WO2020171525A1 - Polyethylene resin composition - Google Patents

Abstract

The present invention relates to a polyethylene resin composition which can be produced into films and fibers having superb physical properties through various processes due to the excellent workability and bubble stability thereof. The polyethylene resin composition comprises: a first polyethylene resin which has a density of 0.950 g/cm ³ to 0.960 g/cm ³, a weight average molecular weight of 80000 g/mol to 100000 g/mol, and a molecular weight distribution of 3.3 to 4.0; and a second polyethylene resin which has a density of 0.950 g/cm ³ to 0.960 g/cm ³, a weight average molecular weight of 500000 g/mol to 600000 g/mol, and a molecular weight distribution of 1.3 to 2.0.

Description

Polyethylene resin composition

Cross-reference with related application(s)

This application claims the interests of priority based on Korean patent application No. 10-2019-0020022 filed on February 20, 2019 and Korean patent application No. 10-2020-0017052 filed on February 12, 2020, and All contents disclosed in the literature are included as part of this specification.

The present invention relates to a polyethylene resin composition capable of producing a film or fiber having excellent physical properties through various processes, as it exhibits excellent processability and bubble stability.

Fiber made of polyethylene resin, for example, a flat yarn made of high-density polyethylene (HDPE) resin, is generally manufactured by cutting a polyethylene resin film into a certain width and stretching it.

The polyethylene resin film usable in this process may generally be a blown film or a casting film made of a polyethylene resin composition. However, depending on whether the polyethylene resin film is a blown film manufactured through a blown process or a casting film manufactured through a casting process, physical properties required for the polyethylene resin composition used as a raw material thereof are different.

For example, in the case of the blown film, the polyethylene resin composition needs to have high bubble stability due to the characteristics of the blown process, and in the case of the casting film, the polyethylene resin composition needs to exhibit a relatively low viscosity and high processability. There is.

However, in general, high bubble stability and high processability are physical properties that are difficult to be compatible with each other, and there is no known polyethylene resin or composition thereof that simultaneously meets these properties.

Therefore, in the past, resin compositions for blown films and casting films have been separately manufactured. As a result, it is true that the overall productivity of the polyethylene resin composition, the economical efficiency of the process, and the like had a great adverse effect.

Accordingly, it has been continuously requested to develop a polyethylene resin composition that exhibits excellent processability and bubble stability at the same time and enables the production of films or fibers having excellent physical properties through various processes such as a blown process or a casting process.

Accordingly, the present invention provides a polyethylene resin composition capable of producing a film or fiber having excellent physical properties through various processes, as it exhibits excellent processability and bubble stability.

The present invention relates to a first polyethylene resin having a density of 0.950 g/cm ³ to 0.960 g/cm ³ , a weight average molecular weight of 80000 g/mol to 150000 g/mol, and a molecular weight distribution of 3.9 to 6.0; And

A polyethylene resin composition comprising a second polyethylene resin having a density of 0.950 g/cm ³ to 0.960 g/cm ³ , a weight average molecular weight of 110000 g/mol to 300000 g/mol, and a molecular weight distribution of 1.5 to 3.8 is provided.

The present invention also provides a polyethylene resin film comprising the polyethylene resin composition.

In addition, the present invention provides a fiber comprising the polyethylene resin composition.

The present invention also provides a method for manufacturing a fiber comprising the step of cutting and stretching the polyethylene resin film.

Since the polyethylene resin composition according to the present invention includes two types of polyethylene resins having predetermined physical properties, it can exhibit a relatively low viscosity in a processing area, excellent processability, and bubble stability at the same time. Therefore, when the polyethylene resin composition is used, a polyethylene resin film having excellent physical properties can be manufactured through various processes such as a blown process or a casting process, and fibers such as flat yarn can be manufactured using this.

1 is a graph showing the results of evaluating the viscosity for each shear rate for polyethylene resin compositions of Examples and Comparative Examples.

2 is a graph showing the results of evaluating changes in complex viscosity by frequency for the polyethylene resin compositions of Examples and Comparative Examples.

