Special resin for polyethylene film as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of high polymer materials, and particularly relates to special resin for a polyethylene film as well as a preparation method and application thereof. The special resin for the polyethylene film is prepared from the following components in parts by weight: 50 to 70 parts of HDPE (High-Density Polyethylene) resin, 20 to 30 parts of LLDPE (Linear Low Density Polyethylene) resin, 0.5 to 3 parts of nano zinc oxide, 5 to 10 parts of maleic anhydride grafted POE (Polyolefin Elastomer) and 0.1 to 0.5 part of antioxidant. The HDPE, the LLDPE and the grafted POE form a three-phase topological structure, so that the bending modulus and the notch toughness can be synchronously improved. The special resin for the polyethylene film, which is prepared by adopting a low-temperature second-order blending process, can keep the toughening effect of an elastomer. The special resin for the polyethylene film prepared by the invention can realize ultrahigh toughness while keeping high rigidity, has long-acting weather resistance, can meet the requirements of packaging films and other high-end fields, is high in processing adaptability, and is suitable for a high-speed film blowing production line.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of high polymer materials, and particularly relates to a special resin for polyethylene film and a preparation method and application thereof. BACKGROUND

[0002] The polyethylene film resin is widely used in the packaging of various articles and in agricultural production due to its excellent chemical stability, thermal stability, water resistance, moisture resistance and good processing performance. However, the traditional polyethylene film resin has the following problems: insufficient long-term thermal oxidation stability, short oxidation induction time, easy aging of outdoor film; poor mechanical strength balance, high tensile strength often accompanied by low elongation at break (low tensile fracture nominal strain), insufficient toughness; rigid (flexural modulus) and toughness (notched impact strength) are difficult to balance, affecting the puncture resistance and processing adaptability of the film; in addition, the polyethylene film resin does not contain bactericidal ingredients, and cannot kill bacteria when used as a packaging film.

[0003] In the prior art, the polyethylene film resin is modified by the following strategies, such as blending traditional LDPE / LLDPE, which can improve the processability, but the tensile yield stress and long-term thermal stability decrease significantly; adding antioxidants can prolong the oxidation induction time, but can easily precipitate to cause defects on the surface of the film. In addition, the modified polyethylene film resin has poor processing adaptability, especially poor melt flow rate stability, which seriously affects the production efficiency of the product. SUMMARY

[0004] The purpose of the present application is to provide a special resin for polyethylene film and a preparation method and application thereof, so as to overcome the shortcomings of the prior art, achieve ultra-high toughness while maintaining high rigidity, have long-acting weather resistance to meet the needs of high-end fields such as packaging film, have strong processing adaptability, and be suitable for high-speed blown film production line.

[0005] In order to achieve the above-mentioned purpose, the technical scheme of the present application is as follows: In a first aspect, the present application provides a special resin for polyethylene film, which consists of the following components in parts by weight: HDPE resin 50-70 parts, LLDPE resin 20-30 parts, nano zinc oxide 0.5-3 parts, maleic anhydride grafted POE 5-10 parts, antioxidant 0.1-0.5 parts.

[0006] The inventors found in the research process that HDPE as the base material can provide the tensile strength and puncture resistance of the film, but the brittleness is relatively large, and the addition of LLDPE can improve the elongation at break and tear resistance, and achieve the balance of rigidity and toughness; the surface hydroxyl group of nano zinc oxide and the carboxyl group of POE grafted with maleic anhydride form hydrogen bonds, which improves the dispersibility of the LLDPE resin in the HDPE resin, thereby improving the transparency of the film; in addition, the nano zinc oxide and the antioxidant synergistically resist oxidation to prolong the oxidation induction time; at the same time, the nano zinc oxide is a high-efficiency and broad-spectrum antibacterial agent, which exhibits stronger sterilization capacity under light conditions, and can kill bacteria when used as a packaging film.

[0007] In some other embodiments, the polyethylene film special resin consists of the following components in parts by weight: 55-65 parts of HDPE resin, 22-28 parts of LLDPE resin, 1-2 parts of nano zinc oxide, 6-10 parts of POE grafted with maleic anhydride, and 0.2-0.4 parts of antioxidant.

