Thermoplastic composite panel and use thereof

Abstract

The application discloses a thermoplastic composite plate and application thereof, and belongs to the technical field of thermoplastic composite materials. The thermoplastic composite plate comprises a laminated structure which is formed by hot-pressing a reinforcing layer and a barrier layer, the reinforcing layer is made of a unidirectional prepreg which is made by hot-pressing a unidirectional continuous fiber after melting and impregnating the thermoplastic resin, and the barrier layer is made of a modified polyolefin resin film and / or a multi-phase resin film. The thermoplastic composite plate is prepared by replacing the aluminum foil with the barrier layer made of the modified polyolefin resin film and / or the multi-phase resin film, so that the material cost is reduced, the interface compatibility between the barrier layer and the resin layer is good, the difference in the thermal expansion coefficient is small, the adhesive is not needed, the hot-pressing and molding can be directly performed, and the interlaminar peeling strength of the composite plate is obviously improved.

Description

Technical Field

[0001] This invention belongs to the technical field of sheet materials for cold chain transportation, specifically relating to a thermoplastic composite sheet and its applications. Background Technology

[0002] Continuous fiber reinforced thermoplastic composite panels, due to their advantages such as lightweight, high impact strength, remanufacturing capability, and environmental recyclability, are gradually replacing traditional thermosetting composite panels and metal profiles, becoming the ideal material for lining products in the cold chain transportation industry. However, in actual use, thermoplastic composite panels are prone to moisture and oxygen penetration through the panels and into the foam core material, which gradually degrades the thermal insulation performance and increases the weight of the enclosure. Furthermore, they are susceptible to aging caused by damp heat, thermo-oxidative aging, and ultraviolet radiation, affecting the service life of both the core material and the panels. Therefore, to improve the durability, stability, and service life of the product, higher requirements are placed on the material's barrier properties, necessitating effective blocking of moisture, oxygen, and light.

[0003] CN 112757729 A discloses a high-barrier thermoplastic composite board, comprising a hot-pressed insulating layer, a functional surface layer, a buffer layer, a reinforcing layer, a barrier layer, and a dielectric layer, wherein the barrier layer is an aluminum-plastic composite film, and the layers are bonded together with adhesive. While this thermoplastic composite board effectively blocks moisture, oxygen, and light, the poor interfacial compatibility and significant difference in thermal expansion coefficients between the aluminum foil and the resin layer degrade the interlayer performance of the board, increasing the risk of internal delamination and separation. This also results in a narrow molding process window and significant processing difficulty. Furthermore, the aluminum-plastic film is expensive, and the internal adhesive bonding is poor, increasing the risk of VOC pollution. The introduction of aluminum foil and adhesive also complicates the subsequent recycling of this thermoplastic composite board. Summary of the Invention

[0004] To address the shortcomings of the existing technology, the present invention aims to provide a thermoplastic composite board and its applications.

[0005] To achieve its purpose, the technical solution adopted by this invention is as follows:

[0006] A thermoplastic composite board includes a layup structure formed by hot-pressing a reinforcing layer and a barrier layer. The reinforcing layer is made of unidirectional prepreg sheet formed by impregnating unidirectional continuous fibers with thermoplastic resin and then pressing it. The barrier layer is made of modified polyolefin resin film and / or multiphase resin film. The modified polyolefin resin film includes the following components in parts by weight: 40-70 parts polyolefin resin, 10-40 parts layered inorganic filler, 5-15 parts inorganic light-blocking agent, 0.2-0.6 parts nucleating agent, 2-8 parts compatibilizer, and 0.05-1 part antioxidant. The multiphase resin film includes the following components in parts by weight: 40-60 parts polyolefin resin, 20-50 parts second resin, 5-15 parts inorganic light-blocking agent, 2-8 parts compatibilizer, and 0.05-1 part antioxidant. The second resin includes at least one of polyamide (PA), ethylene / vinyl alcohol copolymer (EVOH), and polyketone (PK).

[0007] This invention uses a barrier layer made of modified polyolefin resin film and / or multiphase resin film to replace aluminum foil in the preparation of thermoplastic composite boards. This not only reduces material costs, but also ensures good interfacial compatibility between the barrier layer and the resin layer, with a small difference in the coefficient of thermal expansion. No glue is needed for bonding, and the boards can be directly pressed together. This is environmentally friendly and effectively improves the interlayer performance of the composite board, with a significant increase in interlayer peel strength.

