SUPERLINK TM CROSS-LINKABLE ROTOMOULDING RESINS

SUPERLINKTM CROSS-LINKABLE ROTOMOULDING RESINS

Bill Huang

Research Engineer

Ingenia Polymer Corp.

February 2019

Ingenia Polymers In Rotomoulding

• Ingenia is a global supplier to the rotomolding industry with a track record of developing innovative

products

• SuperlinkTM cross-linkable polyethylenes exemplify this commitment to excellence in rotomoulding.

SUPERLINKTM XLPE

• Traditional linear materials do not meet the requirements of high performance

applications including fuel and hydraulic oil tanks:

• High impact and/or low temperature impact

• Improved ESCR

• Improved temperature resistance

• Ingenia SuperlinkTM XLPE can meet these requirements either as a single layer

rotomoulded product or as part of a multilayer solution for applications requiring low

fuel permeation.

3

Property ComparisonResin Type Superlink XLPE Typical LLDPE/HDPE

Density 0.943 0.932-0.942

Impact resistance (ARM test, -40 o C) (ft-lbs) >180 80-160

Brittle failure (%) 0 85%-100%

Tensile elongation (%) 800 865-1000

Flexural Modulus (psi) 110,000 88-110,000

ESCR (hrs) >1000 20-400 typical

HDT (°C)

ASTM D648 at 66psi

67 49-57

Chemical Resistance Excellent Fair

Moldability Excellent Good

Impact Strength vs Density

• Linear PE resins show a negative

correlation between impact

strength and increasing density

• SuperlinkTM XLPE shows highly

improved impact strength relative

to density as compared to linear PE

• Besides improvements in impact

strength, crosslink resins offer

improvements in several

properties…0

20

40

60

80

100

120

140

160

180

200

0.93 0.935 0.94 0.945 0.95 0.955 0.96

Im

pa

ct

Str

en

gth

(ft

-lb

s)

Density (g/cc)

Resin Density vs -40C impact Strength

Reactor resin Superlink XLPE Linear (Reactor resin)

Improved impact-

stiffness balance vs.

linear PE

What is Crosslinking?

• Crosslinking is a chemical reaction

• It is initiated by heat or temperature

• Rate is time and temperature dependent.

• It changes the composition of PE from a

collection of linear thermoplastic polymer

chain to a thermoset network chain

structure

Schematic representation of linear PE molecules

Schematic representation of XLPE molecules

Measuring Crosslinking

• Crosslinking of Superlink resins is initiated by

decomposition of peroxide

• A torque rheometer can measure crosslinking

characteristics

• Viscosity and torque will increase as crosslinking proceeds

• The time to reach a percentage (50 or 90%) of maximum torque is indicative

of the rate of cross-linking. Shorter times = higher rates

Rheology Curve

0

5

10

15

20

25

30

35

40

45

50

0 2 4 6 8 10 12 14 16 18 20 22

Time (minutes)

Torq

ue (Lb.IN

)

Measuring Crosslinking via Torque Rheometer

MHF – Plateau Torque

ML – Minimum Torque

t90 – 90% cure time

t50 – 50% cure time

ts2 – time to reach 2 in-lb above ML (Scorch Time)

Rotomolding Process and Crosslinking

• Linear PE

• Loading of powder

• Heating of mold and powder

• Fusion of resin

• Cooling

• Removal of part

• Cross-linkable PE

• Loading of powder

• Heating of mold and powder

• Fusion of resin

• Chemical crosslinking

• Cooling

• Removal of part

Rotomolding process and Crosslinking

INTERNAL AIR TEMPERATURE

TIME

TE

MP

ER

AT

UR

E

Crosslinking

Resin melting

and fusionCooling

LLDPE

XLPE

• XLPE requires a higher

peak internal air

temperature (PIAT) as

compared to linear PEs

during rotomolding

Impact Resistance vs CycleTime

Time

Imp

ac

t

Impact properties vs. cycle time

• Linear PEs are known to degrade if the rotomoulding cycle is extended. The resin ‘overcooks’,

and undergoes thermal and oxidative degradation. Impact properties are severely negatively

affected

• However XLPEs maintain their impact properties if the rotomoulding cycle is extended beyond the

full gel point.

Peroxide decomposition and crosslinking process

• Measuring gel content of finished product confirms

complete crosslinking

• The gel content is measured by dissolving the PE in

recirculating hot xylene. Linear PEs will completely

dissolve. XLPE will have a content of undissolvable ‘gel’

• A typical gel content of 70-84% indicates full cross-linking

and fully developed physical properties.