[0008] For example, in the polyethylene film special resin: 50, 55, 60, 65 parts of HDPE resin, 20, 22, 25, 28 parts of LLDPE resin, 1, 1.5, 2 parts of nano zinc oxide, 4, 7, 8, 9, 10 parts of POE grafted with maleic anhydride, and 0.2, 0.3, 0.4 parts of antioxidant.

[0009] In some other embodiments, the polyethylene film special resin consists of the following components in parts by weight: 60 parts of HDPE resin, 25 parts of LLDPE resin, 1.5 parts of nano zinc oxide, 8 parts of POE grafted with maleic anhydride, and 0.3 parts of antioxidant. The polyethylene film special resin prepared within this range has the best performance.

[0010] In some other embodiments, the HDPE resin has a melt mass flow rate of 0.5-2 g / 10 min at 190℃ under a load of 2.16 Kg; for example, the HDPE resin has a melt mass flow rate of 0.8-1.5 g / 10 min at 190℃ under a load of 2.16 Kg, such as a melt mass flow rate of 0.8, 1.0, 1.2, 1.5 g / 10 min. The HDPE resin is used to provide a rigid skeleton, thereby improving the bending modulus and tensile yield stress.

[0011] Alternatively, the LLDPE resin is a copolymer of octene, and the LLDPE resin has a melt mass flow rate of 0.8-1.5 g / 10 min at 190℃ under a load of 2.16 Kg. Optionally, the LLDPE resin has a melt mass flow rate of 0.8, 1.0, 1.2, 1.5 g / 10 min, and the LLDPE resin with the melt mass flow rate in this range can achieve the balance of processing fluidity and mechanical strength. The LLDPE resin is used to increase the ductility, thereby improving the tensile fracture nominal strain.

[0012] In some other embodiments, the particle size of the nano-zinc oxide is 20-100 nm; as an example, the particle size of the nano-zinc oxide is 20, 50, 60, 80, 100 nm; the nano-zinc oxide in the particle size range can prolong the oxidation induction time in cooperation with the anti-oxidation; meanwhile, the nano-zinc oxide is a high-efficiency and broad-spectrum antibacterial agent, which exhibits stronger sterilization capacity under light and can kill bacteria when used as a packaging film.

[0013] Alternatively, the grafting rate of the maleic anhydride grafted POE is 0.5-1.5%; optionally, the grafting rate is 0.8, 1.0, 1.2, 1.5%. The maleic anhydride grafted POE in the range has the best interfacial toughening interval. As a compatibilizer, the maleic anhydride grafted POE can promote the compatibility of HDPE / LLDPE, improve the interfacial adhesion and avoid interfacial defects.

[0014] In some other embodiments, the antioxidant is a composite hindered phenolic antioxidant, the composite hindered phenolic antioxidant comprises antioxidant 1010 and antioxidant 168, and the composite mass ratio of the antioxidant 1010 and the antioxidant 168 is 1: (1-2); optionally, the composite mass ratio of the antioxidant 1010 and the antioxidant 168 is 1:1, 1:1.5, 1:2. The antioxidant 1010 as a main antioxidant can capture free radicals and inhibit thermal oxidative degradation, and the auxiliary antioxidant: the antioxidant 168 can decompose hydroperoxide, which is used in cooperation with the antioxidant 1010 for inhibiting thermal oxidation of the resin, prolonging the stable period.

[0015] In the second aspect, the application provides a preparation method of the polyethylene film special resin in the first aspect, which comprises the following steps: (1) mixing HDPE, nano-zinc oxide and an antioxidant, and then feeding into a screw extruder to perform extrusion, so as to obtain a premix material; (2) feeding the premix material, LLDPE and maleic anhydride grafted POE into a screw extruder, and then performing melting, blending, extrusion, water cooling, granulation and drying, so as to obtain the polyethylene film special resin.

[0016] In some other embodiments, in step (1), the extrusion temperature is 190-210℃; the nano-zinc oxide is premixed with the HDPE melt to avoid agglomeration; and the elastomer is introduced in the low-temperature section to prevent thermal degradation.

[0017] Alternatively, in step (2), the extrusion temperature is 170-180℃, and the screw rotation speed is 300-500 rpm.

[0018] In the third aspect, the application provides application of the polyethylene film special resin in the first aspect in preparation of a polyethylene film.

