Biaxially oriented polyolefin materials and their applications in high-temperature resistant films

Abstract

This invention discloses a biaxially oriented polyolefin material and its application in high-temperature resistant films. The biaxially oriented polyolefin material comprises the following raw materials in the following mass percentages: 80-94% dynamically cross-linked polyethylene material, 5-15% cyclic olefin copolymer, and 1-5% polyketone-grafted polyborosiloxane. The polyketone-grafted polyborosiloxane is prepared by reacting polyketone containing carboxyl or amino groups in its molecular structure with epoxy-based hyperbranched polyborosiloxane. The cross-linking structure of the dynamically cross-linked polyethylene material, the cyclic olefin structure of the cyclic olefin copolymer, and the borosiloxane and polyketone structures of the polyketone-grafted polyborosiloxane can improve the high-temperature resistance. Furthermore, the existence of dynamic cross-linking bonds between the dynamically cross-linked polyethylene material and the polyketone-grafted polyborosiloxane can ensure the constant high-temperature resistance of the biaxially oriented polyolefin material.

Description

Technical Field

[0001] This invention belongs to the field of functional polyolefin materials, and particularly relates to biaxially oriented polyolefin materials and their application in high-temperature resistant films. Background Technology

[0002] Polyolefins such as polyethylene and polypropylene have good processing and mechanical properties, and are lightweight and inexpensive, making them widely used as packaging materials. However, polyolefin composite films such as polyethylene (PE) and polypropylene (PP) have low high-temperature resistance and usually shrink and deform at high temperatures.

[0003] CN113969007B discloses a raw material for biaxially oriented high-density polyethylene (BPE) film, the BPE film itself, a method for preparing the film, and its applications. The raw material for the BPE film comprises the following components in weight percentages: 30-70% first high-density polyethylene, 20-50% second high-density polyethylene, and 5-20% processing aid composition. The first high-density polyethylene has a melt flow rate of 2-3 g / 10 min at 190°C under a 2.16 kg load and a density of 0.955-0.970 g / cm³. 3 The second high-density polyethylene has a melt flow rate of 0.01-0.8 g / 10 min at 190°C under a load of 2.16 kg and a melt flow rate of 0.05-10 g / 10 min at 190°C under a load of 5.0 kg, with a density of 0.935-0.955 g / cm³. 3 The processing aid composition comprises the following components in weight percentages: 1-5% fluoropolymer processing aid, 10-49% hydrogenated petroleum resin, and 50-89% ethylene-polar monomer copolymer. The first high-density polyethylene improves the film's heat resistance and provides a suitable processing viscosity during extrusion casting. The second high-density polyethylene has a suitable melt flow rate and density, resulting in a good molecular chain structure. When optimally combined with the first high-density polyethylene, the melt strength is significantly enhanced, forming molecular chain entanglements and a crystalline physical network during stretching, providing the film with biaxial tensile properties. However, the interaction force of the molecular chain entanglements and crystalline physical network formed by the first and second high-density polyethylenes is relatively weak. Furthermore, the high-temperature resistance of both the first and second high-density polyethylenes is not high. Therefore, the high-temperature resistance of the prepared film is significantly lower than that of polypropylene film, limiting its applicability in applications requiring high operating temperatures. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a biaxially oriented polyolefin material. The crosslinking structure of the dynamically crosslinked polyethylene material, the cyclic olefin structure of the cyclic olefin copolymer, and the borosilicate structure and polyketide grafted polyboron siloxane of the polyketide can improve high-temperature resistance. Furthermore, the existence of dynamic crosslinking bonds between the dynamically crosslinked polyethylene material and the polyketide grafted polyboron siloxane ensures the constant high-temperature resistance of the biaxially oriented polyolefin material.

[0005] The purpose of this invention is to provide a biaxially oriented polyolefin material comprising the following raw materials in weight percentages: 80-94% dynamically cross-linked polyethylene material, 5-15% cyclic olefin copolymer, and 1-5% polyketide-grafted polyborosiloxane.

