01 Basics Flexible Foam Chemistry [Compatibility Mode]

Basics Flexible Foam Chemistry

Crystalbelle Low Jens Sassenhagen

Typical Flexible PU Foam Formulation Polyol Isocyanate (TDI)

Water Surfactant Catalysts

16.4 kg

8.3 kg

0.66 kg

0.16 kg

0.066 kg

Quantities being required to produce 1 m3 of flexible foam with a density of 24 kg/m3.

September 2015 | Basics Flexible Foam Chemistry

P a ge | 2

Basic Reactions in PU foaming 1. Poly Polyme meri riza zati tion on be betw twee een n Iso Isocy cyan anat ate e an and d Pol Polyo yoll - Gelling Reaction -

+ Isocyanate

Polyol

Difunctional Isocyanate September 2015 | Basics Flexible Foam Chemistry

Urethane

Triol P ag e | 3

Basic Reactions in PU foaming 2. GasGas-pr prod oduc ucin ing g reac reacti tion on bet betwe ween en iso isocy cyan anat ate e and and wate waterr – blowing reaction -

+ Isocyanate

Water

Carbamic Acid (instable)

- CO2 H R1 Urea


N

H

Amine

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Polyether polyols Initiator

+

Organic Oxide

-∆

Polyether Polyol

KOH Ethylene Glycol

OH OH

Propylene Oxide (PO)

H

Water H

Diol CH3 CH2 O (PO)n (EO) (EO)m m CH2

CH

OH

CH2 O (PO)n (EO) (EO)m m CH2

CH

OH

OH

1,2 Propylene Glycol

CH3

OH

Ethylene Oxide (EO)

EO//PO sequence as well as end groups can vary

OH

Glycerine

Triol

OH

CH2 O

OH

Trimethylolpropane

Butylene Oxide (BO) OH CH2 OH

H3C H2C C

CH2 OH

CH

(PO)n

O (PO)n

CH2 O (PO)n

CH2

OH OH

(EO) (EO)m m CH2 CH2

OH OH

(EO)m CH2

OH OH

(EO (EO)m CH2

CH2

OH CH2 OH September 2015 | Basics Flexible Foam Chemistry

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Differences in Used Polyols for Conventional Slabstock & HR Foam

Conventi Conve ntiona onall Fle Flexib xible le Standard Slabstock • Base Polyol

Molecular Weight (g/mol)

Polymer Polyol


• •

Low reactive (end groups: groups: secondary secondary OH-groups) OH-groups) Homo Polyol 92% PO, 8% EO Hetero Po Polyol 80-9 0-90% PO PO, 10 10-20% EO EO

HR Slabstock

•

High reactive (end groups: primary primary OHgroups)

3 00 0 – 4 0 00

4 50 0 – 6 5 0 0

Optional

Almost always

P a ge | 7

Index Calculation

Importance of the index - Foam Foam de defe fect cts s - safe safety ty (fi (fire re)) - eff effician iciancy cy of foam foam produ production ction - getting getting the right right mechani mechanical cal propertie properties s

It is EXTR EXTREM EMEL ELY Y impo import rta ant to calc calcul ula ate the the ind index befo be forre run unni nin ng a new for formu mula lati tion on !


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Index Calculation The "Index" is a stochiometric number to characterize the ratio between isocyanate groups and groups reactive with isocyanate. It is an important number for everybody involved in polyurethanes. polyurethanes.