Hereinafter, a polyethylene resin composition according to a specific embodiment of the present invention will be described.

According to an embodiment of the present invention, a first polyethylene resin having a density of 0.950 g/cm ³ to 0.960 g/cm ³ , a weight average molecular weight of 80000 g/mol to 150000 g/mol, and a molecular weight distribution of 3.9 to 6.0; And

A polyethylene resin composition comprising a second polyethylene resin having a density of 0.950 g/cm ³ to 0.960 g/cm ³ , a weight average molecular weight of 110000 g/mol to 300000 g/mol and a molecular weight distribution of 1.5 to 3.8 is provided.

As a result of the experiments of the present inventors, as a composition was provided by mixing two types of polyethylene resins satisfying the predetermined physical properties, the polyethylene resin composition may exhibit an appropriate viscosity that is not very high in the processing area, and as a result It was confirmed that it can exhibit suitable excellent processability. In addition, it was confirmed that the resin composition can simultaneously exhibit high bubble stability suitable for a blown process due to the appropriate viscosity range.

Unlike conventional common sense, the polyethylene resin composition exhibits excellent processability and bubble stability at the same time. As a resin having a high molecular weight such as the second polyethylene resin is mixed, the overall resin composition corresponds to the first polyethylene resin. While it may exhibit a low molecular weight and a low viscosity as a whole, it may include a relatively high content of high molecular chains (by addition of the second polyethylene resin) in the high molecular weight region. For this reason, the resin composition of the embodiment may exhibit a viscosity that is not relatively low under the conditions of the blown process, and may exhibit excellent bubble stability.

As described above, as the resin composition of one embodiment simultaneously exhibits excellent processability suitable for a casting process and high bubble stability suitable for a blown process, using the polyethylene resin composition, through various processes such as a blowing process or a casting process. A polyethylene resin film having excellent physical properties can be prepared, and fibers such as flat yarn can be manufactured using this.

Hereinafter, the polyethylene resin composition of one embodiment will be described in more detail for each component.

In the resin composition of the embodiment, the first polyethylene resin is 0.950 g/cm ³ to 0.960 g/cm ³ , or 0.951 g/cm ³ to 0.955 g/cm ³ density, 80000 g/mol to 150000 g/mol, A weight average molecular weight of 85000 g/mol to 130000 g/mol, or 90000 g/mol to 110000 g/mol, and a molecular weight distribution of 3.9 to 6.0, 4.0 to 5.5, or 4.5 to 5.3 may be shown.

As the first polyethylene resin satisfies these physical properties, it is possible to provide fibers such as a polyethylene resin film and/or flat yarn having excellent physical properties. In particular, the resin composition of one embodiment is in a processing area suitable for a casting process. It may indicate a not very high viscosity.

In addition, in the resin composition of the embodiment, the second polyethylene resin is 0.950 g/cm ³ to 0.960 g/cm ³ , or 0.951 g/cm ³ to 0.955 g/cm ³ density, 110000 g/mol to 300000 g/ mol, 120000 g/mol to 200000 g/mol, or 130000 g/mol to 150000 g/mol, and a molecular weight distribution of 1.5 to 3.8, 2.0 to 3.7, or 3.0 to 3.7.

As the second polyethylene resin satisfies these properties, the resin composition of one embodiment may contain relatively many high molecular chains in the high molecular weight region, and the resin composition of one embodiment exhibits excellent bubble stability suitable for a blown process. I can.

On the other hand, the above-described first polyethylene resin may be manufactured and provided to have the above-described physical properties, for example, according to a method known in the example of Published Patent Publication No. 2018-0068715, or the product name SM250 (manufactured by LG Chem. A resin that satisfies the above-described physical properties can be selected and used among commercially available resins under a product name such as ). In addition, the second polyethylene resin described above may be manufactured and provided to have the above-described physical properties, for example, according to a method known in the example of Publication No. 2010-0121449 or 2016-0147638, Alternatively, a resin that satisfies the above-described physical properties can be selected and used among commercially available resins under the product name of the product SP380 (manufactured by LG Chem).