[0006] The polyketone-grafted polyborosiloxane comprises polyketones containing carboxyl or amino groups in their molecular structure and epoxy-based hyperbranched polyborosiloxanes.

[0007] In this scheme, dynamic cross-linked polyethylene material and polyketone-grafted polyborosiloxane have dynamic cross-linking bonds. When stimulated by external environment, these dynamic cross-linking bonds continuously break and recombine, giving the biaxially oriented polyolefin material characteristics such as self-healing, shape memory, stress relaxation, and responsiveness. When the external stimulus disappears, the biaxially oriented polyolefin material returns to its original state. Therefore, biaxially oriented polyolefin material containing dynamic cross-linking bonds can maintain a constant cross-linking density due to the dynamic cross-linking bond exchange reaction. Thus, biaxially oriented polyolefin material with dynamic covalent bonds achieves recyclability and self-healing properties while also exhibiting high high-temperature resistance.

[0008] Furthermore, dynamically cross-linked polyethylene materials have poor compatibility with cyclic olefin copolymers. The addition of polyketide-grafted polyborosiloxane can enhance the compatibility between dynamically cross-linked polyethylene materials and cyclic olefin copolymers.

[0009] Preferably, the biaxially oriented polyolefin material comprises the following raw materials in the following mass percentages: 80-94% dynamically cross-linked polyethylene material, 4.7-14.1% cyclic olefin copolymer, and 1.2-4.1% polyketone-grafted polyborosiloxane.

[0010] The polyketone-grafted polyborosiloxane comprises polyketones containing carboxyl or amino groups in their molecular structure and epoxy-based hyperbranched polyborosiloxanes.

[0011] Preferably, the mass ratio of the polyketide containing carboxyl or amino groups in its molecular structure to the epoxy hyperbranched polyborosiloxane is 2 to 5:1.

[0012] Preferably, the glass transition temperature of the cyclic olefin copolymer is ≥90°C.

[0013] Preferably, the biaxially oriented polyolefin material further includes 0.1-1.8% processing aids.

[0014] More preferably, the biaxially oriented polyolefin material further includes 1.5% processing aids.

[0015] Preferably, the processing aid includes at least one of a dispersant, an antioxidant, and a lubricant.

[0016] Preferably, the dynamically cross-linked polyethylene material includes hydrolyzed dynamically cross-linked polyethylene material.

[0017] Preferably, the structural formula of the polyketide containing carboxyl or amino groups in its molecular structure is shown below:

[0018]

[0019] Wherein, R is selected from carboxyl or amino groups; the number average molecular weight is not less than 20,000 g / mol.

[0020] Preferably, the preparation of the polyketide-grafted polyborosiloxane includes the following steps:

[0021] Polyketones containing carboxyl or amino groups in their molecular structure, epoxy hyperbranched polyborosiloxanes, isocyanates, and solvents are mixed, a catalyst is added, and the mixture is heated to produce polyketone-grafted polyborosiloxanes.

[0022] Preferably, the isocyanate includes at least one selected from xylene diisocyanate, dicyclohexylmethane diisocyanate, diphenylmethane diisocyanate, terephthalimide diisocyanate, hexamethylene diisocyanate, and isophorone diisocyanate. The isocyanate used in this invention exhibits good reactivity with polyketides and epoxy-based hyperbranched polyborosiloxanes containing carboxyl or amino groups in their molecular structure.

[0023] Preferably, the catalyst includes at least one of stannous octoate and dibutyltin dilaurate.

[0024] Preferably, the solvent includes at least one of N,N-dimethylformamide, toluene, N,N-dimethylacetamide, tetrahydrofuran, chloroform, and dichloromethane.

[0025] Preferably, the mass ratio of the polyketide containing carboxyl or amino groups in its molecular structure to the epoxy hyperbranched polyborosiloxane is 2 to 5:1.

[0026] Preferably, the mass ratio of the epoxy-based hyperbranched polyborosiloxane to the isocyanate is 1:1.1 to 1.5.

