Enhancement of Appearance, Stiffness, and Toughness …leaders.4spe.org/spe/conferences/ANTEC2017/papers/66.pdf · ENHANCEMENT OF APPEARANCE, STIFFNESS, AND TOUGHNESS ... 25.4-micron

ENHANCEMENT OF APPEARANCE, STIFFNESS, AND TOUGHNESS OF OLEFINIC BLOWN FILMS WITH CYCIC OLEFIN COPOLYMERS

Paul D. Tatarka

TOPAS Advanced Polymers, Inc., Florence, KY 41042

Abstract

Cyclic olefin copolymers (COC) offer many benefits for packaging films, including stiffness, strength, transparency, gloss, heat resistance, improved thermoforming, moisture, and alcohol barrier to name a few. Using full factorial experimental design, COC glass transition temperature, COC modification and blow-up ratio were studied to show how COC influences performance of several key blown film properties. Three-layer packaging films can be engineered with modified COC to provide higher than expected toughness, strength, and stiffness. By splitting COC into at least two layers in five layer structures, further significant property enhancements are possible without changing COC content.

Introduction

Cyclic olefin copolymers (COC) are amorphous olefinic copolymers consisting of ethylene and norbornene, a bicyclic olefin derived from ethylene and di-cyclopentadiene (DCPD). Steric hindrance, provided by the randomly distributed bulky ring-like norbornene groups built into the polymer chains, prevents ethylene from crystallizing. Glass transition temperature is primarily determined by the fraction of norbornene. Packaging grades of COC are polymerized using efficient single-site catalysts followed by post-polymerization filtration, resulting in low extractables and uncompromised purity, demanded by many food, medical and pharmaceutical applications.

Over the last fifteen years, cyclic olefin copolymers have become a critical and valuable component in numerous packaging applications globally. These include soft shrink, sustainability-promoting TD and MD shrink labels, easy tear pouches, flexible and rigid thermoformed trays, twist wrap, protective packaging, heat seal and barrier films.

Many valuable benefits are provided by COC to commercial packaging films [1-7]. Applications seldom share identical COC value proposition. Low adsorption of medicinal chemistries such as nicotine,

lidocaine and menthol plus good heat sealing properties enable easy-to-extrude polyolefin-based PAN replacement films. Ductility at temperatures 15-25⁰C above Tg coupled with high stiffness imparts excellent thermoforming properties to olefinic film and sheet, enabling uniform material distribution in formed cavity walls and corners. Stiffness, controlled ductility, and linear molecular structure impart easy tear features to polyolefin bags and pouches. Transparency, stiffness, dead-fold, and controlled yield elongation for easy cutting have enabled superior wrapping performance and aesthetics for many olefin-based candy twist films. Very low water, alcohol and acetic acid permeability enable transparent high barrier olefinic pouches, forming films and blister packaging. Rubbery amorphous structure at heat sealing temperatures imparts melt stability, stiffness, and strength, thereby improving performance of olefinic sealant films. Tg, COC content and degree of orientation in multi-layer polyolefin films enable broad tailoring of shrink force and temperature for soft shrink and environmentally friendly shrink label film applications.

Design of Experiments (DOE)

Goal of this DOE is not to create films optimized for any specific application, but to demonstrate how COC will influence PE film properties important to all flexible packaging products. When a discrete layer of COC is added to PE film, what happens to film properties? Are changes to the film influenced by COC glass transition temperature? Does diluting COC with PE compromise any advantage of using COC in the first place? By answering these questions, this study will illustrate many insightful trends, providing film and package designers clear options on how best to use COC.

DOE methods are effective analytic tools. Full 3 x 3 factorial design employs three independent variables: COC Tg, blow up ratio (BUR) and COC modification, each at three levels. COC Tg is a continuous variable, but comprises of three discrete grades with respective Tg of 65, 78 and 110⁰C. BUR of 2.0:1, 2.5:1 and 3.0:1 is another continuous variable.

SPE ANTEC® Anaheim 2017 / 1063

COC modification, a categorical variable, is modification of discrete COC layer. Three levels are unmodified, or neat COC, and COC pellet blends with either 30% LLDPE or 30% COC elastomer. Two sets of non-COC film structures produced at three BUR have been included. Control set consists of three-layer structure with the same LLDPE-LDPE compositional ratio in all layers, identical to the skin layers found in all experimental structures. Generic set consists of heavier gauge three-layer film each layer consisting of the same LDPE rich composition. Experimental trial plan and properties for all 33 films are shown in Table 1.

