Model of microwave assisted thermal adhesion of synthetic ...€¦ · KIT – The Research University in the Helmholtz Association 1IHM, Karlsruhe Institute of Technology (KIT), Kaiserstr

KIT – The Research University in the Helmholtz Association

1IHM, Karlsruhe Institute of Technology (KIT), Kaiserstr. 12, 76131 Karlsruhe, Germany2Carl Meiser GmbH & Co. KG, Stadionstr. 75, 72461 Albstadt, Germany

www.kit.edu

Model of microwave assisted thermal adhesion of synthetic leather to a plastic substrate

Sergey Soldatov1, Jens Meiser2 ,Benjamin Lepers1, Guido, Link1 and John Jelonnek1

Institute for Pulsed Power and

Microwave Technology

2 21.10.2016 S. Soldatov, Model of microwave assisted thermal adhesion of synthetic leather to a plastic substrate, COMSOL Conference, München, 2016

Outline

Motivation

Materials dielectric characterization

Electromagnetic modelling

Heat transfer model (COMSOL)

Optimization

Conclusions

http://www.frimo.com/de/produkte

http://www.frimo.com/de/produkte



3 21.10.2016

Motivation

𝑃𝑎𝑏𝑠 = 2𝜋𝑓휀0휀′ tan 𝛿 𝐸𝑟𝑚𝑠2

Dielectric properties of materials are to be known

HEPHAISTOS Oven http://www.voetsch-ovens.com/en/products/industrial_microwave_system/schunk01.c.59509.en

S. Soldatov, Model of microwave assisted thermal adhesion of synthetic leather to a plastic substrate, COMSOL Conference, München, 2016

http://www.voetsch-ovens.com/en/products/industrial_microwave_system/schunk01.c.59509.en



4 21.10.2016

Heat balance

20C

20C

120C

qconvCooling

Heating

𝑞𝑐𝑜𝑛𝑣 = ℎ 𝑇𝑠𝑢𝑟𝑓 − 𝑇𝑎𝑖𝑟 𝑊 𝑚2

𝑝𝑎𝑏𝑠 =1

2𝜔휀0휀𝑟

′′ 𝐸 2 𝑊 𝑚3

𝝆𝑪𝒑𝝏𝑻

𝝏𝒕= 𝜵 ∙ 𝒌𝜵𝑻 + 𝒑𝒂𝒃𝒔

Heat source




5 21.10.2016

Materials dielectric properties versus temperature

Materials:

Adhesive: Hot melt polyurethane

(HMPUR) blended by carbon

particles

Substrate: ABS-PC

Coating: artificial PVC leather with

textile layer at wrong side

Materials were characterized with

cavity perturbation method and within

working temperature range

Absorption of microwaves in adhesive is predominated!




6 21.10.2016

Electromagnetic Modelling (CST wave Studio.)

Geometry of task. Coating-glue-substrate sandwich

Electric field pattern.

~ 1 m

The aim to find dielectric heat sources in every material




7 21.10.2016

Absorbed microwave power density.

20 40 60 80 100 1200.1

1

10

Glue (co-phased)

Glue (random phasing)

Leather (co-phased)

Leather (random phasing)

Substrate (co-phased)

Substrate (random phasing)

p [

MW

/m3]

T [C]

The cross-link between antennas is negligable

magnetrons are independent (not locked)

the phasing is random

f=2.45 GHz




8 21.10.2016

Heat transfer problem (COMSOL )




9 21.10.2016

Geometry

synthetic leather

Substrate

Glue

The glue is patterned to cover a selected percentage of surface.

Restrict a geometry to a single glue volume.

Neglect the influence of neighboring glue volumes.

PVC leather




10 21.10.2016

Heat transfer model (COMSOL)

interlaced yarns

PVC dense

PVC foam

Air

Substrate

(ABS-PC)Symmetry Axis O

pe

n b

ou

nd

arie

s

-1 -0.5 0 0.5 1 1.5 2 2.5 3 3.5

3.5

3.0

2.5

2.0

1.5

1.0

0.5

0 10-3

10-3

Glue (HMPUR)

Air convection

Vacuum bag (PE)

Heat source in PVC

QPVC’’(t)

Heat source in glue

Qglue’’(t)

Heat source in substrateQABS’’(t)




11 21.10.2016

Properties of materials in the model

Domain

name

Density

[kg/m3]

Specific heat

cp,

[J/kg/K]

thermal

conductivity k

[W/m/K]

Latent

heat

[J/kg]

Thickness along Z

[mm]