[0008] Meanwhile, the modified polyolefin resin film has high crystallinity and low permeability and diffusion coefficients, and has a good blocking effect on water vapor, oxygen and light.

[0009] The multiphase resin membrane also has a good barrier effect on water vapor, oxygen and light. It contains a polar second resin, in which molecules can form strong bonds through hydrogen bonds, making it difficult for non-polar substances such as oxygen to pass through, thus further improving the barrier layer's barrier effect on oxygen.

[0010] Preferably, the second resin is 30 to 40 parts by weight.

[0011] Preferably, the polyolefin resin in the modified polyolefin resin film and the multiphase resin film includes at least one of PE and PP; more preferably, it isotactic PP, which has a regular molecular chain structure and higher crystallinity, which is more conducive to improving the barrier properties of the material.

[0012] Preferably, the layered inorganic filler is selected from at least one of montmorillonite, talc, mica, and kaolin. These layered inorganic fillers have a large aspect ratio, which can extend the path of small molecules through the polymer to a greater extent, making the barrier layer more effective at blocking water vapor and oxygen, while also improving the barrier layer's ability to block light.

[0013] Preferably, the layered inorganic filler comprises 20 to 30 parts by weight.

[0014] Preferably, the inorganic light-blocking agent is selected from at least one of titanium dioxide, zinc sulfide, and zinc oxide. These inorganic light-blocking agents enable the composite panel to achieve complete light coverage, while also improving the barrier layer's ability to block water vapor and oxygen.

[0015] Preferably, the nucleating agent is an organic nucleating agent (e.g., sorbitol and its derivatives, phosphate metal salts or carboxylic acid metal salts) and / or an inorganic nucleating agent (e.g., calcium oxide, calcium carbonate or silicon dioxide).

[0016] Preferably, the compatibilizer in the modified polyolefin resin film and the multiphase resin film includes at least one of maleic anhydride-grafted PP (PP-g-MAH), butyl acrylate-grafted PP (PP-g-BA), dibutyl maleate-grafted PP (PP-g-DBM), and glycidyl methacrylate-grafted PP (PP-g-GMA).

[0017] Preferably, the antioxidants in the modified polyolefin resin film and the multiphase resin film include at least one of aromatic amine antioxidants, hindered phenolic antioxidants, phosphite antioxidants, and organosulfur antioxidants.

[0018] Preferably, the barrier layer is a single-layer structure made of the modified polyolefin resin film.

[0019] Preferably, the preparation method of the single-layer barrier layer includes the following steps: according to the formulation ratio of the modified polyolefin resin film, all components are mixed evenly, and then granulated by an extruder at 180-230°C, and the obtained granules are cast into a film by casting.

[0020] Preferably, the barrier layer has a double-layer structure, which is composed of the modified polyolefin resin film and the multiphase resin film. The double-layer barrier layer composed of the modified polyolefin resin film and the multiphase resin film has better barrier performance and is more effective in blocking water vapor, oxygen and light.

[0021] Preferably, the preparation method of the barrier layer with the double-layer structure includes the following steps: mixing the components of the modified polyolefin resin film and the multiphase resin film evenly, then granulating them by an extruder at 180-260°C, and then forming a double-layer composite film by a double-layer co-extrusion process.

[0022] Preferably, the thickness of the barrier layer is 0.1 to 1.0 mm.

[0023] Preferably, the layup structure is a symmetrical layup with 90° to the outside. This allows the thermoplastic composite board, when used as an inner lining product in cold chain transportation, to exhibit superior mechanical properties, such as tensile strength, tensile modulus, flexural strength, and flexural modulus, in the stacking direction during use. Those skilled in the art will understand that "90° to the outside" means that the fiber direction of the layup surface is perpendicular to the unwinding direction (i.e., the long side direction of the composite board).

[0024] Preferably, the layup structure is one of [90° / 0° / barrier layer / 0° / 90°]n, [90° / 0° / 90° / 0° / barrier layer / 0° / 90°]n, and [90° / 0° / barrier layer / 0° / 90° / 0° / 90°]n, where n represents the number of cycles and is a positive integer. Specifically, the fiber direction parallel to the length direction of the composite board in the unidirectional prepreg layup is 0°, and the fiber direction perpendicular to the length direction of the composite board in the unidirectional prepreg layup is 90°, where both 90° and 0° are reinforcement layers.