Experimental Materials [8-14]

All experimental films are 90-micron (3.54 mil) three-layer structures. Both outer layer consists of 93/7 LLDPE/LDPE. Core layer consists either of 100 percent unmodified COC or 70/30 COC/COC elastomer or LLDPE. Layer ratio is 40/20/40 percent or 36/18/36 microns (1.4/0.7/1.4 mil). Exxon-Mobil Exceed™ 2018KB LLDPE has C6 comonomer, 0.918 g/cc density, 2.0 dg/min melt index with process aid, 800 ppm slip and 2,500 ppm antiblock. Thai PPT 2426H tubular reactor grade LDPE (similar to Lupolen® 2427 H from Lyondell Basell) has 0.924 g/cc density and 1.90 dg/min melt index. Exxon-Mobil Exceed™ 3512CB LLDPE has C6 comonomer, 0.912 g/cc density, 3.5 dg/min melt index without antiblock, slip and processing aid. TOPAS 9506-F500, 8007F-600 and 7010F-600 COC have nominal Tg of 65, 78 and 110⁰C and melt index of 5.5, 10.1 and 9.0 dg/min (230⁰C, 2.16 kg) respectively. COC Elastomer, TOPAS E-140, is a largely amorphous polymer with low level crystallinity with density of 0.94 g/cc. E-140 is a random copolymer without hard and soft segments or dispersed rubber phase morphologies. Melt index, measured at 230⁰C; 2.16 kg, is 2.7 dg/min.

Film appearance is critical for most applications. This fact strongly influenced choices of LLDPE and LDPE used in this study. According to the manufacturer, 25.4-micron (1-mil) blown film of Exceed 2018KB has low haze of 12 percent. 7% LDPE was blended into LLDPE for improvement of process stability and elimination of melt fracture without creating property detriments.

Blown Film Extrusion Process

Three layer blown film line was manufactured by Tomi Machinery Co., Ltd (Japan). Extruder configuration and film fabrication conditions are summarized in Table 2 and Table 3. Film quality was very good. Property Measurement Methods

Several key properties were measured on 90 and 115-micron blown films at room temperature. All measurements were made in accordance with acceptable international methodologies. Total haze was measured per JIS 7136 (ISO 14782) using Haze-Guard 2 manufactured by Toyo Seiki. For internal haze, glass cell and polyethylene glycol solution was used. Surface haze was calculated by subtracting internal from total haze. Tearing strength was measured using transverse tearing specimen at rate of 200 mm/min (7.87 inch/min) at grip distance of 60 mm (2.4 inch) on Tensilon RTM-100 test machine per JIS K7128-3 (ISO 34-1:2004). Determination of Impact Resistance by the Free-Falling Dart Method (ISO 7765-2: 1994(E)) was used to quantify film toughness. Instron Dynatup 9250HV test conditions include 4.4 meter/sec (866 FPM) test speed, 20-mm (0.79-inch) diameter polished tup and 40-mm (1.57-inch) diameter specimen support clamp. Tensile properties were measured using Type 5 specimens at rate of 200 mm/min (7.87 inch/min) on Tensilon RTM-100 test machine per JIS K7127 (ISO 527-3: 1995, Plastics- Determination of Tensile Properties – Part 3). DOE analysis was done using Minitab 17 statistical software. All properties are summarized in Table 1.

Discussion

Stepwise linear regression method was used to fit the best linear model for each property from three main effects: COC Tg, BUR, and COC Modifier, and from all interactions among them. For most properties, interactions were not significant contributors to the fitted model. Therefore, simplified main effects plots are used to show how changes in film properties are influenced by changes among these independent variables.

Main effects plots are graphical snapshots summarizing statistical analysis of each film property. Three linear graphs are shown for each independent design variable: COC Tg, BUR and COC Modifier. Within each graph, data points summarize the effect at


each level. Specifically, these data points are fitted means, derived from the statistical model based on all nine observations at a given level. Linear connections among the data points from continuous independent variable, such as COC Tg and BUR, are valid mathematically. However, linear connection between categorical variables such as COC modifier is not and is depicted as such only as a visual aid. Dashed line which bisects all three main effect graphs show the average response of all 27 DOE experiments. Two additional heavy dashed lines each representing average response for 90-micron 93/7 m-h-LLDPE/LDPE control and for 115-micron 80/20 LDPE/m-h-LLDPE generic films. Average response for these films are calculated from three BUR experiments. Haze

Within DOE, overall total haze overall averaged of 7.1 percent (Figure 1). Non-COC control and generic polyolefin films averaged 10.5 and 10.4 percent respectively. These differences are noticeable to the naked eye. Simply sandwiching 18-micron discrete COC layer in between two blend layers of 93% m-h-LLDPE / 7% LDPE lowered average total haze by an unexpected average of 3.5 percent! Within this DOE, total haze for all individual COC-LLDPE compositions varied between 5.9 and 8.0 percent. But average effect for each independent variable at any level was small. COC Tg did not have any detectable influence, about 0.2 percent. BUR and COC modifier influenced total haze by less than 1 percent.