Index

Isocyanate amount used =

Isocyanate amount calculated for equivalenc e

⋅

100

The concept of equivalent weights: For example: X g of component A is equivalent to

equivalent weight

molecular mass =

functionality

Y g of component B


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Index Calculation Calculation Equivalent We Weights ights

Isocyanates equivalent weight isocyanate

42 100

molecular mass =

functionality

⋅

=

% NCO

Polyol equivalent weight polyol

56 1000

molecular mass =

functional ity

⋅

=

OH number

Water equivalent weight water


18

molecular mass =

funtionali ty

=

2

g =

9

g

P a ge | 10

Index Calculation Example Formulation 100.0 pphp Polyol, OH number 47 mg KOH /g 4.0 pphp water Various amounts stabilizer, catalysts 50.9 pphp TDI 80 (NCO content = 48 %)

Equivalent weight 1 191g 9g not considered 87.5 g

This means: 1 191 g of polyo polyoll is equival equivalent ent to 87.5 87.5 g of of isocyanat isocyanate e 9 g of wate waterr is equivalen equivalentt to 87.5 g of isocyanat isocyanate e    

7.35 pphp of isocyanate are necessary for 100 pphp of polyol. 38.9 pphp of isocyanate are necessary for 4 pphp of water. In total 46.2 pphp of isocyanate are necessary for equivalence. 50.9 pphp of isocyanate are used which is an excess of 10 %, Index is <110>.


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Isocyanate Parts and Index Calculation (Alternative) (Parts Component 1 * OH# Component 1 + Parts Component 2 * OH# Component 2 + . . . / 56100) * ( 4200 / NCO content) = Parts Isocyanate * (requested Index / 100) = Parts Isocyanate Isocyanate with corrected Index

xamp!e"

(Po!yo! 1$ %0 Parts * OH# 56 + Po!yo! 2$ 10 Parts * OH# 2& + 'ater 4 Parts * OH# 62(( / 56100) * ( 4200 / 4&) = 4)*1& * (115 / 100) = 54*26

+imp!e"

(%0 * 56 + 10 * 2& + 4 * 62(( / 56100) * ( 4200 / 4&) = 4)*1& * (115 / 100) = 54*26

,e-end" 56100



/o!ec!ar /ass o OH 3 1000 to transer rom mi!!i-ram to -ram$

42 00



/o!ec!ar /ass o NCO 3 100 to compensate the percent$

Components 

OHnctiona! aw /ateria!s Po!yo!s* 'a 'ater* Cross,iner* 7$

[NCO conten contentt in TDI 80 = 48!


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Index Calculation Calculating the index by using the computer: •

some foaming machines have it already implemented

•

some separate programs are available from consultants

But a simple EXCEL spread sheet may also help …

Additional comment: •

Nice calculations are fine, BUT: −

Make sure that the pumps really have the right dosage!

−

Regular metering of the pumps is required!


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Influence of TDI Index


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Influence of TDI index on physical foam properties Formulation: 100 4.0 1.0 0.10 1 .0 0.20 variable T 80 index

p p p p p p

Polyol (OHN: 47 mg/g) Water TEGOSTAB ® BF 2370 TEGOAMIN ® 33 TEGOCOLOR ® Blue KOSMOS ® 29 T 80 index

[pphp]

T 80

Rise time [s]

Foam height [cm]

Foam settling [cm]

Density [kg/m³]

Air permeability*

CLD hardness 40 % compression [kPa]

Tensile strength [kPa]

Elongation [%]

Compression Ball set 22 h, rebound 70 °C, 90 % [%] compression [%]

85

39,1

134

24,2

- 0,10

28,9

36

2,6

95

260

85

25

95

43,7

119

27,1

+ 0,40

25,6

37

2,3

100

260

15

45

105

48,3

109

29,3

+ 0,40

24,5

33

3,2

115

230

12

43

115

52,9

102

31,4

+ 0,10

24,1

51

4,5

100

170

12

30

125

57,5

99

33,2

+ 0,40

23,6

> 170

5,6

90

110

13

28

135

62,1

102

35,1

+ 0,90

23,5

> 288

8,1

90

80

29

40

* Air permeability has been measured as back pressure (mm water column) which is obtained by an air stream passing the foam with constant speed. The lower the given value, the more open celled is the foam structure.


