High temperature resistant pp honeycomb tube, preparation method therefor, and application thereof

Abstract

Disclosed the present invention are a high temperature resistant PP honeycomb tube, a preparation method therefor, and an application thereof. The high temperature resistant PP honeycomb tube is formed by a plurality of PP tubes fixedly bonded into a whole. An inner diameter of each PP tube is 3-10 mm, and a wall thickness thereof is 0.1-1 mm; the PP tube comprises a tube body and an adhesive film layer arranged on a surface of the tube body; the tube body comprises the following components: a PP resin, the PP resin having a melting index of 15-70 g / 10min under test conditions of 230°C and 2.16 kg; the adhesive film layer comprises the following components: a POE resin, a melting temperature of the POE resin being 100-130°C; and a weight ratio of the PP resin to the POE resin is (80-95):( 4-15). The high temperature resistant PP honeycomb tube of the present invention has the advantages of low odor, low harmful substance content, and recyclability, and also has excellent high temperature mechanical properties.

Description

A high-temperature resistant PP honeycomb tube and its preparation method and application Technical Field

[0001] The present invention belongs to the technical field of honeycomb sandwich panels, and in particular relates to a high-temperature resistant PP honeycomb tube and a preparation method and application thereof. Background Art

[0002] Sandwich panels, known for their lightweight construction, are increasingly being used in automotive spare tire covers. Early sandwich panels often featured a paper honeycomb core, known for its excellent high-temperature load-bearing properties and resistance to degradation. However, the production process requires thermoplastic adhesives or thermosetting resins to bond the sandwich structure's surface layers to the paper honeycomb core. This results in excessive odor and hazardous substance content, failing to comply with national regulations. Furthermore, the product has a low recyclability rate.

[0003] To reduce the odor and harmful substances in sandwich panels and improve their recyclability, thermoplastic polypropylene (PP) circular tubular honeycomb cores are increasingly being used to replace traditional paper honeycombs. However, the mechanical properties of PP honeycomb sandwich panels degrade significantly at high temperatures, with bending properties degrading by over 50% at temperatures of 80°C. Therefore, to expand the application range of PP honeycomb sandwich panels, it is urgent to improve the high-temperature mechanical properties of the PP honeycomb core.

[0004] Summary of the Invention

[0005] In order to solve the deficiencies in the above-mentioned prior art, the purpose of the present invention is to provide a high-temperature resistant PP honeycomb tube and a preparation method and application thereof.

[0006] In order to achieve its purpose, the technical solution adopted by the present invention is:

[0007] A high-temperature resistant PP honeycomb tube, which is composed of several PP tubes fixedly bonded together, the inner diameter of the PP tube is 3 to 10 mm, and the wall thickness is 0.1 to 1 mm. The PP tube includes a tube body and an adhesive film layer provided on the surface of the tube body, the tube body includes the following components: PP resin, the melt index of the PP resin under test conditions of 230°C and 2.16 kg is 15 to 70 g / 10 min; the adhesive film layer includes the following components: POE resin, the melting temperature of the POE resin is 100 to 130°C; the weight ratio of the PP resin to the POE resin is (80 to 95):(4 to 15).

[0008] The melt index of the PP resin is tested according to GB / T 3682.1-2018, and the melting temperature of the POE resin is tested according to ISO 11357-3:2011 Plastics Differential Scanning Calorimetry (DSC) Part 3.

[0009] The present invention prepares PP honeycomb tubes by selecting PP with the above-mentioned melt index as the base material, which ensures the extrusion efficiency of the PP honeycomb tubes while also better controlling the diameter of the extruded PP honeycomb tubes. At the same time, the present invention also effectively improves the interface temperature resistance of the PP honeycomb tubes by selecting POE with the above-mentioned melting temperature as the bonding medium between the PP honeycomb tubes, so that the PP honeycomb tubes still have a high interface strength at high temperatures, the bending performance retention rate at a high temperature of 80°C is greatly improved, and the mechanical properties are better maintained. If the melting temperature of the POE resin is too high, the baking and bonding temperature must also be increased accordingly. Generally, the baking and bonding temperature needs to be about 20°C higher than the melting temperature of the POE resin to fully melt the POE, and PP will soften at about 155°C, causing the PP honeycomb tube to deform. If the melting temperature of the POE resin is too low, the interface of the PP honeycomb tube in a high temperature environment will be damaged first, resulting in serious attenuation of the high temperature performance of the PP honeycomb tube.