• Increased toughness

• Increased stress crack resistance

• Increased notch crack resistance

• Increased abrasion resistance

Gel test apparatus

GEL Analysis

Outside Surface

(mold)

Inside Surface

84%

79.8%

71.8%

• Due to the nature of the rotomoulding process – where heat is applied from the

outside – the part thickness has a gradient in heat history and corresponding gel

level. the gel content will be higher on the outside wall.

Property Comparison

• Superlink has been tested extensively and has a proven track record of 20+ years

• Superlink XLPE outperforms linear materials

• Superlink has also been evaluated against industry competitive XLPEs and

demonstrates superior processability and properties

• Differences between XLPE resins can be attributed to differences in:

• Base resin

• Crosslinking system (peroxide type, concentration and use of co-additives)

• Antioxidant system

• UV additives

• Pigments

14

Comparison of Industry XLPEs

• Ingenia regularly benchmarks its SuperlinkTM XLPE versus industry competitors

Property Comparison

Resin Type SL110NA Competitive 1 SL110CA

Lot# 113218 (Natural) Natural 112376 (Black)

Density 0.942 0.941 0.942

Impact resistance (ARM test, -40 o C, ¼“) (ft-

lbs)

183 181 186

Tensile Strength at Yield (psi) 2921 2806 2935

Tensile Strength at Break (psi) 899 904 860

Flexural Modulus (psi) 113,000 101,200 111,800

ESCR (hrs)

100% Igepal

10% Igepal

>1000

>1000

>1000*

>1000*

>1000

>1000

HDT (°F)

ASTM D648 at 66 psi

264 psi

152

104

141*

98*

*from datasheet. All other properties measured


Crosslink Time (t50)

0

5

10

15

20

25

30

35

40

300 320 340 360 380 400 420

Temperature (F)

Tim

e (

min

)

Superlink 110 Competitive 1

• Rheological studies show that Ingenia

Superlink has a longer crosslinking time (t50

and t90) at lower temperatures and a similar

crosslinking time at higher temperatures to

competitive XLPE

• A lower reactivity at low temperatures allows

Superlink to fully fill the mold, fill out detail,

and fully fuse without entrapped air bubbles,

before crosslinking

• A higher reactivity at higher temperatures

allows Superlink to fully crosslink without

extended heating cycles

REACTIVITY OF CROSSLINKABLE RESINS

INCREASING TEMPERATURE

RE

AC

TIV

ITY

Superlink 110 Competitive

Crosslinking curing temperatures

Fusion and melting

temperatures


• Crosslinking time is inversely

proportional to reactivity.

• Superlink is less reactive at lower

temperatures and has increased

reactivity at higher temperatures

• This provides good moldability

• Good fill and detail

• Complete melting and fusion prior to

crosslinking

• Efficient molding times


Maximum Torque (Crosslink Density)

vs. Temperature

0

10

20

30

40

50

300 320 340 360 380 400 420

Temperature (F)

To

rqu

e (

in.l

b)

Superlink 110 Competitive 1

• Rheological studies show that

Superlink has a higher maximum

torque than industry competitive

XLPE

• Maximum torque is an indication

of crosslink density and gel

content


%Elongation vs QUV Exposure Time

0

100

200

300

400

500

600

700

800

900

1000

0 200 400 600 800 1000

QUV Time (hrs)

Ten

sile S

train

(%

)

SL110:113218 Competitive 1

• Ingenia has carried out extensive

long term testing of Superlink and

competitive XLPE

• Ingenia Superlink has superior

QUV resistance to industry

competitive XLPE

• All XLPEs have comparatively low UV

resistance compared to well stabilized

linear resins.


Tensile Elongation vs Xenon Arc Exposure Time

0

200

400

600

800

1000

0 1000 2000 3000 4000

Exposure (hrs)

Elo

ng

ati

on

(%

)

SL110NA Competitive 1

• The UV performance of

Superlink was confirmed by

Xenon Arc Weatherometer,

which is considered more

representative to real world

conditions than QUV


• Materials have also been

evaluated for resistance to

thermal aging


Different Formulation XLPE Thermal Aging

Performance at 80C

0

200

400

600

800

1000

0 5 10 15 20 25

Thermal Aging Time (Weeks)

Te

ns

ile

Elo

ng

ati

on

(%

)

SL110NA Competitive 1

• SuperlinkTM shows

equivalent performance to

industry competitive XLPE in

thermal aging tests

Long Term Testing of SuperlinkTM

• HYDROSTATIC PRESSURE TESTING (ASTM D1998/D2837)

• LTHS: LONG TERM HYDROSTATIC STRENGTH

• Samples are exposed to pressurized high temperature water for an extended

period of time

• Property that resists stress in the hoop direction generally due to hydrostatic forces

in applications such as pipe, pressure vessels or upright storage tanks

• LTHS improves as MW increases (this is why pipe is extruded from high to very high