Figure 1: Main Effects Plot for Total Haze

Total haze is comprised of internal and surface haze. Main effects plot for internal haze identifies COC modifier as the only significant independent variable (Figure 2). Internal haze shows no change with respect

to changes in level of COC Tg and BUR. DOE average for all COC-LLDPE films is 3.5 percent, which is significantly lower than 4.9 percent control film. Unmodified COC had about 0.5 percent lower internal haze on average than modified COC films with either LLDPE or E-140. BUR and COC modifier influences surface haze (Figure 3). DOE average for all COC-LLDPE films is 3.6 percent, which is substantially lower than 5.6 percent control film. Both BUR and COC modifier had modest effect. From 2:1 to 3:1, BUR increased surface haze linearly by little more than 1 percent. Unmodified COC had about 1 percent lower haze on average than modified COC films with either LLDPE or E-140. Presence of single discrete layer of COC in LLDPE film has significant influence on all haze properties. However, these haze properties are less sensitive to process change and COC composition. Benefits of two discrete COC layers or splitting LLDPE into multiple layers will be discussed later in this paper.

Figure 2: Main Effects Plots for Internal Haze

Figure 3: Main Efffects Plot for Surface Haze


Tear Strength

Enabled by linear molecular chains, narrow molecular weight distribution, and sterically hindered bulky norbornene groups, COC imparts controllable tear property in many packaging films, especially pouches and bags. Linear tear can be tailored by COC content, grade, location within the film structure and processing conditions. Alignment of the molecular chains in the direction of flow or orientation will reduce tear resistance. Depending on processing conditions, including blow and draw ratios, tear resistance can be reduced in MD, TD or balanced in both directions. However, gauge variation and non-uniform web tension during film winding may contribute to inconsistencies.

Inserting single 18-micron COC layer to 90-micron LLDPE/LDPE film with a single COC layer reduces average TD and MD tear strength from 102 to 71 N/mm and 96 to 70 N/mm respectively (Figures 4 & 5). TD and MD tear strength are similar, suggesting balanced orientation. Changes to BUR have no definitive effect on tear properties in this study. 110⁰C Tg COC lowers average TD and MD strength from about 78 to 67 and 76 to 70 N/mm respectively. COC modification with either LLDPE or E-140 lowers TD and MD tear strength from about 84-81 to 66-63 N/mm respectively. This finding is expected. E-140 and LLDPE are narrow molecular weight metallocene catalyzed linear polymers, susceptible to molecular alignment during orientation, reducing tear resistance. Unmodified 65⁰ C Tg COC, relatively speaking, provides incrementally more tear strength.

Figure 4: Main Effects Plot for TD Tear Strength

Figure 5: Main Effects Plot for MD Tear Strength Secant Modulus

Significantly higher stiffness is one of the many key benefits imparted by COC into polyolefin films. Inserting single 18-micron COC layer to 90-micron LLDPE/LDPE film on average more than doubles 1% TD and 1% MD secant modulus (TD and MD modulus) from 234 to 483 MPa and from 207 to 469 MPa respectively (Figure 6 & 7). Not surprisingly, all 90-micron COC-LLDPE/LDPE films which contains 20 percent COC are much stiffer than the 115-micron LDPE/LLDPE generic film, suggesting that gauge reduction is possible without property loss. Changes to BUR did not influence TD and MD modulus. COC Tg has small positive effect. Unmodified COC films have average TD and MD modulus of 572 and 538 MPa respectively. Adding 30% LLDPE or 30% E-140 reduces average TD modulus to 434 and 438 MPa and MD modulus to 421 and 462 MPa respectively. 30% LLDPE modification reduces total COC content from 20 to 14 weight percent. But the targeted 18-micron COC layer thickness is essentially the same, enabling preservation of much of the stiffness benefit imparted by COC.