[0027] Preferably, the amount of catalyst used is 0.1 to 0.5% of the total mass of polyketides containing carboxyl or amino groups in their molecular structure and epoxy hyperbranched polyborosiloxanes.

[0028] Preferably, the heating reaction is carried out at a temperature of 30–110°C for 5–12 hours.

[0029] Preferably, the dynamically cross-linked polyethylene material comprises polyethylene prepared by reacting it with a silane coupling agent.

[0030] More preferably, the dynamically cross-linked polyethylene material is prepared according to Example 1 of CN102875877B.

[0031] Preferably, the preparation of the hydrolyzed dynamically cross-linked polyethylene material includes the following steps:

[0032] Dynamically cross-linked polyethylene material is mixed with an alcohol-water mixture and stirred to obtain a hydrolysate of the dynamically cross-linked polyethylene material.

[0033] Preferably, the mass ratio of the dynamically cross-linked polyethylene material to the alcohol-water mixture is 1:10 to 50.

[0034] Preferably, the alcohol-water mixture comprises a mixture of ethanol and water, wherein the mass ratio of ethanol to water is 0.5 to 2:1.

[0035] Preferably, the stirring temperature is room temperature, and the stirring time is 2 to 5 hours.

[0036] Another object of the present invention is to provide a method for preparing the aforementioned biaxially oriented polyolefin material, comprising the following steps:

[0037] Dynamically cross-linked polyethylene material, polyketide-grafted polyborosiloxane, cyclic olefin copolymer, and optional processing aids are mixed and melt-extruded and granulated using a twin-screw extruder to obtain biaxially oriented polyolefin material.

[0038] Preferably, the melting temperature is 200–240°C.

[0039] More preferably, the melting temperature is 220°C.

[0040] Preferably, the extrusion temperature is 190℃~210℃.

[0041] More preferably, the extrusion temperature is 200°C.

[0042] Preferably, the screw speed of the extruder is 200-400 r / min.

[0043] More preferably, the screw speed of the extruder is 300 r / min.

[0044] Another object of the present invention is to provide a high-temperature resistant film, comprising a film prepared from the aforementioned biaxially oriented polyolefin material. Detailed Implementation

[0045] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions in the embodiments of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention.

[0046] Example 1: Preparation of polyketone-grafted polyborosiloxane.

[0047] 35g of a polyketone containing carboxyl groups, 10g of an epoxy-modified hyperbranched polyborosiloxane, 12g of xylene diisocyanate, and 100g of toluene were added to a reaction flask. 0.14g of dibutyltin dilaurate was added, and the mixture was heated to 110°C for 8 hours. The solvent was removed by vacuum distillation, and the mixture was washed with ethanol and dried to obtain the polyketone-grafted polyborosiloxane. The structure of the polyketone containing carboxyl groups is shown below.

[0048]

[0049] The number-average molecular weight is 30,000–50,000 g / mol.

[0050] Example 2: Preparation of hydrolyzed dynamically cross-linked polyethylene material.

[0051] 10g of dynamically cross-linked polyethylene material was mixed with 300g of an alcohol-water mixture (150g ethanol and 150g water), stirred at room temperature for 3 hours, and the solvent was removed by vacuum distillation to obtain the hydrolysate of the dynamically cross-linked polyethylene material.

[0052] Example 3: Preparation of biaxially oriented polyolefin material.

[0053] 80g of dynamically cross-linked polyethylene material, 14.1g of cyclic olefin copolymer (purchased from Topas Advanced Polymers, grade 6013F-04, glass transition temperature 138℃), 4.1g of polyketide-grafted polyborosiloxane prepared in Example 1, 0.6g of PPA fluorinated lubricant, 0.5g of polyester polymeric dispersant, 0.4g of antioxidant 1010, and 0.3g of antioxidant 168 were mixed and melt-extruded into granules using a twin-screw extruder. The melt temperature was 220℃, the extrusion temperature was 200℃, and the screw speed of the extruder was 300r / min to obtain a biaxially oriented polyolefin material.

[0054] Example 4: Preparation of biaxially oriented polyolefin material.

