A PET high-filling extruded composite material and preparation method thereof

Abstract

The present invention relates to a PET high-filling extruded composite material and a preparation method thereof. The extruded molding material comprises: 20-45 parts by weight of PET, 0.1-2 parts by weight of a chain extender, 40-60 parts by weight of an inorganic filler, 4-9 parts by weight of low-flow high-density polyethylene, 1-6 parts by weight of an ultra-high molecular weight polyethylene, 1-5 parts by weight of a compatibilizer, and 1-6 parts by weight of a coupling agent; the sum of all other components except the chain extender is 100 parts by weight. The mixed components are subjected to twin-screw extrusion granulation and then to single-screw extrusion molding to produce a PET high-filling composite material product with excellent comprehensive performance.

Description

Technical Field

[0001] The invention belongs to the field of polymer material processing and molding, and particularly relates to a PET high-filling extrusion composite material and a preparation method thereof. Background Art

[0002] Currently, highly filled polyvinyl chloride (PVC) sheets are widely used. However, some additives (plasticizers and heat stabilizers) added to PVC during high-filling processes are not environmentally friendly, and the combustion and decomposition of PVC release toxic gases, which are harmful to the environment and human health. Compared to PVC, polyethylene terephthalate (PET) is more environmentally friendly and non-toxic, with high hygienic safety and excellent mechanical properties. It is widely used in areas such as food packaging. Using PET resin as the base material and adding inorganic fillers, PET sheets and profiles can be extruded to produce environmentally friendly, non-toxic, and high-performance PET sheets. For example, Chinese patent publication number CN 106928668 A proposes a modified PET thick plate and an extrusion molding method thereof. The components, by mass percentage, are: 80-120 parts of PET resin, 1-10 parts of a processing modifier, 20-40 parts of a plasticizer, 10-20 parts of a filler, 6-10 parts of a stabilizer, and 1-3 parts of a lubricant. The filler is nano-activated calcium carbonate with a particle size of 10-50 nm and treated with a silane coupling agent. According to the examples, the net content of the filler in the formula is only 8.47-9.86%.

[0003] Unlike PVC high-filler extrusion molding, due to the extremely low melt strength of PET itself, adding a high content of inorganic fillers to PET results in extremely poor die extrusion molding characteristics of the PET / filler composite melt. When extruded from the die head, the melt sags severely, and the PET / filler melt exhibits a dispersed state like tofu dregs, which cannot be drawn down (the melt stream is prone to breakage during drawing down), making it difficult to continuously extrude well-shaped sheets and profiles. Furthermore, due to the inherent brittleness of PET, as the filler content increases, the resulting composite material loses its toughness and is difficult to meet application requirements. This poses significant difficulties in achieving PET high-filler extrusion molding to replace traditional PVC high-filler composite materials. Summary of the Invention

[0004] In order to solve the above-mentioned problems existing in the prior art, the present invention provides a PET high-filled extruded composite material and a preparation method thereof. Through comprehensive melt strength modification (viscosity modification) and toughening modification, etc., continuous extrusion molding of PET with a high inorganic filler content is achieved, thereby obtaining a PET high-filled composite material extrusion product with low cost and excellent comprehensive performance.

[0005] In order to achieve the purpose of the invention, the present invention adopts the following technical solution: a PET high-filling extrusion composite material, comprising the following components: 20-45 parts by weight of PET, 0.1-2 parts by weight of a chain extender, 40-60 parts by weight of an inorganic filler, 4-9 parts by weight of low-fluidity high-density polyethylene, 1-6 parts by weight of an ultra-high molecular weight polyethylene, 1-5 parts by weight of a compatibilizer, and 1-6 parts by weight of a coupling agent; except for the chain extender with a low content, the sum of all other components is 100 parts by weight.

[0006] In a preferred embodiment of the present invention, the PET resin can be made of virgin material (the intrinsic viscosity of PET is greater than 0.8 dL / g) or recycled material (preferably PET bottle recycled material), or a mixture thereof.

