A polyolefin resin composition, a method for preparing the same, and an application thereof

Abstract

The application discloses a polyolefin resin composition and a preparation method and application thereof, and the polyolefin resin composition comprises the following components in parts by weight: linear PE resin 60-92 parts; HDPE 2-10 parts; and cyclic polyolefin resin 6-30 parts; the content of bicycloheptene in the cyclic polyolefin resin is greater than or equal to 75%, and the heat distortion temperature is greater than or equal to 127 DEG C. The polyolefin resin composition has good extinction effect and is suitable for packaging materials with high extinction effect requirements.

Description

Technical Field

[0001] This invention relates to the field of packaging materials technology, specifically to a polyolefin resin composition, its preparation method, and its application. Background Technology

[0002] Film blowing is a common processing method for polyolefin materials, and matting materials are widely used in packaging and other applications. The matting materials for blown films on the market are primarily based on Borealis's bimodal LLDPE. Due to patent protection, other synthetic chemical companies cannot produce similar materials, resulting in a monopoly for Borealis. However, due to high market demand, supply often falls short of demand and prices are high. Therefore, finding ways to modify materials to achieve a matting effect using blown film technology is of great significance. Summary of the Invention

[0003] To overcome the shortcomings of the prior art, this invention proposes a polyolefin resin composition, its preparation method, and its application. The polyolefin resin composition provided by this invention possesses excellent matting effect and flowability, making it suitable for packaging materials requiring high matting performance. It overcomes technological barriers and can replace products from foreign companies.

[0004] Specifically, this is achieved through the following technical solutions:

[0005] A polyolefin resin composition, comprising, by weight, the following components:

[0006] 60-92 parts of linear PE resin

[0007] HDPE 2-10 parts

[0008] 6-30 parts of cyclic polyolefin resin

[0009] The cyclic polyolefin resin contains ≥75% dicyclohepten and has a heat distortion temperature ≥127℃. For cyclic polyolefin resins containing a specific content of dicyclohepten, commercially available cyclic polyolefin resin products can be used, or they can be prepared in-house using existing methods. For example, dicyclohepten monomers and ethylene monomers can undergo copolymerization under a catalyst, and the reaction conditions and degree of polymerization can be controlled. Existing conventional methods for determining dicyclohepten content can be used in this invention. The higher the dicyclohepten content in the cyclic polyolefin resin, the higher the heat distortion temperature. The heat distortion temperature is tested according to the method specified in GB / T 1634J-2019 "Determination of Load Deflection Temperature of Plastics Part 1: General Test Methods".

[0010] Preferably, the cyclic polyolefin resin contains 80-83% dicyclohepten, and has a heat distortion temperature of 150℃~170℃. The dicyclohepten content in the cyclic polyolefin resin affects the material's flowability and haze.

[0011] Preferably, the cyclic polyolefin resin is one or more of ethylene / bicycloheptene copolymer, propylene / bicycloheptene copolymer, or ethylene / propylene / bicycloheptene multi-component copolymer.

[0012] Furthermore, the linear PE resin is a linear PE resin synthesized with C4-C8 as the matrix, and the melt index is 0.2-3 g / 10 min at 190℃ and 2.16 kg.

[0013] Furthermore, the viscosity of the HDPE is 2000-4000 Pa·s under test conditions of 190℃ and 100HZ. The viscosity was tested according to the method specified in ISO 11443-2014 "Plastics—Determination of flowability of plastics by capillary and slotted rheometer".

[0014] Furthermore, the HDPE has a melt index of 0.01-0.3 g / 10 min at 190℃ and 2.16 kg, a number average molecular weight of 25,000-60,000, and a molecular weight distribution of 3-6.

[0015] Preferably, the HDPE has a melt index of 0.03-0.1 g / 10 min at 190℃ and 2.16 kg, a number average molecular weight of 35,000-50,000, and a molecular weight distribution of 4-5.

[0016] Furthermore, it also includes 0.1-0.3 parts of processing aids. The processing aids are one or more of antioxidants or anti-aging agents.

[0017] The present invention also provides a method for preparing the above-mentioned polyolefin resin composition, comprising the following steps:

[0018] S1: Weigh out each component according to the ratio, premix them, and obtain the premix;

[0019] S2: The premix from step S1 is fed into an extruder for melt blending and extrusion granulation to obtain the polyolefin resin composition.

[0020] Furthermore, the extruder is a twin-screw extruder with a screw length-to-diameter ratio of (36-48):1, a barrel temperature of 180-220℃, and a screw speed of 300-600 r / min. A suitable screw length-to-diameter ratio is beneficial for the uniform distribution of components.