[0055] 94g of dynamically cross-linked polyethylene material, 4.7g of cyclic olefin copolymer (purchased from Topas Advanced Polymers, grade 6013F-04, glass transition temperature 138℃), 1.2g of polyketide-grafted polyborosiloxane prepared in Example 1, 0.03g of PPA fluorinated lubricant, 0.02g of polyester polymeric dispersant, 0.03g of antioxidant 1010, and 0.02g of antioxidant 168 were mixed and melt-extruded into granules using a twin-screw extruder. The melt temperature was 220℃, the extrusion temperature was 200℃, and the screw speed of the extruder was 300r / min to obtain a biaxially oriented polyolefin material.

[0056] Example 5: Preparation of biaxially oriented polyolefin material.

[0057] 88g of dynamically cross-linked polyethylene material, 8.2g of cyclic olefin copolymer (purchased from Topas Advanced Polymers, grade 6013F-04, glass transition temperature 138℃), 2.3g of polyketide-grafted polyborosiloxane prepared in Example 1, 0.5g of PPA fluorinated lubricant, 0.5g of polyester polymeric dispersant, 0.3g of antioxidant 1010, and 0.2g of antioxidant 168 were mixed and melt-extruded into granules using a twin-screw extruder. The melt temperature was 220℃, the extrusion temperature was 200℃, and the screw speed of the extruder was 300r / min to obtain a biaxially oriented polyolefin material.

[0058] Example 6: Preparation of biaxially oriented polyolefin material.

[0059] 88g of hydrolysate of the dynamically cross-linked polyethylene material prepared in Example 2, 8.2g of cyclic olefin copolymer (purchased from Topas Advanced Polymers, brand name 6013F-04, glass transition temperature 138℃), 2.3g of polyketide-grafted polyborosiloxane prepared in Example 1, 0.5g of PPA fluorinated lubricant, 0.5g of polyester polymeric dispersant, 0.3g of antioxidant 1010, and 0.2g of antioxidant 168 were mixed and melt-extruded into granules using a twin-screw extruder. The melt temperature was 220℃, the extrusion temperature was 200℃, and the screw speed of the extruder was 300r / min to obtain a biaxially oriented polyolefin material.

[0060] Comparative Example 1: Preparation of biaxially oriented polyolefin materials.

[0061] 98.5g of dynamically cross-linked polyethylene material, 0.5g of PPA fluorinated lubricant, 0.5g of polyester polymeric dispersant, 0.3g of antioxidant 1010, and 0.2g of antioxidant 168 were mixed and melt-extruded into granules using a twin-screw extruder. The melt temperature was 220℃, the extrusion temperature was 200℃, and the screw speed of the extruder was 300r / min to obtain biaxially oriented polyolefin material.

[0062] Comparative Example 2: Preparation of biaxially oriented polyolefin materials.

[0063] 98.5g of cyclic olefin copolymer (purchased from Topas Advanced Polymers, grade 6013F-04, glass transition temperature 138℃), 0.5g of PPA fluorinated lubricant, 0.5g of polyester polymeric dispersant, 0.3g of antioxidant 1010, and 0.2g of antioxidant 168 were mixed and melt-extruded into granules using a twin-screw extruder. The melt temperature was 220℃, the extrusion temperature was 200℃, and the screw speed of the extruder was 300r / min to obtain a biaxially oriented polyolefin material.

[0064] Comparative Example 3: Preparation of biaxially oriented polyolefin materials.

[0065] 98.5g of polyketide-grafted polyborosiloxane, 0.5g of PPA fluorinated lubricant, 0.5g of polyester polymeric dispersant, 0.3g of antioxidant 1010, and 0.2g of antioxidant 168 prepared in Example 1 were mixed and melt-extruded into granules using a twin-screw extruder. The melt temperature was 220°C, the extrusion temperature was 200°C, and the screw speed of the extruder was 300 r / min to obtain a biaxially oriented polyolefin material.

[0066] Comparative Example 4: Preparation of biaxially oriented polyolefin materials.