MW resins)

• Roto XLPE is generally 30% higher LTHS vs LLDPE of similar density

• Critical for large tanks (i.e. wall thickness/material usage, process window for thick

walled parts)

Long Term Hydrostatic Testing

• Preparation of samples for LTHS

• Samples are tested until failure

Ingenia 4" PEX at 73F

y = -0.0268x + 3.3578

y = -0.031x + 3.3578

R2 = 0.8856

3.12

3.16

3.20

3.24

3.28

3.32

3.36

3.40

-1 0 1 2 3 4 5 6 7 8

Log Time (Hrs)

Log S

tress (

psi)

Predicted

(SIM slope + Burst intercept)

Burst 100,000

1674 psi

1595 psi

Long Term Hydrostatic Testing

• Testing at different pressure and temperature allows extrapolation to extended times

at lower temperatures

Ingenia 4" PEX at 150F

y = -0.0329x + 3.0986

R2 = 0.9791

2.94

2.96

2.98

3.00

3.02

3.04

3.06

3.08

3.10

0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50 4.00

Log Time (Hrs)

Log

Str

ess (

psi)

WHAT DOES ALL OF THIS MEAN TO THE MOLDERS?

• Superlink offers improved properties over linear materials for high performance

applications including large chemical tanks and fuel tanks

• Performance has been demonstrated in extensive laboratory and field testing and

supported by industry certifications:

• UNECE-R34 TUV certificate for wheel vehicle part application;

• UL94 HB burning test certificate,

• Open fire resistance testing certificate per ABYC H24 specification for marine fuel tank application

(provided on request)

• Processability and performance are improved versus industry competitive XLPE.

Molders observations

• Lower scrap rate

• Faster cycle time

• Fewer defects and rejects (Pinholes, Voids, Blemishes)

XLPE applications

• Fuel tanks for gasoline and diesel

• (single layer or part of a multilayer solution depending on local fuel permeability requirements)

• Large chemical tanks

• Road barriers

• Waste bin covers

• Go-cart bodies

• High impact doors

XLPE Grades

SL110 Series: High performance XLPE resin with wide processing window.

SL120 Series: ‘Low odor’ product

SL114 Series: High flow, high productivity grade for molding challenging product

design at very high oven temperatures, short oven times with

moderated gel content.

SL230 series: High adhesion grade for bonding to metal. Used for lining metal tanks

in order to provide excellent chemical resistance.

• Oven temperature ~510F—600F (265C to 315C)

• PIAT target: SL110 series----195C to 210C

SL120 series----195C to 205C



• We suggest the use of AXEL WB 4606 mold release for all SuperlinkTM resins

• 2” vent opening.

• Cycle time: ~18 to 28 minutes depending on part thickness and design, mold

specifics and oven temperature.

Processing Guidelines for SUPERLINKTM

Benefits of SuperlinkTM

Greatly improved stiffness - toughness balance as compared with LLDPE and HDPE:

Improved temperature resistance

Improved abrasion resistance

Improved stress crack resistance

propagation failure

SuperlinkTM was developed to meet the demanding requirements for applications

requiring outstanding durability, improved abrasion and scratch resistance and

improved ESCR.

©2019 Ingenia Polymers. To the extent the user is entitled to disclose and distribute this document, the user may forward, distribute, and/or photocopythis copyrighted document only if unaltered and complete, including all of its headers, footers, disclaimers, and other information. You may not copy thisdocument to a Web site. The information in this document relates only to the named product or materials when not in combination with any other productor materials. We based the information on data believed to be reliable on the date compiled, but we do not represent, warrant, or otherwise guarantee,expressly or impliedly, the merchantability, fitness for a particular purpose, suitability, accuracy, reliability, or completeness of this information or theproducts, materials, or processes described. The user is solely responsible for all determinations regarding any use of material or product and anyprocess in its territories of interest. We expressly disclaim liability for any loss, damage, or injury directly or indirectly suffered or incurred as a result of orrelated to anyone using or relying on any of the information in this document. There is no endorsement of any product or process, and we expresslydisclaim any contrary implication. The terms, “we”, “our”, "Ingenia Polymers", or "Ingenia" are used for convenience. ‘Superblend’, ‘Superlink’, ‘Rototuf’,‘RotoliteTM’ etc. are trademarks of Ingenia Polymers.

SUPERLINK TM CROSS-LINKABLE ROTOMOULDING RESINS

Documents

Transcript of SUPERLINK TM CROSS-LINKABLE ROTOMOULDING RESINS