[0025] Preferably, the thermoplastic composite board further includes a release film layer, a functional surface layer, a buffer layer, and a medium layer. The medium layer is disposed on one surface of the layup structure, and the buffer layer, the functional surface layer, and the release film layer are disposed sequentially from the inside to the outside on the other surface of the layup structure.

[0026] Preferably, the release film layer is a BOPET film with a thickness of 10–50 μm. This release film has good adhesion to the functional surface layer and is easy to peel off at the interface.

[0027] Preferably, the thickness of the functional surface layer is 0.1 to 0.5 mm, its water absorption rate is <0.01%, and its surface dyne value is <38.

[0028] Preferably, the functional surface layer comprises the following components in parts by weight: 75-90 parts of polyolefin resin, 3-10 parts of functional additives, and 5-15 parts of filler.

[0029] Preferably, the functional additive comprises the following components in parts by weight: 0.5-2 parts antibacterial agent, 0.5-2 parts antifungal agent, 0.5-2 parts light stabilizer, 0.5-2 parts silicone masterbatch, 0.5-1 part slip agent, and 0.5-1 part nonionic antistatic agent.

[0030] Preferably, the filler of the functional surface layer includes at least one of titanium dioxide, zinc oxide, zinc sulfide, magnesium oxide, and silver oxide.

[0031] Preferably, the buffer layer is a spunlace or hot-rolled nonwoven fabric material with a surface density of 20-40 gsm.

[0032] Preferably, the medium layer is a hydroentangled or thermally rolled nonwoven fabric material with a surface density of 75–125 gsm.

[0033] Preferably, the thermoplastic composite board is prepared by: sequentially stacking and pressing the release film layer, functional surface layer, buffer layer, layup structure and medium layer to obtain the thermoplastic composite board.

[0034] The present invention also provides the application of the thermoplastic composite board in cold chain transportation.

[0035] A liner for cold chain transportation, comprising the aforementioned thermoplastic composite board.

[0036] Compared with existing technologies, the beneficial effects of this invention are as follows: The barrier layer provided by this invention has a good barrier effect against water vapor, oxygen, and light. Furthermore, the barrier layer has good interfacial compatibility with the continuous fiber-reinforced thermoplastic composite material, with a small difference in thermal expansion coefficients, stable molding and processing, effectively improving the interlayer performance of the board, resulting in high interlayer peel strength and reducing the risk of internal delamination and separation. Through hot-pressing composite, no adhesive bonding is required, making it environmentally friendly, safe, and easier to recycle. Simultaneously, this invention also optimizes the layup structure, adopting a 90° outward layup method, resulting in superior mechanical properties of the thermoplastic composite material, making it more suitable for inner lining products used in cold chain transportation. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of one embodiment of the thermoplastic composite board described in this invention.

[0038] In the figure, the release film layer is 1, the functional surface layer is 2, the buffer layer is 3, the reinforcement layer is 4, the barrier layer is 5, and the dielectric layer is 6. Detailed Implementation

[0039] The technical solution of the present invention will be further described below with reference to embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0040] Some of the raw materials come from the following sources, but are not limited to these:

[0041] 1. Grade PP, model T30S, purchased from Lanzhou Petrochemical;

[0042] 2. Unregulated PP, model R520Y, purchased from SK Korea;

[0043] 3. Layered inorganic filler, layered talc powder, model HTP05L, purchased from Imfabi;

[0044] 4. Spherical inorganic filler, titanium dioxide, grade R-24, Sakai Chemical, Japan;

[0045] 5. Inorganic light-shielding agent, zinc sulfide, commercially available, the same type used in parallel tests;

[0046] 6. Nucleating agent, carboxylic acid metal salt organic nucleating agent, model TMA-3, purchased from Shanxi Chemical Research Institute;

[0047] 7. Compatibilizer: Maleic anhydride-grafted polypropylene, commercially available; the same type was used in parallel tests.

[0048] 8. Antioxidant: SONOX 225G, commercially available; the same type was used in parallel tests.

[0049] 9. PA, model M2800, purchased from Xinhui Meida;

[0050] 10. EVOH, model L171B, purchased from Kuraray Corporation, Japan;

[0051] 11. PK, model M630A, purchased from Hyosung, South Korea.

