Polyethylene material with crystal nucleus density self-regulation and preparation method thereof

Abstract

The application belongs to the field of materials, and relates to a polyethylene material with self-regulation of crystal nucleus density and a preparation method thereof. ‑1 The ratio A1 of the absorption intensity of the polyethylene material at 964 cm ‑1 The ratio A2 of the absorption intensity of the linear low-density polyethylene resin at 964 cm ‑1 The ratio A2 of the absorption intensity of the linear low-density polyethylene resin at 964 cm ‑1 The difference A1-A2 between the ratio A1 and the ratio A2 is 0.04-0.15. Compared with the existing additive nucleating agent or solvent treatment technology, the application is prepared by double-screw extrusion granulation, and is more simple to operate, and has good repeatability and stability.

Description

Technical Field

[0001] This invention belongs to the field of materials, specifically relating to a polyethylene material with self-regulating crystal nucleus density and its preparation method. Background Technology

[0002] Controlling the crystallization kinetics of polymers is significant not only for academic research but also for industrial applications. Rapid solidification of polymers from the melt ensures dimensional stability and reduces costs. While this solidification process is rapid for linear polyethylene (LLDPE), for LLDPE, the crystallization process requires the continuous selection and transport of suitable crystal sequences from the entangled melt, a kinetic limitation that slows down the crystallization rate. Added nucleating agents are often used to lower the nucleation free energy barrier, increasing the crystallization rate and nucleus density.

[0003] Melt memory in crystallization is defined as the presence of residual crystals or ordered aggregates above the melting temperature. During subsequent cooling, these residual crystals lower the nucleation free energy, leading to a faster crystallization rate. Due to the presence of the partially ordered structure of the former crystals, homopolymers crystallize from such melts at a faster rate than from completely random melts. This melt region exhibiting a "memory" of a previously ordered state may also originate from remnants of less entangled polymer chains or shear melts (which have not relaxed to an equilibrium random coil state). The melt memory effect typically influences subsequent crystallization, such as with increases in crystallization temperature or rate, morphological changes, smaller overall grain size, and even morphological transformations in polymorphic systems. Studies have found that polyethylene samples exhibiting melt memory effects were almost always pre-treated with a solution. For example, polyethylene resin was recrystallized in a 0.01% w / v xylene solution at 120°C, using acetone as a precipitant for the copolymer. Most additives dissolve in xylene, thus removing a significant amount of additives, including processing aids and antioxidants, from the solution precipitate. The presence of these additives interferes with the melt memory of the copolymer. No melt memory effect was observed in the initial sample without solution treatment. This indicates that the melt memory effect only becomes apparent after the additives are removed. This is because the additives interfere with self-nucleation. Melt memory effect in commercially available linear low-density polyethylene is rarely observed without removing the additives. Summary of the Invention

[0004] This invention provides a polyethylene material and a method for preparing the same. The polyethylene material has a micro-crosslinked structure, and its crystal nucleus density and final properties can be controlled by adjusting the melting temperature.

[0005] A first aspect of the present invention provides a polyethylene material with self-regulating crystal nucleus density, said polyethylene material being formed from linear low-density polyethylene resin, and wherein the polyethylene material has a 964 cm⁻¹ density measured by infrared spectroscopy. -1 The absorption intensity at 1367 cm⁻¹ is similar to that at 1367 cm⁻¹. -1 The ratio of the absorption intensity at point A1 to the infrared measurement of 964 cm⁻¹ of linear low-density polyethylene resin. -1 The absorption intensity at 1367 cm⁻¹ is similar to that at 1367 cm⁻¹. -1 The difference between the absorption intensities at point A1 and point A2 is 0.04 to 0.15, preferably 0.07 to 0.11.

