New Developments in Adhesive Resins for Oriented Barrier // PP Film Applications. Development Center Materials Lab.

New Developments in

New Developments in

Adhesive Resins

Adhesive Resins

Applications

Applications

for Oriented Barrier // PP Film

for Oriented Barrier // PP Film

Development Center Materials Lab. HIROTAKA UOSAKI

Contents

1. Characteristics of Adhesive Resins

2. New Developments in Adhesive Resins

for Oriented Barrier // PP Film Applications

3. Summary

Contents

1. Characteristics of Adhesive Resins

a. What Are Adhesive Resins and What Are Their Basic Features?

b. Functions of Adhesive Resins

c. Applications of Adhesive Resins

2. New Developments in Adhesive Resins

for Oriented Barrier // PP Film Applications

3. Summary

What Are Adhesive Resins and What Are Their Basic Features?

Basic Features:

1．They have a wide adhesion range

Adhesive resins bond to PA, EVOH, polystyrene, polyesters,

polycarbonate, polyolefins and metals such as steel and aluminum.

2．They have durability

Adhesive resins exhibit durable adhesion after aging treatment, retort treatment and immersion in gasoline, etc.

3．They offer easy processing

Adhesive resins can be used in a wide variety of co-extrusion processes for bottles, tubes, sheets and films.

Definition:

Adhesive resins are resins that are able to combine different materials.

Functions of Adhesive Resins

ＰＡ, EVOH, Metal, etc. Polyethylene Polypropylene

Adhesive

Adhesive

resins

resins

Gas barrier material

Moisture barrier material

¾ Bottles: Beverages, Pesticides ¾ Films: Food

¾ Oriented films: Food ¾ Coating films: Food Applications

Adhesive resins add new functions to packaging by

adhering polyolefinｓ with polar materials

Chemical Structure of Adhesive Resins

Polyolefin

PE or PP

Adhesive resin

：MAH, etc.

Graft reaction

Functional groups

incorporated

How Do Adhesive Resins Adhere?

PO AD Polar Material PA EVOH PET, etc. Chemical reaction Diffusion

(1) To polyolefin

⇒ By diffusion (Compatibility)

Bonding by Thermal Reaction

3 Factors Phenomenon Processing Heat energy Processing pressure Processing speed Processing temperature

Temperature Time Pressure

Wetting

Co-Extrusion Processes

Resin A Resin B Cast film Sheets Blown film Co-Extrusion Blow bottles Single, Tandem Co-extrusion Extrusion coating Sand lamination Adhesive lamination Solvent, Water, etc. Thermal lamination

Applications of Adhesive Resins

Structure:

PET//PE/tie/EVOH/tie/PE

Structure:

PP/PP/tie/EVOH/tie/PP

Structure:

Contents

1. Characteristics of Adhesive Resins

2. New Developments in Adhesive Resins

for Oriented Barrier // PP Film Applications

a. Advantages of Barrier // PP Oriented Film Applications

b. Targets and Concept for Development

c. Newly Developed Adhesive Resins

Oriented Barrier Film Applications

9PVDC//EVA 9PA//PE

9EVOH//PE

Shrinkable film (fresh meat, cheese), Stretch film, Casing film, Thermoformed film, etc.

9Good thermal resistance

9Higher mechanical properties (Stiffness, Puncture, etc.) Poor thermal resistance

⇒ Not enough for intensive boiling, retort due to PE structure

Barrier // PP film:

Longer shelf-life,

1.E+05 1.E+06 1.E+07 1.E+08 1.E+09 1.E+10 50 60 70 80 90 100 110 120 130 140 150 Temperature [deg C] E' [Pa ] PP based PEbased

Viscoelasticity of PE and PP-Based Adhesive

85 ℃ 120 ℃

3 ℃/min, 1 Hz

PP-based adhesive resin maintains the elastic modulus at over 120 ℃.

Adhesion Strength at Elevated Temperature

Film: PP or PE/tie/EVOH=40/10/20 microns (non-stretch film)

PP-based adhesives exhibit good adhesion at elevated temperature. 0 2 4 6 8 10 23_℃ 85_℃ 120_℃ A d he s ion s tr e ngt h [ N /1 5 m m ] PP based PE based

Adhesion Performance of Conventional Grades after Orientation

In the case of conventional grades,

adhesion strength is drastically decreased by orientation. ⇒ Target adhesion in this study is 1 N/15mm after 3 X 3

orientation.