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16.4 kg

8.3 kg

0.66 kg

0.16 kg

0.066 kg



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Influence of Catalysts

Gelling reaction

Blowing reaction

(mainly tin)

+ Isocyanate

Polyol

(mainly amine)

+ Isocyanate

Urethane

Water

Carbamic Acid (instable)

- CO2

Urea September 2015 | Basics Flexible Foam Chemistry

Amine P a ge | 17

Influence of Catalysts Blowing Reaction Amines TEGOAMIN ®

Gelling Reaction Tin Salts KOSMOS ® Balanced Catalysis – Optimum Processing Insufficient crosslinking high settling, splits Collapse

Foam too closed, blow off to bottom or sides Shrinkage


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Influence of Amine Catalyst Concentration


P a ge | 19

Influence of TEGOAMIN ® DMEA on foam physical properties Formulation: 100 4.0 1.0 1.0 0.20 52.9 variable ®

p p p p p p

TEGO DMEA [pphp]

Polyol (OHN: 47) Water TEGOSTAB ® BF 2370 TEGOCOLOR ® KOSMOS ® 29 T 80 <115> Tegoamin ® DMEA Rise time [s]

Foam height [cm]

Foam settling [cm]

Density [kg/m³]

Air CLD hardness 40 % permeability* compression [kPa]


Elongation [%]


without

122

31,4

+ 0,7

22,7

> 300

5.2

105

180

> 85

45

0,05

113

30,4

+ 0,40

24,0

57

4,3

105

160

> 85

35

0,10

106

30,7

+ 0,40

23,9

38

4,3

100

140

52

35

0,20

99

30,9

+ 0,20

24,2

22

4,1

95

140

23

38

0,40

86

31,5

+ 0,10

24,0

13

3,8

90

130

12

38

0,80

73

31,0

- 0,20

23,9

12

3,3

90

140

> 85

40



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Influence of Stannous Octoate Concentration


P a ge | 21

Influence of stannous octoate concentration on foam physical properties Formulation: 100 4.0 1.0 0.15 1 .0 52.9 variable ®

p p p p p p

Polyol (OHN: 47) Water TEGOSTAB ® BF 2370 TEGOAMIN ® 33 TEGOCOLOR ® Green T 80 <115> KOSMOS ® 29

KOSMOS 29 [pphp]

Rise time [s]

Foam height [cm]

Foam settling [cm]

Density [kg/m³]

without

> 160

20,0

collapse

-

0,05

> 160

26,3

-

0,10

150

29,8

0,20

101

0,33 0,40

Air permeability*



Elongation [%]

Compression set 22 h, 70 °C, 90 % compression [%]

Ball rebound [%]

-

-

-

-

-

-

26,8

8

2,8

60

105

11

55

+ 0,20

23,8

17

3,1

95

180

8

42

31,5

+ 0,10

23,2

26

4,4

95

150

17

32

-

35,6

+ 0,40

-

> 300

-

-

-

-

-

-

36,3

+ 0,70

-

>> 300

-

-

-

-

-

* Air permeability has been measured as back pressure (mm water column) which is obtained by an air stream passing the foam with constant speed. The lower the given value, the more open celled is the foam structure. September 2015 | Basics Flexible Foam Chemistry

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Influence of stannous octoate level on CLD hardness Formulation 10 0 4 .0 1 .2 0 .1 0 4 8 .3

p p p p p

Polyol (OHN: 47) H2O Silicone surfactant TEGOAMIN ® 33 T 80 <105> Density [kg/m³]

Air permeability*

CLD 40 % [kPa]

B 8110 0.15 p 0.20 p 0.25 p

KOSMOS ® 29 KOSMOS ® 29 KOSMOS ® 29

24.6 24.9 24.0

12 57 > 272

3.1 4.0 4.2

BF 2370 0.15 p 0.20 p 0.25 p


24.6 24.6 24.6

10 17 > 125

3.1 3.7 4.3

B 8002 0.15 p 0.20 p 0.25 p


25.4 25.7 25.4

6 7 40

3.3 3.7 4.3

* Air permeability has been measured as back pressure pressur e (mm water column) which is obtained by an air stream passing the foam with constant speed. The lower the given value, the more open celled is the foam structure. September 2015 | Basics Flexible Foam Chemistry

