KR20220044056A - Method for predicting injection molding troubleshooting of polyethylene resin - Google Patents

Abstract

Provided in the present invention is a novel prediction method capable of easily predicting an injection molding failure rate in a short time by using variable material properties of a polyethylene resin.

Description

Method for predicting injection molding failure of polyethylene resin

The present invention relates to a method for predicting injection molding failure of a polyethylene resin.

Polyethylene resin has excellent mechanical properties such as rigidity, impact resistance, environmental stress cracking resistance (ESCR) and elongation properties, and also has excellent chemical resistance, corrosion resistance, and electrical properties, so films, sheets, pipes, food containers, It is widely used in various fields such as pressure-resistant bottles.

It is molded and commercialized in various ways according to each use. Injection molding is a method of putting polyethylene resin prepared in the form of beads, pellets or chips into an injection molding machine, injecting it and processing it into a desired shape. there is. However, during injection molding, molding defects occur due to various factors such as the injection environment and the physical properties of the polyethylene resin.

Hair is one of the molding defects that occurs when the resin that has not yet hardened is stretched in the gate area of the cap during cap injection molding using polyethylene resin. The hair generation mechanism can be divided into two stages, a first stage in which initial hair is generated, and a second stage in which the generated hair is increased, and factors affecting each stage are different. Specifically, factors affecting initial hair generation include solidification temperature, Tc distribution, and mold design, and factors affecting hair growth include viscosity and elongational viscosity.

Hair generation is affected not only by the physical properties of the polyethylene resin, but also by the characteristics of the mold. For example, even if hair does not occur in one mold, hair may occur in another type of mold. Accordingly, in order to accurately evaluate hair defects, it is necessary to conduct experiments in various molds. However, in this case, there is a problem in that the amount of the resin to be used increases and the evaluation time also increases.

Accordingly, it is necessary to develop a method for easily predicting hair failure during injection molding based only on the molecular structure or basic physical property information of the resin.

An object of the present invention is to provide a method for easily predicting injection molding defects, particularly hair defects, within a short time by using the rheological properties of the resin.

According to one embodiment of the present invention, for a polyethylene resin, using an ARES rheometer, shear viscosity at 230° C. and a shear rate of 0.05 to 500 s ⁻¹ , and an extensional viscosity measuring device attached to the ARES rheometer. Measuring the elongational viscosity under the conditions of 190 ° C., Henkey strain 0.1 s ^-1 , and stretching for 30 seconds, respectively; And using the shear viscosity at a shear rate of 40 s ^-1 among the shear viscosities of the polyethylene resin, and the elongational viscosity, calculating the value of the hair generation rate during injection molding using the polyethylene resin; A method for predicting injection molding failures is provided.

With the method according to the present invention, it is possible to easily predict molding defects, particularly hair, in a short time during injection molding of polyethylene resin. Also, by using this, it is possible to easily select a polyethylene resin that does not cause hair during injection molding, particularly bottle cap injection molding.

BRIEF DESCRIPTION OF THE DRAWINGS It is the graph which observed the shape change of the shear viscosity of a polyethylene resin.
2 is a graph showing the relationship between the shear viscosity and the elongational viscosity of a polyethylene resin.

The terminology used herein is used to describe exemplary embodiments only, and is not intended to limit the invention. The singular expression includes the plural expression unless the context clearly dictates otherwise. In this specification, terms such as "comprises", "comprising" or "have" are intended to designate the presence of an embodied feature, step, element, or a combination thereof, but one or more other features or steps; It should be understood that the possibility of the presence or addition of components, or combinations thereof, is not precluded in advance.

Since the invention may have various changes and may have various forms, specific embodiments will be illustrated and described in detail below. However, this is not intended to limit the invention to the specific disclosed form, it should be understood to include all modifications, equivalents and substitutes included in the spirit and scope of the invention.

Throughout this specification, 'polyethylene' or 'ethylene (co)polymer' is a concept including both ethylene homopolymer and/or a copolymer of ethylene and alpha-olefin.

In addition, in the present specification, the term 'polyethylene resin' refers to a resin or resin composition including the ethylene (co)polymer, and an additive belonging to the art to which the present invention belongs in general to such a homopolymer or copolymer. It is a concept including all the resin compositions that may be further added.