[0007] Adding chain extenders to PET causes chain extension reaction in PET during extrusion, which increases melt viscosity and melt strength, but the improvement in melt strength is limited; low-fluidity high-density polyethylene has a low melt flow rate (MFR) and low melt fluidity, but has high melt strength and excellent impact resistance. Adding low-fluidity high-density polyethylene with a low melt flow rate (MFR) on the basis of PET chain extension modification can further improve the melt strength of PET. On the other hand, it can also compensate for the brittleness of PET itself and the increased brittleness caused by the addition of inorganic fillers, and to a certain extent can improve the toughness of the composite material (correspondingly, it will also cause a decrease in flexural modulus and heat resistance, so the amount added should not be too high). The viscosity of high-density polyethylene will decrease to a certain extent at the processing temperature of PET as high as 260°C, and the addition amount cannot be too high. Therefore, its improvement in the melt strength of the composite system still cannot meet the needs of continuous and stable extrusion molding. Therefore, ultra-high molecular weight polyethylene is further added; due to its extremely high molecular weight (viscosity-average molecular weight greater than 1 million), ultra-high molecular weight polyethylene still maintains an extremely high melt viscosity (melt flow rate close to 0) at 260°C. Adding an appropriate amount of ultra-high molecular weight polyethylene helps to further increase the melt viscosity of the system and improve the melt strength of the composite, so that the melt drawing operation in the continuous extrusion process of the composite system can be carried out, thereby realizing continuous and stable extrusion molding of PET / inorganic filler composite systems with high filling content.

[0008] In order to improve the compatibility of low-fluidity high-density polyethylene and ultra-high molecular weight polyethylene with PET resin, an appropriate amount of compatibilizer is added. In order to improve the interface bonding between inorganic fillers and PET, low-fluidity high-density polyethylene and ultra-high molecular weight polyethylene, an appropriate amount of coupling agent is added, thereby obtaining a PET high-filling extruded composite material with excellent performance.

[0009] In a preferred embodiment of the present invention, the chain extender is selected from one of epoxy chain extenders, acid anhydride chain extenders and isocyanate chain extenders.

[0010] In a preferred embodiment of the present invention, the inorganic filler is at least one of powders including but not limited to calcium carbonate and talc, or a carrier-free particle of one of these, including but not limited to calcium carbonate and talc, or a masterbatch with a carrier content of less than 15%. The addition of an inorganic filler can significantly reduce product cost while improving mechanical properties such as flexural modulus and heat resistance.

[0011] In a preferred embodiment of the present invention, the low-fluidity high-density polyethylene is selected from powder or pellets having a melt flow rate (MFR) of less than 0.1 g / 10 min (test conditions: 230° C., load 5 kg).

[0012] In a preferred embodiment of the present invention, the ultra-high molecular weight polyethylene is selected from polyethylene resin (powder) with a viscosity-average molecular weight of 1 to 3 million.

[0013] In a preferred embodiment of the present invention, the compatibilizer is selected from glycidyl methacrylate grafted polyolefin elastomer (POE-g-GMA) or maleic anhydride grafted polyolefin elastomer (POE-g-MAH).

[0014] In a preferred embodiment of the present invention, the coupling agent is selected from a powdered silane coupling agent or a powdered titanate coupling agent.

[0015] The present invention also provides a method for preparing the PET high-filling extruded composite material, comprising the following steps:

[0016] First, the dried PET and chain extender are mixed evenly in a certain proportion, and then mixed evenly with other components. The mixture is fed into a twin-screw extruder for extrusion granulation. After drying, it is fed into a single-screw extruder for continuous extrusion molding to obtain PET high-filling extruded composite products.

[0017] In a preferred embodiment of the present invention, the highly filled PET extruded composite material product is a plate, sheet or profile.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] In the present invention, in a filling system of PET and an inorganic filler, low-fluidity high-density polyethylene is used to enhance the melt strength of the PET on the basis of a chain extender for chain extension reaction of the PET, and ultra-high molecular weight polyethylene is further used to increase the viscosity of the PET. This significantly improves the melt strength of the PET filling system, thereby improving the extrusion molding characteristics (melt draw-down capability) of the PET high-filler system and achieving continuous extrusion molding of PET composite materials with high filler content. The addition of the low-fluidity high-density polyethylene helps to improve the toughness of the composite system, the addition of the compatibilizer improves the interfacial compatibility between the low-fluidity high-density polyethylene and the ultra-high molecular weight polyethylene organic components and the PET, and the addition of the coupling agent improves the interfacial bonding between the inorganic filler and the PET, the low-fluidity high-density polyethylene and the ultra-high molecular weight polyethylene, thereby obtaining an inorganic high-filled PET composite extruded product with good comprehensive performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The following is further explained with reference to the accompanying drawings.