[0006] A second aspect of the present invention provides a method for preparing a polyethylene material with self-regulating crystal nucleus density, comprising granulating linear low-density polyethylene resin by twin-screw extrusion to obtain the polyethylene material; wherein the linear low-density polyethylene resin has the following characteristics: a density of 0.900–0.940 g / cm³. 3 Melt index: 0.50–5.0 g / 10 min; In the TREF curve of temperature-elution fractionation, more than 45% of the molecules elute within the range of 35–90 °C, while the remaining less than 55% elute within the range of 90–105 °C; 964 cm⁻¹ infrared spectroscopy measurement. -1 The absorption intensity at the peak and at 1367 cm⁻¹ -1 The ratio of the absorption intensities of the peaks to that of A2 is 0.001 to 0.030.

[0007] A third aspect of the present invention provides a polyethylene material prepared by the above-described preparation method.

[0008] The polyethylene material described in this invention possesses a micro-crosslinked structure, and its nucleus density changes with melt temperature, exhibiting strong self-regulating ability in nucleus density. Therefore, the nucleus density and final properties of polyethylene can be controlled by adjusting the melt temperature. Compared to existing nucleating agent or solvent treatment techniques, the method of this invention utilizes twin-screw extrusion granulation, which is simpler to operate and offers better repeatability and stability. The polyethylene material of this invention has promising applications in polyethylene films and other fields.

[0009] Other features and advantages of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0010] Exemplary embodiments of the present invention will be described in more detail with reference to the accompanying drawings.

[0011] Figure 1 Polarized light microscope images of the samples in Example 1 as they were cooled from different melting temperatures to 40°C are shown. (a) Melting temperature 200°C, (b) Melting temperature 150°C.

[0012] Figure 2 Polarizing microscope images of the samples in Example 2 as they were cooled from different melting temperatures to 40°C are shown. (a) Melting temperature 200°C, (b) Melting temperature 150°C.

[0013] Figure 3 Polarized light microscope images of the samples in Example 3 as they were cooled from different melting temperatures to 40°C are shown. (a) Melting temperature 200°C, (b) Melting temperature 150°C.

[0014] Figure 4 Polarizing microscope images of the samples in Comparative Example 1 as they were cooled from different melting temperatures to 40°C are shown. (a) Melting temperature 200°C, (b) Melting temperature 150°C.

[0015] Figure 5 Polarizing microscope images of the samples in Comparative Example 2 as they were cooled from different melting temperatures to 40°C are shown. (a) Melting temperature 200°C, (b) Melting temperature 150°C.

[0016] Figure 6 Polarized light microscope images of the samples in Comparative Example 3 as they were cooled from different melting temperatures to 40°C are shown. (a) Melting temperature 200°C, (b) Melting temperature 150°C. Detailed Implementation

[0017] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0018] This invention provides a polyethylene material with self-regulating crystal nucleus density, said polyethylene material being formed from linear low-density polyethylene resin, and the polyethylene material having a 964 cm⁻¹ density measured by infrared spectroscopy. -1 The absorption intensity at 1367 cm⁻¹ is similar to that at 1367 cm⁻¹. -1 The ratio of the absorption intensity at point A1 to the infrared measurement of 964 cm⁻¹ of linear low-density polyethylene resin. -1 The absorption intensity at 1367 cm⁻¹ is similar to that at 1367 cm⁻¹. -1 The difference between the absorption intensities at point A1 and point A2 is 0.04 to 0.15, preferably 0.07 to 0.11.

[0019] According to the present invention, preferably, the linear low-density polyethylene resin forming the polyethylene material has the following characteristics: a density of 0.900 to 0.940 g / cm³. 3 Melt index: 0.50–5.0 g / 10 min; In the TREF curve of temperature-elution fractionation, more than 45% of the molecules elute within the range of 35–90 °C, while the remaining less than 55% elute within the range of 90–105 °C; 964 cm⁻¹ infrared spectroscopy measurement. -1The absorption intensity at the peak and at 1367 cm⁻¹ -1 The ratio of the absorption intensity of the peaks to that of peak A2 is 0.001 to 0.030, preferably 0.005 to 0.020.