In addition, in the present invention, when analyzing data or graphs, it is possible to visually confirm and analyze the data or graphs directly, or confirm and analyze the data or graphs by a fitting method using a computer program. The computer program used at this time may use a commercial program widely known in the technical field to which the present invention belongs, such as Excel, Origin, Matlab, Mathematica, or Igor Pro.

In addition, the coefficient value, the intercept value, the index value, etc. used in each mathematical formula in the present invention may be values determined experimentally in advance, which may vary depending on the characteristics of the resin to be measured or predicted. It is not necessarily limited to this.

Hereinafter, a method for predicting injection molding failure of a polyethylene resin according to a specific embodiment of the present invention, and a method for selecting polyethylene having excellent injection moldability using the same will be described.

When an injection-molded product is separated from the mold after injection molding using a polyethylene resin, the polyethylene resin part that is not sufficiently solidified during the cooling process during the injection molding process, especially the part in contact with the hot runner, is stretched and hair is generated.

1 is a graph observing the shape of the shear viscosity of a polyethylene resin, and FIG. 2 is a graph showing the relationship between the shear viscosity and the elongational viscosity of the polyethylene resin.

Referring to FIGS. 1 and 2 , based on the black curve in FIG. 1 , when the temperature is lowered during injection processing, the shear viscosity increases in the overall range while maintaining the shape as shown in the red dotted line. In this case, 40 s ^-1 (or Since the shear viscosity at 40 /s) also increases, it is advantageous in terms of reducing hair defects. However, since the shear viscosity at a strong shear rate of 1000 s ^-1 or more generated during injection processing also increases, an injection processing load is generated. On the other hand, in the case of a Newtonian fluid-like viscosity remodeling type like the blue dotted line, the shear viscosity can be significantly lowered compared to the reference at a low shear rate, which is more advantageous in terms of hair generation reduction.

On the other hand, Figure 2 is a comparison of the shear viscosity and the elongational viscosity. In general, at a low shear rate and elongation rate, Truton's rule is applied. However, when the shear rate and elongation rate increase, this law no longer holds, and therefore it is necessary to utilize both the shear viscosity and the elongation viscosity in predicting the rate of hair generation.

Therefore, the present inventors studied the effect of the shear viscosity and tensile viscosity of the polyethylene resin on hair generation. Through repeated experiments under various conditions, the shear viscosity of the polyethylene resin was higher than a certain level when the injection molded product was separated into a mold. It was confirmed that hair does not occur because the non-solidified part is stretched and broken, and when the shear viscosity of the polyethylene resin is small below a certain level, the stretched resin is recovered and no hair is generated. In addition, it was confirmed that the higher the elongational viscosity of the polyethylene resin, the smaller the sagging, so the hair generation rate decreased. That is, when the shear viscosity of the polyethylene resin was less than a certain level or exceeded a certain level, and when the elongational viscosity was greater than a certain level, no hair was generated.

In addition, the shear viscosity and tensile viscosity of the polyethylene resin collected from the above experimental results, and the hair generation rate values during injection molding were regression-analyzed in the form of a function using a computer program, and a relational expression between the shear viscosity and the hair generation rate was derived. , was used to calculate the injection molding defect of the polyethylene resin, especially the hair generation rate.

Specifically, the injection molding failure prediction method of the polyethylene resin according to an embodiment of the present invention,

For the polyethylene resin, shear viscosity at 230°C and shear rate 0.05 to 500 s ⁻¹ using an ARES rheometer, and 190° C., Henkey strain 0.1 s ⁻¹ using an elongational viscometer attached to the ARES rheometer and measuring the elongational viscosity under the conditions of stretching for 30 seconds (step 1); and

Using the shear viscosity at a shear rate of 40 s ^-1 among the shear viscosities of the polyethylene resin, and the elongational viscosity, calculating the value of the hair generation rate during injection molding using the polyethylene resin (step 2); includes.

Meanwhile, in the present invention, 'Hair' is a type of processing defect that occurs in the process of injection molding, and refers to a phenomenon in which the injection-molded resin is elongated near the gate during injection molding. In the present invention, using 1.6 to 2.4 g of polyethylene resin, holding pressure 300 to 1000 bar, holding pressure time 0.5 to 2.0 seconds, cooling time 0.5 to 3.0 seconds, injection temperature 190 to 250 ° C., injection speed 50 to 100 mm / s, improvement 6 When injection molding is performed under the conditions of 25 mm to 25 mm and a back pressure of 5 to 100 bar, a case in which the length of the stretched polyethylene resin is 2.5 mm or more is defined as hair, and a case less than 2.5 mm is defined as a high gate phenomenon.

