Session E9.6 Catalyst alternatives to replace DBTDL and

• Jicable’15, 21 - 25 June 2015 - Versailles - France• Jicable’15, 21 - 25 June 2015 - Versailles - France

Session E9.6

Catalyst alternatives to replace DBTDL and crosslinking speed improvement

Sophie LEVIGOUREUX

sl1

Diapositive 1

sl1 sophie levigoureux; 18/06/2015

• Jicable’15, 21 - 25 June 2015 - Versailles - France

CONTENTS

• Introduction

• Silane crosslinking

• State of the art about catalyst alternatives

• Key parameters to improve crosslinking speed

• Experiments

• Conclusion


INTRODUCTION

• Silane crosslinking:– Needs a catalyst to speed up the reactions• Most common one: DBTDL (DiButyl Tin DiLaurate)

• Classification according to CLP regulation:

– Increasing demand to suppress sauna stage to improve manufacturing cycle time

Risk Risk phrases Pictogram

Reprotoxic 1B H360FD

Mutagenic 2 H341

Toxic for specific target organs (STOT SE 1 & STOT RE 1)

H370 & H372

Very toxic to environment H400 & H410

Corrosive for eyes and skin H314 & H318

Objective: Develop an insulation formula able to crosslink in ambient conditionswithout containing any CMR product and with less hazardous catalyst


FOCUS ON

• LV overhead cables according to the French standard NF C 33-209

Test Parameters Unit Value

HST

Test temperature °C 200 ± 3

Tensile force N/cm² 30

Maximum elongation % 100

Maximum residual elongation % 15

Mechanical characteristicsafter ageing

Temperature °C 150

Time h 240

∆ Tensile strength % ± 25

∆ Elongation at break % ± 25

Main specifications impacted:


Silane crosslinking

• Three reaction stages1/ Vinylsilane grafting onto polymer chains

2/ Hydrolysis of silane functions to silanol

3/ Condensation of silanol groups to create siloxane bonds

- Decomposition of peroxide- Reaction of radicals on polymer- Silane grafting on polymer

- Reaction of water molecules with alkoxysilane

=> Catalyzed by an hydrolysis catalyst

- Creation of 3 dimensional network by reaction of silanol functions

=> Catalyzed by a condensation catalyst

Catalyst

Catalyst


Silane crosslinking

• How do tin-based catalysts work

-Hydrophobic part to facilitate the dispersion

-Polar groups + empty orbitals to guarantee

coordination of reactive molecules

Hydrolysis Condensation

Proposed transition state of DBTDL in literature


State of the art about catalyst alternatives

Catalyst

Base Acid

Amine Hydroxide

Lewis Brönsted

Tin-based

Other metals-based

Carboxylic

Sulphonic

1 2

3 4



• Base catalysts– Amines

• Example : 1,8- Diazabicyclo[5.4.0] undec- 7- ene,

• Classification:

• Comparison with sulphonic acid

• Same crosslinking with 30% higher amount and with silane matrix containing higher silane content

1

Risk phrases Pictogram

H 301: Toxic if swallowed.

H314: Causes severe skin burns and eye damage.

H290: May be corrosive to metals.

H412: Harmful to aquatic life with long‐lasting effects

Less efficiency and risk of metal corrosion (tools)



• Base catalysts– Hydroxides

• Examples : KOH, CsOH*H2O

• Classification

• Comparison with sulphonic acid

• Lower gel content

• Best results with CsOH*H2O: 13% less gel content

Risk phrases Pictogram

H 302: Harmful if swallowed.

H314: Causes severe skin burns and eye damage.

H290: May be corrosive to metals (for KOH).