In addition, the first and second polyethylene resins may be, for example, a copolymer of ethylene and an alpha olefin having 3 or more carbon atoms. At this time, the alpha olefin is propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, 1-octene, 1-decene, 1-undecene, 1-dodecene, It may include 1-tetradecene, 1-hexadecene, and mixtures thereof. Among these, the olefin polymer may be a copolymer of ethylene and 1-butene.

In addition, the resin composition of the embodiment is a weight ratio of the first and second polyethylene resins described above, for example, 80:20 to 90:10, 82:18 to 88:12, or 83:17 to 87:13 Can be included as. As a result, the viscosity range of the processing region represented by the resin composition of the exemplary embodiment may be further optimized, thereby exhibiting improved processability in the casting process, and more excellent bubble stability.

The resin composition of the embodiment including the first and second polyethylene resins described above may have a density of 0.950 g/cm ³ to 0.960 g/cm ³ , or 0.951 g/cm ³ to 0.955 g/cm ³ , According to ISO 1133, a melt index (MI _2.16 ) measured under a temperature of 230° C. and a load of 2.16 kg may be 0.5 to 0.9, or 0.55 to 0.8.

In addition, the resin composition of the embodiment has a melt index (MI ₅ ) measured under a temperature of 230° C. and a load of _5.0 kg according to ISO 1133, divided by the MI _2.16, and a MI ₅ /MI _2.16 value of 3.5 to 4.0, or 3.6 To 3.8.

By satisfying the above-described density range, fibers such as films and flat yarns exhibiting excellent physical properties can be prepared with the resin composition of one embodiment. In addition, as the properties of the melt index and the melt index ratio are satisfied, excellent processability in the casting process and excellent bubble stability in the blown process can be exhibited.

In addition, the resin composition of the embodiment has a weight average molecular weight of 110000 g/mol to 150000 g/mol, or 115000 g/mol as a whole in terms of mechanical properties and processability of a film and/or fiber formed therefrom. To 140000 g/mol, and a molecular weight distribution of 4.5 to 5.3, or 4.6 to 5.0.

Meanwhile, according to another embodiment of the present invention, a polyethylene resin film comprising the above-described polyethylene resin composition is provided. This polyethylene resin film may be a casting film or a blown film.

Regardless of the type of film, the film of the other embodiment may have excellent physical properties as a whole, and may be economically and effectively manufactured due to excellent processability, etc., as it is manufactured using the resin composition of the embodiment having excellent processability and bubble stability.

In addition, the film of another embodiment may be prepared as a film by mixing the above-described first and second polyethylene resins to prepare the resin composition of one embodiment, and then by a conventional melt blown method or casting method. However, the method of manufacturing the film is not limited thereto, and since a conventional film manufacturing process can be applied without any particular limitation, an additional description thereof will be omitted.

According to another embodiment of the invention, a fiber comprising the polyethylene resin composition of the embodiment is provided.

These fibers may be in the form of flat yarn, etc., and may be manufactured through the polyethylene resin film of the other embodiment. For example, it may be prepared by a method of cutting and stretching the polyethylene resin film of the other embodiment to a predetermined width.

However, the manufacturing method of the fiber is not limited thereto, and since a conventional fiber manufacturing process can be applied without any particular limitation, an additional description thereof will be omitted.

Hereinafter, the action and effect of the invention will be described in more detail through specific examples of the invention. However, this is presented as an example of the invention, and the scope of the invention is not limited to any meaning.