[0019] In a fourth aspect, the present application provides a polyethylene film, which is made of the polyethylene film special resin according to the first aspect, and the thickness of the polyethylene film is 10-20 μm.

[0020] Advantages of the present application: (1) The components and the proportion of the polyethylene film special resin in the present application are reasonable, the HDPE can provide the tensile strength and the puncture resistance of the film, the addition of the LLDPE can improve the elongation at break and the tear resistance, and the rigid and tough balance is achieved; the hydrogen bond is formed between the surface hydroxyl group of the nano zinc oxide and the carboxyl group of the maleic anhydride grafted POE, the dispersibility of the LLDPE resin in the HDPE resin is improved, and thus the transparency of the film is improved; in addition, the nano zinc oxide and the antioxidant cooperate to prolong the oxidation induction time; at the same time, the nano zinc oxide is a high-efficiency and broad-spectrum antibacterial agent, and the zinc ions released in the plastic show stronger sterilization capacity under light, and the bacteria can be killed when the film is used as a packaging film.

[0021] (2) The HDPE, the branched LLDPE and the grafted POE in the present application form a three-phase topological structure, and the bending modulus and the notched toughness can be simultaneously improved.

[0022] (3) The polyethylene film special resin prepared by the low-temperature two-stage blending process in the present application can maintain the elastomer toughening effect. DETAILED DESCRIPTION

[0023] Those skilled in the art will understand that the following examples are only used to illustrate the present application, and should not be regarded as limiting the scope of the present application. The specific conditions are not indicated in the examples, and the conventional conditions or the conditions recommended by the manufacturer are used. The components used are not indicated by the manufacturer, and are all conventional products that can be obtained on the market.

[0024] Example 1 A polyethylene film special resin and a preparation method thereof 1. A polyethylene film special resin, which is composed of the following components in parts by weight: 60 parts of HDPE resin (melt index 1 g / 10 min), 25 parts of LLDPE resin (melt index 1 g / 10 min), 1.5 parts of nano zinc oxide (particle size 50 nm), 8 parts of maleic anhydride grafted POE (grafting rate 1%), and 0.3 parts of antioxidant (the mass ratio of antioxidant 1010 and antioxidant 168 is 1:1.5).

[0025] 2. A preparation method of the polyethylene film special resin, comprising the following steps: (1) After the HDPE, the nano zinc oxide and the antioxidant are mixed, they are added into a screw extruder for first-stage extrusion (the temperature of the first-stage extrusion is 200°C), and a premixed material is obtained; (2) The premix, LLDPE and maleic anhydride grafted POE are added into a screw extruder (the temperature of extrusion is 175℃, and the screw rotation speed is 400 rpm), and the polyethylene film special resin is prepared after melting, blending, extrusion, underwater cutting and fluidized bed drying.

[0026] The present application does not make special limitation to the extrusion blow molding process of the polyethylene film, and the extrusion blow molding process commonly used in the art can be adopted.

[0027] Example 2 A polyethylene film special resin and a preparation method thereof, different from example 1, the polyethylene film special resin is composed of the following components by weight fraction: HDPE resin (melt index 1.2 g / 10min) 50 parts, LLDPE resin (melt index 1.2 g / 10min) 30 parts, nano zinc oxide (particle size 50 nm) 0.5 parts, maleic anhydride grafted POE (grafting rate 1.2%) 5 parts, antioxidant (the complex mass ratio of antioxidant 1010 and antioxidant 168 is 1:1) 0.1 parts.

[0028] The preparation method is consistent with example 1.

[0029] Example 3 A polyethylene film special resin and a preparation method thereof, different from example 1, the polyethylene film special resin is composed of the following components by weight fraction: HDPE resin (melt index 1.5 g / 10min) 70 parts, LLDPE resin (melt index 1.5 g / 10min) 20 parts, nano zinc oxide (particle size 100 nm) 3 parts, maleic anhydride grafted POE (grafting rate 0.8%) 10 parts, antioxidant (the complex mass ratio of antioxidant 1010 and antioxidant 168 is 1:2) 0.5 parts.

[0030] The preparation method is consistent with example 1.

[0031] Comparative example 1 The commercially available Dow 2045G is adopted.

