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1 Lisa Bindgård, Xylophane AB 13th TAPPI European PLACE Conference 2011 Bregenz - Session 3 - Paper 1

Renewable Xylan-based Barrier for Packaging

Presented by:

Lisa BindgårdTitle:

Xylophane AB

13TH TAPPI

EUROPEAN PLACE CONFERENCE

30 May - 1 June 2011 Bregenz, Austria

Xylophane




Structure

• This is Xylophane

• Xylan – the raw material

• Material properties

• Process of application

• Multi-layer structure

• Results from customer projects

• Status

• Conclusion




Xylophane = xylan-based barrier againstoxygen, grease and aroma

Xylan-based coating

Xylan‐based coatings can provide oxygen barrier, aroma barrier and grease barrier properties.




Xylan – natural polysaccharide

Molecular structure of arabinoxylan

Xylan is a natural polysaccharide present in wood and agricultural residues. Xylan belongs

to the group of hemicelluloses. The molecular structure shown relates to arabinoxylan

which has a backbone of xylose units and substituents of arabinose.




Xylan content in barley husks

Xylan40-50%

Cellulose15-25%Other

Starch10-25%

5

The results in this presentation relate to arabinoxylan derived from barley husks. The xylan

fraction in barley husks is about 40‐50%. Apart from xylan barley husks contain e.g. starch

and cellulose.




Feed stock for xylan production

• Availability of husks/hulls

• 70 000 – 100 000 tons/year in Sweden

• > 5 000 000 tons/year in Europe

• Low value by-product – no competition with food

• Alternative end-use of feed stock:

• animal feed - not ideal from nutrition point of

view

• incineration – inefficient due to high ash content

The availability of xylan in agricultural by‐products is huge. More than 5 000 000 tons of

husks and hulls are generated in Europe every year. Husks and hulls are today a low‐value

by‐product which is not competing with food. Alternative end‐uses such as animal feed and

incineration for energy extraction are limited. Husks and hulls have limited nutrition value

and are therefore not ideal from an animal feed point of view. Incineration of husks and

hulls is inefficient due to high ash content.




From agriculture by-products to xylan-basedbarrier in multilayer packaging

Grains are peeled and the husks and hulls goes into the process. The grain itself goes for

food production. Xylan is isolated by extraction and a powder is generated. The powder is

mixed with additives and dispersed/dissolved in water. Dispersion coating is used to apply

the barrier layer onto paper, cardboard or plastics. The material can then be further

coated, converted and filled to form complete packages with barrier properties.




Comparison oxygen barrier properties

OTR (cc/m2/day)

Aluminium foil << 1

Xylan-based barrier < 10

EVOH < 10

PVdC < 10

PA MXD6 50

OPET 250

LDPE 10 000

5 µm, 23°C, 50% RH

The table shows a comparison of barrier properties of xylan‐based coatings and

commercially available barrier materials. A xylan‐based coating of 5 g/m2 gives rise to

oxygen barrier properties below 10 cc/m2/day. This is in the same range as the synthetic

barrier plastic EVOH.




Excellent grease barrier properties foradvanced applications

Coated side

Reverse side

• KIT-level 12 can be obtained onto

suitable paper and board substrates

• Xylan-based barrier resists penetrationof aggressive substances such asetheric oils

Xylan‐based coatings also exhibit excellent grease barrier properties. KIT level 12 can be

obtained onto paper and board based substrates. It can also resist penetration of

aggressive substances such as etheric oils.




Example of end-use applications

Exemple of suitable end‐uses for xylan‐based barriers are board and paper based

packaging for dry and greasy foods such as snacks, dehydrated soups and sauces, coffee,

spices and petfood. In the future xylan‐based coatings could potentially also be used in

liquid packaging board.




Process of application: dispersion coating

• Several coating techniques possible e.g. blade

coating, air knife, curtain coating, roll coating

• Application onto paper, board and plastics

• Coating trials in industrial and pilot scale have

showed

– Good processability

– No blocking

– No blistering

Coating trial at UMV Coating

Systems, Säffle

Xylan‐based coatings are applied by dispersion coating. Several techniques could be used

such as roll coating, air knife, curtain coating and blade coating.

Application onto paper and cardboard is advantageous since this type of substrates lack

barrier properties by the nature. In addition dispersion coating is an available technique in

paper and cardboard production and barrier properties can thus be applied online or

offline. A further advantage is that a renewable barrier coating is added onto a renewable

base substrate.

Coating trials have shown that the processability of xylan‐based coatings is good. The

material has a low tendency to block and form blisters.




Viscosity of dispersion

Viscosity for slurry with (top curve) and without (bottom curve) filler.

T=45°CT=30°C

The xylan‐based slurry shows a shear thinning behavior. The viscosity is strongly dependent

on the xylan concentration which limits the maximum dry content. The dry content could

thus be increased by addition of inorganic fillers. The viscosity decreases with increased

temperature. Application in elevated temperature , e.g. 45 °C, can enable a higher

coat weight and reduce the amount of water that needs to be dried off.