Figure 6: Main Effects Plot for TD Secant Modulus


Figure 7: Main Effects Plot for MD Secant Modulus Impact Resistance and Toughness

Polyolefin films always have noteworthy toughness and durability. In the main effect plot, 90-micron LLDPE/LDPE control film has respectable average peak impact resistance of 89.2 N (Figure 8). Within DOE, impact resistance of all LLDPE-COC films has slightly higher average of 92.1 N. COC Tg and COC modifier have significant influence on impact resistance. Single layer addition of unmodified COC into LLDPE/LDPE films reduced average impact resistance slightly to 86.7 N. However, performance differs among COC Tg variables. Films made with 110⁰C Tg COC show decreased average impact resistance from 98 to 88.1 N. Modifiers can improve impact resistance. 30 % LLDPE and 30% E-140 added to COC increases impact resistance to 90.3 and 99.2 N respectively. Films made with 65⁰C Tg COC modified with E-140 have average impact resistance of 104.7 N; nearly 20 percent above that of the LLDPE control film and close to the average 108.7 N for 115-micron LDPE/LLDPE generic film. COC imparts toughness into polyolefin films, which become more impact resistant than equal gauge LLDPE films and may enable gauge reduction of thicker LDPE films without compromise. On average, higher molecular weight, 65⁰C Tg COC improves impact resistance by approximately 10 percent as compared against 78⁰C Tg COC, 97.8 and 90.3 N respectively. If puncture resistance is a critical value proposition for a given application, 9506F-500, not 8007F-600, must be considered a primary option.

Figure 8: Main Effects Plot for Impact Resistance

Impact energy shows similar trends (Figure 9). COC Tg and COC modifier influence impact energy too, but in a manner that depends on COC ductility. 110⁰C Tg COC decreases average impact energy from 0.92 to 0.70 J. 30% LLDPE and 30% E-140 added into unmodified COC increase average impact energy from 0.68 J to 0.77 and 0.97 J respectively. Films made with 65⁰C Tg COC modified with E-140 have average impact energy of 1.15 J, close to the 1.55 J of the 90-micon LLDPE control film.

Figure 9: Main Effects Plot for Impact Energy Tensile Properties - Yield

Adding single 18-micron COC layer into 90-micon LLDPE/LDPE film improves TD and MD tensile yield strength (Figures 10 & 11). Both control and generic films have relatively low tensile yield strength. Within DOE, TD and MD tensile yield strength on average improved from 11.2 to 14.2 MPa and 11.2 to 14.9 MPa respectively. COC modifier influenced TD and MD tensile yield strength the most. Unmodified COC provides highest average TD and MD tensile yield,


17.6 and 18.3 MPa respectively. COC modified with LLDPE reduces TD and MD tensile yield by approximately 40 percent from 17.6 to 11.0 and 18.3 to 11.4 MPa respectively. COC modified with E-140 reduces TD and MD tensile yield by less than 20 percent, from 17.6 to 14.2 and 18.3 to 14.8 MPa, suggesting better molecular compatibility.

Figure 10: Main Effects Plot for TD Yield

Figure 11: Main Effects Plot for MD Yield

Efficient COC modifier and amount are important choices that influence tensile yield. As seen in the main effects plots, diluting COC with 30% LLDPE does not provide any enhancement. Performance difference observed between LLDPE and E-140 is due to many factors, including, but not limited to molecular weight, molecular weight distribution, chemical functionality, comonomer type and content. Five to fifteen weight percent LLDPE, especially m-h-LLDPE, is an excellent and cost effective modifier for COC. However, similar amount of E-140 is expected to be more efficient due to chemical similarity.

Elongation at Yield

Control and generic films have high TD and MD elongation at yield; 90-micron LLDPE/LDPE and 115-micron LDPE/LLDPE average 74 and 84 percent and 86 and 104 percent respectively (Figures 12 & 13). Adding a discrete layer of COC to LLDPE/LDPE film significantly decreased TD and MD elongation at yield, each averaging 12 percent. COC Tg, BUR and COC modifier did not influence TD and MD elongation at yield in any meaningful way. COC has high strength and low ductility. Applications such as twist wrap and heat seal film, typically require some ductility reduction to enable easy cutting without stretching or distortion, thereby maintaining dimensional integrity of the finished product. Imparting an easy cut feature into most PE packaging films requires less than 10 weight percent COC, and often about 5 weight percent, depending on the ductility and stiffness of PE.

Figure 12: Main Effects Plot for TD Elong. at Yield

Figure 13: Main Effects Plot for MD Elong.at Yield


Break

Both control and generic films show high TD and MD tensile strength; 42.8 and 42.5 MPa for 90-micron LLDPE/LDPE and 32.6 and 19.6 MPa for 115-micron LDPE/LLDPE (Figure 14 & 15). Blown films with m-h-LLDPE strain harden more than LDPE rich films, resulting in higher TD and MD tensile strength. COC by itself has very high tensile strength. However, addition of 18-micron COC layer prevents m-h-LLDPE rich films from elongating, limiting strain hardened tensile strength. TD and MD tensile strength dropped from 42.8 to 19.4 MPa and from 42.5 to 21.6 MPa respectively.

