2 3 scale-up rule for double bubble tubular process … · ipp_ipp1782 – 14.1.04/druckhaus...

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FILM

M. Takashige1*, T. Kanai2, T. Yamada3

1 Idemitsu Unitech Co, Hyogo, Japan2 Idemitsu Petrochemical Co, Chiba, Japan3 Kanazawa University, Ishikawa, Japan

Scale-up Rule for Double Bubble Tubular Processof PA6 Film

The analysis of scale-up rule for double bubble tubular filmprocess of PA6 was investigated. The scale-up rule previouslyproposed for a blown film process by the authors was appliedto a double bubble tubular film process with a small-scale plantfor research (pilot plant) and a large-scale plant for commer-cial production (production plant).

According to the scale-up rule based on the equivalentstretching stress between the pilot and production plants, theequivalence of stretching stability, birefringence pattern anddeformation pattern were confirmed.

It has been confirmed that the proposed scale-up rule is ap-plicable to predict the physical properties such as film impactstrength and the bubble stability for the large-scale tubular filmprocess on the basis of the experimental results obtained fromthe pilot plant.

1 Introduction

In recent years, environmental problems have come into ques-tion in the packaging industry. As these problems, the de-chlor-ination and the waste reduction have been closed up in this in-dustry. The waste reduction especially has been a seriousproblem. In order to achieve this waste reduction, there is a ra-pid increasing shift from an one-way bottle to a standing pouchfor repackaging use in an effort to utilize resources effectively.Biaxially oriented PA films, which are thin and strong, are in-dispensable for many applications.

Several kinds of manufacturing processes have been devel-oped to produce the biaxially oriented PA6 film featured byhigh strength. Among them, the double bubble tubular processproducing biaxially stretched PA6 film is the best one in termsof impact strength. It is valued highly for the purpose of distri-bution of safety products.

The technology, which was established in a pilot plant, mustbe applied to the large-scale production. It was examined forthe purpose of the demonstration of scale-up theory of the dou-ble bubble tubular stretching technology.

The double bubble tubular film process is closely related tothe tubular film process, so we use the basic studies reportedon the tubular film process.

Various works have modeled the tubular film process as fol-lows:

The initial investigation has been started by Alfrey [1] on thetubular film process and was extended Pearson [2] to the kine-matic analysis and stress analysis based on membrane theory.In a subsequent series of papers, Pearson and Petrie [2] elabo-rated on this analysis and made specific calculations for an iso-thermal Newtonian fluid model. An isothermal viscoelasticmodel was described by Petrie [3]. Analysis of temperaturefields and the interaction with kinematics was first consideredin papers by Han, Park, [4] and Petrie in 1975. These effortshave been continued by Wagner [5 to 6] in a later paper. Kanaiand White [7] considered local kinematics and heat transferrates as well as bubble stability.

Those results were used as the basis for construction of amodel of the dynamics, heat transfer and structure develop-ment in tubular film extrusion. A later report [8] representedan advance on earlier papers on modeling by inclusion of crys-tallization and more quantitative representations of local heattransfer rates. These research works apply for theoretical ana-lysis of the tubular film extrusion and its application forHMW-HDPE [9]. Further using the theoretical equations ontubular film extrusion, the authors presented a scale-up rule[10].

There are several published papers on double bubble tubu-lar stretching technology [11 to 22] formability and structureanalysis for much resin such as PET, PBT, PPS, PA6-12 andPA12 that are reported by White, Kang, Song, Rhee et al.[13 to 22]. Research report on the scale-up technology islimited. The analyses of deformation behavior of PA6 werereported previously according to stretching stress analyses[23]. Our previous paper discussed three topics: relationshipbetween process condition and film stretching stress; defor-mation rate during double bubble process, birefringence;and scale-up rule for double bubble tubular film process. Re-search reports using a production plant are limited.

At this time, two types of plants, which are a pilot plantand a large-scale production, are used. The stretched bubblesamples were produced by pilot plant and large-scale produc-tion.