Effect of precoating

13

Precoating

Xylan-based coating

Board / Paper

Board / Paper

Xylan-based coating

• Reduced coat weight of barrier coating

• Improved properties

• Cost-efficient solution

In order to get good barrier values, the substrate needs to be homogeneous and not too

porous. By applying a precoating onto the paper or cardboard, a more even surface is

created.

Also the water penetration into the hydrophilic paper or board is reduced by precoating. If

the water‐based xylan coating is absorbed into the paper or board, an uneven xylan‐based

coating layer is obtained resulting in deteriorated barrier properties. Absorption of the

water‐based xylan coating into the paper or board can also result in fiber rising which

penetrates the barrier layer and creates pinholes.





Cardboard

Precoating

Xylan-based coating

Cross section SEM picture of a multilayer material consisting of cardboard, precoating and

xylan‐based coating.





Board with / without precoating Xylan-based coating

#Pre-coating

type

Coat

weight

[g/m2]

Precoating

Water

absorption

COBB

[g/m2]

Surface

roughness

Bendtsen

[ml/min]

Coat

weight

[g/m2]

Grease

barrier

KIT

Oxygen

barrier

OTR

[cc/m2/day]

1 - 0 29.8 ±0.6 414±34 10 8 ±0.6 >100

2 A 6 8.7±3.0 222±40 10 12 ±0 3.5

3 B 6 8.2±3.5 235±39 10 12 ±0 8.6

4 C 6 11.8±2.9 269±38 10 12 ±0 6.9

The table illustrates the effect of precoating on the oxygen barrier properties of the xylan‐

based coating. The water absorption and surface roughness have been measured on

precoated and non‐precoated board. The grease and oxygen barrier properties obtained

when subsequently applying the xylan‐based coating onto these boards are also presented.

The oxygen barrier properties are clearly improved for samples with precoating compared

to the sample without precoating. The precoating formulation can be optimized for the

current paper or board substrate. However as can be seen in the table, the use of different

precoating types in this study only had a slight effect on the oxygen barrier properties

obtained from the xylan‐based coating.




Precoating: Prevention of blocking byadding filler

Subtrate Amount of filler Time

min

Load

kg

Temp. Level o f b lock ing

MG, 50 g/m2 non 20 10 23°C 4

MG, 50 g/m2 low 20 10 23°C 4

MG, 50 g/m2 medium 20 10 23°C 1

MG, 50 g/m2 high 20 10 23°C 1

MG, 50 g/m2 non 50 4 105°C 6

MG, 50 g/m2 low 50 4 105°C 6

MG, 50 g/m2 medium 50 4 105°C 2

MG, 50 g/m2 high 50 4 105°C 1

Qualitative evaluation of blocking :Level 1= no blocking and Level 7 = fiber tear

Precoating chemicals have shown high tendency to block. The effect of the addition of

inorganic filler on blocking tendency was studied.

Three different filler levels were added (low, medium and high) based on dry content of

precoating dispersion. Stripes of MG‐paper 7x29 cm were cut and coated using K‐Control

Coater 202. The samples were dryed in oven at 105°C for 2 minutes. Two samples were put

together topside vs coating and were covered with a metal plate and a weight of 10 or 4 kg

in ambient temperature or 105 °C. After 20‐50 minutes the metal plate was removed and

blocking was evaluated by tearing the samples apart from each other. The level of blocking

was graded at a 7‐grade scale were 1 relates to no blocking and 7 relates to fiber tear.

The results show that a medium or high filler level in the coating formulation strongly

reduces the blocking tendency of the coating.




Paper board

Further conversion – Extrusion coating ofmoisture barrier

• Extrusion coating of moisture barrier onto

paper board with xylan-based coating

• Xylan-based barrier could withstand the

extrusion coating process

• Adhesion measured with Y-peel

Machine setup for Y-peel test

Pre-coatingXylan-based coating

LDPE

To achieve a multilayer material with moisture barrier properties as well as heat sealability

xylan‐based coating could be combined with extrusion coated plastics. The xylan‐based

coating can resist the extrusion coating process and a good adhesion could be obtained

between the xylan‐based coating and the extrusion coated plastic. In this project the

adhesion was measured with Y‐peel. In the Y‐peel test, the board is fixed in a 3‐clamp

arrangement were the free ends are fixed at a constant angle 90°. The method has got a

better repeatability than e.g. T‐peel.




Adhesion

Good adhesion

Y‐peel test was used to measure the adhesion between the xylan‐based coating and board,

between the xylan‐based coating and pre‐coating, and between the xylan‐based coating

and LDPE. Uncoated board with LDPE was used as reference. When measuring the

adhesion between the xylan‐based coating and board, the fracture was cohesive which

means that the fracture was within the board. Fibers could clearly be seen on the fracture

surface.

The adhesion between the xylan‐based coating and LDPE (precoating+X/LDPE and X/LDPE)

was lower than the adhesion between the uncoated board and LDPE (Board/LDPE). This

may depend on better mechanical interlocking due to the higher surface roughness of

uncoated board compared to xylan‐based coating onto uncoated board and pre‐coated

board. The adhesion between LDPE and the xylan‐based coating on uncoated and on pre‐

coated board were similar.

