GLOBAL PROCESS OF FLEXIBLE POLYURETHANE FOAMS RECYCLING BY...

Funded by: Funded by:

UNIVERSITY OF CASTILLA-LA MANCHA

INSTITUTE OF CHEMICAL AND ENVIRONMENTAL

TECHNOLOGY

GLOBAL PROCESS OF FLEXIBLE POLYURETHANE FOAMS RECYCLING BY

SPLIT – PHASE GLYCOLYSIS

D. Simón, A. de Lucas, Ana M. Borreguero and Juan

F. Rodríguez

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1.1. Essential concepts

1.2. Recycling Processes

i) Physical Processes

ii) Chemical Processes

INDEX

1. INTRODUCTION

2. EXPERIMENTAL INSTALLATION

3. RESULTS AND DISCUSSION

3.2. Catalyst selection

3.3. Optimal conditions

3.4. Glycolysis upper phase

3.5. Glycolysis bottom phase

3.1. Low weight glycol selection


1. INTRODUCTION

1.1. ESSENTIAL CONCEPTS

Polyurethane synthesis

n HO-R-OH + n O=C=N-R´-N=C=O [ -CO-NH-R´-NH-CO-O-R-O- ]n

Polyol Isocyanate Urethane

Polyurethane types

-Foams

-CASE

Flexible Rigid


1. INTRODUCTION

1.1. ESSENTIAL CONCEPTS

PU world consumption in 2010

>12 million tons

6º in the plastic market

Production in Spain in 2010

≈ 200.000 tons

7º in the national plastic market

elastomers

8.8% duromers 0.4%

flexible foams

44.2% integral foams

7.0%

rigid foams

37.3%

others

2.3%

GREAT AMOUNT OF WASTES

RECYCLING


1. INTRODUCTION

1.2. RECYCLING PROCESSES

i) Physical Processes


• Hydrolysis

Φ-NH-CO-O-R’ + H2O Φ-NH2 + CO2 + HO-R’

Urethane Water Amine Polyol

• Aminolysis

Φ-NH-CO-O-R’ + NH2-R” Φ-NH-CO-NH-R” + HO-R’

Urethane Amine Urea Polyol

• Phosphorolysis

• Pyrolysis


1. INTRODUCTION

1.2. RECYCLING PROCESSES


• Glycolysis

Φ-NH-CO-O-R’ + OH-R”-OH Φ-NH-CO-O-R”-OH + HO-R’

Urethane Glycol Carbamate Polyol

Large glycol excess Biphasic product Split – Phase

Bottom phase

Upper phase

Recovered polyol Glycol excess



Scrap PU foam Recovered Polyol


GLYCOLYSIS AGENT (G.A):

Low weight glycol + catalyst

INDUSTRIAL PU FOAM WASTE

Polyether Polyol F-4811 + TDI

RECOVERED POLYOL

GLYCOLYSIS AGENT EXCESS

1. JACKETED 1L FLASK

2. REFLUXING CONDENSER

3. N2 ATMOSPHERE

4. STIRRER

5. TEMPERATURE CONTROL SYSTEM

6. CONTINUOUS FEEDER




3.1. LOW WEIGHT GLYCOL SELECTION

glycol / DEA

0 20 40 60 80 100 120 140 160 180 200 0

5

10

15

20

25

MEG

MPG DEG

0 20 40 60 80 100 120 140 160 180 200

0

10

20

30

40

50

60

70

80

90

MEG

MPG

DEG

OLIGOMERS POLYOL

WPU:Wag = 1:1.5

WDEG:WDEA = 6:1

T = 190 ºC



3.1. LOW WEIGHT GLYCOL SELECTION

glycol / DEA

Propylenic glycols increase phases mutual

solubility

MPG provides a strong polluted

product

DPG does not allow phase separation

DEG SEEMS TO OFFER THE BEST

PERFORMANCE

DPG

polyol

10 12 14 16 18

10 min

40 min

1 h 40 min

3 h 40 min

retention time (min) GLYCOL MEG DEG MPG DPG*

Viscosity 25ºC (cp) 830 584 632 346

Acidity (mg KOH/g) 0.016 0.010 0.014 0.073

Hydroxyl number (mg KOH/g) 157 155 179 -

Water (%) 0.55 0.42 0.23 0.51

% Polyol ( w/w) 72 83 63 <25

Optimal glycol: DEG



3.2. CATALYST SELECTION

ALKALINE – ALKALINE EARTH

0

10

20

30

40

50

60

70

80

90

0 50 100 150 200

time reaction (min)