In addition, in the present invention, 'Hair generation rate' refers to a holding pressure of 300 to 1000 bar, a holding pressure of 0.5 to 2.0 seconds, a cooling time of 0.5 to 3.0 seconds, an injection temperature of 190 to 250° C., an injection speed of 50 to 100 mm/s, and an improvement of 6 to 25 mm. And when the polyethylene resin is injection molded under injection molding conditions of 5 to 100 bar back pressure, specifically, when 20 kg of polyethylene resin is molded into a PC01881 standard bottle cap (top plate thickness 1.0 mm) , the total The ratio of the number of injection-molded products in which hair is generated to the number is expressed as a percentage.

Specifically, the hair generation rate can be defined and calculated by Equation 1 below:

[Equation 1]

Hair generation rate (%)= [ B / A ] ⅹ100

In Equation 1, A is a holding pressure of 300 to 1000 bar, a holding pressure of 0.5 to 2.0 seconds, a cooling time of 0.5 to 3.0 seconds, an injection temperature of 190 to 250° C., an injection speed of 50 to 100 mm/s, an improvement of 6 to 25 mm, and a back pressure of 5 When a polyethylene resin is molded under injection molding conditions of to 100 bar, specifically, when a 20 kg polyethylene resin is molded with a PC01881 standard bottle cap (top plate thickness 1.0 mm), it means the total number of injection-molded products manufactured,

B denotes the number of injection-molded products in which hair is generated in injection-molded products manufactured by injection molding under the above conditions.

Hereinafter, each step will be described in detail.

First, in the prediction method according to an embodiment of the present invention, step 1 is a step of measuring the shear viscosity and the tensile viscosity of the polyethylene resin, respectively.

The polyethylene resin may include polyethylene, and optionally conventional additives according to the use of the polyethylene resin.

In addition, the polyethylene is an ethylene homopolymer consisting only of ethylene repeating units derived from an ethylene monomer; or an ethylene/alpha-olefin copolymer comprising an alpha olefin repeating unit derived from an alpha olefin monomer together with the ethylene repeating unit; may be, and the polyethylene resin may include a mixture of the ethylene homopolymer and the ethylene/alpha-olefin copolymer.

Specific examples of the alpha-olefin monomer include propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, 1-octene, 1-decene, 1-undecene, 1- There exist dodecene, 1-tetradecene, 1-hexadecene, 1-eicocene, etc., and 2 or more types of these can also be used.

Although the physical properties of the polyethylene are not particularly limited, it is preferable as long as it satisfies the physical property requirements required for manufacturing a conventional bottle cap or for manufacturing a bottle cap.

The shear viscosity of the polyethylene resin can be measured using an ARES rheometer, specifically, using an ARES rotational rheometer, and using a parallel plate as a geometry, at 230° C. and a shear rate of 0.05 to The shear viscosity is measured at 500 s ⁻¹ , and the shear viscosity at a shear rate of 40 s ⁻¹ among the measured shear viscosities can be obtained by interpolation using the carreau-Yasuda model. In this case, the gap between the plates in the parallel plate may be 0.5 to 2 mm, and more specifically, 0.7 to 1.5 mm.

In addition, the measurement of the elongational viscosity of the polyethylene resin is, specifically, using an elongation viscosity fixture (EVF) attached to an ARES-G2 rheometer (manufactured by TA Instruments) at 190° C., Hencky strain (Hencky). rate) 0.1 s ^-1 , and may be performed under the conditions of stretching for 30 seconds.

Next, the value of the hair generation rate is calculated using the shear viscosity and the elongational viscosity measured in step 1.

Specifically, the value of the hair generation rate may be calculated according to the following Equation 2-1 or 2-2 based on the elongational viscosity of the polyethylene resin:

[Equation 2-1]

Value of hair generation rate = -0.0022η _shear ² + 6.44 η _shear - 4652 (when the elongational viscosity of the polyethylene resin is 14,000 Pa·S or more)

[Equation 2-2]

Value of hair generation rate = 20 (η _shear /700) - 5 (η _shear /700) ² (when the elongational viscosity of the polyethylene resin is less than 14,000 Pa S)

In Equations 2-1 and 2-2, η _shear is measured using an ARES rotational rheometer as described above, and using a parallel plate as a geometry to measure the shear viscosity at 230°C and a shear rate of 0.05 to 500 s ⁻¹ , and shear among the measured shear viscosity It is the shear viscosity value of the polyethylene resin obtained by interpolating the shear viscosity at a rate of 40 s ^-1 using the Carreau-Yasuda model.