PVC dense [7] 1200 1800 0.15 0.2125

PVC foam 800 900 0.10 0.2125

Interlaced yarns [8] 200 1200 0.04 0.475

Glue [5] 950 1500…1700 0.19 5*104 0.35

Substrate (ABS)[6] 1080 1300 0.19 2.5

Air 1 1000 0.026 0.35




12 21.10.2016

Heat transfer model with COMSOL (II)

10:32:30 10:33:00 10:33:30 10:34:00 10:34:30

0

20

40

60

80

100

Te

mp

era

ture

, C

time

"2" between Leather & Substrate, C

"1" between Leather & Vacuum bag, C

Magnetron power, P/Pmax*100%

100 s

Model

Experim

ent

tHEAT=102 s

h=7 W/K/m2 (natural convection)

𝒑𝒂𝒃𝒔=2.5… 15 MW/m3

kinterlaced yarns= 0.04 W/m/K

Model describes satisfactory the experiment

Note: thermocouples are slow as compared with

„ideal“ temperature in the model




13 21.10.2016

Optimization of process

To decrease the time of heating (below 60 s), but reach the melting point in glue! (~120 °C)

To reduce the heat load in the coating material (PVC leather damage temperature ~80 °C)

interlaced yarns

PVC dense

PVC foam

Air

Substrate

(ABS-PC)

-1 -0.5 0 0.5 1 1.5 2 2.5 3 3.5

3.5

3.0

2.5

2.0

1.5

1.0

0.5

0 10-3

10-3

2. To increase the heating rate (pabs)

1. To increase the cooling rate (𝑞𝑐𝑜𝑛𝑣)

3. To improve the insulation (k) < 80 °C

110…130 °C




14 21.10.2016

Leather is

hotter than

Glue!!

ZtHEAT=85 s

h=7 W/K/m2

pglue <5.5 MW/m3

natural air convection

Z

X

Y

Z, m

Substrate

Glu

e

PV

C L

eath

er

Tem

per

atu

re, C

Inte

rlac

ed y

arns

T, CZtHEAT=14 s

h=70 W/K/m2

pglue<23.0 MW/m3

forced air convection

Z

X

Y

T, C

Substrate

Glu

e

PV

C L

eath

er

Z, m

Tem

per

atu

re, C

Inte

rlac

ed y

arn

s

Optimization: absorbed power and surface cooling

reference case optimized




15 21.10.2016

Optimization: heat conductivity of textile layer

Temperature gradient is more dependent on the absorbed power in glue, pglue.

The heating time is dependent both on k and pglue

0.02 0.03 0.04 0.05 0.06 0.07 0.08

70

80

90

100

110

120

130

Glue

PVC Leather

T, C

a)

0.02 0.03 0.04 0.05 0.06 0.07 0.080

2

4

6

8

10

12

14

16

18

kinterlaced yarns

, W/m/K

b)

Hea

ting t

ime,

s

0.02 0.03 0.04 0.05 0.06 0.07 0.08

70

80

90

100

110

120

130 c)

Glue

PVC Leather

T, C

0.02 0.03 0.04 0.05 0.06 0.07 0.080

2

4

6

8

10

12

14

16

18d)

Hea

ting t

ime,

s

kinterlaced yarns

, W/m/K

pglue< 23 MW/m3

h=70 W/K/m2

The time required for heating 2/3 of

the glue volume above 120 C.

pglue< 30 MW/m3

h=70 W/K/m2




16 21.10.2016

Coating of a cover of the glove box of Land Rover




17 21.10.2016

Conclusions

Microwave assisted bonding of PVC artificial leather to the

plastic substrate is possible but requires the optimization of

the process and materials.

Such an optimization is inevitable without numerical

modelling which gives us the understanding how and where

the energy is absorbed, how it is transferred and dissipated in

materials.

Optimization of

absorbed microwave power (loss factor of glue),

heat sink at the leather surface and

fabric layer insulating properties

allow to reach the melting temperature in the hot-melt glue

keeping the coating material below its damage temperature.




18 21.10.2016 S. Soldatov - Microwave assisted bonding of synthetic leather to plastic substrates, 3GCMEA Cartagena (Spain), 25-29

July 2016

Thank you for your attention!

ACKNOWLEDGMENTS

This research is funded by the Federal Ministry for Economic Affairs and Energy (BMWi) within the funding

action “Zentrale Innovationsprogramm Mittelstand (ZIM)” under funding number KF3158002CJ3.

Documents

Model of microwave assisted thermal adhesion of synthetic ...€¦ · KIT – The Research University in the Helmholtz Association 1IHM, Karlsruhe Institute of Technology (KIT), Kaiserstr