P a ge | 23

Working with Methylene Chloride Methylene Chloride requires a certain amount of Stannous Octoate: Octoate: 2.5 pphp MC 5.0 pphp MC 7.5 pphp MC 10.0 pphp MC 12.5 pphp MC 15.0 pphp MC 20.0 pphp MC 25.0 pphp MC 30.0 pphp MC


        

0.20 pphp Stannous Octoate 0.25 pphp Stannous Octoate 0.25 pphp Stannous Octoate 0.30 pphp Stannous Octoate 0.35 pphp Stannous Octoate 0.40 pphp Stannous Octoate 0.48 pphp Stannous Octoate 0.55 pphp Stannous Octoate 0.60 pphp Stannous Octoate

P a ge | 24



16.4 kg

8.3 kg

0.66 kg

0.16 kg

0.066 kg


Amount Amou nt of Stabilizer is relatively small September 2015 | Basics Flexible Foam Chemistry

P a ge | 25

Functions of Surfactants for Flexible Foam Improves Emulsification transparent activator blend homogenous distribution of foam properties

Controls cell opening stable foam without shrinkage

Stabilized rising foam and avoid coalescence guarantees fine/regular cell structure

Maintain Foam Strut Integrity Regulates nucleation desired cell size September 2015 | Basics Flexible Foam Chemistry

P ag e | 2 6

Tasks of Silicone Surfactants in a Foaming Process Emulsification • prom promot ote e un unif ifor orm m mixi mixing ng of of form formul ulat atio ion n ingr ingred edie ient nts s Nucleation • prom promot ote e gen gener erat atio ion n of of nuc nucle lea ation tion site sites s • supp suppor ortt bubb bubble le for forma mati tion on and and pre preve vent nt coa coale lesc scen ence ce Stabilization • prov provid ide e ph phy ysica sicall stabi stabilility ty to expa expand ndin ing g foam foam ma mass ss • redu reduce ces s foa foam m de defe fect cts s cau cause sed d by shea shearr for force ces s • redu reduce ces s spre spread ad of ph phy ysica sicall prop proper erti ties es in in the the blo block ck Processing • impr improv ove e the the op oper erat atin ing g win windo dow w for for cel celll o ope peni ning ng • con control trol blow low-of -off and and foam foam poros orosit ity y


P a ge | 27

Definition of Processing Latitude Processing Latitude Defines the sensitivity of the foam stability to varying amounts of stabilizer or at a given stabilizer concentration to varying amounts of tin catalyst.

Shrinkage

g n i s s e c o r P

Stable foam

Splits Collapse

narrow

broad

Surfactant dosage

processing latitude September 2015 | Basics Flexible Foam Chemistry

P a ge | 28

Foam Stabilization

Minimum Stability Required

Chemical Stabilization

Physicochemical Stabilization

Polymerization: Reactivity of the Chemicals

Physcial Interactions:

Catalysts

SURFACTANTS


P a ge | 29

Interaction between chemical and physical stabilization physical stabilization

• Surfactant type • Surfactant concentration • TDI Index • Tin concentration • Cross linker • Amine type • Amine concentration • Polyol viscosity

Conv. slabstock September 2015 | Basics Flexible Foam Chemistry

chemical stabilization

HR slabstock

Esterfoam P a ge | 30

Influence of Silicone Surfactant Quantity September 2015 | Basics Flexible Foam Chemistry

P a ge | 31

Influence of silicone surfactant type and quantity on foam physical properties Formulation: 100 4 .0 0 .1 0 1 .0 0 .2 0 52.9 variable

p p p p p p

Polyol (OHN: 47) H2O TEGOAMIN ® 33 TEGOCOLOR ® Red KOSMOS ® 29 T 80 <115> TEGOSTAB ® BF 2370 ®

TEGOSTAB BF 2370 [pphp]

Rise time [s]

Foam height [cm]