Examples 1 to 5 and Comparative Examples 1 to 4: Polyethylene resin composition

First, the polyethylene resin compositions of Examples and Comparative Examples were prepared using the polyethylene resins shown in Table 1 below. The weight average molecular weight, molecular weight distribution and density of these polyethylene resins were measured and evaluated in the same manner as in Test Examples described below:

	Product name (manufacturer)	Weight average molecular weight (g/mol)	Molecular weight distribution	Density (g/cm 3 )
PE1	SM250 (LG Chemical)	100k	5.0	0.952
PE2	SP380 (LG Chemical)	140k	3.7	0.952
PE3	SM100(LG Chemical)	110k	10.9	0.952
PE4	SP360 (LG Chemical)	120k	3.6	0.946
PE5	E308 (Korea Oil Painting)	138k	6.3	0.956
PE6	3392 (Hanwha Chemical)	122k	4.1	0.954

The polyethylene resins of Examples 1 to 5 and Comparative Examples 1 to 4 were prepared by mixing the polyethylene resins of PE1 to PE6 in the amounts shown in Table 2 below:

	Content (% by weight)
	PE1	PE2	PE3	PE4	PE5	PE6
Example 1	84	16	0	0	0	0
Example 2	85	15	0	0	0	0
Example 3	86	14	0	0	0	0
Example 4	83	17	0	0	0	0
Example 5	87	13	0	0	0	0
Comparative Example 1	0	0	76	24	0	0
Comparative Example 2	0	0	0	0	100	0
Comparative Example 3	0	0	0	0	0	100
Comparative Example 4	50	0	0	0	50	0

Test Example: Evaluation of physical properties

PE1 to PE6 used in Examples and Comparative Examples, the polyethylene resin compositions prepared in Examples and Comparative Examples, and physical properties in the process of preparing a film therefrom were evaluated by the following method:

(1) Density (g/cm ³ ): The density was measured according to ASTM D792 standard.

(2) Molecular weight (Mw, Mn) and molecular weight distribution (Mw/Mn): The weight average molecular weight (Mw) and number average molecular weight (Mn) were determined using gel permeation chromatography (GPC, gel permeation chromatography, manufactured by Water). Measured. Polymer Laboratories PLgel MIX-B 300 mm length column was used to evaluate using a Waters PL-GPC220 instrument. The evaluation temperature was 160°C, 1,2,4-trichlorobenzene was used as a solvent, and the flow rate was measured at a rate of 1 mL/min. The sample was prepared at a concentration of 10 mg/10 mL, and then supplied in an amount of 200 μL. The values of Mw and Mn were derived using a calibration curve formed using polystyrene standards. The molecular weight of polystyrene standards is 2,000 g/mol/ 10,000 g/mol/ 30,000 g/mol/ 70,000 g/mol/ 200,000 g/mol/ 700,000 g/mol/ 2,000,000 g/mol/ 4,000,000 g/mol/ 10,000,000 g/mol. Nine types were used.

The molecular weight distribution was calculated from Mw and Mn measured by the above-described method.

(3) MI _2.16 and MI ₅ /MI _2.16 : Melt Index of MI _2.16 and MI ₅ were measured according to ISO 1133 (230°C, 2.16kg or 5kg load) standard. From these measurement results, MI ₅ /MI _2.16 was calculated.

(4) Viscosity evaluation by shear rate

Viscosity for each shear rate was measured using a Goettfert Rheo-Tester 2000. The olefin copolymer melt was discharged through a capillary die (flat die, 180° angle) with a ratio (L/D) of length (L) to diameter (D) of 15. After equilibrating the sample at 240° C. for 5 minutes, the viscosity for each shear rate was evaluated at the same temperature.

(5) Evaluation of changes in complex viscosity by frequency

The complex viscosity by frequency was measured using an ARES-G2 rheometer manufactured by TA Instruments (New Castle, Delaway, USA). For the measurement sample, use parallel plates with a diameter of 25.0mm at 190°C so that the gap is 2.0mm, and the measurement is in dynamic frequency sweep mode with 5% strain and 0.05 rad/s frequency. A total of 41 points were measured up to 500 rad/s, 10 points for each decade, and complex viscosity values for each frequency were derived. Power law fitting was performed using TA Orchestrator, a measurement program.

(6) Machining load evaluation

The processing load was measured using a Collin Teach Line E16 extruder. The sample for measurement was extruded at 240° C. at 200 rpm, and the processing load (A, Ampere) applied at this time was measured.

(7) Die deposit evaluation

When extruding at 200 rpm at 240° C. using Collin's Teach Line E16 extruder, it was evaluated whether or not a die deposit was observed with the naked eye.