[0020] According to the present invention, preferably, the density of the linear low-density polyethylene is 0.905–0.935 g / cm³. 3 Preferably, it is 0.910–0.930 g / cm³. 3 The melt index of the linear low-density polyethylene is 0.55 to 4.5 g / 10 min, preferably 0.60 to 4.0 g / 10 min.

[0021] According to the present invention, preferably, the comonomer of the linear low-density polyethylene is at least one selected from butene, hexene, and octene; the comonomer content is 1.0 to 5.0 mol%.

[0022] According to the present invention, preferably, the 964 cm⁻¹ infrared measurement of the polyethylene material is... -1 The absorption intensity at the peak and at 1367 cm⁻¹ -1 The ratio of the absorption intensity of the peaks, A1, is 0.03 to 0.18, preferably 0.09 to 0.12.

[0023] According to the present invention, preferably, the polyethylene material is obtained by twin-screw extrusion granulation of the linear low-density polyethylene resin.

[0024] This invention also provides a method for preparing a polyethylene material with self-regulating crystal nucleus density, comprising granulating linear low-density polyethylene resin by twin-screw extrusion to obtain the polyethylene material; wherein the linear low-density polyethylene resin has the following characteristics: density of 0.900–0.940 g / cm³. 3 Melt index: 0.50–5.0 g / 10 min; In the TREF curve of temperature-elution fractionation, more than 45% of the molecules elute within the range of 35–90 °C, while the remaining less than 55% elute within the range of 90–105 °C; 964 cm⁻¹ infrared spectroscopy measurement. -1 The absorption intensity at the peak and at 1367 cm⁻¹ -1 The ratio of the absorption intensities of the peaks to that of A2 is 0.001 to 0.030.

[0025] According to the present invention, preferably, the extrusion temperature during the extrusion process is 185-230°C and the extrusion speed is 30-400 rpm.

[0026] According to the present invention, preferably, the density of the linear low-density polyethylene is 0.905–0.935 g / cm³. 3 Preferably, it is 0.910–0.930 g / cm³. 3 .

[0027] According to the present invention, preferably, the melt index of the linear low-density polyethylene is 0.55 to 4.5 g / 10 min, more preferably 0.60 to 4.0 g / 10 min.

[0028] According to the present invention, preferably, the infrared measurement of 964 cm -1 The absorption intensity at the peak and at 1367 cm⁻¹ -1 The ratio of the absorption intensities of the peaks to that of A2 is 0.005 to 0.020.

[0029] According to the present invention, preferably, the comonomer of the linear low-density polyethylene is at least one selected from butene, hexene, and octene; the comonomer content is 1.0 to 5.0 mol%.

[0030] The present invention also provides a polyethylene material prepared by the above-described preparation method. This polyethylene material possesses the aforementioned characteristics.

[0031] The present invention will be further described below with reference to the embodiments, but the scope of the present invention is not limited to these embodiments.

[0032] The equipment, testing methods, and raw materials involved in the examples and comparative examples are as follows:

[0033] Gel permeation chromatography (GPC): The molecular weight and molecular weight distribution of the samples were determined using a PL-GPC220 GPC from Polymer Laboratories, UK. The chromatographic column consisted of three tandem Plgel 10μm MIXED-B columns. The solvent and mobile phase were both 1,2,4-trichlorobenzene (containing 0.025% antioxidant 2,6-dibutyl-p-cresol). The column temperature was 150℃, and the flow rate was 1.0 mL / min. Narrow-distribution polystyrene standards were used for universal standardization.

[0034] Temperature-elution fractionation (TREF): Performed on a PolymerChar TREF300 instrument (Spain), using 1,2,4-trimethylbenzene as the solvent. The sample was crystallized from 95°C to a stable temperature of 35°C at a cooling rate of 0.1°C / min. Then, the solvent was eluted at a rate of 0.5 mL / min, with the elution temperature increased from 35°C to 130°C at a heating rate of 1°C / min.