368 Hanser Publishers, Munich Intern. Polymer Processing XVIII (2003) 4

* Mail address: M. Takashige, Idemitsu Unitech Co., Ltd. 841-3Kou, Shirahama-cho, Himeji-city, Hyogo, Japan©

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2 Experimental

2.1 Equipments

Apparatus used for the double bubble tubular film process isshown in Fig. 1. Using a screw extruder (L/D = 24) with a dia-meter of 40 mm equipped with an annular die with the diameterof 75 mm and the lip clearance of 1 mm and with a water-cool-ing ring having the diameter of 90 mm non-stretched film wasproduced at a resin temperature 265 °C and blow-up ratio of1.2. The initial film was stretched simultaneously in the pro-cess and transverse directions by using inside bubble air, adrawing machine composed of two pairs of pinch rolls and aheating furnace (a far infrared radiation heater is self-con-tained). The stretched film was heat-set using a heat treatmentdevice. The equipment is called pilot plant.

Using an extruder (L/D = 25) with the diameter of 115 mmequipped with a circular die with the diameter of 300 mm andthe lip clearance of 1 mm and with a water-cooling ring havingthe diameter of 330 mm non-stretched film was produced at aresin temperature 265 °C and the blow-up ratio of 1.1. Theraw film is stretched simultaneously in the process both in ma-chine direction and transverse by using internal bubble air, adrawing machine composed of two pairs of pinch rolls and aheating furnace (a far infrared radiation heater is self-con-tained). The stretched film is heat-set using a heat-set treatmentdevice. The equipment is called a large-scale production plant.

2.2 Material

The material used was Ube Nylon 1024FD15 (PA6) with meanmolecular weight of 24,000 and the relative viscosity ofgr = 3.75 in 98 % sulfuric acid as a solvent.

2.3 Experimental Method

The process conditions of non-stretched film are 265 °C for re-sin temperature at the die exit 1.2 for blow up ratio, and 6.0 fordraw down ratio respectively. Film was quenched in water at18 °C to lower crystallinity. The stretching device consists of aheating/stretching furnace and an air ring. The air ring, which

injects air downward at an angle of 45 °C, was installed at theupper part of the heating furnace and air ring.

The standard condition for stretching process was set at310 °C for process temperature (heater set temperature) andMD (Machine Direction)/TD (Transverse Direction) = 3.0/3.2for stretching ratio respectively. The thickness of non-stretchedfilm was 130 lm, and it became 13.5 lm after stretching. Thestretched film was heat treated to prevent shrinkage, using aheat treatment device of the tenter process.

The stretching ratio of both MD and TD are determined bythe inside bubble pressure and the different roll speeds betweentop rolls and bottom rolls. In this manner, the second bubble issimultaneously stretched in both machine direction and trans-verse direction.

Fig. 2 shows the measurement method of stretching stress.Stretching stresses were calculated with help of Eqs. 1 and 2,

rMD = (DP · R)/HL, (1)

rTD = (T/r)/2pHLR, (2)

where DP, T, R, r and HL are inside bubble pressure, tension,final bubble radius, radius of bottom nip roll and final filmthickness respectively. The bubble internal pressure was ob-tained using the digital manometer (Yokogawa Hokushin).The bubble diameter uniformity was measured in order toevaluate the stability of the stretching bubble. The bubble dia-meter uniformity was normalized by the mean bubble dia-meter as:

Bubble diameter uniformity (%) = (maximum diameter – mini-mum diameter)/mean diameter/2 × 100. (3)

The deformation rate Df is defined as follows:

Df = (D0/D) × (1/t) × (1/10), (4)

where D0, D and t are thickness of unstretched film, thicknessof stretched film and time of deformation respectively. Thecomputed value of (D0/D) × (1/t) × 100 gives the value (%/s).When the value (%/s) is 1,000, the deformation rate is definedas 1.0.

The samples were collected under two conditions in whichthe deformation rate of Eq. 4 differed. The 1.0 and 0.6 were se-lected as deformation rate in pilot plant. In addition, 1.0 and 0.5were selected as deformation rate in the large-scale productionplant. Films were made under these two conditions by the pilotplant and the large-scale production one.


M. Takashige et al.: Scale-up Rule for Double Bubble Tubular Process

Intern. Polymer Processing XVIII (2003) 4 369

Fig. 1. Schematic view of double bubble tubular film process

Fig. 2. Measurement method of stretching stress

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2.4 Evaluation of Deformation Bubble

The bubble stability is closely related to the deformation film,but it is very difficult to measure the deformation pattern dur-ing the second bubble inflation, because the heating apparatuscovers bubble.

In order to analyze the behavior of deformation pattern,the extruder and take-up device were stopped and bubblesample was collected. Bubble width pattern and film thick-ness pattern at each position of the bubble sample were mea-sured by using stopped bubble sample. Stretching ratio ateach position was calculated by using bubble width and filmthickness pattern.