[0010] Furthermore, if the PP tube's inner diameter is too small and its wall thickness is too large, the tube will become heavier, failing to realize its lightweight characteristics. This will also increase the cost and processing difficulty. If the inner diameter is too large, the tube's rigidity will be reduced. If the wall thickness is too small, uneven wall thickness will easily occur during the production process, resulting in significant variability in the performance of the final product.

[0011] Preferably, the PP resin has a melt index of 25 to 50 g / 10 min at 230° C. and 2.16 kg. Using PP with this melt index allows for better control of the diameter of the extruded PP pipe.

[0012] Preferably, the PP resin is a homopolymer PP resin. Compared with a copolymer PP resin, the heat resistance of the homopolymer PP resin used in the present invention is better.

[0013] Preferably, the melting temperature of the POE resin is 110-120°C.

[0014] Preferably, the tube body comprises the following components in parts by weight: 80-95 parts of PP resin and 1-5 parts of other additives, including but not limited to nucleating agents, antioxidants, masterbatches, and the like.

[0015] Preferably, the inner diameter of the PP tube is 5-8 mm, and the wall thickness is 0.3-0.5 mm.

[0016] The present invention also provides a method for preparing the high-temperature resistant PP honeycomb tube, which comprises the following steps:

[0017] (1) Preparation of PP tubes by co-extrusion process;

[0018] (2) The PP tube prepared in step (1) is closed in a fixed frame, and then heated at 130-150° C. for 15-25 minutes to soften the adhesive film layer on the PP tube and allow adjacent PP tubes to adhere to each other, and then cooled and shaped to obtain the high-temperature resistant PP honeycomb tube.

[0019] Preferably, the equipment used in the co-extrusion process is a single-screw extruder, and the formula components of the tube body and the formula components of the adhesive film layer are respectively added into the corresponding barrels of the extruder. The screw diameter of the formula components of the tube body is 60 mm, and the screw diameter of the formula components of the adhesive film layer is 40 mm. The temperature of the extruder is controlled at 170-200°C.

[0020] The present invention also provides the use of the high-temperature resistant PP honeycomb tube in preparing a sandwich panel.

[0021] The present invention also provides a sandwich panel, which includes a honeycomb core made of the high-temperature resistant PP honeycomb tube and surface layers arranged on the upper surface and the lower surface of the honeycomb core.

[0022] The honeycomb core is produced by cutting the high-temperature resistant PP honeycomb tube into the desired thickness. This is done by hot cutting, where the high-temperature resistant PP honeycomb is heated by electric heating wires at a temperature of 190-220°C. The thickness of the honeycomb core is determined by the spacing between the heating wires.

[0023] The present invention also provides application of the sandwich panel in preparing a spare tire cover for an automobile.

[0024] The present invention also provides a spare tire cover for an automobile, which is made of the sandwich panel.

[0025] Compared with the existing technology, the beneficial effects of the present invention are as follows: the high-temperature resistant PP honeycomb tube provided by the present invention not only has the advantages of low odor, low harmful substance content and recyclability of the thermoplastic honeycomb core, but also has excellent high-temperature mechanical properties. When used as the honeycomb core of a sandwich sandwich panel, the bending performance retention rate of the sandwich sandwich panel at a high temperature of 80°C can still reach more than 53%, solving the technical problem of the existing PP honeycomb sandwich panel with obvious attenuation of mechanical properties at high temperatures. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] FIG1 is a schematic structural diagram of the sandwich panel of the present invention. DETAILED DESCRIPTION

[0027] The technical solutions of the present invention will be further described below in conjunction with embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative efforts shall fall within the scope of protection of the present invention.

[0028] The raw materials of the examples and comparative examples can be obtained through commercial channels, and the sources are as follows:

[0029] PP-1, homopolymer PP resin, model PP HP150G, melt index 15g / 10min (230℃, 2.16kg), manufacturer Saudi National Petrochemical;

[0030] PP-2, homopolymer PP resin, model PP N-Z30S, melt index 25g / 10min (230℃, 2.16kg), manufacturer: Sinopec Maoming Branch;

[0031] PP-3, homopolymer PP resin, model PP H9018, melt index 50g / 10min (230℃, 2.16kg), manufacturer: PetroChina Lanzhou Petrochemical Company;

[0032] PP-4, homopolymer PP resin, model PP H-MN60, melt index 65g / 10min (230°C, 2.16kg), manufacturer: Sinopec Beihai Refining and Chemical Co., Ltd.