[0021] The present invention also provides the application of the above-mentioned polyolefin resin composition in the preparation of packaging materials, such as food packaging.

[0022] Compared with the prior art, the beneficial effects of the present invention are:

[0023] (1) This invention discloses a polyolefin resin composition, which uses linear PE resin, and has advantages such as sufficient supply and low cost compared with other special PE materials;

[0024] (2) The HDPE used in this invention has the characteristics of narrow molecular weight distribution and high molecular weight, which can improve the haze of the material. On the other hand, its viscosity is high, which can adjust the shortcomings of insufficient blown film melt strength caused by excessive melt index due to cyclic polyolefin.

[0025] (3) The cyclic polyolefin used in this invention is a cyclic polyolefin with a high content of bicyclohepten, which can greatly improve the overall matting effect of the film. Detailed Implementation

[0026] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0027] Research has shown that adding cyclic polyolefin resins with a dicyclohepten content of ≥75% can significantly improve the overall matting effect of the film. However, while adding cyclic polyolefin resins can improve the matting effect, it can also cause the melt index to become too high, thus affecting the material's strength. This invention introduces HDPE, which has a narrow molecular weight distribution and a high molecular weight. To a certain extent, HDPE can improve the material's haze. Furthermore, its high viscosity can compensate for the insufficient melt strength of blown film caused by an excessively high melt index due to cyclic polyolefins.

[0028] <Preparation of Examples and Comparative Examples>

[0029] The raw materials used in the embodiments and comparative examples of this invention are all commercially available, but are not limited to these materials:

[0030] Linear PE resin with a melt index of 2 g / 10 min at 190℃ and 2.16 kg, grade LLDPE 1002BU, purchased from ExxonMobil.

[0031] Cyclic polyolefin resin A, ethylene / dicyclohepten copolymer, dicyclohepten content = 75%, grade TOPAS5013, heat distortion temperature 127℃, purchased from Polyplastics Corporation, Japan.

[0032] Cyclic polyolefin resin B, ethylene / dicyclohepten copolymer, dicyclohepten content = 78%, grade TOPAS6013, heat distortion temperature 130℃, purchased from Polyplastics Corporation, Japan.

[0033] Cyclic polyolefin resin C, ethylene / bicyclohepten copolymer, bicyclohepten content = 80%, grade TOPAS6015, heat distortion temperature 150℃, purchased from Polyplastics Corporation, Japan.

[0034] Cyclic polyolefin resin D, ethylene / bicycloheptene copolymer, bicycloheptene content = 83%, grade TOPAS6017, heat distortion temperature 170℃, purchased from Polyplastics Corporation, Japan.

[0035] Cyclic polyolefin resin E, ethylene / bicyclohepten copolymer, bicyclohepten content = 65%, grade TOPAS8007, heat distortion temperature 75℃, purchased from Polyplastics Corporation, Japan.

[0036] HDPE(A), with a viscosity of 2300 Pa·s, a number-average molecular weight of 45000, a molecular weight distribution of 4, grade HDPE6097, was purchased from China Petroleum & Chemical Corporation.

[0037] HDPE(B), with a viscosity of 850 Pa·s, a number-average molecular weight of 44,000, a molecular weight distribution of 4, and a grade of HDPEFL8008, was purchased from China Petroleum & Chemical Corporation.

[0038] LLDPE: Grade FB2230, purchased from Borealis;

[0039] Antioxidant, antioxidant 1010 and antioxidant 168 (1:1) compound, commercially available;

[0040] Anti-aging agent, commercially available.

[0041] Unless otherwise specified, the components (e.g., antioxidants, anti-aging agents) in the parallel embodiments and comparative examples of this invention are all commercially available products.

[0042] The preparation methods of the embodiments and comparative examples of the present invention are as follows:

[0043] S1: Weigh each component according to the proportions in Table 1 and Table 3, premix them, and obtain the premix;

[0044] S2: The premix from step S1 is fed into a twin-screw extruder for melt blending and extrusion granulation to obtain a polyolefin resin composition.

[0045] The twin-screw extruder has a screw length-to-diameter ratio of 40:1, a melt zone temperature of 200-220℃, and a screw speed of 400 r / min.

[0046] Unless otherwise specified, the word "parts" in this instruction manual means "parts by weight".

[0047] <Test Standards>

[0048] The performance test methods for each embodiment and comparative example of the present invention are as follows:

[0049] Unless otherwise specified, the melt index and melt flow rate involved in the present invention are tested according to the methods specified in GB / T 3682-2018 "Plastics - Determination of melt mass-flow rate (MFR) and melt volume-flow rate (MVR) of thermoplastics";

[0050] The resin viscosity performance is tested according to the methods specified in ISO 11443-2014 "Plastics - Determination of the flow properties of plastics using capillary and slit-die rheometers".