On the other hand, in Equations 2-1 and 2-2, shear viscosity and elongation viscosity values for polyethylene resins of various physical properties, and hair generation rate values confirmed during injection molding of the polyethylene resins, are collected, and these data are computerized. It can be derived by regression analysis in the form of a function using a program, specifically, an origin program.

Specifically, when the elongational viscosity of the polyethylene resin measured according to the above-described method is 14,000 Pa.S or more, the phenomenon of stretching around the gate does not occur due to the high elongational viscosity. In general, the factor that determines hair is whether or not an initial high gate occurs when the injection mold is removed from the injection mold. Since the higher the shear viscosity, the higher the viscoelasticity of the polyethylene resin, so that when the injection mold is removed from the injection mold, the resin does not stretch but breaks, which is advantageous in terms of hair failure. In Equation 2-1, a negative term reflects the effect of the high shear viscosity of the polyethylene resin on the hair defect rate.

In addition, when the elongational viscosity of the polyethylene resin is less than 14,000 Pa.S, when the injection mold falls from the injection mold due to the low elongational viscosity, hair occurs when the resin is stretched, so it is important not to stretch the resin at the beginning. At this time, if the shear viscosity is small, the time for the stretched resin to recover is quicker, so it shows advantageous properties in terms of hair failure. A negative term in Equation 2-2 reflects the effect of the low shear viscosity of the polyethylene resin on the hair defect rate.

As supported by the examples below, the hair defect rate value of the polyethylene resin calculated according to Equation 2-1 or 2-2 shows a very high correlation coefficient (R ² ) value of 0.950 or more with the actually measured hair generation rate. . As a result, the hair generation rate of the polyethylene resin or the injection molding failure can be predicted with very high reliability by the formula derived above.

On the other hand, the polyethylene resin having a low hair generation rate or predicted to have improved injection molding defects by the above method may have a shear viscosity of less than 1,300 Pa·S or greater than 1,600 Pa·S.

The shear viscosity of the polyethylene resin is measured using an ARES rotational rheometer as described above, and using a parallel plate as a geometry to measure the shear viscosity at 230°C and a shear rate of 0.05 to 500 s ^-1 Among the shear viscosities, the shear viscosity at a shear rate of 40 s ^-1 can be obtained by interpolation using the Carreau-Yasuda model.

In addition, the polyethylene resin may have an elongational viscosity of more than 14,000 Pa·S.

As described above, the elongational viscosity of the polyethylene resin was specifically measured at 190° C., Hencky strain using an elongation viscosity fixture (EVF) attached to an ARES-G2 rheometer (manufactured by TA Instruments). rate) 0.1 s ^-1 , and can be obtained by measuring under the conditions of stretching for 30 seconds.

In addition, the polyethylene resin may include polyethylene satisfying one or more, two or more, or all three of the following conditions 1) to 3):

1) Melt index (measured under a load of 2.16 kg at a temperature of 190 °C according to ASTM D 1238 standard): 0.6 to 2 g/10min;

2) melt flow rate ratio (MI ₅ /MI _2.16 ): 2.8 to 4.2; and

3) Density (measured according to ASTM D1505 standards): 0.950 to 0.960 g/cm ³ .

Specifically, the polyethylene has a density of 0.950 g/cm ³ or more, measured according to ASTM D1505, and 0.960 g/cm ³ or less, more specifically 0.950 g/cm ³ or more, or 0.951 g/cm ³ greater than or equal to 0.960 g/cm ³ or less or 0.956 g/cm ³ or less. By having a density within the above range, excellent pressure resistance characteristics and dimensional stability may be exhibited.

In addition, the polyethylene may have a melt index (MI _2.16 ) of 0.6 to 2 g/10 min. The melt index of polyethylene affects processability during injection molding. If MI _2.16 is less than 0.6 g/10min, there is a risk that the processing pressure may increase and processability may decrease, and if MI 2.16 exceeds 2 g/10min, dimensional stability may decrease due to high fluidity. The polyethylene in the present invention can exhibit excellent dimensional stability and workability in a well-balanced manner by having a melt index within the above range.