% b

y w

eig

ht

Li

Na

K

Ca

Sr

Sn

Ba

0

5

10

15

20

0 50 100 150 200

time reaction (min)

% b

y w

eig

ht Li

Na

K

Ca

Sr

Ba

Sn

WPU:WDEG = 1:1.5

Ccat =6*10-2 m DEG

Tª = 190 ºC


TRANSITION METAL



0

10

20

30

40

50

60

70

80

90

0 50 100 150 200

time reaction (min)

% b

y w

eig

ht

Co

Ni

Cu

Zn

Y

Sn

0

2

4

6

8

10

12

14

16

18

20

0 50 100 150 200

time reaction (min)

% b

y w

eig

ht

Co

Ni

Cu

Zn

Y

Sn

WPU:WDEG = 1:1.5

Ccat =6*10-2 m DEG

Tª = 190 ºC


CATION Viscosity

25ºC (cp)

Hydroxyl number

(mg KOH/g)

Total amine

(mg KOH/g) Poliol (%)

Li 570 172 6.69 82.4

Na 584 178 6.04 74.7

K 591 171 9.59 79.0

Ca 576 171 8.78 79.3

Sr 598 176 7.64 81.5

Ba 619 197 0.40 79.3

Co 1068 191 8.80 75.3

Ni 667 181 14.60 79.0

Cu 1454 235 0.28 71.0

Zn 705 184 16.27 80.3

Y > 2000 175 19.62 51.2

Sn 550 198 5.23 82.3


STANNOUS OCTOATE IMPROVED

ALTERNATIVE TO THE DESCRIBED CATALYSTS



Surprisingly Sn Octoate that

catalyses the PU foaming process,

also catalyses the glycolysis

process¡¡¡





3.3. OPTIMAL CONDITIONS

3.3.1. CATALYST CONCENTRATION

Reaction # PU foam (g) DEG (g) Stannous octoate (g) Stannous octoate

(moles)

Stannous octoate

(% G.A.)

R-1 300 440 10.5 0.026 2.3

R-2 300 442 8 0.020 1.8

R-3 300 444 6 0.015 1.3

R-4 300 446 4 0.010 0.9

Tr=190ºC WPU:WG.A=1:1.5




3.3.1. CATALYST CONCENTRATION

At low catalyst concentration, there is a strong dependence with the improvement in the reaction time, but at high concentrations

the slope of the dependence curve decreases.

From 1.3 % to up the improvement in the reaction rate would not be noticeable, approaching zero order behaviour.

Concentration of polyol in the upper phase is not a function of catalyst concentration.

Stannous octoate optimal concentration: 1.3 % G.A.




3.3.2. WPU:WG.A

Reaction # PU foam (g) DEG (g) Stannous octoate(g)

Stannous octoate

(moles) WPU:WG.A

R-3 300 444 6 0.015 1:1.5

R-5 400 444 6 0.015 1:1.125

R-6 500 444 6 0.015 1:0.9

WPU:WG.A.=1:0.9; Wcat=1.3 % G.A.; Treaction=189ºC. a) Final product view

b) Homogeneous product. Intense orange coloration detail

a) b)

Tr=190ºC WSnOct=1.3% G.A




3.3.2. WPU:WG.A

WPU:WG.A.= 1:0.9 (500 g PU) → low polyol content in the upper phase

WPU:WG.A. = 1:1.125 (400 g PU) → similar polyol content in the upper phase in comparison with 1 : 1.5 ratio (300 g PU)

WPU:WG.A. = 1:1.125 (400 g PU) → reaction time is only 10 minutes more in comparison with 1: 1.5 ratio (300 g PU)

Optimal mass ratio of PU foam to glycolysis agent: 1 : 1.125

Tr=190ºC

WSnOct=1.3% G.A




3.3.3. Temperature

Reaction # Temperature (ºC) WPU:WG.A PU foam(g) DEG (g) Stannous octoate

(g)

Stannous octoate

(moles)

R-5 189 1:1.125 400 444 6 0.015

R-7 184 1:1.125 400 444 6 0.015

R-8 179 1:1.125 400 444 6 0.015

179 º C → low polyol content in the upper phase

homogenous product

184 º C → slow recovery process(150 min reaction time)