[0032] Comparative example 2 A polyethylene film special resin and a preparation method thereof, different from example 1, the polyethylene film special resin is composed of the following components by weight fraction: HDPE resin (melt index 1 g / 10min) 60 parts, nano zinc oxide (particle size 50 nm) 1.5 parts, maleic anhydride grafted POE (grafting rate 1%) 8 parts, antioxidant (the complex mass ratio of antioxidant 1010 and antioxidant 168 is 1:1.5) 0.3 parts.

[0033] The preparation method is consistent with that of Example 1.

[0034] Comparative Example 3 A polyethylene film special resin and a preparation method thereof, different from Example 1, the polyethylene film special resin, the addition of nano zinc oxide is omitted, which is composed of the following components in parts by weight: HDPE resin (melt index 1 g / 10min) 60 parts, LLDPE resin (melt index 1 g / 10min) 25 parts, maleic anhydride grafted POE (grafting rate 1%) 8 parts, antioxidant (the mass ratio of antioxidant 1010 and antioxidant 168 is 1:1.5) 0.3 parts.

[0035] The preparation method is consistent with that of Example 1.

[0036] Comparative Example 4 A polyethylene film special resin and a preparation method thereof, different from Example 1, the polyethylene film special resin, the maleic anhydride grafted POE is replaced by PE-g-MAH (maleic anhydride grafted PE resin, grafting rate 1%), which is composed of the following components in parts by weight: HDPE resin (melt index 1 g / 10min) 60 parts, LLDPE resin (melt index 1 g / 10min) 25 parts, nano zinc oxide (particle size 50nm) 1.5 parts, PE-g-MAH (grafting rate 1%) 8 parts, antioxidant (the mass ratio of antioxidant 1010 and antioxidant 168 is 1:1.5) 0.3 parts.

[0037] The preparation method is consistent with that of Example 1.

[0038] Comparative Example 5 A polyethylene film special resin and a preparation method thereof, different from Example 1, the polyethylene film special resin, the antioxidant is single antioxidant 1010, which is composed of the following components in parts by weight: HDPE resin (melt index 1 g / 10min) 60 parts, LLDPE resin (melt index 1 g / 10min) 25 parts, nano zinc oxide (particle size 50nm) 1.5 parts, maleic anhydride grafted POE (grafting rate 1%) 8 parts, antioxidant (antioxidant 1010) 0.3 parts.

[0039] The preparation method is consistent with that of Example 1.

[0040] Comparative Example 6 A polyethylene film special resin and a preparation method thereof, different from Example 1, the polyethylene film special resin, the antioxidant is single antioxidant 168, which is composed of the following components in parts by weight: HDPE resin (melt index 1 g / 10 min) 60 parts, LLDPE resin (melt index 1 g / 10 min) 25 parts, nano zinc oxide (particle size 50 nm) 1.5 parts, maleic anhydride grafted POE (grafting rate 1%) 8 parts, antioxidant (antioxidant 168) 0.3 parts.

[0041] The preparation method is consistent with that of Example 1.

[0042] Performance test The polyethylene film special resin prepared by the examples and comparative examples was tested for performance, and the results are shown in Table 1. The test method for oxidation induction time refers to the standard ISO 11357-6, the test methods for tensile strength, tensile fracture nominal strain and tensile yield stress all refer to the standard ISO 527-2, and the test method for notched impact strength all refers to the standard ISO 179-1.

[0043] Table 1 Performance of polyethylene film special resin

[0044] As can be seen from Table 1, the performance of Examples 1-3 of the present application is significantly better than that of Comparative Examples 1-6, and the performance of Example 1 is the best, which is because of the synergistic effect between the components. The performance of Comparative Example 1 is significantly lower than that of Comparative Example 1.

[0045] Comparative Example 2 omits the addition of LLDPE resin and only uses HDPE as the base material, which can provide tensile strength and puncture resistance of the film, but has greater brittleness, resulting in poor elongation at break.

[0046] Comparative Example 3 omits the addition of nano zinc oxide, which cannot form hydrogen bonds with the carboxyl groups of maleic anhydride grafted POE, resulting in poor dispersibility of LLDPE resin in HDPE resin, oxidation induction time reduced to 32 min (loss of synergistic effect of nano ZnO and antioxidant), mechanical properties decreased (poor dispersibility leading to interface defects), and the polyethylene film resin does not contain a bactericidal component, which cannot kill bacteria when used as a packaging film.