[0021] Figure 1 This is a diagram of the extrusion molding state of PET high-filled sheet. DETAILED DESCRIPTION

[0022] The specific embodiments of the present invention are described below with reference to the examples. However, the following examples are only used to illustrate the present invention in detail and are not intended to limit the scope of the present invention in any way.

[0023] The composition of the highly filled PET extrusion molding material is: 20-45 parts by weight of PET, 0.1-2 parts by weight of a chain extender, 40-60 parts by weight of an inorganic filler, 4-9 parts by weight of low-fluidity high-density polyethylene, 1-6 parts by weight of an ultra-high molecular weight polyethylene, 1-5 parts by weight of a compatibilizer, and 1-6 parts by weight of a coupling agent; except for the chain extender with a relatively low content, the total of all other components is 100 parts by weight.

[0024] PET resin can be made from either virgin (with an intrinsic viscosity greater than 0.8 dL / g, preferably 0.85 dL / g or higher), recycled (preferably recycled PET bottles), or a mixture. Virgin offers superior extrusion molding properties and product mechanical properties, while recycled PET or a combination of virgin and recycled PET can further reduce costs.

[0025] The chain extender should be one of the epoxy, anhydride, or isocyanate chain extenders. The chain extender can be in powder or masterbatch form. For virgin PET and / or low PET content, the chain extender dosage should be lower. For recycled PET and / or high PET content, the chain extender dosage should be higher.

[0026] The inorganic filler may include, but is not limited to, at least one of calcium carbonate and talc powders, or may include, but is not limited to, one of the aforementioned calcium carbonate and talc powders, uncarrier particles, or masterbatches with a carrier content of less than 15%. Masterbatches with high carrier content, such as PE or PP carrier filler masterbatches, can negatively impact the melt strength of the composite due to increased melt fluidity of the carrier at the high temperatures of PET processing. Therefore, carrier-free particles or masterbatches with low carrier content are preferred.

[0027] Low-flow high-density polyethylene (HDPE) should be prepared as a powder or pellet with a melt flow rate (MFR) of less than 0.1 g / 10 min (test conditions: 230°C, 5 kg load). When the inorganic filler is in powder form, HDPE is preferred; when the inorganic filler is in granular form, HDPE pellets are preferred, as this facilitates material mixing. However, excessive addition of HDPE may significantly reduce the flexural modulus and thermal performance of the finished product.

[0028] Ultra-high molecular weight polyethylene (UHMWPE) uses a resin (powder) with a viscosity-average molecular weight of 1-3 million, preferably 1-2 million. As the filler content increases, its dosage should be appropriately reduced to avoid excessive increases in the melt viscosity of the composite system, which would increase extrusion resistance.

[0029] The compatibilizer is glycidyl methacrylate grafted polyolefin elastomer (POE-g-GMA) or maleic anhydride grafted polyolefin elastomer (POE-g-MAH).

[0030] The coupling agent is a powdered silane coupling agent or a titanate coupling agent. The solid powder coupling agent is convenient for mixing the coupling agent with the inorganic filler.

[0031] In order to maximize the uniform dispersion of the chain extender in the PET matrix resin to ensure sufficient chain extension reaction, the powdered chain extender is first pre-mixed with an appropriate amount of liquid paraffin and PET until uniform, and then the mixture is mixed with talcum powder, low-fluidity high-density polyethylene, ultra-high molecular weight polyethylene, compatibilizer and coupling agent until uniform, and then directly fed into the twin-screw extruder for extrusion. After water cooling or air cooling, it is pelletized by a pelletizer to obtain highly filled modified PET pellets. After drying, it is extruded and formed by a single-screw extruder. Its extrusion state is as follows Figure 1 shown.

[0032] If the specific gravity of the product needs to be reduced, extrusion foaming molding can be performed by adding a chemical foaming agent or injecting a physical foaming agent on the basis of the above.