There are no standard values to rank the adhesion results since it depends on application.

According to a board manufacturer, WDdesc > 0.3mJ/mm means excellent adhesion,

WDdesc ≈ 0.3mJ/mm means good adhesion. The LDPE adhesion can be improved by

further corona treatment of the substrate and also by ozone treatment of LDPE in the

extrusion nip.




Customer project: Xylan-based barrier asgrease and aroma barrier in industrial sacks

• Development project in cooperation

with two customers

• Three problems to solve which were all

related to penetration of etheric oils:

– Grease stains on sack paper

– Labels fell off

– Loss of weight during storage (up to 5%)

An industrial test to verify xylan‐based coating as grease and aroma barrier in industrial

sacks for spices was performed in cooperation with sack manufacturer Jonsac AB and spice

producer Bodén & Lindeberg. had three problems related to the current barrier function of

their paper sacks:

1.Grease stains were formed on the outside of the sack due to penetration of etheric oils.2.Labels fell off due to grease penetration.

3.The weight of the sacks was drastically reduced during storage due to e.g. penetration of

etheric substances.




OXYGEN

GREASE

AROMA

• Dispersion coating of xylan-based

barrier in industrial scale

• Sack production in industrial scale

• Filling with product (spices)

• Storage test and evaluation

Xylan-based barrier

LDPE

Sack paper

Customer project: Xylan-based barrier asgrease and aroma barrier in industrial sacks

A xylan‐based coating was applied onto LDPE‐coated Kraft paper by dispersion coating.

Three layer sacks were manufactured of which the layer coated with xylan‐based barrier

was put in the middle. 200 sacks were filled with each 20 kg of cardamom in an industrial

filling process and those were stored for 6‐8 weeks in a warm storage area. The sacks were

visually evaluated and weighed and the results were compared to three layer reference

sacks without xylan‐based coating.




Customer project: Grease barrier problemsolved!

Reference With xylan-based barrier

”You have certainly been successful with the barrier. It works very wellfor the packaging of etheric oils and grease containing spices.

We have had problems with fat stains on the outside of the paper sacks

and labels that were falling off due to etheric oils penetrating the bags.With a xylan-based barrier we could eliminate this problem.”

Peter Karlsson, Stores Manager, Bodén & Lindeberg

The results showed that a xylan‐based barrier layer in the sack construction gave rise to

excellent grease barrier properties for the current application. There were no grease stains

on the outside of the package and the labels were still stuck on the sacks containing a

xylan‐based coating. The weight reduction during storage was just one tenth of the weight

reduction of the reference bags (0.5% instead of 5%).




Customer project: Xylan-based coating asoxygen barrier in crisp bags

• Project performed with packaging

material converter

• Driver: to find sustainable alternatives

to metalized film

• Application: paper-based bags for

potato crisps

In another project crisp bags with a xylan‐based oxygen barrier instead of metalized foil

were produced to obtain a more sustainable packaging solution. The project was

performed in cooperation with a converter and a crisp producer.




Customer project: Xylan-based coating asoxygen barrier in crisp bags

• Dispersion coating of xylan-based coating

• Extrusion coating of moisture barrier

• Conversion to crisp bags in conventional

bag filling equipment

SampleWVTR

(38 ° C, 90% RH)

g/m2/day

WVTR(23 °̊ C, 50% RH)

g/m2/day

OTR(23 ° C, 50% RH)

cc/m2/day

Paper/pre-coating/xylan-based coating/LDPE 13.6 1.4 3.8

Pre‐coating as well as xylan‐based coating were applied onto MG‐paper using dispersion

coating equipment with two coating stations. The material was further coated with a layer

of LDPE using extrusion coating equipment.

The oxygen transmission rate as well as the water vapor transmission rate (ASTM F 1249‐

05) of the multilayer material were measured. The barrier properties obtained were

suitable for the contemplated application. The multilayer material was further converted

to crisp bags and filled with potato crisps. The conversion was successfully done with the

existing bag conversion and filling equipment.




Status: Development in cooperationwith customers

• Development projects in lab, pilot and

industrial scale with potential customers

• Strategic development projects with

board and paper producers

• Market entry application projects with

brand owners and converters




Status: Pilot production plant

• Pilot unit for xylan production

• Optimisation of production

process for further upscaling

• Production of raw material for

customer trials and commercial

material for niche applications




Customer projects and product/process optimisation will

form base for volume production decision

2009 2010 2011 2012

Start pilot Decision

for volume

production

Customer projects: lab tests, pilot & industrial trials

Product development

Process optimisation




Summary

• Xylan-based barrier - a renewable alternative to

synthetic plastics and metal foils

• Optimization of multi-layer structure important

• Development of xylan-based barrier in cooperation

with customer to prepare for commercial use




Thanks for yourattention!

Please

remember

to

turn

in

your evaluation sheet...

PRESENTED BY

Lisa BindgårdM.Sc. in Engineering Biology

Xylophane AB

E-mail: [email protected]

Xylophane

renewable xylan-based barrier for packaging3_1

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