Figure 14: Main Effects Plot for TD Break

Figure 15: Main Effects Plot for MD Break

COC Tg, specifically norbornene content, influences TD and MD tensile break. On average, 65 & 78 ⁰C Tg COC has TD and MD tensile break strength of 20.6 and 22.0 MPa relative to 17.1 and 20.8 MPa for films using 110⁰C Tg COC. COC modification offers incremental improvement too. E-140 is more effective than LLDPE at preserving TD and MD tensile strength,

averaging 23.4 versus 16.7 MPa and 25.3 versus 19.3 MPa respectively. COC films modified with LLDPE have 30% less COC content on weight percentage basis than those without modifier, which may contribute to lower tensile strength. BUR has little effect. Elongation at Break

Control and generic films have high TD and MD elongation at break; 90-micron LLDPE/LDPE and 115-micron LDPE/LLDPE average 750 and 710 percent and 720 and 530 percent respectively (Figures 16 & 17). Single 18-micron COC layer significantly reduces average TD and MD elongation at break of LLDPE/LDPE films to 270 and 180 percent. Low ductility of COC is responsible for limiting extensibility of LLDPE and LDPE.

Figure 16: Main Effects Plot for TD Elong. at Break

Figure 17: Main Effects Plot for MD Elong. at Break

COC Tg, BUR and COC modifier did influence TD and MD elongation at break. Films with 68⁰C COC Tg impart higher average TD and MD elongation at


break, 300 and 230 percent, than 80 & 110⁰C Tg COC, ranging between 200 and 140 percent. On average, 150 and 130 percent TD and MD elongation at break is typical for unmodified COC films. COC modification certainly helps. TD and MD elongation at break improves on average to 318 and 170 percent with LLDPE and to 350 and 220 percent with E-140. Adding modifiers such as LLDPE or E-140 improves ductility of COC. Low density plastomers and very low density polyethylene (VLDPE) should be explored as modifiers for COC. BUR has minimal influence on elongation at break. Property Gains by Splitting COC and LLDPE into More Layers [15]

This DOE reveals loss of PE tensile properties and impact energy from the addition of COC. This loss, however, can be minimized by simply splitting COC into two layers. Thinner discrete COC layers provide less restriction to elongation of m-h-LLDPE and any PE.

In one study (Table 4), three and five-layer 152-micron (6-mil) cast films, each containing 20 percent unmodified COC, demonstrate this advantage. Structure with layer ratio of 40/20/40 m-h-LLDPE / COC / m-h-LLDPE are split into 31/10/18/10/31 m-h-LLDPE / COC / m-h-LLDPE / COC / m-h-LLDPE. TD/MD tensile break strength improved from 20.9 to 24.4 MPa and 20.2 to 23.3 MPa. TD/MD elongation at break improved from 330 to 430 percent and 330 to 410 percent. Total haze is surprisingly reduced from 38 to 19 percent. Radar plot (Figure 18) graphically illustrate percent deviation of the five-layer film from the normalized three-layer film for thirteen properties. Splitting 30.5-micron (1.2-mil) COC layer into two 15.2-micron (0.6-mil) layers improves tensile properties, especially ductility, and lower total haze without detrimentally changing other properties.

In another study (Table 5), three and five-layer 152-micron (6-mil) cast films, each containing 20 percent modified COC, demonstrate this advantage too. Structures with layer ratio of 40/20/40 m-h-LLDPE / 65⁰C Tg COC + 30% E-140) / m-h-LLDPE are split into 31/10/18/10/31 m-h-LLDPE / COC / m-h-LLDPE / COC / m-h-LLDPE. Impact resistance improved from 153 to 182 N. Impact energy improved from 1.8 to 2.6 J. TD/MD tensile break strength improved from 23 to 25 MPa and 22 to 24 MPa. TD/MD elongation at break improved from 480 to 540 percent and 450 to 500 percent. Expectedly, TD/MD tensile modulus dropped

Table 4: 3 vs. 5 Layer Split Unmodified COC

Figure 18: 3 vs. 5 Layer Split Unmodified COC from 731 to 430 MPa and 657 to 353 MPa, but remains much higher than most polyolefin films without COC. Radar plot (Figure 19) graphically illustrate percent deviation of the five-layer film from the normalized three-layer film for thirteen properties. Splitting 30.5-micron (1.2-mil) modified COC layer into two 15.2-micron (0.6-mil) layers enables more strain hardening thereby improving tensile break properties and impact resistance.