[0051] Add the polyolefin resin compositions prepared in each embodiment and comparative example to a blown film machine. The processing temperature is 170-210°C, the blow-up ratio is between 1:1 and 1:5, and the thickness of the single-layer film is adjusted to about 50 μm. Use this film sample to test the light transmittance, haze, and surface gloss. The light transmittance and haze are tested according to the methods specified in GB / T 2410-2008 "Determination of light transmittance and haze of transparent plastics"; the gloss is tested from a 60° angle according to the methods specified in GB / T 8807-1988 "Test method for specular gloss of plastics".

[0052] Table 1. Formulations of Embodiments and Comparative Examples

[0053]

[0054]

[0055] Table 2. Performance Test Results of Embodiments and Comparative Examples

[0056]

[0057] The extinction performance of the material can be judged according to the haze, light transmittance, and gloss of the material. The greater the haze, the better the extinction performance; the greater the light transmittance, the better the extinction performance; the smaller the gloss, the better the extinction performance. In addition, since blown film is a common processing method for polyolefin materials, the melt flow rate (fluidity) of the material is also one of the indicators that need to be controlled. When the melt flow rate of the material is between 0.2-2 g / 10 min, it can all be applicable to the blown film process. However, when the material is below 1 g / 10 min, its processing range will be wider and the blown film will be easier.

[0058] Generally, when the haze of the polyolefin material is greater than 70%, the light transmittance is greater than 90%, and the gloss is less than 15%, it is qualified.

[0059] More preferably, when the haze is greater than 88%, the light transmittance is greater than 92%, and the gloss is less than 7%, it is good.

[0060] Compared with Examples 1 and 2, Examples 3 and 4 show better matting properties because the content of dicyclohepten in the cyclic polyolefin resin is within the preferred range.

[0061] Compared with Example 9, Comparative Example 1 had a dicyclohepten content of less than 75%, resulting in a significant decrease in haze and a significant increase in gloss, indicating that Comparative Example 1 had poor extinction performance.

[0062] Compared with Example 9, Comparative Example 2 did not add HDPE, which resulted in a decrease in haze and an increase in gloss, thus deteriorating the matting performance of Comparative Example 2.

[0063] Comparative Example 4 used commercially available Borealis LLDPE 2230 blown film matting material. Compared with commercially available matting materials, Examples 3 and 4 of this invention had similar light transmittance, but their haze and gloss were better than Comparative Example 4. It can be considered that the polyolefin resin provided by this invention is comparable to existing products, and even has better matting performance. In Comparative Example 3, the viscosity of HDPE was below 2000 Pa·s, which led to a significant decrease in haze, a decrease in light transmittance, and an increase in gloss in Comparative Example 3. Therefore, Comparative Example 3 had poor matting performance.

[0064] Example 10

[0065] The composition of Example 1 was blown into a film, and the following results were obtained: haze of 88%, light transmittance of 93%, and gloss of 7.2%. This demonstrates that the polyolefin composition provided by the present invention has good matting effect and is suitable for packaging materials requiring high matting performance.

[0066] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A polyolefin resin composition, characterized in that, By weight, it includes the following components: 60-92 parts of linear PE resin HDPE 2-10 parts 6-30 parts of cyclic polyolefin resin The HDPE grade is HDPE 6097, purchased from China Petroleum & Chemical Corporation; The cyclic polyolefin resin contains 80-83% dicyclohepten and has a heat distortion temperature of 150℃~170℃.

2. The polyolefin resin composition according to claim 1, characterized in that, The cyclic polyolefin resin is one or more of ethylene / bicycloheptene copolymer, propylene / bicycloheptene copolymer, or ethylene / propylene / bicycloheptene multi-component copolymer.

3. The polyolefin resin composition according to claim 1, characterized in that, The melt index of the linear PE resin is 0.2-3 g / 10 min at 190 °C and 2.16 kg.

4. The polyolefin resin composition according to claim 1, characterized in that, It also includes 0.1-0.3 parts of processing aids.

5. A method for preparing a polyolefin resin composition according to any one of claims 1-4, characterized in that, Includes the following steps: S1: Weigh out each component according to the ratio, premix them, and obtain the premix; S2: The premix from step S1 is fed into an extruder for melt blending and extrusion granulation to obtain the polyolefin resin composition.

6. The use of the polyolefin resin composition according to any one of claims 1-4 in the preparation of packaging materials.

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