[0052] Examples 1-14

[0053] Examples 1-14 provide a thermoplastic composite board comprising a release film layer 1, a functional surface layer 2, a buffer layer 3, a layup structure, and a medium layer 6, which are sequentially stacked and hot-pressed together using a Teflon press. The hot-pressing temperature of the press is 180-250°C, the pressure is 1-6 bar, and the cooling temperature is 10-40°C.

[0054] The release film layer is a 30μm thick fully transparent BOPET film.

[0055] The functional surface layer has a thickness of 0.2 mm and is composed of the following components in parts by weight: 85 parts polypropylene resin (SP 179, Sinopec), 1 part antibacterial agent (inorganic silver ion antibacterial agent masterbatch IKM50G, Japan's Pinran Clean & Me), 1 part mildew inhibitor (isothiazolinone CIT, Bio-Chemical), 1 part light stabilizer (Tinuvin 770, BASF), 1 part silicone masterbatch (LYMB2418, Wacker Chemie), 0.5 parts slip agent (polyethylene wax Licowax PE520, Clariant), 0.5 parts nonionic antistatic agent (Hostastat HS-1, Clariant), and 10 parts titanium dioxide. The functional surface layer is prepared by mixing all components evenly according to the formulation ratio and then casting it into a film at a processing temperature of 180–230°C.

[0056] The buffer layer is made of hot-rolled PET nonwoven fabric with a surface density of 40 gsm, and the medium layer is made of hot-rolled PET nonwoven fabric with a surface density of 80 gsm.

[0057] The layup structure consists of two reinforcing layers 4 and a barrier layer 5 disposed between the two reinforcing layers. Each reinforcing layer is made of two unidirectional prepreg sheets with 60% fiber content unidirectional continuous glass fibers, which are melt-impregnated with polypropylene resin and then pressed into shape. The layup pattern of the layup structure is 90° / 0° / barrier layer / 0° / 90°.

[0058] The barrier layer is a single-layer structure. The barrier layers in Examples 1 to 7 are made of modified polyolefin resin membranes, and the barrier layers in Examples 8 to 14 are made of multiphase resin membranes. The formulations of the modified polyolefin resin membranes in Examples 1 to 7 are shown in Table 1, and the formulations of the multiphase resin membranes in Examples 8 to 14 are shown in Table 2.

[0059] The modified polyolefin resin film is prepared as follows: all components are mixed evenly using a high-speed mixer, and then granulated by a twin-screw extruder at 180-230℃. The granules are then cast into a 0.4mm thick film.

[0060] The preparation method of multiphase resin membrane is as follows: all components are mixed evenly using a high-speed mixer, and then granulated by a twin-screw extruder at 180-260℃. The granules are then cast into a 0.4mm thick film.

[0061] Comparative Examples 1-5 provide a thermoplastic composite panel that differs from Examples 1-7 only in the material of the barrier layer; the structure and thickness of the other structural layers and barrier layers are identical. The barrier layer of Comparative Examples 1-5 is made from a resin film with the formulation shown in Table 1, and the preparation method of this resin film is the same as that for modified polyolefin resin films.

[0062] Comparative Examples 6 and 7 provide a thermoplastic composite panel that differs from Examples 8 to 14 only in the material of the barrier layer; the structure and thickness of the other structural layers and barrier layers are identical. The barrier layer of Comparative Examples 6 and 7 is made of a resin film with the formulation shown in Table 2, and the preparation method of this resin film is the same as that for multiphase resin films.

[0063] Table 1. Formula of modified polyolefin resin film in parts by weight

[0064]

[0065] Note: "-" in the table indicates that the component was not added, and the same applies below.

[0066] Table 2. Multiphase resin membrane formulation by weight

[0067]

[0068] Performance Test 1

[0069] The thermoplastic composite panels prepared in Examples 1-14 and Comparative Examples 1-7 were subjected to the following performance tests: 1. Water vapor transmission rate, referring to ASTM E96-2014 (38℃);

[0070] 2. Oxygen permeability, refer to ASTM D3985-2017 (23℃);

[0071] 3. Opacity: Standard light source, measured using a transmittance tester.

[0072] The test results are shown in Table 3.

[0073] Table 3

[0074]

[0075]

[0076] Example 15

[0077] Example 15 provides a thermoplastic composite board, which differs from Example 1 only in the layup method of the layer structure. The layup method of Example 15 is 0° / 90° / barrier layer / 90° / 0°.

