyethers are used in most applications in
contact with water, especially at high
temperatures, because they exhibit greater
hydrolytic stability compared to polyesters.
 Many of cylinders cured in autoclaves are
polyethers, because they resist better to the
effect of water vapor during cure.
 The hydrolytic stability of polyester compounds
may be significantly improved with the addition of
polycarbodiimide (Stabaxol P).
 Polyether rollers also tend to develop less heat
when compared to polyester cylinders.

27. POLYETHER and POLYESTER
 Polyethers are used in most applications in
contact with water, especially at high
temperatures, because they exhibit greater
hydrolytic stability compared to polyesters.
 Many of rolls cured in autoclaves are polyethers,
because they resist better to the effect of water
vapor during cure.
 The hydrolytic stability of polyester compounds
may be significantly improved with the addition of
polycarbodiimide (Stabaxol P).
 Polyether rollers also tend to develop less heat
when compared to polyester rolls.

28. Compounding and Mixing
 Composition practices of other
rubbers like: natural or synthetic
can usually be employed in the
composition of the millable
elastomers, but also specific
practices for these polymers were
developed.

29. Compounding and Mixing
 As filler, carbon black is used to obtain maximum
mechanical resistance and abrasion resistance.
 The silica is usually used as the white charge.
 The silanes are often used with the silica to
reduce heat generation and promote increased
physical properties and abrasion resistance.
 Vulcanized vegetable oils are used especially in
low durometer compounds to help absorb high
levels of plasticizer contributing to softening and
aid in processing and extrusion, and promote
dimensional stability.

30. Compounding and Mixing
 As plasticizer, adipates, phthalates,
esters and coumarone-indene resin have
shown good characteristics in
manufacturing operations.
 The coumarone-indene resin plasticizers
are effective in curing of sulfur-based
compounds, but are not used in the
peroxide curing due to the interaction
with the curing agent.

31. Compounding and Mixing
 Since most synthetic rubbers,
millable polyurethanes can be
cured by any systems based on
sulfur or peroxide.
 Peroxide cure are primarily used to
obtain low permanent set and
improved heat resistance
properties.

32. Compounding and Mixing
 Uretanos com altos níveis de poliéster podem
também ser curados com isocianato. Compostos
curados por este método são vulcanizados
rapidamente e têm baixa estabilidade na
armazenagem.
 No entanto, os vulcanizados exibem boas
propriedades físicas, especialmente em
aplicações de 78A a 70D Shore.
 Co-agentes à base de acrilatos como o Sartomer
SR-350 ou Saret 500, podem ser usados com
sucesso para aumentar a dureza de compostos
curados à base de peróxido quando usados de
10 a 20 phr. A forma líquida desses produtos
também ajuda a controlar a viscosidade em
compostos com alto peso molecular.

33. Compounding and Mixing
 The processing aids used
effectively in urethane compounds
include polyethylene glycol, low
molecular weight polyethylene,
stearic acid and TE 88 XL.

34. Mixing Techniques
 The millable polyurethane
compounds may be mixed with
conventional mills, internal mixers,
and other internal mixers.

35. Molds
 The molds must be chrome plated or
made of stainless steel as the
peroxide vulcanization is extremely
corrosive

36. Molds

37. Molds

38. References
 TSE Industries – Technical Literature
 Rubber Technology - Morton

39. Thank You
LT Comércio de Borrachas e Representações Ltda
Av. Pedro Severino Jr., 366 Cj. 35
São Paulo – SP
04310-060
Tel: +55 (11) 5581-0708
E-mail: info@ltquimicos.com.br