1 COC Layer 2 COC Layers6-mil 40% m-h-LLDPE 31% m-h-LLDPE

Cast Extrusion 10% COC20% COC 18% m-h-LLDPE

10% COCProperty Unit 40% m-h-LLDPE 31% m-h-LLDPE

Fast Puncture Force N 156 153Fast Puncture Energy J 1.4 1.3

MD Tensile Yield MPa 17.2 17.3TD Tensile Yield MPa 17.9 17.1

MD Elong. @ Yield % 8 8TD Elong. @ Yield % 8 8MD Tensile Break MPa 20.2 23.3TD Tensile Break MPa 20.9 24.4

MD Elong. @ Break % 330 410TD Elong. @ Break % 330 430TD Tensile Modulus MPa 966 925MD Tensile Modulus MPa 952 959

Total Haze % 38 19COC: 78⁰C Tg m-h-LLDPE: 0.912 g/cc; 3.5 dg/min


Table 5: 3 vs. 5 Layer Split Modified COC

Figure 19: 3 vs. 5 Layer Split Modified COC

Conclusions

Our exploration of tensile properties, impact resistance, tear strength and optics as a function of BUR, COC Tg and COC modification provides packaging designers and film manufacturers useful information to improve packaging performance. Results show an exception balance of properties can be achieved. They can be easily tailored and optimized to the specific requirement for any application.

Addition of one or more discrete layers of amorphous COC to LLDPE based blown film significantly reduces total haze, including its internal

and especially surface haze components. Modification of the COC layer has little effect, including melt blending 30 percent of the same LLDPE into the discrete COC layer.

Addition of at least one discrete layer of amorphous COC, 20% of the structure, to LLDPE based blown film, more than doubles secant modulus. Modifying 78 & 110 ⁰C Tg COC with either LLDPE or E-140 modestly reduces stiffness. BUR did not influence secant modulus.

Addition of at least one discrete layer of amorphous COC to LLDPE based blown film modestly improves impact resistance. COC Tg and COC modifier have strong effect. Films made with 65⁰C Tg COC modified with E-140 have impact resistance nearly 20 percent above that of the LLDPE control film and close to the average for heavier gauge LDPE/LLDPE generic film.

Addition of at least one discrete layer of amorphous COC to LLDPE based blown film significantly reduces tear resistance. Modifying 78 & 110 ⁰C Tg COC with linear polymers will incrementally reduce tear strength. BUR did not influence tear strength.

Addition of at least one discrete layer of amorphous COC to LLDPE based blown film significantly reduces tensile properties. COC Tg and COC modifier has modest effect. 65⁰C Tg COC modified with E-140 had the least adverse effect on tensile properties. BUR did not influence tensile properties. However, splitting COC into two layers reduces loss in PE tensile strength, elongation, and impact resistance. Splitting COC into more than two layers will likely reduce this loss further, enabling efficient use of COC for all packaging film applications.

BUR in the range of 2:1 to 3:1 has minimal effect on LLDPE-COC film properties, suggesting stable films can be made at higher blow-up ratios.

Acknowledgments

I would like to thank the following people who contributed to this paper: Adam Barton, and Tim Kneale of TOPAS Advanced Polymers; Yoji Nishizawa, Takateru Onodera and technical staff of Polyplastics Co.(Japan), for blown film extrusion and mechanical property testing.

1 COC Layer 2 COC Layers6-mil 40% m-h-LLDPE 31% m-h-LLDPE

Cast Extrusion 10% COC20% COC 18% m-h-LLDPE

10% COCProperty Unit 40% m-h-LLDPE 31% m-h-LLDPE

Fast Puncture Force N 153 182Fast Puncture Energy J 1.8 2.6

MD Tensile Yield MPa 13.9 13.7TD Tensile Yield MPa 14.0 13.0

MD Elong. @ Yield % 9 9TD Elong. @ Yield % 12 13MD Tensile Break MPa 22 24TD Tensile Break MPa 23 25

MD Elong. @ Break % 450 500TD Elong. @ Break % 480 540TD Tensile Modulus MPa 731 430MD Tensile Modulus MPa 657 353

Total Haze % 16 16COC: 70% 65⁰C Tg COC + 30% E-140m-h-LLDPE: 0.912 g/cc; 3.5 dg/min


References

1. R.R. Lamonte and D. McNally, “Uses and

Processing of Cyclic Olefin Copolymers,” Plastics Engineering, (June 2000).

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3. P.D. Tatarka, “Improved Properties and Cost Efficiencies of Cyclic Olefin Copolymer Enhanced Forming Films,” SPE-ANTEC Tech Papers, 1149-1153 (2007).

4. P.D. Tatarka, “Elastomeric Cyclic Olefin Copolymers,” (47) Fall 188th Technical Meeting of Rubber Division, ACS, October 2015.

5. E. Unsal, A. Xue, Y. Patil, H. Pham, and A. Poslinski, “Binary Blends of Cycloolefin Copolymers,” SPE-ANTEC Tech Papers, 2068-2074 (2014).