[0033] In order to analyze the melt flow rate of PET modified pellets to indirectly indicate the melt strength of the material (generally, the lower the melt flow rate, the higher the melt strength), the test was conducted according to GB / T3862-2000. During the test, samples were taken at the same time interval and the average mass of the samples was calculated. The calculation formula is as follows:

[0034]

[0035] Where, MFR is the melt flow rate of PET modified pellets, g / 10min;

[0036] m—average mass, g;

[0037] t—time interval, s.

[0038] The following is the test method for the performance of molded products:

[0039] Bendability testing was conducted according to GB / T 9341-2008, using a specimen size of 80 × 10 × 4 mm, a span of S = 64 mm, and a speed of 2 mm / min. For non-standard specimens of extruded sheet, since the sheet thickness h ranges from 1 to 3 mm, the sheet was cut into specimens for bending testing (h = 2 mm) according to the national standard, with a span of S1 = 16h, or 32 mm. Five standard specimens were selected for each group, and the results were averaged.

[0040] Vicat softening temperature is an important indicator for measuring the heat resistance of composite materials. A Vicat softening point tester with thermal deformation is used. According to the standard GB / T1633-2018, the sample size is length × width × thickness = 10 × 10 × 4 mm, and the Vicat softening temperature test is carried out on the standard sample using the A50 method.

[0041] Example 1

[0042] PET with an intrinsic viscosity of 0.85 dL / g was selected as the base resin. By weight, the following components were used: 40 parts PET, 0.3 parts chain extender, 50 parts PP carrier talc masterbatch, 4 parts low-flow high-density polyethylene with an MFR of 0.04 g / 10 min (test conditions: 230°C, 5 kg load), 3 parts ultra-high molecular weight polyethylene with a molecular weight of 1.5 million, 2 parts compatibilizer, and 1 part coupling agent. After uniform mixing as described above, the mixture was extruded into pellets using a Φ20 twin-screw extruder. After drying, the melt flow rate of the pellets tested was 0.67 g / 10 min, and sheet extrusion was performed using a Φ45 single-screw extruder. The twin-screw barrel temperatures in zones 1 through 5 were 160°C, 230°C, 250°C, 260°C, and 250°C, respectively; the die temperature was 250°C; and the screw speed was 60 r / min. The single-screw barrel temperatures in zones 1 through 3 were 210°C, 250°C, and 260°C, respectively; the mold temperatures in zones 1 through 3 were 260°C, 240°C, and 225°C, respectively; and the screw speed was 15 r / min. The extrusion process was stable, yielding the highly filled PET sheet product. The performance test results are shown in Table 1: a flexural modulus of 2.92 GPa and a Vicat softening point of 212.7°C, representing improvements of 54.4% and 183.6%, respectively, compared to pure PET.

[0043] Example 2

[0044] PET with an intrinsic viscosity of 0.85 dL / g was selected as the base resin. By weight, the following components were used: 26 parts PET, 0.2 parts chain extender, 55 parts calcium carbonate powder, 9 parts low-flow high-density polyethylene with an MFR of 0.04 g / 10 min (test conditions: 230°C, 5 kg load), 3 parts ultra-high molecular weight polyethylene with a molecular weight of 1.5 million, 3 parts compatibilizer, and 4 parts coupling agent. After uniform mixing as described above, the mixture was extruded into pellets using a Φ20 twin-screw extruder. After drying, the pellets had a melt flow rate of 0.67 g / 10 min, and were then extruded into sheets using a Φ45 single-screw extruder. The twin-screw barrel temperatures for zones 1 to 5 were 160°C, 230°C, 250°C, 260°C, and 255°C, respectively; the die temperature was 250°C; and the screw speed was 60 r / min. The single-screw barrel temperatures for zones 1 to 3 were 210°C, 255°C, and 260°C, respectively; the mold temperatures for zones 1 to 3 were 260°C, 240°C, and 225°C, respectively; and the screw speed was 15 r / min. The extrusion process was stable, yielding the highly filled PET sheet product. The performance test results are shown in Table 1, showing a flexural modulus of 3.15 GPa and a Vicat softening point of 223.5°C.