PP/tie/EVOH=160/40/40 microns → Stretching Stretching Temp.: 100 degrees C

0 2 4 6 8 10 12 14 16 Original 2×2 3×3 Ad he s ion 　 st reng th（N /15m m )

Target and Experimental Conditions

Target

Adhesion strength

≧ 1 N/15mm at 23 ℃

+ at 120

℃

Experimental conditions

Film: PP/tie/EVOH=160/40/40 microns

→ Stretching

Stretching Temp.: 100 degrees C

Draw ratio: 3 X 3 (1.5 m/min)

Hypotheses of Low Adhesion after Orientation

There are two hypotheses:

(1) Decrease of chemical bonding density by orientation

(2) Destruction of chemical bonds

by stress generated during orientation

3×3

：Bonding point

Adhesive resin

How to Improve Adhesion Performance-1

3×3 ：Bonding point

Counter concept

Increasing chemical bonding points

⇒ Increase functional groups of adhesive resin

First hypothesis for low adhesion:

Effect of Increased Functional Groups

Adhesion increases as the grafting ratio of adhesive resin rises. However, the improvement is insignificant.

PP/tie/PA=160/40/40 microns → Stretching Stretching Temp.: 100 degrees C

Draw ratio: 3 X 3 (1.5 m/min)

0.0 0.5 1.0 1.5 2.0 0 1 2 3 4 5 Grafting ratio Adhesi on 　 st re ngt h （N/ 1 5 mm)

How to Improve Adhesion Performance-2

Counter concept

Reducing stress acting on

the interface

⇒ Make tie layer low modulus

Second hypothesis for low adhesion:

Destruction of chemical bonds

by stress generated during orientation

Adhesive resin

How to Improve Adhesion Performance-2

Adhesive resin Adhesive resin EVOH, PA

(1) High modulus of adhesive resin

Crystal phase of matrix

Crystal phase of reacting molecule

(2) Low modulus of adhesive resin

Reacting point is flexible. Reacting point is inflexible.

EVOH, PA

Orientation

Orientation

Reacting point is destroyed.

Measures to Make Tie Layer Low Modulus

1. Use high ethylene content random polypropylene

(High C2-PP)

as base material

2. Modify matrix PP using

ethylene-based elastomer

(C2-EL)

For making tie layer low modulus:

Adhesion Comparison-1

PP/tie/EVOH=160/40/40 microns → Stretching Stretching Temp.: 100 degrees C

Draw ratio: 3 X 3 (1.5 m/min)

Adhesion is improved, but the performance is not enough, especially at elevated temperature.

0.0 0.5 1.0 1.5 2.0 23_℃ 85_℃ 120_℃ A d he s ion s tr e ngt h [ N /1 5 m m ] Conventional grade High C2-PP C2-EL

New Design for Oriented Barrier // PP Film

For making tie layer low modulus:

⇒ Decrease crystallinity of matrix PP

For good adhesion at elevated temperature

⇒ Increase crystallinity of matrix PP

Trade-off

Requested design

Making adhesive low modulus, while maintaining

its thermal mechanical resistance, is needed.

Adhesion Comparison-2

PP/tie/EVOH=160/40/40 microns → Stretching Stretching Temp.: 100 degrees C

Draw ratio: 3 X 3 (1.5 m/min)

New grade shows good adhesion from 23 ℃ to 120 ℃.

0.0 0.5 1.0 1.5 2.0 23_℃ 85_℃ 120_℃ A d he s ion s tr e ngt h [ N /1 5 m m ] Conventional grade High C2-PP C2-EL New grade

0 1 2 3

200 300 400 500 600 700 Young modulus [MPa]

A dhe s io n s tr e ngt h [N /15 mm]

Effect of Young Modulus to Adhesion

PP/tie/EVOH=160/40/40 microns → Stretching Stretching Temp.: 100 degrees C

Draw ratio: 3 X 3 (1.5 m/min)

Adhesion is improved by lowering the modulus of the tie layer.

The new grade shows the best performance at 23 ℃ because of the lowest modulus.

High C2-PP

New grade

C2-EL

at 23 ℃

Viscoelastic Comparison

The new grade maintains the elastic modulus at over 120 ℃, while high C2-PP decreases from 110 ℃.

⇒ The new grade exhibits good adhesion at 120 ℃.

3 ℃/min, 1 Hz 1.E+05 1.E+06 1.E+07 1.E+08 1.E+09 1.E+10 50 60 70 80 90 100 110 120 130 140 150 Temperature [deg C] E' [P a] Conventional grade High C2r- PP New grade

Summary

New improvements in adhesive resins for oriented PP

barrier film applications are:

1. New designs involve making the tie layer low

modulus while maintaining its thermal mechanical

resistance.

2. Adhesion is improved to over 1N/15mm and

adhesion performance is maintained at elevated

temperatures.

Thank you

New Technology

for

Oriented Barrier // PP Film

Applications