[0047] Comparative Example 4 replaces the maleic anhydride grafted POE with PE-g-MAH (maleic anhydride grafted PE resin, grafting rate 1.0%), the interface bonding is weak, the elastomer toughening effect of POE is missing, and the tensile strength / modulus is significantly reduced (low stress transfer efficiency due to decreased compatibility).

[0048] The antioxidant of the comparative example 5 is a single antioxidant 1010, which cannot decompose hydroperoxide and further inhibit thermal oxidation, resulting in a shortened stabilization period. The antioxidant of the comparative example 6 is a single antioxidant 168, which cannot capture free radicals and inhibit the degradation of auxiliary antioxidants, resulting in a shortened stabilization period. The composite antioxidant mainly affects long-term stability.

[0049] In addition, the polyethylene film special resin of the example 1 is made into a 15 μm packaging film, and the tensile strength retention rate after 1000 h of accelerated aging is significantly higher than that of the comparative example 1.

[0050] In summary, the scheme of the present application realizes "rigid and tough balance-dispersed enhancement-long-term stability", while maintaining high rigidity, it realizes ultra-high toughness oxidation induction time > 45 min, long-term weather resistance: meets the melt flow rate stability of high-end field requirements such as packaging film, processing adaptability: suitable for high-speed blown film production line.

[0051] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A polyethylene film speciality resin characterised in that, The polyethylene film special resin is composed of the following components in parts by weight: HDPE resin 55-65 parts, LLDPE resin 22-28 parts, nano zinc oxide 1-2 parts, maleic anhydride grafted POE 6-10 parts, and antioxidant 0.2-0.4 parts. The polyethylene film special resin is composed of the following components in parts by weight: HDPE resin 55-65 parts, LLDPE resin 22-28 parts, nano zinc oxide 1-2 parts, maleic anhydride grafted POE 6-10 parts, and antioxidant 0.2-0.4 parts.

2. The polyethylene film specialty resin according to claim 1, characterized in that, The polyethylene film special resin is composed of the following components in parts by weight: HDPE resin 55-65 parts, LLDPE resin 22-28 parts, nano zinc oxide 1-2 parts, maleic anhydride grafted POE 6-10 parts, and antioxidant 0.2-0.4 parts.

3. The polyethylene film specialty resin according to claim 1, characterized in that, The HDPE resin has a melt mass flow rate of 0.5-2 g / 10 min at 190℃ under a load of 2.16 Kg.

4. The polyethylene film specialty resin according to claim 1, characterized in that, Alternatively, the LLDPE resin is a copolymer of octene, and the LLDPE resin has a melt mass flow rate of 0.8-1.5 g / 10 min at 190℃ under a load of 2.16 Kg. The nano zinc oxide has a particle size of 20-100 nm.

5. The polyethylene film specialty resin according to claim 1, wherein Alternatively, the maleic anhydride grafted POE has a grafting rate of 0.5-1.5%. The antioxidant is a composite hindered phenolic antioxidant, which includes antioxidant 1010 and antioxidant 168, and the composite mass ratio of the antioxidant 1010 to the antioxidant 168 is 1: (1-2).

6. The polyethylene film specialty resin according to claim 1, wherein The method comprises the following steps:

7. A process for the preparation of a polyethylene film speciality resin as claimed in any one of claims 1 to 6, characterised in that, (1) mixing the HDPE, nano zinc oxide, and antioxidant, and then feeding them into a screw extruder to obtain a premix; (2) feeding the premix, LLDPE, and maleic anhydride grafted POE into the screw extruder, and then performing melting, blending, extrusion, water cooling, granulation, and drying to obtain the polyethylene film special resin. In step (1), the extrusion temperature is 190-210℃.

8. The method of producing a polyethylene film specialty resin according to claim 7, characterized by, Alternatively, in step (2), the extrusion temperature is 170-180℃, and the screw rotation speed is 300-500 rpm.

9. Use of the polyethylene film special resin of any one of claims 1-6 in the preparation of a polyethylene film. The polyethylene film has a thickness of 10-20 μm.

10. A polyethylene film, characterized by, ​

Images