[0045] Example 3

[0046] PET with an intrinsic viscosity of 0.85 dL / g was selected as the base resin. By weight, the following components were used: 24 parts PET, 0.2 parts chain extender, 58 parts carrier-free talc particles, 9 parts low-flow high-density polyethylene with an MFR of 0.04 g / 10 min (test conditions: 230°C, 5 kg load), 2 parts ultra-high molecular weight polyethylene with a molecular weight of 1.5 million, 3 parts compatibilizer, and 4 parts coupling agent. After uniform mixing as described above, the mixture was extruded into pellets using a Φ20 twin-screw extruder. After drying, the melt flow rate of the pellets tested was 0.69 g / 10 min, and sheet extrusion was performed using a Φ45 single-screw extruder. The twin-screw barrel temperatures for zones 1 to 5 were 160°C, 230°C, 250°C, 265°C, and 260°C, respectively; the die temperature was 250°C; and the screw speed was 60 r / min. The single-screw barrel temperatures for zones 1 to 3 were 210°C, 260°C, and 260°C, respectively; the mold temperatures for zones 1 to 3 were 260°C, 240°C, and 225°C, respectively; and the screw speed was 15 r / min. The extrusion process was stable, yielding the highly filled PET sheet product. The performance test results are shown in Table 1, showing a flexural modulus of 3.36 GPa and a Vicat softening point of 235.8°C.

[0047] Example 4

[0048] PET with an intrinsic viscosity of 0.85 dL / g was selected as the base resin. By weight, the following components were used: 45 parts PET, 0.5 parts chain extender, 40 parts calcium carbonate powder, 7 parts low-flow high-density polyethylene with an MFR of 0.04 g / 10 min (test conditions: 230°C, 5 kg load), 4 parts ultra-high molecular weight polyethylene with a molecular weight of 1.5 million, 1 part compatibilizer, and 3 parts coupling agent. After uniform mixing as described above, the mixture was extruded into pellets using a Φ20 twin-screw extruder. After drying, the pellets had a melt flow rate of 0.63 g / 10 min, and were then extruded into sheets using a Φ45 single-screw extruder. The twin-screw barrel temperatures for zones 1 to 5 were 160°C, 230°C, 250°C, 260°C, and 250°C, respectively; the die temperature was 250°C; and the screw speed was 60 r / min. The single-screw barrel temperatures for zones 1 to 3 were 210°C, 250°C, and 260°C, respectively; the mold temperatures for zones 1 to 3 were 260°C, 240°C, and 225°C, respectively; and the screw speed was 15 r / min. The extrusion process was stable, yielding the highly filled PET sheet product. The performance test results are shown in Table 1, showing a flexural modulus of 3.05 GPa and a Vicat softening point of 218.3°C.

[0049] Example 5

[0050] PET bottle recycled material was selected as the base resin. By weight, the PET recycled material was 42 parts, the chain extender was 1.2 parts, the calcium carbonate powder was 40 parts, the low-flow high-density polyethylene with an MFR of 0.04g / 10min (test conditions: 230℃, load 5kg) was 8 parts, the ultra-high molecular weight polyethylene with a molecular weight of 1.5 million was 4 parts, the compatibilizer was 2 parts, and the coupling agent was 4 parts. After mixing uniformly according to the above method, the pellets were extruded into pellets using a Φ20 twin-screw extruder. After drying, the melt flow rate of the pellets was tested to be 1.02g / 10min. Sheet extrusion was performed using a Φ45 single-screw extruder. The twin-screw barrel temperatures for zones 1 to 5 were 160°C, 230°C, 250°C, 260°C, and 250°C, respectively; the die temperature was 250°C; and the screw speed was 60 r / min. The single-screw barrel temperatures for zones 1 to 3 were 210°C, 250°C, and 260°C, respectively; the mold temperatures for zones 1 to 3 were 260°C, 240°C, and 225°C, respectively; and the screw speed was 15 r / min. The extrusion process was stable, yielding the highly filled PET sheet product. The performance test results are shown in Table 1, showing a flexural modulus of 2.52 GPa and a Vicat softening point of 202.6°C.