[0035] FTIR spectroscopy: Measurements were performed at room temperature using a Thermo Scientific Nicolet 6700 infrared spectrometer in transmission mode. The spectral range was 400-4000 cm⁻¹. -1 The resolution is 2cm. -1 .

[0036] Polarizing microscopy (PLM): The crystallization and melting behavior of the sample was observed using a BX51 high-magnification optical microscope from Olympus, Japan. The sample thickness was approximately 30 μm. The sample was heated from 40°C to a temperature T above the observed melting temperature. s The sample was left to stand for 5 minutes, then cooled to 40°C at a rate of 10°C / min. The crystal morphology of the sample was observed after cooling to room temperature.

[0037] Twin-screw extrusion: A WP ZSK25 twin-screw extruder was used. The length-to-diameter ratio (L / D) was 25 / 1. The extruded granules were collected to prepare samples.

[0038] Example 1

[0039] Linear low-density polyethylene resin (Dow's Dowlex 2045G, melt index 1.0 g / 10 min; density 0.920 g / cm³) was used. 3 The comonomer type is octene; the comonomer content is 2.38 mol%; in the temperature-washing classification TREF curve, 67% of the molecules eluted in the range of 35–90℃, and the remaining 33% eluted in the range of 90–105℃; the infrared spectroscopy measurement represents the degree of crosslinking of polyethylene at 964 cm⁻¹. -1 The absorption intensity at the peak and at 1367 cm⁻¹ -1 The absorption intensity ratio of the peak (A2 = 0.02) was 0.02. The polyethylene material was melt-blended and extruded using a twin-screw extruder at temperatures of 188℃, 207℃, 200℃, 200℃, 195℃, and 190℃, with a melt pressure of 38 bar and an extrusion speed of 355 rpm. The extruded granules were collected to prepare samples. The 964 cm⁻¹ of the polyethylene material was measured using infrared spectroscopy. -1 The absorption intensity at 1367 cm⁻¹ is similar to that at 1367 cm⁻¹. -1 The ratio of the absorption intensity at point A1 is 0.09.

[0040] The sample was heated from 40°C to a temperature T above the observed melting temperature. s For example, the sample is heated to 200°C, held for 5 minutes, and then cooled to 40°C. The sample is then heated from 40°C to a temperature T above the observed melting temperature. s For example, the temperature was set at 150℃ for 5 minutes, then lowered to 40℃. The heating and cooling rates were both 10℃ / min. The crystal morphology of the sample was observed after cooling to room temperature, and the results are as follows: Figure 1 As shown, the crystal nucleus density of the sample changes with the melt temperature. Compared with crystallization at 200℃, crystallization at 150℃ produces finer crystals and a significantly higher crystal nucleus density.

[0041] Example 2

[0042] Linear low-density polyethylene resin (Sinopec DFDA9085, melt index 0.75 g / 10 min; density 0.920 g / cm³) was used. 3 The comonomer type is butene; the comonomer content is 3.89 mol%; in the temperature-washing classification TREF curve, 61% of the molecules flowed out in the range of 35–90℃, and the remaining 39% flowed out in the range of 90–105℃; the infrared spectral density representing the degree of crosslinking of polyethylene is 964 cm⁻¹. -1 The absorption intensity at the peak and at 1367 cm⁻¹ -1 The absorption intensity ratio of the peak (A2 = 0.02) was 0.02. The polyethylene material was melt-blended and extruded using a twin-screw extruder at temperatures of 188℃, 207℃, 200℃, 200℃, 195℃, and 190℃, with a melt pressure of 38 bar and an extrusion speed of 355 rpm. The extruded granules were collected to prepare samples. The 964 cm⁻¹ of the polyethylene material was measured using infrared spectroscopy. -1 The absorption intensity at 1367 cm⁻¹ is similar to that at 1367 cm⁻¹. -1 The ratio of the absorption intensity at point A1 is 0.11.