2

Less crosslinking efficiency and risk of metal corrosion (tools)



• Acid catalysts – Lewis acids

• Examples: DOTL, Copper(II) acetylacetonate, Isopropyl triisostearoyl titanate, Butyl tin dihydroxide chloride

• Classification: depends on molecules

• Comparison with DBTL, DOTL or sulphonic acid

• Worst or better efficiency depending on catalyst : Titanate catalyst -> lower HST value in ambient conditions

Molecule Risk phrases Pictogram

Copper(II) acetylacetonate

H315: Causes skin irritationH335: May cause respiratory irritation

H319: Causes serious eye irritation

Butyl tin dihydroxide

chloride

H302: Harmful if swallowedH312 + H332: Harmful in contact with skin of if inhaled

H315 + H335: Causes skin irritation and may cause respiratory irritation. H319: Causes serious eye irritation

3

Good efficiency can be obtained with lower hazard



• Acid catalysts – Brӧnsted acids

• Exemple: stearic acid, palmitic acid, 4-Dodecylbenzene sulfonic acid, Dinonyl-naphthalene Disulfonic Acid

• Classification:

• Lower efficiency of carboxylic acids compared to DOTL

• Better gel content with sulphonic acids compared to DBTDL and Sn(Octoate)

Molecule Risk phrases Pictogram

Stearic and palmitic acid Not classified as hazardous-

4-Dodecylbenzenesulfonic acid

H314: Causes severe skin burns and eye damage

Better efficiency can be obtained with lower hazard

4


Key parameters to improve crosslinking

Improvement of crosslinking speed

Silane grafted polymerFillers or additives

Able to create bonds with silanol groups

Reinforcement

Catalyst masterbatch

Catalystmolecule

Catalyst amount

Polymer

Additives

Silane

Polymer nature

Peroxide

Molecule

Amount

Molecule

Amount

2 Higher MFI and lower melting temperature = better dispersion property

Amorphous polymer = improvement of moisture permeability

3

Any additives able to improve catalyst dispersion in the matrix

4

Fillers or additives creating Si-O-Si bonds with the siloxane network

5

Fillers leading to better mechanical properties at high temperature

1

Ability of polymer to react with free radicals and to be grafted by silane


Experiments

• Selection of catalysts according to potential efficiency and classification

• Manufacturing of catalyst masterbatches (1,5 – 4,0% catalyst)

Number Nature Classification

1 Di-sulfonic acid Not classified as hazardous

2 Carboxylic acid Not classified as hazardous

3 Carboxylic acid Not classified as hazardous

4 Carboxylate of titanium H226: Flammable liquid and vapourH319: Causes serious eye irritation.

5 Tin-based STOT SE 2 - H371: May cause damage to organs.

6 Tin-basedSTOT SE 2 - H371: : May cause damage

to organsH412: Harmful to aquatic life with long

lasting eff ects.

7 AmineH319: Causes serious eye irritation.


Experiments

• First assessment : visco-elastic torque measurement (S’)

Principle: measurement of the crosslinking capability of polyolefin having hydrolysable silane groups in presence of water

- Method: mixing silane grafted polyethylene + catalyst + hydrate molecule (water releasing) and measurement of viscoelastic torque (S’) at 200°C

Tin-based catalysts

Non tin-based catalysts


Experiments

• HST assessment⇒ Formulas adjustment for each catalyst to get similar final crosslinking

⇒ Extrusion at around 1,4 mm

85°C water bath : Slower crosslinking with

catalysts n°2 and 3

Ambient conditions(23 ± 5)°C and 50% RH :

Similar crosslinking speed with catalyst n°1 and 5


Experiments

• Other factors studied to improve crosslinking

Addition of fillers or additives: 2 hours in 85°C water bath

⇒ Up to -34% HST decreasing

Modifying polymer carrier: Ambient conditions

⇒ Quicker crosslinking


Experiments

• Development of a new formula

Optimization of:- Silane content- Catalyst n°1 (not classified as

hazardous)- Catalyst percentage & catalyst

masterbatch formula- Addition of fillers and additives

Before aging After aging

TS (Mpa) EB (%) ∆ TS (%) ∆ EB (%)

Specification ≥ 14.5 ≥ 200 ± 25 ± 25

Results 15.4 350 +15 -17


Conclusion

Possibility to develop an insulation formula with:– Catalyst not classified as hazardous according to GHS system

– Crosslinking in ambient conditions between 1 and 2 weeks

– By formulating an optimized formula (additives, fillers, polymer)

• Jicable’15, 21 - 25 June 2015 - Versailles - France• Jicable’15, 21 - 25 June 2015 - Versailles - France

Thank you

Documents

Session E9.6 Catalyst alternatives to replace DBTDL and