The birefringence was measured of a stretched film samplewas taken from the pilot plant and large-scale production runs.The birefringence was measured by using BH2 (type OlympusBH-2, Japan) at each point. The birefringence meansDn12 = Dn13 –Dn23 = n1 – n2. 1 = machine direction, 2 = trans-verse direction, 3 = thickness direction.

The deformed samples under the various conditions duringthe stretching process were taken and each of them was in-serted between two polarizing plates crossed with each otherto observe and assess the deformation state of stretching bub-bles by shedding light from below. Each sample under eachcondition was photographed using a high sensitivity film.

The anisotropy of the orientation of film from the stretchingstart point to stretching end was observed. The observation eva-luation of stretching bubble stop sample from the pilot plantand large-scale production was carried out.

The crystal structure evaluation of the stretch film samplefrom the pilot plant and large-scale production was also carriedout. The change of the crystal structure of stretching deforma-tion process of PA6 film was evaluated using the infrared ab-sorption evaluation (Infrared spectroscopy). The value of the atype crystal structure used 928 cm – 1 absorbency, and the valueof c type crystal structure used 977 cm – 1 absorbency. The ratioof α type crystal structure and c type crystal structure was mea-sured and was evaluated continuously for the flowing directionof the bubble.

The ratio α and c was expressed the α/c ratio. The relation-ship between α/c ratio and uniaxial stretching ratio was mea-sured too.

2.5 Mechanical Properties

Mechanical property evaluation of the stretched film samplecollected from the pilot plant and large-scale production wascarried out. Film impact strength, penetrate strength, tensilestrength at break and tensile elongation at break were mea-sured.

3 Theoretical Background

The scale-up rule of tubular film process are set up theoreti-cally here [23]. We did not think it necessary to scale the en-ergy balance because of the introduction of the heating ringshown in Fig. 1 controls the key non-isothermal features ofthe process.

The force balance on the double bubble tubular film is devel-oped from membrane theory. Membrane theory leads to a bal-ance of forces on the film between positions Z and take-up po-sition L. This has the form:

FL= 2pRHrMD cos h + p(RL2 – R2) · DP. (5)

The stress rMD and rTD are related to the pressure DP throughthe expression:

H · rMD/R1 + H · rTD/R2 = DP, (6)

where FL is the bubble tension, RL the final bubble radius, andR1 and R2 are appropriate radii of curvature.

R1 = ((1 + dR/dZ)2)3/2/d2R/dZ2), (7)

R2 = R/cos h. (8)

The maximum stretching stress rMD and rTD are closely re-lated to the physical properties of film. The maximum stressat the stretching final is used to set up the scale-up rule. At thestretching final point, bubble diameter is equal to final bubblediameter.

rMD = FL/2pRLHL, (9)

rTD = DP · RL/HL, (10)

where HL is the final film thickness. By using the analysis ofdimensionless terms, stress rMD and rTD are presented by fol-lowing equations.

rMD = (A + B(RL/R0)2)/2p · Qg0/R0RLHL = G1 · Qg0/R0RLHL,

(11)

rTD = (B/p) · Qg0RL/R03HL = G2 · Qg0RL/R0

3HL, (12)

where Q is the out-put rate, g0 is the viscosity, R0 is the initialbubble radius, ZL is the axial distance between beginning pointand final point of bubble inflation where A and B are constantsunder the same conditions of RL/R0, VL/V0, and ZL/R0, and G1

and G2 are constants under the condition of constant stretchingratio of machine direction, stretching ratio of transverse direc-tion.

Table 1 shows the scale up rule. It is found that stretchingstress was a function of film thickness and square of bubblediameter. In case of changing bubble radius R and film thick-ness H into KR and LH, output rate K2LQ is needed. This prin-ciple is called the scale-up rule.

The experimental condition is shown at Table 2. In presentexperiment, it was examined using deformation rate 1.0 condi-tion according to the scale-up rule. Deformation rate 0.6 (0.5)which was not according to the scale-up rule was used for thecomparison. By fixing the thickness, only the diameter chan-ged, and the scale-up rule was examined.