[0043] The sample was heated from 40°C to a temperature T above the observed melting temperature. s For example, the sample is heated to 200°C, held for 5 minutes, and then cooled to 40°C. The sample is then heated from 40°C to a temperature T above the observed melting temperature. s For example, the temperature was set at 150℃ for 5 minutes, then lowered to 40℃. The heating and cooling rates were both 10℃ / min. The crystal morphology of the sample was observed after cooling to room temperature, and the results are as follows: Figure 2 As shown, the crystal nucleus density of the sample changes with the melt temperature. Compared with crystallization at 200℃, crystallization at 150℃ produces finer crystals and a significantly higher crystal nucleus density.

[0044] Example 3

[0045] Linear low-density polyethylene resin (DFDA6010 produced by Sinopec, with a melt index of 0.95 g / 10 min and a density of 0.921 g / cm³) was used. 3 The comonomer type is hexene; the comonomer content is 3.3 mol%; in the temperature-elution fractionation TREF curve, 47% of the molecules eluted in the range of 35–90℃, and the remaining 53% eluted in the range of 90–105℃; the infrared spectral density representing the degree of crosslinking of polyethylene is 964 cm⁻¹. -1 The absorption intensity at the peak and at 1367 cm⁻¹ -1The absorption intensity ratio of the peak (A2 = 0.01) was 0.01. The polyethylene material was melt-blended and extruded using a twin-screw extruder at temperatures of 188℃, 207℃, 200℃, 200℃, 195℃, and 190℃, with a melt pressure of 38 bar and an extrusion speed of 355 rpm. The extruded granules were collected to prepare samples. The 964 cm⁻¹ of the polyethylene material was measured using infrared spectroscopy. -1 The absorption intensity at 1367 cm⁻¹ is similar to that at 1367 cm⁻¹. -1 The ratio of the absorption intensity at point A1 is 0.12.

[0046] The sample was heated from 40°C to a temperature T above the observed melting temperature. s For example, the sample is heated to 200°C, held for 5 minutes, and then cooled to 40°C. The sample is then heated from 40°C to a temperature T above the observed melting temperature. s For example, the temperature was set at 150℃ for 5 minutes, then lowered to 40℃. The heating and cooling rates were both 10℃ / min. The crystal morphology of the sample was observed after cooling to room temperature, and the results are as follows: Figure 3 As shown, the crystal nucleus density of the sample changes with the melt temperature. Compared with crystallization at 200℃, crystallization at 150℃ produces finer crystals and a significantly higher crystal nucleus density.

[0047] Comparative Example 1

[0048] Linear low-density polyethylene resin (Dow's Dowlex 2045G, melt index 1.0 g / 10 min; density 0.920 g / cm³) was used. 3 The comonomer type is octene; the comonomer content is 2.38 mol%; in the temperature-washing classification TREF curve, 67% of the molecules eluted in the range of 35–90℃, and the remaining 33% eluted in the range of 90–105℃; the infrared spectroscopy measurement represents the degree of crosslinking of polyethylene at 964 cm⁻¹. -1 The absorption intensity at the peak and at 1367 cm⁻¹ -1 The absorption intensity ratio of the peaks (A2 = 0.02) is increased from 40℃ to a certain temperature T above the observed melting temperature. s For example, the sample is heated to 200°C, held for 5 minutes, and then cooled to 40°C. The sample is then heated from 40°C to a temperature T above the observed melting temperature. s For example, the temperature was set at 150℃ for 5 minutes, then lowered to 40℃. The heating and cooling rates were both 10℃ / min. The crystal morphology of the sample was observed after cooling to room temperature, and the results are as follows: Figure 4 As shown, the nucleus density of the sample did not change with the melt temperature. Compared to crystallization at 200℃, the nucleus density of the sample did not change when crystallized at 150℃.