(8) Bubble stability evaluation

When film-forming was performed using a film blowing method, the generated bubbles were visually observed and evaluated. If the bubble was not shaken, it was evaluated as stable, and if it was shaken, it was evaluated as unstable. The film forming temperature was set at 150 to 250°C, and the blow up ratio (BUR) was performed at 1.2.

The physical properties of the evaluated polyethylene resin composition are summarized in Table 3 below. However, the result of evaluating the change of the complex viscosity for each frequency is shown in FIG.

	MI 2.16 (g/10min)	MI 5 /MI 2.16	Density (g/cm 3 )	Mw(g/mol)	Molecular weight distribution	Machining load (A)	Die deposit occurs	Bubble stability (Bur1.2)
Example 1	0.76	3.72	0.952	120000	4.9	1.8	X	stability
Example 2	0.69	3.64	0.952	124000	4.7	1.8	X	stability
Example 3	0.60	3.73	0.955	132000	4.7	1.8	X	stability
Example 4	0.79	3.75	0.952	115000	4.9	1.8	X	stability
Example 5	0.58	3.76	0.952	134000	4.7	1.8	X	stability
Comparative Example 1	1.15	4.04	0.952	106000	9.6	1.2	O	Instability
Comparative Example 2	0.86	3.29	0.956	138000	6.3	2.0	X	stability
Comparative Example 3	1.14	2.91	0.954	122000	4.1	2.0	X	Instability
Comparative Example 4	0.80	3.54	0.954	120000	5.5	2.0	X	Instability

As shown in Table 3 and FIGS. 1 and 2, it was confirmed that the resin composition of the Example contained two types of polyethylene resins having specific physical properties, and thus exhibited excellent processability and bubble stability compared to the Comparative Example.

In particular, the composition of the Example was evaluated to have a relatively low processing load compared to the Comparative Example, exhibit excellent processability due to no die deposit, and also excellent bubble stability. In contrast, it was confirmed that Comparative Examples 1 and 4 in which two polyethylene resins having different physical properties from the examples were mixed and Comparative Examples 2 and 3 using one polyethylene resin exhibited poor processability and/or bubble stability.

Claims (10)

1. A first polyethylene resin having a density of 0.950 g/cm ³ to 0.960 g/cm ³ , a weight average molecular weight of 80000 g/mol to 150000 g/mol, and a molecular weight distribution of 3.9 to 6.0; And

   A polyethylene resin composition comprising a second polyethylene resin having a density of 0.950 g/cm ³ to 0.960 g/cm ³ , a weight average molecular weight of 110000 g/mol to 300000 g/mol, and a molecular weight distribution of 1.5 to 3.8.
2. The polyethylene resin composition according to claim 1, comprising the first polyethylene resin: the second polyethylene resin in a weight ratio of 80:20 to 90:10.
3. The method of claim 1, wherein the composition has a density of 0.950 g/cm ³ to 0.960 g/cm ³ ,

   A polyethylene resin composition having a melt index (MI _2.16 ) of 0.5 to 0.9 measured under a temperature of 230° C. and a load of 2.16 kg according to ISO 1133.
4. The polyethylene resin according to claim 3, wherein the composition has a melt index (MI ₅ ) measured under a temperature of 230°C and a load of _5.0 kg according to ISO 1133 divided by the MI _2.16 and a MI ₅ /MI _2.16 value of 3.5 to 4.0 Composition.
5. The polyethylene resin composition according to claim 3, wherein the composition has a weight average molecular weight of 110000 g/mol to 150000 g/mol.
6. The polyethylene resin composition of claim 3, wherein the composition has a molecular weight distribution of 4.5 to 5.3.
7. A polyethylene resin film comprising the polyethylene resin composition according to any one of claims 1 to 6.
8. The polyethylene resin film according to claim 7, which is a casting film or a blown film.
9. A fiber comprising the polyethylene resin composition of any one of claims 1 to 6.
10. A method for producing a fiber comprising the step of cutting and stretching the polyethylene resin film of claim 7.

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