On the other hand, in the present invention, the melt index of polyethylene can be measured under a load of 2.16 kg at 190° C. according to ASTM D 1238, and melted for 10 minutes according to ASTM D 1238, and the polymer is melted for 10 minutes. is expressed as the weight (g) of

In addition, the polyethylene may exhibit a melt flow rate ratio (MFRR, MI ₅ /MI _2.16 ) of 2.8 to 4.2. Excellent workability can be exhibited by having a melt flow rate ratio within the above range.

In the present invention, the MFRR of polyethylene is the melt index (MI ₅ ) value measured at 190 ° C., 5 kg load condition according to ASTM 1238, and the melt index (MI _2.16 ) measured at 190 ° C., 2.16 kg load condition according to ASTM 1238 ) divided by the value.

As described above, since the method according to one embodiment of the present invention uses only the rheological properties of the polyethylene resin, it is possible to easily predict injection molding failure, particularly hair, within a short time. In addition, by using this, it is possible to easily select a polyethylene resin capable of exhibiting excellent injection moldability or an effect of improving injection molding defects during injection molding.

Hereinafter, through specific examples of the invention, the operation and effect of the invention will be described in more detail. However, these embodiments are merely presented as an example of the invention, and the scope of the invention is not defined thereby.

<Example>

A commercially available polyethylene resin having the characteristics as summarized in Table 1 was obtained and prepared.

1) Melt index (MI _2.16 ): It was measured under a load of 2.16 kg under a temperature condition of 190 ° C according to ASTM D 1238 standard.

2) Melt flow rate ratio (MFRR, MI ₅ /MI _2.16 ): According to ASTM D 1238, a value measured under a 5 kg load at a temperature of 190 ° C. (MI ₅ ) was obtained by dividing by the MI _2.16 value.

3) Density: Measured at 23°C according to ASTM D1505 standard.

4) Shear viscosity (40 s ^-1 shear viscosity)

ARES rotational rheometer was used and the shear viscosity was measured at 230°C and a shear rate of 0.05 to 500 s ⁻¹ using a parallel plate as a geometry, and among the measured shear viscosities, shear at a shear rate of 40 s ⁻¹ The viscosity was obtained by interpolation using the Carreau-Yasuda model. At this time, the gap between the plates in the parallel plate was set to 1.0 mm.

5) Enlogational viscosity

Using an extensional viscosity measuring device (EVF) attached to an ARES-G2 rheometer (manufactured by TA Instruments), it was measured under the conditions of 190°C, Henkey's strain rate of 0.1 s ^-1 , and stretching for 30 seconds.

The measurement results are shown in Table 1 below.

MI _2.16
(g/10min) MFRR density
(g/cm ³ ) 40 s ^-1 shear viscosity
(Pa S) Enlogational viscosity
(Pa S) Example 1 1.25 4.20 0.952 1126.1 12172.6 Example 2 0.88 4.01 0.952 1368.4 13625.0 Example 3 1.06 4.11 0.953 1563.2 12943.8 Example 4 1.14 3.98 0.951 1324.1 15227.2 Example 5 0.88 4.01 0.952 1861.3 19237.2 Example 6 0.61 3.75 0.952 1745.1 15632.8 Example 7 0.80 3.65 0.956 1628.8 17663.9 Example 8 2.00 2.82 0.952 1292.8 14938.7

With respect to the polyethylene resin, injection molding was performed using a mold with a top plate thickness of 1.0 mm under the same conditions as in Tables 2 and 3 below, except that the outer diameter was 28 mm, the top plate thickness was 1 mm, and the gate shape was a star shape. And manufactured a bottle cap for cold fill according to PCO1881 standard.

Polyethylene resin usage
(g) hold pressure
(bar) hold time
(s) cooling time
(s) injection temperature
(℃) injection speed
(mm/s) improvement
(mm) back pressure
(bar) 1.6 to 2.4 300~1000 0.5 to 2.0 0.5 to 3.0 190 to 250 50 to 100 6 to 25 5 to 100

A bottle cap for cold fill was injection-molded in the same manner as above using 20 kg of the polyethylene resin, and the ratio of the number of bottle caps having hair defects to the total number of manufactured bottle caps was calculated.

From the above experiments, the shear viscosity and elongational viscosity of the polyethylene resin, and the hair generation rate value in the bottle cap prepared using the same were collected, and these data were regression-analyzed in the form of a function to derive the following equation.