6. N. Aubee, H. Larrazabal, T. Kneale, “Blending of Cyclic Olefins in sLLDPE for Improved Bubble Stability and Output Rates on Blown Film Extrusion Processes,” SPE-International Polyolefins Conference, 2009.

7. P.D. Tatarka, U.S. Patent 8,986,820 (2015). 8. Exceed™ 2018KB technical data sheet,

ExxonMobil Corporation, May 2015. 9. Lupolen® 2427 H technical data sheet, Lyondell

Basell, UL Prospector. May 2015. 10. Exceed™ 3512CB technical data sheet,

ExxonMobil Corporation, May 2015. 11. TOPAS® 9506F-500 technical data sheet, TOPAS

Advanced Polymers, June 2014. 12. TOPAS® 8007F-600 technical data sheet, TOPAS

Advanced Polymers, June 2014. 13. TOPAS® 7010F-600 technical data sheet, TOPAS

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9,452,593 (2016).

Table 1: Design of Experiments Data Summary


Table 2: Extruder Configuration

VariableI VariableI VariableII VariableIIITotalHaze

InternalHaze

SurfaceHaze

ImpactResistancePeakForce

ImpactResistance

TotalPenetration

Energy

1.0%SecantModulus(MD)

1.0%SecantModulus(TD)

TearingStrength(MD)

TearingStrength(TD)

ExperimentNumber COCGrade COCTg(°C) BUR COCModification % % % Newton Joule MPa MPa N/mm N/mm

1 9506F-500 68 2 100%9506F-500 5.9 3.2 2.7 96.3 0.82 532 568 118 1212 9506F-500 68 2 70%9506F-500/30%LLDPE 7.5 3.6 3.9 96.4 0.79 393 445 65 653 9506F-500 68 2 70%9506F-500/30%TOPASE-140 7.1 3.2 3.9 107.0 1.28 448 437 67 714 9506F-500 68 2.5 100%9506F-500 6.4 3.4 3.0 89.3 0.73 546 567 62 665 9506F-500 68 2.5 70%9506F-500/30%LLDPE 7.0 4.0 3.0 95.3 0.97 421 445 70 706 9506F-500 68 2.5 70%9506F-500/30%TOPASE-140 7.7 3.3 4.4 98.1 0.95 418 411 68 707 9506F-500 68 3 100%9506F-500 6.8 3.2 3.6 91.8 0.74 546 581 98 998 9506F-500 68 3 70%9506F-500/30%LLDPE 8.3 3.7 4.6 96.7 0.82 402 404 70 719 9506F-500 68 3 70%9506F-500/30%TOPASE-140 8.3 4.0 4.3 109.0 1.23 453 396 69 67

Average(9506F-500) 7.2 3.5 3.7 97.8 0.92 462 473 76 78


Average(8007F-600) 7.1 3.6 3.5 90.3 0.80 486 481 66 68


Average(7010F-600) 7.1 3.5 3.5 88.3 0.70 506 492 70 67DOEAverage 7.1 3.5 3.6 92.1 0.81 485 482 71 71

28 80%LDPE/20%LLDPE 2:1 NoModification 9.3 4.9 4.4 105.0 1.60 227 231 107 12329 80%LDPE/20%LLDPE 2.5:1 NoModification 9.7 5.8 3.9 103.0 1.59 219 242 111 12630 80%LDPE/20%LLDPE 3:1 NoModification 12.2 6.6 5.6 118.0 1.91 218 232 119 123

LDPE/LLDPEAverage 10.4 5.8 4.6 108.7 1.70 221 235 112 124

34 93%m-h-LLDPE+7%LDPE 2:1 NoModification 9.8 4.8 5.0 88.4 1.47 198 235 94 10135 93%m-h-LLDPE+7%LDPE 2.5:1 NoModification 10.1 4.8 5.3 91.5 1.64 202 240 97 10436 93%m-h-LLDPE+7%LDPE 3:1 NoModification 11.5 5.0 6.5 87.7 1.54 228 237 98 103

LLDPE/LDPEAverage 10.5 4.9 5.6 89.2 1.55 209 237 97 103

VariableI VariableI VariableII VariableIII

TensileYield

Strength(MD)

TensileYield

Strength(TD)

ElongationatYield(MD)

ElongationatYield(TD)

TensileBreak

Strength(MD)

TensileBreak

Strength(TD)

ElongationatBreak(MD)

ElongationatBreak(TD)