370 Intern. Polymer Processing XVIII (2003) 4

Diameter Thickness Out put rate rMD rTD

R0 H Q 1 1KR0 LH Q 1/K2L 1/K2LKR0 LH K2LQ 1 1

Table 1. Scale-up Rule

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A differential heat balance over a length dz for the tubularfilm process has the form:

qCpQ cos h dT/dz = – 2pR[h(T – Tair) + ek(T4 – Troom4)]

+ Q DHf cos h dX/dz, (13)

Here T is the bubble temperature, Tair the cooling air tempera-ture, Troom the room temperature, h the local convective heattransfer coefficient, q the density, Cp the specific heat capacity,e emissivity, k the Stefan-Boltzmann constant, DHf the heat offusion, and X the crystalline fraction.

Dimensionless variables are defined as follows:

r = R/R0 w = H/R0 l = z/R0 s = T/T0.

Equation may be rewritten as:

s’ = – rαC sec h(s– sa)– rD sec h(s4 – sa4) + FX’, (14)

where

C = h0T0/(qCpQT0/2pR02), (15)

D = T04ek/(qQT0/2pR0

2), (16)

F = DHf/CpT0. (17)

sa represents the reduced temperature of the surroundings.During the non-stretching process, water temperature and

cooling ring length were set so that the density of the raw filmmay become the same value fixed. During the stretching pro-cess, heater temperature, air cool condition and heating furnacelength were set so that the dimensionless value C, D and F maybecome the same value fixed.

4 Results and Discussion

4.1 Stretching Stress

Table 3 shows the relationship between stretching stress, bub-ble stability and process conditions. The stretching stress level

by pilot plant and large-scale production one was identical indeformation rate 1.0, and the formation of the scale-up rulewas confirmed. The bubble diameter uniformity and the bubblestability were also reproduced in deformation rate 1.0. Whenthe deformation rate was decreased, the stretching stress low-ered and the bubble stability also lowered.




Scale-up condition

Item Pilotplant (A)

Productionplant (C)

Magnifi-cation

Deformation rate 1.0 1.0 1.0Tube diameter (mm 1) 90 330 3.7

Output rate (kg/h) 17.6 240.0 13.6Thickness of raw film (lm) 130 130 1.0

Stretching ratio 3.0/3.2 3.0/3.2 1.0

Comparison condition

Item Pilotplant (B)

Productionplant (D)

Magnifi-cation

Deformation rate 0.6 0.5 –Tube diameter (mm 1) 90 330 –

Output rate (kg/h) 10.6 120.0 –Thickness of raw film (lm) 130 130 –

Stretching ratio 3.0/3.2 3.0/3.2 –

Table 2. Experimental conditions

Fig. 3. Picture of bubble shape during the second bubble inflation of pi-lot plant (A), top, and production plant (C), bottom, deformation rate 1

Scale-up condition

Item Pilotplant (A)

Productionplant (C)

Deformation rate 1.0 1.0Stretching-stress (TD) MPa 95 92

Bubble-stability GOOD GOODBubble diameter uniformity % ± 0.4 ± 0.3

Comparison condition

Item Pilotplant (B)

Productionplant (D)

Deformation rate 0.6 0.5Stretching-stress (TD) MPa 75 68

Bubble-stability NOT GOOD NOT GOODBubble diameter uniformity % ± 0.8 ± 1.5

Table 3. Stretching Stress and Bubble Stability

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4.2 Evaluation of Deformation Bubble

Fig. 3 shows typical example of bubble shape during the sec-ond bubble inflation stopped sample. The large sample the dia-meter of 3.7 times and the out-put rate of 13.6 times as to a con-dition according to the scale-up rule was made.

Fig. 4 and 5 show the relationship between stretching ratioand distance from air ring (dimensionless). The stretching ra-tio of transverse direction increases slowly under the low de-

formation rate. The stretching ratio of machine direction in-creases rapidly compared with the one of the transversedirection.

The difference between stretching ratio in machine directionand transverse direction were calculated. Fig. 6 and 7 showsthe relationship and variance between stretching ratio in themachine direction and transverse direction. The stretching ratioof machine direction is larger than the one of transverse direc-tion at all position. Especially in the condition of low deforma-


Fig. 4. Stretching ratio pattern in each posi-tion for small-scale pilot plant A, deformationrate 1 (A), and for pilot plant B, deformationrate 0.6 (B)

Fig. 5. Stretching ratio pattern in each posi-tion for large-scale production plant C, defor-mation rate 1 (A), and for pilot plant D, defor-mation rate 0.5 (B)

Fig. 6. Difference of stretching ratio in eachposition for small-scale pilot plant A, deforma-tion rate 1 (A), and for pilot plant B, deforma-tion rate 0.6 (B)

Fig. 7. Difference of stretching ratio in eachposition for large-scale production plant C,deformation rate 1 (A), and for pilot plant D,deformation rate 0.5 (B)

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tion rate, the stretching ratio of machine direction has larger va-lue than in the transverse direction. It was confirmed that thestretching deformation condition agreed with the measuring re-sult of pilot plant and large-scale production by adjusting thesize scale. This result suggests that the scale up rule of bubblediameter is applicable.