[0033] PP-5, homopolymer PP resin, model PP HP500G, melt index 3 g / 10 min (230°C, 2.16 kg), manufacturer LyondellBasell;

[0034] PP-6, homopolymer PP resin, model RP5007, melt index 75g / 10min (230℃, 2.16kg), manufacturer Daelim, South Korea;

[0035] PP-7, copolymer PP resin, model number TAIRIPRO K9017, melt index 17 g / 10 min, manufacturer Formosa Plastics Corporation;

[0036] POE-1, melting temperature 100°C, model Engage 8480, manufacturer Dow Chemical;

[0037] POE-2, melting temperature 110°C, model FL 39 F, manufacturer Versalis SpA;

[0038] POE-3, melting temperature 120°C, model LLDPE LL6201, manufacturer ExxonMobil Chemical;

[0039] POE-4, melting temperature 130°C, model DMDA-8920, manufacturer Dow Chemical;

[0040] POE-5, melting temperature 73°C, model Engage 8003, manufacturer Dow Chemical;

[0041] POE-6, melting temperature 140°C, model FL7641, manufacturer The Polyolefin Company (Singapore) Pte Ltd;

[0042] The auxiliary agent is a commercially available antioxidant, and the same one is used in the examples and comparative examples.

[0043] Examples 1 to 10

[0044] Examples 1 to 10 provide a high-temperature resistant PP honeycomb tube composed of several PP tubes fixedly bonded together. The PP tubes have an inner diameter of 8 mm and a wall thickness of 0.5 mm. The PP tubes consist of a tube body and an adhesive film layer applied to the surface of the tube body. The tube body is made of PP resin and additives (parts by weight are shown in Table 1). The adhesive film layer is made of POE resin (parts by weight are shown in Table 1). The components of the tube body and adhesive film layer are calculated in equal parts by weight.

[0045] The preparation methods of the high temperature resistant PP honeycomb tubes of Examples 1 to 10 are as follows:

[0046] (1) A PP tube was prepared by co-extrusion using a single screw extruder. The formula components of the tube body and the formula components of the adhesive film layer were added into the corresponding barrels of the extruder respectively. The screw diameter of the formula components of the tube body was 60 mm, and the screw diameter of the formula components of the adhesive film layer was 40 mm. The temperature of the extruder was controlled at 170-200°C, and the extruded PP tube was pulled into a vacuum water tank for cooling and shaping. The vacuum pressure was 0.003±0.001MPa, the cooling water temperature range was 13±2°C, and the pulling speed range was 150-300m / min.

[0047] (2) The PP tube prepared in step (1) is closed in a fixed frame, and then pushed into an oven and heated at 130-150° C. for 15-25 minutes to soften the adhesive film layer on the PP tube and allow adjacent PP tubes to adhere to each other, and then cooled and shaped to obtain the high-temperature resistant PP honeycomb tube.

[0048] Table 1 Note: “-” in the table means that the component is not added, the same below.

[0049] Comparative Examples 1 to 7 provide a PP honeycomb tube with an inner diameter of 8 mm and a wall thickness of 0.5 mm. The weight formula thereof is shown in Table 2. The preparation method refers to the preparation method of Examples 1 to 10.

[0050] Table 2

[0051] The PP honeycomb tubes prepared in Examples 1 to 10 and Comparative Examples 1 to 7 were respectively made into sandwich panels. The preparation method was as follows: the PP honeycomb tube was hot-cut into a honeycomb core of a certain thickness, and then a layer of surface layer material (the surface layer material was a PP / GF composite material) was laid on the upper and lower surfaces of the honeycomb core. The panels were heated and melted at 205° C., and a pressure of 3 bar was applied to bond the surface layer material to the honeycomb core. Finally, the panels were cooled and shaped to obtain sandwich panels.

[0052] The prepared sandwich panels were tested according to the GB-T 1456-2005 sandwich structure bending performance test standard.