[0049] Comparative Example 2

[0050] Linear low-density polyethylene resin (Sinopec DFDA9085, melt index 0.75 g / 10 min; density 0.920 g / cm³) was used. 3 The comonomer type is butene; the comonomer content is 3.89 mol%; in the temperature-washing classification TREF curve, 61% of the molecules flowed out in the range of 35–90℃, and the remaining 39% flowed out in the range of 90–105℃; the infrared spectral density representing the degree of crosslinking of polyethylene is 964 cm⁻¹. -1 The absorption intensity at the peak and at 1367 cm⁻¹ -1 The absorption intensity ratio of the peaks (A2 = 0.02) is increased from 40℃ to a certain temperature T above the observed melting temperature. s For example, the sample is heated to 200°C, held for 5 minutes, and then cooled to 40°C. The sample is then heated from 40°C to a temperature T above the observed melting temperature. s For example, the temperature was set at 150℃ for 5 minutes, then lowered to 40℃. The heating and cooling rates were both 10℃ / min. The crystal morphology of the sample was observed after cooling to room temperature, and the results are as follows: Figure 5 As shown, the nucleus density of the sample did not change with the melt temperature. Compared to crystallization at 200℃, the nucleus density of the sample did not change when crystallized at 150℃.

[0051] Comparative Example 3

[0052] Linear low-density polyethylene resin (DFDA6010 produced by Sinopec, with a melt index of 0.95 g / 10 min and a density of 0.921 g / cm³) was used. 3 The comonomer type is hexene; the comonomer content is 3.3 mol%; in the temperature-elution fractionation TREF curve, 47% of the molecules eluted in the range of 35–90℃, and the remaining 53% eluted in the range of 90–105℃; the infrared spectral density representing the degree of crosslinking of polyethylene is 964 cm⁻¹. -1 The absorption intensity at the peak and at 1367 cm⁻¹ -1 The absorption intensity ratio of the peaks (A2 = 0.01) is increased from 40℃ to a certain temperature T above the observed melting temperature. s For example, the sample is heated to 200°C, held for 5 minutes, and then cooled to 40°C. The sample is then heated from 40°C to a temperature T above the observed melting temperature. s For example, the temperature was set at 150℃ for 5 minutes, then lowered to 40℃. The heating and cooling rates were both 10℃ / min. The crystal morphology of the sample was observed after cooling to room temperature, and the results are as follows: Figure 6 As shown, the nucleus density of the sample did not change with the melt temperature. Compared to crystallization at 200℃, the nucleus density of the sample did not change when crystallized at 150℃.

[0053] As can be seen from the above, the polyethylene material prepared by this invention has a micro-crosslinked structure, which allows for the control of the crystal nucleus density and final properties of polyethylene by adjusting the melting temperature. Compared with existing technologies, this method has better repeatability and stability, and is simpler to operate.

[0054] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

[0055] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

Claims

1. A polyethylene material with self-regulating crystal nucleus density, characterized in that, The polyethylene material was obtained by twin-screw extrusion granulation of linear low-density polyethylene resin; and the polyethylene material measured by infrared spectroscopy had a 964 cm⁻¹ diameter. -1 The absorption intensity at 1367 cm⁻¹ is similar to that at 1367 cm⁻¹. -1 The ratio of the absorption intensity at point A1 to the infrared measurement of 964 cm⁻¹ of linear low-density polyethylene resin. -1 The absorption intensity at 1367 cm⁻¹ is similar to that at 1367 cm⁻¹. -1 The difference between the absorption intensities at point A1 and point A2, A1-A2, is 0.04 to 0.

15. The linear low-density polyethylene resin has the following characteristics: density The concentration is 0.900–0.940 g / cm³. 3 Melt index: 0.50–5.0 g / 10 min; In the TREF curve of temperature-elution fractionation, more than 45% of the molecules elute within the range of 35–90 °C, while the remaining less than 55% elute within the range of 90–105 °C; 964 cm⁻¹ infrared spectroscopy measurement. -1 The absorption intensity at the peak and at 1367 cm⁻¹ -1 The ratio of the absorption intensities of the peaks to that of A2 is 0.001–0.030; The extrusion temperature during the extrusion process is 185–230℃, and the extrusion speed is 30–400 rpm.