4.3 Birefringence

The birefringence of samples at each position Dn12 was meas-ured. Fig. 8 and 9 shows the relationship between birefringenceand distance from air ring (dimensionless) under the differentdeformation rates. Birefringence under the low deformationrate is clearly larger than one under the high deformation rate.These results correspond to the experimental ones obtainedstretching ratio difference shown in Fig. 6 and 7. As a result

of evaluating the birefringence of the stretching developingsample of pilot plant and large-scale production, it was foundthat birefringence pattern by the deformation process was al-most identical.

4.4 Observation of Polarizing Plates of Deformed Bubbles

For the purpose, of observing deformed bubbles stretching offilm depending on stretching conditions, a suddenly stoppedand cut sample during stretching process was taken. Under thisspecified process, conditions, and a comparative evaluationwas studied in terms of anisotropy through the polarizingplates.

Fig. 10 and 11 show the results through the polarizing plateof the deformed bubble samples. It suggests that the deforma-tion range is broad under the low deformation rate. This obser-




Fig. 8. Birefringence vs. distance from airring for small-scale pilot plant A, deformationrate 1 (A), and for pilot plant B, deformationrate 0.6 (B)

Fig. 9. Birefringence vs. distance from airring for large-scale production plant C, defor-mation rate 1 (A), and for pilot plant D, defor-mation rate 0.5 (B)

Fig. 10. Observation of polarizing plate of thesecond bubble sample for small-scale pilotplant A, deformation rate 1 (left), and B, defor-mation rate 0.6 (right)

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vation has close relation to the stretching ratio pattern. As a re-sults of observation of deformed bubble sample of pilot plantand large-scale production, it was found that deformation pat-tern by the deformation process was almost identical.

4.5 Crystal Structure

The relationship between α/c ratio and distance from air ring(dimensionless) is plotted in Fig. 12 and 13. When the stretch-ing condition was different, the way of the change of the crystal

structure of the deformation process differed. In the Fig. 12 and13, the α/c ratio increases slowly under the low deformationrate (0.5, 0.6) in initial step. On the contrary, the α/c ratio in-creases rapidly under the high deformation rate (1.0) in initialstep. In addition, the α/c ratio immediately decreases in middlestep.

The relationship between α/c ratio and uniaxial stretchingmagnification is shown in the Fig. 14. When the uniaxialstretching ratio increases, α/c ratio increases. It is confirmedthat the α/c ratio affected the difference of stretching ratio(MD-TD). It is proven that the value of the α/c ratio in the


Fig. 11. Observation of polarizing plate of the second bubble sample for large-scale production plant C, deformation rate 1

Fig. 12. Crystal structure ratio pattern vs. dis-tance from air ring for small-scale pilot plantA, deformation rate 1 (A), and for pilot plantB, deformation rate 0.6 (B)

Fig. 13. Crystal structure ratio pattern vs. dis-tance from air ring for large-scale productionplant C, deformation rate 1 (A), and for pilotplant D, deformation rate 0.5 (B)

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Fig. 12 and 13 is related to the stretching ratio difference (MD-TD). These findings reflect the result of stretching ratio differ-ence of the stretching deformation process shown in the Fig. 6and 7.

As a result of evaluation of the α/c ratio of deformed bubblesample of pilot plant and large-scale production, it was foundthat crystal structure pattern by the deformation process wasalmost identical.

4.6 Film Mechanical Property

Film mechanical property has close relation to the stretchingratio pattern. The scale-up aptitude of pilot plant and large-scale production was evaluated using change process of thefilm physical property. Table 4 shows the mechanical property.Film impact strength; penetrate strength, tensile strength atbreak and tensile elongation at break point were showed alsowith same value. Because of evaluation of film physical prop-erty of pilot plant and large-scale production, it was found thatfilm physical property by the deformation process was almostidentical. It was proven that physical property was also repro-duced, when the scale-rule was followed.

In case of changing bubble radius R and film thickness Hinto KR and LH, we can get some bubble stability, deformationstyle and film physical property to keep output rate K2LQ.Namely, the scale-up rule is applicable to keep the same defor-mation rate.