[Equation 2-1]

Value of hair generation rate = -0.0022η _shear ² + 6.44 η _shear - 4652

[Equation 2-2]

Value of hair generation rate = 20 (η _shear /700) - 5 (η _shear / 700) ²

In Equations 2-1 and 2-2, η _shear is the shear viscosity value of the polyethylene resin measured by the method described above.

Using the derived formula, the injection molding defect rate of the polyethylene resin according to Examples 1 to 12, that is, the hair generation rate, was calculated and predicted. The results are shown in Table 3 below.

injection temperature
(℃) Hair generation rate (%) measured value predicted value Example 1 230 10.0 11.4 Example 2 230 2.5 1.7 Example 3 230 30.0 39.1 Example 4 230 20.0 18.1 Example 5 190 0 0 Example 6 230 0 0 Example 7 230 0 0 Example 8 230 0 0

Referring to Table 3, it can be seen that the correlation coefficient (R ² ) value between the actually measured hair generation rate and the predicted value predicted by the equation is about 0.950, showing a very high value. It can be confirmed that the hair generation rate of the polyethylene resin or the injection molding defect can be predicted with very high reliability by the equation derived from the example.

Claims (6)

For the polyethylene resin, shear viscosity at 230°C and shear rate 0.05 to 500 s ⁻¹ using an ARES rheometer, and 190° C., Henkey strain 0.1 s ⁻¹ using an elongational viscometer attached to the ARES rheometer , and measuring the elongational viscosity under the conditions of stretching for 30 seconds, respectively; and
Using the shear viscosity at a shear rate of 40 s ^-1 among the shear viscosities of the polyethylene resin, and the elongational viscosity, calculating the value of the hair generation rate during injection molding using the polyethylene resin;
A method for predicting injection molding failure of polyethylene resin.
According to claim 1,
The hair is, using 1.6 to 2.4 g of polyethylene resin, holding pressure 300 to 1000 bar, holding pressure 0.5 to 2.0 seconds, cooling time 0.5 to 3.0 seconds, injection temperature 190 to 250° C., injection speed 50 to 100 mm/s, improvement 6 At the time of injection molding under the conditions of 25 mm to 25 mm and a back pressure of 5 to 100 bar, the length of the stretched polyethylene resin is 2.5 mm or more, a prediction method.
According to claim 1,
The hair generation rate is, holding pressure 300 to 1000 bar, holding pressure 0.5 to 2.0 seconds, cooling time 0.5 to 3.0 seconds, injection temperature 190 to 250° C., injection speed 50 to 100 mm/s, improvement 6 to 25 mm, and back pressure 5 to 100 bar In the case of injection molding a polyethylene resin under the injection molding conditions of , a prediction method that represents the ratio of the number of injection-molded products with hair to the total number of manufactured injection-molded products as a percentage.
According to claim 1,
The value of the hair generation rate is calculated according to the following Equation 2-1 or 2-2 based on the elongational viscosity of the polyethylene resin, a prediction method:
[Equation 2-1]
Value of hair generation rate = -0.0022η _shear ² + 6.44 η _shear - 4652 (when the elongational viscosity of the polyethylene resin is 14,000 Pa·S or more)
[Equation 2-2]
Value of hair generation rate = 20 (η _shear /700) - 5 (η _shear /700) ² (when the elongational viscosity of the polyethylene resin is less than 14,000 Pa·S)
In Equations 2-1 and 2-2, η _shear is measured using an ARES rotary rheometer and using a parallel plate as a geometry to measure the shear viscosity at 230°C and a shear rate of 0.05 to 500 s ⁻¹ , and among the measured shear viscosities, a shear rate of 40 s ⁻ This is the shear viscosity value of the polyethylene resin obtained by interpolating the shear viscosity at ¹ using the carreau-Yasuda model.
According to claim 1,
The polyethylene resin, the shear viscosity is less than 1300 Pa · S, or more than 1600 Pa · S, the prediction method.
According to claim 1,
The polyethylene resin, including polyethylene satisfying one or more of the following conditions 1) to 3), prediction method:
1) Melt index (measured under a load of 2.16 kg at a temperature of 190 °C according to ASTM D 1238 standard): 0.6 to 2 g/10min
2) melt flow rate ratio (MI ₅ /MI _2.16 ): 2.8 to 4.2; and
3) Density (measured according to ASTM D1505 standards): 0.950 to 0.960 g/cm ³ .

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