[0067] 88g of dynamically cross-linked polyethylene material, 8.2g of cyclic olefin copolymer (purchased from Topas Advanced Polymers, grade 8007F-04, glass transition temperature 78℃), 2.3g of polyketide-grafted polyborosiloxane prepared in Example 1, 0.5g of PPA fluorinated lubricant, 0.5g of polyester polymeric dispersant, 0.3g of antioxidant 1010, and 0.2g of antioxidant 168 were mixed and melt-extruded into granules using a twin-screw extruder. The melt temperature was 220℃, the extrusion temperature was 200℃, and the screw speed of the extruder was 300r / min to obtain a biaxially oriented polyolefin material.

[0068] Comparative Example 5: Preparation of biaxially oriented polyolefin materials.

[0069] 88g of dynamically cross-linked polyethylene material, 8.2g of cyclic olefin copolymer (purchased from Topas Advanced Polymers, grade 6013F-04, glass transition temperature 138℃), 2.3g of epoxy hyperbranched polyborosiloxane (raw material from Example 1), 0.5g of PPA fluorinated lubricant, 0.5g of polyester polymeric dispersant, 0.3g of antioxidant 1010, and 0.2g of antioxidant 168 were mixed and melt-extruded into granules using a twin-screw extruder. The melt temperature was 220℃, the extrusion temperature was 200℃, and the screw speed of the extruder was 300r / min to obtain biaxially oriented polyolefin material.

[0070] Comparative Example 6: Preparation of biaxially oriented polyolefin materials.

[0071] 88g of dynamically cross-linked polyethylene material, 8.2g of cyclic olefin copolymer (purchased from Topas Advanced Polymers, grade 6013F-04, glass transition temperature 138℃), 2.3g of polyketide containing carboxyl groups in the raw material molecular structure of Example 1, 0.5g of PPA fluorinated lubricant, 0.5g of polyester polymeric dispersant, 0.3g of antioxidant 1010, and 0.2g of antioxidant 168 were mixed and melt-extruded into granules using a twin-screw extruder. The melt temperature was 220℃, the extrusion temperature was 200℃, and the screw speed of the extruder was 300r / min to obtain a biaxially oriented polyolefin material.

[0072] The biaxially oriented polyolefin materials of Examples 3-6 and Comparative Examples 1-6 were respectively added to a twin-screw extruder with an aspect ratio of 40:1 to be processed into a uniform melt. The melt was extruded and cast through a die to prepare a film casting. The die temperature was 230°C. The film casting was stretched with a preheating temperature of 120°C, a stretching temperature of 130°C, a heat setting temperature of 130°C, a corona surface treatment with a strength of 38 mN / m, and then wound up to obtain biaxially oriented polyolefin films of Examples 7-10 and Comparative Examples 7-12 with a thickness of 25 μm.

[0073] The biaxially oriented polyolefin films of Examples 7-10 and Comparative Examples 7-12 were tested for heat shrinkage rate and dart impact breakage quality performance. The results are shown in Table 1.

[0074] Heat shrinkage rate: The heat shrinkage rate of the film at 130℃ for 2 minutes was tested using a heating oven, in accordance with GB / T10003 2008.

[0075] Dart impact damage quality: Test according to Method A in GB / T 9639.1-2008.

[0076] Table 1. Performance test results.

[0077]

[0078] As shown in Table 1, the biaxially oriented polyolefin film prepared by the present invention has advantages such as high temperature resistance and good toughness.

[0079] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that after reading this application specification, they can still modify or make equivalent substitutions to the specific implementation of the present invention, but these modifications or changes do not depart from the protection scope of the pending claims of the present invention.