ExperimentNumber COCGrade COCTg(°C) BUR COCModification MPa MPa % % MPa MPa % %

1 9506F-500 68 2:1 100%9506F-500 17.7 16.5 10.0 9.9 23.0 19.1 178 2472 9506F-500 68 2:1 70%9506F-500/30%LLDPE 15.0 14.4 13.9 12.3 24.7 23.0 233 3493 9506F-500 68 2:1 70%9506F-500/30%TOPASE-140 12.3 12.6 15.2 11.6 25.0 23.6 247 3864 9506F-500 68 2.5:1 100%9506F-500 17.3 17.1 11.5 11.0 20.4 18.3 173 1935 9506F-500 68 2.5:1 70%9506F-500/30%LLDPE 10.3 10.6 12.1 10.9 19.3 18.1 225 3676 9506F-500 68 2.5:1 70%9506F-500/30%TOPASE-140 13.4 13.0 14.6 12.7 24.9 24.8 277 3777 9506F-500 68 3:1 100%9506F-500 16.6 16.3 14.2 13.1 18.1 17.3 161 1718 9506F-500 68 3:1 70%9506F-500/30%LLDPE 9.8 8.8 13.1 13.4 18.6 17.2 254 3549 9506F-500 68 3:1 70%9506F-500/30%TOPASE-140 13.0 14.2 15.6 13.4 24.3 25.9 280 304

Average(9506F-500) 13.9 13.7 13.4 12.0 22.0 20.8 225 305


Average(8007F-600) 15.1 14.6 11.9 11.5 22.0 20.4 199 298


Average(7010F-600) 15.6 14.4 10.3 11.1 20.8 17.1 115 204DOEAverage 14.9 14.2 11.9 11.6 21.6 19.4 180 269

28 80%LDPE/20%LLDPE 1 2:1 NoModification 11.4 8.4 108.4 81.2 27.4 38.5 680 75129 80%LDPE/20%LLDPE 1 2.5:1 NoModification 10.6 8.8 108.4 85.7 14.3 38.5 407 79230 80%LDPE/20%LLDPE 1 3:1 NoModification 9.8 9.0 94.0 85.0 17.2 20.7 514 607

LDPE/LLDPEAverage 10.6 8.7 103.6 84.0 19.6 32.6 534 717

34 93%m-h-LLDPE+7%LDPE 1 2:1 NoModification 10.7 10.9 84.1 76.4 42.2 42.8 708 72135 93%m-h-LLDPE+7%LDPE 1 2.5:1 NoModification 11.1 10.7 86.1 69.9 42.1 42.6 707 76836 93%m-h-LLDPE+7%LDPE 1 3:1 NoModification 11.9 12.0 87.0 75.0 43.2 43.1 725 773

LLDPE/LDPEAverage 11.2 11.2 85.7 73.8 42.5 42.8 713 754


Table 3: Fabrication Conditions

Extruder A B CScrewDiameter(mm) 40 40 40

L/D 26:1 26:1 26:1

ScrewDesignGeneralPurpose;

non-barrier

Custom;transitionwithdoubleflights;twomixingsections

GeneralPurpose;non-barrier

BarrelTemperature(°C)FeedZone 40 40 40

BarrelZone1 180 210 180BarrelZone2 180 200 180BarrelZone3 180 190 180Adaptor 180 220-230 180

DieTemperature(°C)DieZone1 180 180 180DieZone2 180 180 180DieZone3 180 180 180

Condition Measured&CalculatedValues

DieDiameter(mm) 106DieGap(mm) 2.5

FrostLineHeight(cm) 25AirRingTemperature(°C) 25

AirRingBlowerSpeed(m3/min) 36FilmSpeed(m/min) 10.5

BlowUpRatio(BUR) 2.0:1 2.5:1 3.0:1DrawDownRatio(DDR) 11.5:1 9.2.:1 7.6:1

TotalRate(kg/hr) 27.5 34.9 41.7SpecificOutput(kg/hr/cm) 0.83 1.05 1.25

Extruder A&C B A&C B A&C B

Pressure,Adaptor(kg/cm2) 134-180 39-75 157-183 45-65 173-209 40-76ScrewSpeed(RPM) 56-58 26 71-73 33 84-89 40-49

Rate(kg/hr) 11.0-11.4 5.1 14.0-14.4 6.5 16.5-17.3 7.9

For115-micronLLDPE/LDPETotalRate(kg/hr) 35.2 44.6 53.3

SpecificOutput(kg/hr/cm) 1.06 1.34 1.60


Documents

Enhancement of Appearance, Stiffness, and Toughness …leaders.4spe.org/spe/conferences/ANTEC2017/papers/66.pdf · ENHANCEMENT OF APPEARANCE, STIFFNESS, AND TOUGHNESS ... 25.4-micron