[0051] Example 6

[0052] PET (virgin) with an intrinsic viscosity of 0.85 dL / g and PET bottle recycled material were selected as the matrix resin. By weight, the following components were used: 20 parts virgin PET, 15 parts recycled PET, 0.8 parts chain extender, 45 parts calcium carbonate powder, 9 parts low-flow high-density polyethylene with an MFR of 0.04 g / 10 min (test conditions: 230°C, 5 kg load), 5 parts ultra-high molecular weight polyethylene with a molecular weight of 1.5 million, 2 parts compatibilizer, and 4 parts coupling agent. After uniform mixing according to the above method, the mixture was extruded into pellets using a Φ20 twin-screw extruder. After drying, the melt flow rate of the pellets tested was 0.86 g / 10 min. Sheet extrusion was performed using a Φ45 single-screw extruder. The twin-screw barrel temperatures for zones 1 to 5 were 160°C, 230°C, 250°C, 260°C, and 250°C, respectively; the die temperature was 250°C; and the screw speed was 60 r / min. The single-screw barrel temperatures for zones 1 to 3 were 210°C, 250°C, and 260°C, respectively; the mold temperatures for zones 1 to 3 were 260°C, 240°C, and 225°C, respectively; and the screw speed was 15 r / min. The extrusion process was stable, yielding the highly filled PET sheet product. The performance test results are shown in Table 1, showing a flexural modulus of 2.98 GPa and a Vicat softening point of 213.9°C.

[0053] Comparative Example 1

[0054] PET with an intrinsic viscosity of 0.85 dL / g was selected as the base resin, with 45 parts by weight of PET, 50 parts by weight of PP carrier talc masterbatch, and 5 parts of coupling agent. After uniform mixing, the pellets were extruded through a Φ20 twin-screw extruder. The twin-screw barrel temperatures for zones 1 to 5 were 160°C, 230°C, 250°C, 260°C, and 250°C, respectively, with a die temperature of 250°C and a screw speed of 60 r / min. After drying, the pellets exhibited a melt flow rate of 29.8 g / 10 min, and sheet extrusion was performed using a Φ45 single-screw extruder. The twin-screw barrel temperatures in zones 1 to 5 were 160°C, 230°C, 250°C, 260°C, and 250°C, respectively; the die head temperature was 250°C, and the screw speed was 60 r / min. The single-screw barrel temperatures in zones 1 to 3 were 210°C, 250°C, and 260°C, respectively; the mold temperatures in zones 1 to 3 were 260°C, 240°C, and 225°C, respectively; and the screw speed was 15 r / min. During extrusion, the material flow experienced severe melt hammering, exhibiting a tofu-like, divergent state that made molding impossible.

[0055] Comparative Example 2

[0056] PET with an intrinsic viscosity of 0.85 dL / g was selected as the base resin, with 45 parts by weight of PET, 0.5 parts by weight of chain extender, 50 parts by weight of PP carrier talc masterbatch, and 5 parts of coupling agent. After uniform mixing, the pellets were extruded through a Φ20 twin-screw extruder. The twin-screw barrel temperatures for zones 1 to 5 were 160°C, 230°C, 250°C, 260°C, and 250°C, respectively, with a die temperature of 250°C and a screw speed of 60 r / min. After drying, the pellets exhibited a melt flow rate of 21.13 g / 10 min, and sheet extrusion was performed using a Φ45 single-screw extruder. The twin-screw barrel temperatures in zones 1 to 5 were 160°C, 230°C, 250°C, 260°C, and 250°C, respectively; the die head temperature was 250°C; and the screw speed was 60 r / min. The single-screw barrel temperatures in zones 1 to 3 were 210°C, 250°C, and 260°C, respectively; the mold temperatures in zones 1 to 3 were 260°C, 240°C, and 225°C, respectively; and the screw speed was 15 r / min. The melt hammer phenomenon of the material flow was found to be somewhat alleviated during extrusion, but melt drafting was still difficult and successful molding was not possible.