Foam settling [cm]

Density [kg/m³]

Air permeability*



Elongation [%]


without

70

-

collapse

-

-

-

-

-

-

-

0,25

88

-

collapse

-

-

-

-

-

-

-

0,50

103

30,9

- 1,30

23,8

11

4,6

115

140

7

42

1,00

103

31,3

+ 0,10

23,4

21

4,5

105

170

9

32

2,00

112

31,7

+ 0,60

23,2

> 257

4,3

105

160

9

25

4,00

120

31,4

+ 1,00

23,8

> 300

4,1

100

160

9

23



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Efficiency in Flex Foam Production

Influence of Raw Material Temperature


P a ge | 33

Influence of Raw Material Temperature Increa Increase se in raw mater material ial temper temperatu ature re Acce Accele lera rati tion on of the the blow blowin ing g & gel gelliling ng reac reacti tion on  Fast Faster er crea creami ming ng & shor shorte terr rise rise time times s  Foam is getting les less stable Higher er set settl tlin ing, g, wo wors rsen enin ing g of the the dens densit ity y spre spread ad  High  Catal ataly ysts sts leve levell nee eed d to be adjust justed ed But also  Higher core temperature!! (Risk of Fire!



see SAFETY presentation!)

Influence of raw material temperature on rise time and settling in a low density formualtion D 18 kg/m 3 BF 2370

Temp. of Polyol & TDI

B 8 27 5

Rise Time (s)

Settling (cm)

Rise Time (s)

Settling (cm)

17°C

98

1, 6

106

1 ,8

19°C

90

2, 0

104

2 ,0

21°C

86

2, 5

93

2 ,3

23°C

80

2, 8

89

2 ,4

25°C

75

3, 1

88

2 ,6


P a ge | 34

Efficiency in Flex Foam Production

Influence of Humidity


P a ge | 35

Influence of Humidity Moisture in raw materials Humidity might result in moisture absorption by raw materials (especially polyol) which results in a wrong water loading (lower density and lower hardness).

Humidity in the storage area for block curing Moisture enters the curing foam block and reacts with the remaining isocyanate. The isocyanate isocyanate is therefore no longer available for the final crosslinking (formation of allophanates and biuret groups). The result is a lower hardness. This effect effect is based on the amount of air entering the curing foam block and the water content of the air. It might therefore be less pronounced for foams with relative closed cell structure. It is also less pronounced if the air penetration is reduced by PE foil at the top and at the sides. But it could be observed for open-celled foams.


P a ge | 36

Influence of Humidity 80,00 75,00 70,00 65,00 60,00 ] r 55,00 a b 50,00 m [ 45,00 r u o 40,00 p a 35,00 v r e 30,00 t a 25,00 w

20,00 15,00 10,00 5,00 0,00 0, 00

5,00

10, 00

15, 00

20, 00

25,00

30,00

35,00

40, 00

temperature [°C]

If the relative humidity is the same s ame (for example 80%), there is in absolute numbers 3 times more moisture in the air at 25 °C (summer) than at 5°C (winter). Foam might therefore be softer in summer time. Empirical values exhibit for Central Europe during summer time a water concentration con centration of 10.0 -10.5 g/m³ and for winter time 4.5 g/m³. Caution: relative humidity needs to related to the saturation satu ration value at a given temperature.


P a ge | 37

Influence of Humidity Correction of humidity variations variations

Increase / Decrease of the index to compensate for "lost" isocyanate: Empirical values for Central Europe and 25 kg/m³ ether foam: 2 - 3 index points more in summer time time versus winter winter time

Different geographical geographical regions have different climatic conditions but might need similar or even stronger adjustments. For example the rain season in South East Asia requires requires stronger corrective measures despite a more constant temperature profile. It is overall important to analyze the typical development of the absolute water content of the air at a given location over the year. Furthermore day-to-day day-to-day variations might also require slight corrective measures.


P a ge | 38

01 Basics Flexible Foam Chemistry [Compatibility Mode]

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