Claims

1. A biaxially oriented polyolefin material, characterized in that, The raw materials include the following percentages by weight: 80-94% dynamically cross-linked polyethylene material, 5-15% cyclic olefin copolymer, and 1-5% polyketone-grafted polyborosiloxane; The polyketone-grafted polyborosiloxane comprises polyketones containing carboxyl or amino groups in their molecular structure and epoxy-based hyperbranched polyborosiloxanes. The glass transition temperature of the cyclic olefin copolymer is ≥90℃; The structure of the polyketone is shown below: Wherein, R is selected from carboxyl or amino groups; the number average molecular weight is not less than 20,000 g / mol; The preparation method of the dynamically cross-linked polyethylene material includes the following steps: The following formula is used: 5% low-density polyethylene powder; 0.15% vinyltrimethoxysilane coupling agent; 0.015% dicumyl peroxide; 0.01% stannous octoate; the balance is heat-resistant polyethylene. The mixture is blended, extruded, granulated, and molded into a dynamically cross-linked polyethylene material and then into a finished product. The specific implementation steps are as follows: Step 1: Weigh the low-density polyethylene powder according to the mass percentage, add it to a high-speed mixer and stir for 5 minutes at a speed of 500 r / min; Step 2: Weigh out the vinyltrimethoxysilane coupling agent by mass percentage and spray it evenly onto the low-density polyethylene powder being stirred. Step 3: Weigh out dicumyl peroxide by mass percentage and add it to the low-density polyethylene powder being stirred. Step 4: Weigh out stannous octoate by mass percentage and add it to the low-density polyethylene powder being stirred. Step 5: Continue stirring for 20 minutes at a speed of 500 rpm. Remove the stirred powder and place it in a drying oven to bake for 2 hours at a temperature of 85°C. Step 6: Take out the baked powder, weigh out the heat-resistant polyethylene according to the formula ratio, and put it into a high-speed mixer to mix for 10 minutes at a speed of 500 r / min; Step 7: The mixed raw materials obtained in Step 6 are fed into a twin-screw extruder granulator. After melt extrusion into a wire, cooling, and pelletizing, dynamic cross-linked polyethylene material is obtained. The process parameters are as follows: the mixed raw materials are added using an auxiliary feeding system at a feeding speed of 80 r / min; the main screw speed is 260 r / min; the temperatures of Zone 1, Zone 2, Zone 3, Zone 4, Zone 5, Zone 6, Zone 7, Zone 8, Zone 9, Zone 10 are 220°C, and the die temperature is 220°C; the pelletizing speed of the pelletizer is 300 r / min.

2. The biaxially oriented polyolefin material as described in claim 1, characterized in that, The mass ratio of the polyketone containing carboxyl or amino groups in its molecular structure to the epoxy hyperbranched polyborosiloxane is 2~5:

1.

3. The biaxially oriented polyolefin material as described in claim 1, characterized in that, The biaxially oriented polyolefin material also includes 0.6-1.8% processing aids.

4. The biaxially oriented polyolefin material as described in claim 1, characterized in that, The dynamically cross-linked polyethylene material includes hydrolyzed dynamically cross-linked polyethylene material.

5. The biaxially oriented polyolefin material as described in claim 1, characterized in that, The preparation of the polyketide-grafted polyborosiloxane includes the following steps: Polyketones containing carboxyl or amino groups in their molecular structure, epoxy hyperbranched polyborosiloxanes, isocyanates, and solvents are mixed, a catalyst is added, and the mixture is heated to produce polyketone-grafted polyborosiloxanes.

6. The biaxially oriented polyolefin material as described in claim 4, characterized in that, The preparation of the hydrolyzed, dynamically cross-linked polyethylene material includes the following steps: Dynamically cross-linked polyethylene material is mixed with an alcohol-water mixture and stirred to obtain a hydrolysate of the dynamically cross-linked polyethylene material.

7. The method for preparing the biaxially oriented polyolefin material according to any one of claims 1 to 6, characterized in that, Includes the following steps: Dynamically cross-linked polyethylene material, polyketide-grafted polyborosiloxane, cyclic olefin copolymer, and optional processing aids are mixed and melt-extruded and granulated using a twin-screw extruder to obtain biaxially oriented polyolefin material.

8. A high-temperature resistant film, characterized in that, It includes materials prepared from biaxially oriented polyolefin materials as described in any one of claims 1 to 6.

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