[0078] Example 16

[0079] Example 16 provides a thermoplastic composite board, which differs from Example 1 only in the barrier layer.

[0080] The barrier layer in Example 16 has a bilayer structure, composed of the modified polyolefin resin film of Example 1 and the multiphase resin film of Example 8. The preparation method of this bilayer barrier layer is as follows: the components of the modified polyolefin resin film and the multiphase resin film are mixed uniformly using a high-speed mixer, and then granulated at 180–260°C using a twin-screw extruder. The resulting granules are then processed into a 0.4 mm bilayer composite film using a conventional bilayer co-extrusion process, thus obtaining the barrier layer.

[0081] Comparative Example 8

[0082] Comparative Example 8 provides a thermoplastic composite board, which differs from Example 1 only in the barrier layer. The barrier layer of Comparative Example 8 adopts the barrier layer of Example 1 as described in CN 112757729 A.

[0083] Performance Test 2

[0084] The thermoplastic composite panels prepared in Examples 1, 15-16, and Comparative Example 8 were subjected to performance tests, and the test methods are as follows:

[0085] 1. The interlaminar peel strength of the barrier layer in composite panels shall be in accordance with ASTM D1876-2008;

[0086] 2. Tensile strength, refer to ASTM D638-2010;

[0087] 3. Bending strength, refer to ASTM D790-2017.

[0088] The test results are shown in Table 4.

[0089] Table 4

[0090]

[0091] 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 modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A thermoplastic composite board, characterized in that, The invention comprises a layered structure formed by hot-pressing a reinforcing layer and a barrier layer. The reinforcing layer is made of a unidirectional prepreg sheet formed by impregnating unidirectional continuous fibers with thermoplastic resin and then pressing it. The barrier layer is made of a modified polyolefin resin film and / or a multiphase resin film. The modified polyolefin resin film comprises the following components in parts by weight: 40-70 parts polyolefin resin, 30-40 parts layered inorganic filler, 5-10 parts inorganic light-blocking agent, 0.2-0.6 parts nucleating agent, 2-8 parts compatibilizer, and 0.05-1 part antioxidant. The multiphase resin film comprises the following components in parts by weight: 40-60 parts polyolefin resin, 30-40 parts second resin, 5-15 parts inorganic light-blocking agent, 2-8 parts compatibilizer, and 0.05-1 part antioxidant. The second resin comprises at least one of polyamide, ethylene / vinyl alcohol copolymer, and polyketone. The modified polyolefin resin membrane and the multiphase resin membrane both contain isotactic polyolefin (PP).

2. The thermoplastic composite board as described in claim 1, characterized in that, The barrier layer is a single-layer structure made of the modified polyolefin resin film.

3. The thermoplastic composite board as described in claim 1, characterized in that, The barrier layer has a double-layer structure, which is composed of the modified polyolefin resin film and the multiphase resin film.

4. The thermoplastic composite board as described in claim 1, characterized in that, The thickness of the barrier layer is 0.1~1.0mm.

5. The thermoplastic composite board as described in claim 1, characterized in that, The ply structure is a symmetrical ply with 90° on the outside.

6. The thermoplastic composite board as described in claim 5, characterized in that, The layup structure is constructed using one of the following methods: [90° / 0° / barrier layer / 0° / 90°]n, [90° / 0° / 90° / 0° / barrier layer / 0° / 90°]n, or [90° / 0° / barrier layer / 0° / 90° / 0° / 90°]n, where n represents the number of cycles and is a positive integer.

7. The thermoplastic composite board as described in claim 1, characterized in that, The layered inorganic filler is selected from at least one of montmorillonite, talc, mica, and kaolin.

8. The thermoplastic composite board as described in claim 1, characterized in that, The inorganic light-shielding agent is selected from at least one of titanium dioxide, zinc sulfide, and zinc oxide.

9. The thermoplastic composite board according to any one of claims 1 to 8, characterized in that, It also includes a release film layer, a functional surface layer, a buffer layer, and a dielectric layer. The dielectric layer is disposed on one surface of the layup structure, and the buffer layer, the functional surface layer, and the release film layer are disposed sequentially from the inside to the outside on the other surface of the layup structure.

10. A liner for cold chain transportation, characterized in that, Including the thermoplastic composite sheet as described in any one of claims 1 to 9.

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