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

Transcription

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

2 Contents 1. Characteristics of Adhesive Resins 2. New Developments in Adhesive Resins for Oriented Barrier // PP Film Applications 3. Summary

3 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

4 What Are Adhesive Resins and What Are Their Basic Features? Definition: Adhesive resins are resins that are able to combine different materials. 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.

5 Functions of Adhesive Resins Gas barrier material PA, EVOH, Metal, etc. Adhesive resins Moisture barrier material Polyethylene Polypropylene Adhesive resins add new functions to packaging by adhering polyolefins with polar materials Applications Bottles: Beverages, Pesticides Films: Food Oriented films: Food Coating films: Food

6 Chemical Structure of Adhesive Resins Polyolefin Adhesive resin Functional groups incorporated Graft reaction PE or PP :MAH, etc.

7 How Do Adhesive Resins Adhere? (1) To polyolefin By diffusion (Compatibility) (2) To polar material By chemical reaction PO AD Polar Material PA EVOH PET, etc. Diffusion Chemical reaction

8 Bonding by Thermal Reaction Temperature Time Pressure 3 Factors Heat energy Wetting Phenomenon Processing temperature Processing speed Processing pressure Processing Adhesive strength depends on processing conditions.

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

10 Applications of Adhesive Resins Structure: PET//PE/tie/EVOH/tie/PE Structure: PP/PP/tie/EVOH/tie/PP Structure: HD/Reg/tie/EVOH/tie/HD Structure: PE/tie/PA/EVOH/PA/tie/PE

11 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 3. Summary

12 Oriented Barrier Film Applications Shrinkable film (fresh meat, cheese), Stretch film, Casing film, Thermoformed film, etc. PVDC//EVA PA//PE EVOH//PE Poor thermal resistance Not enough for intensive boiling, retort due to PE structure Barrier // PP film: Good thermal resistance Higher mechanical properties (Stiffness, Puncture, etc.) Longer shelf-life, Good for a wide range of products

13 Viscoelasticity of PE and PP-Based Adhesive 1.E+10 1.E+09 3 /min, 1 Hz E' [Pa] 1.E+08 1.E+07 PP based PE based 1.E+06 1.E Temperature [deg C] PP-based adhesive resin maintains the elastic modulus at over 120. PP-based resin is expected to exhibit good adhesion at 120.

14 Adhesion Strength at Elevated Temperature Film: PP or PE/tie/EVOH=40/10/20 microns (non-stretch film) Adhesion strength [N/15mm] PP based PE based PP-based adhesives exhibit good adhesion at elevated temperature.

15 Adhesion Performance of Conventional Grades after Orientation PP/tie/EVOH=160/40/40 microns Stretching Stretching Temp.: 100 degrees C Adhesion strength (N/15mm) Original 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.

16 Target and Experimental Conditions Target Adhesion strength 1 N/15mm at 23 Experimental conditions + at 120 Film: PP/tie/EVOH=160/40/40 microns Stretching Stretching Temp.: 100 degrees C Draw ratio: 3 X 3 (1.5 m/min)

17 Hypotheses of Low Adhesion after Orientation There are two hypotheses: (1) Decrease of chemical bonding density by orientation 3 3 :Bonding point (2) Destruction of chemical bonds by stress generated during orientation EVOH, PA Adhesive resin

18 How to Improve Adhesion Performance-1 First hypothesis for low adhesion: Decrease of chemical bonding density by orientation 3 3 :Bonding point Counter concept Increasing chemical bonding points Increase functional groups of adhesive resin

19 Effect of Increased Functional Groups PP/tie/PA=160/40/40 microns Stretching Stretching Temp.: 100 degrees C Draw ratio: 3 X 3 (1.5 m/min) Adhesion strength (N/15mm) Grafting ratio Adhesion increases as the grafting ratio of adhesive resin rises. However, the improvement is insignificant.

20 How to Improve Adhesion Performance-2 Second hypothesis for low adhesion: Destruction of chemical bonds by stress generated during orientation EVOH, PA Adhesive resin Counter concept Reducing stress acting on the interface Make tie layer low modulus

21 How to Improve Adhesion Performance-2 (1) High modulus of adhesive resin Crystal phase of reacting molecule Crystal phase of matrix EVOH, PA Adhesive resin Orientation Reacting point is inflexible. Reacting point is destroyed. (2) Low modulus of adhesive resin EVOH, PA Adhesive resin Orientation Reacting point is flexible. Reacting point is kept.

22 Measures to Make Tie Layer Low Modulus For making tie layer low modulus: Decrease crystallinity of matrix PP 1. Use high ethylene content random polypropylene (High C2-PP) as base material 2. Modify matrix PP using ethylene-based elastomer (C2-EL)

23 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 strength [N/15mm] Conventional grade High C2-PP C2-EL Adhesion is improved, but the performance is not enough, especially at elevated temperature.

24 New Design for Oriented Barrier // PP Film For making tie layer low modulus: Decrease crystallinity of matrix PP Trade-off For good adhesion at elevated temperature Increase crystallinity of matrix PP Requested design Making adhesive low modulus, while maintaining its thermal mechanical resistance, is needed.

25 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) Adhesion strength [N/15mm] Conventional grade High C2-PP C2-EL New grade New grade shows good adhesion from 23 to 120.

26 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 strength [N/15mm] New grade High C2-PP C2-EL Young modulus [MPa] at 23 Conventional grade 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.

27 Viscoelastic Comparison 3 /min, 1 Hz 1.E+10 1.E+09 Conventional grade High C2r- PP New grade E' [Pa] 1.E+08 1.E+07 1.E+06 1.E Temperature [deg C] 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.

28 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.

29 Thank you New Technology for Oriented Barrier // PP Film Applications