>189 º C → DEG excessive evaporation

increase of the extent of secondary reactions

Optimal reaction temperature: 189 ºC

→

→

WPU:WG.A=1:1.125 WSnOct=1.3% G.A



SCRAP FROM

FLEXIBLE PU FOAM

FRESH GLYCOL

CATALYST

TWO PHASE

GLYCOLYSIS

RIGID

POLYOL

BOTTOM PHASE

ALCOXYLATION

VACUUM

DISTILLATION

RECOVERED

GLYCOL

RESIDUE

PROPYLENE

OXIDE

CATALYST RIGID PU

FOAM

UPPER

PHASE

FLEXIBLE

PU FOAM

EXTRACTION

WATER

FLEXIBLE

POLYOL

EXTRACT



3.4. GLYCOLYSIS UPPER PHASE

Liquid - Liquid Extraction

Optimal Conditions

Temperature: 90ºC

pH: 4-5

Mass ratio: 1:1

Centrifugation

Glycolysis Upper Phase Glycolysis Upper Phase after L-L Extraction

Hydroxyl number(mg KOH/g) 198 Hydroxyl number(mg KOH/g) 63



3.4. GLYCOLYSIS UPPER PHASE

FOAM FORMULATIONS

A100-R0 A75-R25 A50-R50 A0-R100

ALCUPOL F-4811 100 75 50 -

Recovered polyol - 25 50 100

OHN polyol mixture 48 50.5 58 63

Water 4.60 4.60 4.60 4.60

Tegoamin 33 0.10 0.10 0.10 0.10

Niax A-1 0.05 0.05 0.05 0.05

Silicon L-620 LV 1.40 1.40 1.40 1.40

Stannous octoate 0.20 0.20 0.20 020

TDI (80:20) 54.58 54.99 56.21 57.02

Index 105 105 105 105

REPLACEMENT UP TO 50% WITHOUT CHANGE



SCRAP FROM

FLEXIBLE PU FOAM

FRESH GLYCOL

CATALYST

TWO PHASE

GLYCOLYSIS

RIGID

POLYOL

BOTTOM PHASE

ALCOXYLATION

VACUUM

DISTILLATION

RECOVERED

GLYCOL

RESIDUE

PROPYLENE

OXIDE

CATALYST RIGID PU

FOAM

UPPER

PHASE

FLEXIBLE

PU FOAM

EXTRACTION

WATER

FLEXIBLE

POLYOL

EXTRACT


10 12 14 16 18

distillate

bottoms

inte

nsit

y (

a.u

.)

retention time (min)

50 mbar DEG

Vacuum distillation

50 mbar

0 50 100 150 200 2500

5

10

15

20

FRESH DEG

RECOVERED

% b

y w

eig

ht

reaction time (min)

WPU:WGA = 1:1.5

WDEG:WOctSn = 3.4*10-2 m

T = 189 ºC:1

Reuse of most excess of glycol after

catalyst adjustment:

OLIGOMERS


3.5. GLYCOLYSIS BOTTOM PHASE


Mw eq= 147 g/mol

POLYOL INITIATOR mol INITIATOR mol KOH/mol

INITIATOR

mol PO/mol

INITIATOR

SYNTHESIS

TIME (min)

TDA-1 TDA 1.64 0.0208 6.345 80

RDES-0.5 RDES 0.41 0.0205 3.146 74

RDES-1 RDES 0.41 0.0205 6.268 123

RDES-2 RDES 0.41 0.0205 12.537 280

retention time (min)

10 15

residuo de vacio

inte

nsid

ad

(u

.a.)

tiempo de retención (min)

Pm ≈ 300

Pm ≈ 175

DEG

inte

nsity (

a.u

.)

vacuum residue Contains active H :

DEG, aromatic amines, carbamates…

NH2H2N

Polyol R499 based on TDA


3.5. GLYCOLYSIS BOTTOM PHASE


T100-125 T50-125 T0-125

R-458 100 100 100

TDA-1 101 50 0

RDES-1 0 50 100

Water 1.02 1.09 1.02

POLYCAT-8 1.04 1.04 1.07

Tegostab B8404 2.18 2.13 2.09

MDI 264 249 237

Index 125 124 125

Tc(s) 15 20 20

Tmc(s) 110 110 97

Density (Kg m-3) 72 63 67

T50-125

T0-125

T100-125

BOTTOM PHASE VALORIZATION BOTTOM PHASE VALORIZATION: foaming

FOAM FORMULATIONS

VACCUM RESIDUE CAN BE USED AS

INITIATOR IN THE SYNTHESIS OF NEW

POLYOLS


Diego Simón Herrero

UNIVERSITY OF CASTILLA-LA MANCHA

INSTITUTE OF CHEMICAL AND ENVIRONMENTAL

TECHNOLOGY

GLOBAL PROCESS OF FLEXIBLE POLYURETHANE FOAMS RECYCLING BY

SPLIT – PHASE GLYCOLYSIS

GLOBAL PROCESS OF FLEXIBLE POLYURETHANE FOAMS RECYCLING BY...

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