2. The polyethylene material with self-regulating crystal nucleus density according to claim 1, wherein, 964 cm of polyethylene material measured by infrared spectroscopy -1 The absorption intensity at 1367 cm⁻¹ is similar to that at 1367 cm⁻¹. -1 The ratio of the absorption intensity at point A1 to the infrared measurement of 964 cm⁻¹ of linear low-density polyethylene resin. -1 The absorption intensity at 1367 cm⁻¹ is similar to that at 1367 cm⁻¹. -1 The difference between the absorption intensities at point A1 and point A2, A1-A2, is 0.07 to 0.

11.

3. The polyethylene material with self-regulating crystal nucleus density according to claim 1, wherein, The linear low-density polyethylene resin measured at 964 cm⁻¹ using infrared spectroscopy. -1 The absorption intensity at the peak and at 1367 cm⁻¹ -1 The ratio of the absorption intensities of the peaks to that of A2 is 0.005 to 0.

020.

4. The polyethylene material with self-regulating crystal nucleus density according to claim 1, wherein, The linear low-density polyethylene has a density of 0.905–0.935 g / cm³. 3 The melt index of the linear low-density polyethylene is 0.55 to 4.5 g / 10 min.

5. The polyethylene material with self-regulating crystal nucleus density according to claim 4, wherein, The linear low-density polyethylene has a density of 0.910–0.930 g / cm³. 3 The melt index of the linear low-density polyethylene is 0.60 to 4.0 g / 10 min.

6. The polyethylene material with self-regulating crystal nucleus density according to claim 1, wherein, The comonomer of the linear low-density polyethylene is at least one selected from butene, hexene, and octene; the comonomer content is 1.0–5.0 mol%.

7. The polyethylene material with self-regulating nucleus density according to claim 1, wherein, The infrared measurement of the polyethylene material was 964 cm⁻¹. -1 The absorption intensity at the peak and at 1367 cm⁻¹ -1 The ratio of the absorption intensities of the peaks, A1, is 0.03 to 0.

18.

8. The polyethylene material with self-regulating crystal nucleus density according to claim 7, wherein, The infrared measurement of the polyethylene material was 964 cm⁻¹. -1 The absorption intensity at the peak and at 1367 cm⁻¹ -1 The ratio of the absorption intensities of the peaks, A1, is 0.09 to 0.

12.

9. A method for preparing a polyethylene material with self-regulating crystal nucleus density as described in any one of claims 1-8, comprising granulating linear low-density polyethylene resin by twin-screw extrusion to obtain the polyethylene material; wherein the linear low-density polyethylene resin has the following characteristics: a density of 0.900–0.940 g / cm³. 3 Melt index: 0.50–5.0 g / 10 min; In the TREF curve of temperature-elution fractionation, more than 45% of the molecules elute within the range of 35–90 °C, while the remaining less than 55% elute within the range of 90–105 °C; 964 cm⁻¹ infrared spectroscopy measurement. -1 The absorption intensity at the peak and at 1367 cm⁻¹ -1 The ratio of the absorption intensities of the peaks to that of A2 is 0.001–0.030; The extrusion temperature during the extrusion process is 185–230℃, and the extrusion speed is 30–400 rpm.

10. The preparation method according to claim 9, wherein, The linear low-density polyethylene has a density of 0.905–0.935 g / cm³. 3 The linear low-density polyethylene has a melt index of 0.55–4.5 g / 10 min; the infrared spectral density is 964 cm⁻¹. -1 The absorption intensity at the peak and at 1367 cm⁻¹ -1 The ratio of the absorption intensity of the peaks to A2 is 0.005 to 0.020; the comonomer of the linear low-density polyethylene is at least one of butene, hexene, and octene; the comonomer content is 1.0 to 5.0 mol%.

11. The preparation method according to claim 10, wherein, The linear low-density polyethylene has a density of 0.910–0.930 g / cm³. 3 The melt index of the linear low-density polyethylene is 0.60 to 4.0 g / 10 min.

Images