[0057] Comparative Example 3

[0058] PET with an intrinsic viscosity of 0.85 dL / g was selected as the base resin, 30 parts by weight of PET, 0.3 parts by weight of chain extender, 50 parts by weight of PP carrier talc masterbatch, 15 parts of low-flow high-density polyethylene with an MFR of 0.04 g / 10 min (test conditions: 230°C, load 5 kg), 2 parts of compatibilizer, and 3 parts of coupling agent. After uniform mixing, the pellets were extruded through a Φ20 twin-screw extruder. The twin-screw barrel temperatures for zones 1 to 5 were 160°C, 230°C, 250°C, 260°C, and 250°C, respectively, with a die temperature of 250°C and a screw speed of 60 r / min. After drying, the melt flow rate of the pellets tested was 2.95 g / 10 min, and sheet extrusion was performed using a Φ45 single-screw extruder. The twin-screw barrel temperatures for zones 1 through 5 were 160°C, 230°C, 250°C, 260°C, and 250°C, respectively; the die temperature was 250°C; and the screw speed was 60 r / min. The single-screw barrel temperatures for zones 1 through 3 were 210°C, 250°C, and 260°C, respectively; the mold temperatures for zones 1 through 3 were 260°C, 240°C, and 225°C, respectively; and the screw speed was 15 r / min. Melt stretching was largely achieved, but the extrusion process was unstable, with occasional breakage. The sheet performance test results are shown in Table 1: the flexural modulus was 1.28 GPa and the Vicat softening point was 128.5°C. Compared to the pure material, the flexural modulus decreased by 30.0%; compared to Example 1, the flexural modulus decreased by 56.2% and the Vicat softening point decreased by 39.6%.

[0059] Table 1 PET sheet performance test results

[0060]

[0061]

[0062] As shown in the Examples, Comparative Examples, and Table 1, the present invention enhances the melt strength and melt viscosity of the PET / inorganic filler system through chain extension and the addition of low-flow high-density polyethylene and ultra-high molecular weight polyethylene, improving the extrusion molding properties of highly filled systems. This enables continuous and stable extrusion molding of PET / inorganic filler composites at high filler contents, resulting in excellent physical and mechanical properties. This is of great significance for replacing traditional highly filled PVC composites.

[0063] The above examples are only some embodiments of the present invention, not all embodiments. Those skilled in the art may modify these embodiments based on the above embodiments, and these embodiments are still covered by the claims of the present invention. Any replacement or modification based on the technical solution of the present invention shall be included in the scope of protection of the present invention.

Claims

1. A PET high-filling extrusion composite material, characterized in that: The invention comprises the following components: 20-45 parts by weight of PET, 0.1-2 parts by weight of a chain extender, 40-60 parts by weight of an inorganic filler, 4-9 parts by weight of low-fluidity high-density polyethylene, 1-6 parts by weight of an ultra-high molecular weight polyethylene, 1-5 parts by weight of a compatibilizer, and 1-6 parts by weight of a coupling agent; the total amount of all components except the chain extender having a relatively low content is 100 parts by weight; the chain extender is selected from one of epoxy chain extenders, acid anhydride chain extenders, and isocyanate chain extenders; the low-fluidity high-density polyethylene is selected from powder or granules with a melt flow rate (MFR) of less than 0.1 g / 10 min; and the ultra-high molecular weight polyethylene is selected from a polyethylene resin with a viscosity-average molecular weight of 1 to 3 million.

2. The PET highly filled extruded composite material according to claim 1, characterized in that The PET resin is made of new material or recycled material or a mixture thereof; the new material is PET with an intrinsic viscosity greater than 0.8dL / g, and the recycled material is PET bottle recycled material.

3. The PET highly filled extruded composite material according to claim 1, characterized in that The inorganic filler is selected from at least one of calcium carbonate and talc powder.

4. The PET highly filled extruded composite material according to claim 1, characterized in that The ultra-high molecular weight polyethylene is selected from polyethylene resins with a viscosity-average molecular weight of 1 to 2 million.

5. The PET highly filled extruded composite material according to claim 4, characterized in that: Ultra-high molecular weight polyethylene is a powder.

6. The PET highly filled extruded composite material according to claim 1, characterized in that: The compatibilizer is selected from glycidyl methacrylate grafted polyolefin elastomer POE-g-GMA or maleic anhydride grafted polyolefin elastomer POE-g-MAH.

7. The PET highly filled extruded composite material according to claim 1, characterized in that: The coupling agent is selected from powdered silane coupling agent or powdered titanate coupling agent.

8. The method for preparing a PET highly filled extruded composite material according to any one of claims 1 to 7, characterized in that: The following steps are involved: First, the dried PET is mixed evenly with the chain extender, and then mixed evenly with other components. The mixture is fed into a twin-screw extruder for extrusion granulation. After drying, it is fed into a single-screw extruder for continuous extrusion molding to obtain a PET high-filling extruded composite material product.

9. The preparation method according to claim 8, characterized in that The PET high-filling extruded composite material product is a plate, sheet or profile.

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