The scale-up rule is applicable to predict the physical prop-erties and bubble stability. As a result, of the experimental eva-luation we found that the stretching stress and deformation

pattern were very important factors to producing biaxially or-iented PA6 film by double bubble tubular process. We can pre-dict the bubble stability and film physical properties for large-scale double bubble tubular film extrusion carried out by usingthe pilot plant and a small amount of resin.

5 Conclusion

In the study on the scale-up rules for the double bubble tubularprocess, the conclusions obtained were as follows.1. The application of the scale- up rule which was set up theo-

retically, was evaluated by using both the pilot plant and thelarge-scale production, under the conditions of controllingthe relationship between output and film width (etc.). Ac-cording to the scale-up rule, namely bubble radius R, filmthickness H and output rate Q for the pilot plant and KR,LH and K2LQ for the large-scale production plant respec-tively.

2. Both pilot plant and large-scale production showed thesame stretching bubble stability, the equivalent stretchingstress, the equivalent birefringence pattern and the equiva-lent crystal structure pattern, when kept at the same defor-mation rate.

3. In the observation through the polarizing plate of the bub-ble sample, which shows deformation pattern, the equalityof deformation pattern was also confirmed.

4. It is found that the scale-up rule which was set up theoreti-cally is applicable to predict the physical properties andbubble stability for large-scale double bubble tubular filmprocess, once the experiment is carried out by using the pi-lot plant and a small amount of resin.

References

1 Alfrey, T.: SPE Trans. 5, p. 68 (1965)2 Pearson, J. R. A., Petrie, C. J. S.: Plastics Polym. 38, p. 85 (1970)3 Petrie, C. J. S: Rheol. Acta 12, p. 82 (1973)4 Han, C. D., Park, J. Y.: J. Appl. Polym. Sci. 19, p. 3277 (1975)5 Wagner, M. H.: Rheol. Acta 15, p. 40 (1976)6 Wagner, M. H.: Dr.-Ing. Dissertation, University of Stuttgart (1978)7 Kanai, T., White, J. L.: Polym. Eng. Sci. 24, p. 1185 (1984)8 Kanai, T., White, J. L.: J. Polym. Eng. 5, p. 135 (1985)9 Kanai, T., Kimura, M., Asano, Y.: J. Plastic Film Sheeting 2, p. 224

(1986)10 Kanai, T.: Int. Polym. Process. 1, p. 137 (1987)11 Kanai, T., Takashige, M.: Seni Gakkaishi, 41, p. 272 (1985)12 Takashige, M.: Film Processing. Progress in Polymer Processing

Series, in: Kanai, T., Campbell, G. (Eds.), Hanser, Munich (1999)13 Kang, H. J., White, J. L.: Polym. Eng. Sci. 30, p. 1228 (1990)14 Kang, H. J., White, J. L., Cakmak, M.: Int. Polym. Process. 5, p. 62

(1990)15 Kang, H. J., White, J. L.: Int. Polym. Process. 7, p. 38 (1992)16 Rhee, S., White, J. L.: Polym. Eng. Sci. 39, p. 1260 (1999)17 Song. K., White, J. L.: Polym. Eng. Sci. 40, p. 902 (2000)18 Song. K., White, J. L.: Int. Polym. Process. 15, p. 157 (2000)19 Song. K., White, J. L.: Polym. Eng. Sci. 40, p. 1122 (2000)20 Rhee, S., White, J. L.: SPE Antec. Tech. Papers. 59, p. 1446 (2001)21 Rhee, S., White, J. L.: SPE Antec. Tech. Papers. 59, p. 1451 (2001)22 Rhee, S., White, J. L.: Int. Polym. Process. 16, p. 272 (2001)23 Takashige, M., Kanai, T.: Int. Polym. Process. 5, p. 287 (1990)

Date received: July 29, 2003Date accepted: September 2, 2003




Fig. 14. Crystal structure ratio pattern vs. uniaxial stretching ratio

Item Pilotplant (A)

Productionplant (C)

Deformation rate 1.0 1.0Film impact strength (J/m) 88,000 89,000

Penetration strength (N) 9.9 10.0Tensile strength at break MD (MPa) 250 255

TD (MPa) 312 319Tensile elongation at break MD (%) 126 129

TD (%) 113 110

Table 4. Physical Property

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2 3 scale-up rule for double bubble tubular process … · ipp_ipp1782 – 14.1.04/druckhaus...

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