[0053] The test results are shown in Table 3.

[0054] Bending performance retention rate (%) = bending bearing capacity at 80°C / bending bearing capacity at 23°C × 100%

[0055] Table 3

[0056] Effect Analysis: Examples 1-4 and Comparative Examples 1-2 demonstrate that the melt index of the PP in the tube layer affects the high-temperature mechanical properties of the sandwich panel. Using PP with a melt index of 15-70 g / 10 min (230°C, 2.16 kg) results in a more uniform tube diameter and less dispersion, which facilitates the coordinated bending of the PP tubes in the sandwich panel at high temperatures. Consequently, the sandwich panel exhibits superior high-temperature mechanical properties. Examples 1, 5-7, and Comparative Examples 3-4 demonstrate that the melt temperature of the POE in the adhesive film layer affects the high-temperature mechanical properties of the sandwich panel. Using POE with a melt temperature of 100-130°C exhibits superior high-temperature mechanical properties. Examples 1 and 10 also demonstrate that using homopolymer PP resins provides superior temperature resistance compared to copolymer PP resins. In Comparative Example 3, the POE used had a low melting temperature, which caused the interface of the PP honeycomb tube to be damaged first in a high-temperature environment, resulting in a serious decline in the high-temperature performance of the sandwich panel. In Comparative Example 4, the POE used had a high melting temperature, requiring a temperature of 160°C or higher to fully melt during baking and bonding, but failed to fully melt at 130-150°C, resulting in poor bonding to the PP tube and ultimately poor high-temperature mechanical properties of the sandwich panel. Increasing the baking and bonding temperature to above 160°C would cause the PP honeycomb tube to deform, also resulting in poor mechanical properties of the sandwich panel.

[0057] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A high temperature resistant PP honeycomb tube, characterized in that: The invention is composed of a plurality of PP tubes fixedly bonded together, wherein the inner diameter of the PP tube is 3 to 10 mm and the wall thickness is 0.1 to 1 mm; the PP tube comprises a tube body and an adhesive film layer arranged on the surface of the tube body, wherein the tube body comprises the following components: a PP resin, wherein the melting index of the PP resin under the test conditions of 230° C. and 2.16 kg is 15 to 70 g / 10 min; the adhesive film layer comprises the following components: a POE resin, wherein the melting temperature of the POE resin is 100 to 130° C.; and the weight ratio of the PP resin to the POE resin is (80 to 95):(4 to 15).

2. The high temperature resistant PP honeycomb tube according to claim 1, characterized in that: The melt index of the PP resin under the test conditions of 230° C. and 2.16 kg is 25 to 50 g / 10 min.

3. The high temperature resistant PP honeycomb tube according to claim 1, characterized in that: The PP resin is a homopolymer PP resin.

4. The high temperature resistant PP honeycomb tube according to claim 1, characterized in that: The melting temperature of the POE resin is 110-120°C.

5. The high temperature resistant PP honeycomb tube according to any one of claims 1 to 4, characterized in that: The tube body comprises the following components in parts by weight: 80-95 parts of PP resin and 1-5 parts of other additives, wherein the other additives comprise at least one of a nucleating agent, an antioxidant and a masterbatch.

6. The method for preparing a high temperature resistant PP honeycomb tube according to any one of claims 1 to 5, characterized in that: The steps include: (1) Preparation of PP tube by co-extrusion process; (2) The PP tube prepared in step (1) is closed in a fixed frame, and then heated at 130-150° C. for 15-25 minutes to soften the adhesive film layer on the PP tube and allow adjacent PP tubes to bond to each other, and then cooled and shaped to obtain the high temperature resistant PP honeycomb tube.

7. Use of the high temperature resistant PP honeycomb tube according to any one of claims 1 to 5 in the preparation of sandwich panels.

8. A sandwich panel, characterized in that: It comprises a honeycomb core made of the high temperature resistant PP honeycomb tube according to any one of claims 1 to 5, and surface layers arranged on the upper surface and the lower surface of the honeycomb core.

9. Use of the sandwich panel as claimed in claim 7 in preparing a spare tire cover for an automobile.

10. A spare tire cover for an automobile, characterized in that: Made of the sandwich panel as claimed in claim 8.

Images