PET high-filling extrusion composite material and preparation method thereof

Abstract

The invention relates to a PET high-filling extrusion composite material and a preparation method thereof. An extrusion molding material comprises the following components in parts by weight: 20-45 parts of PET, 0.1-2 parts of a chain extender, 40-60 parts of an inorganic filler, 4-9 parts of low-fluidity high-density polyethylene, 1-6 parts of ultra-high molecular weight polyethylene, 1-5 parts of a compatilizer and 1-6 parts of a coupling agent. The sum of all the components except the chain extender is 100 parts by weight. The mixed components are extruded and granulated through double screws and then are extruded and molded through a single screw, so that the PET high-filling composite material product with excellent comprehensive performance is prepared.

Description

Technical Field

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

[0002] At present, the application of polyvinyl chloride (PVC) high-filled sheet materials is relatively common. However, some additives (plasticizers, heat stabilizers) added during high filling of PVC have low environmental protection, and the combustion and decomposition of PVC will release toxic gases, which cause harm to the environment and human health. Compared with PVC, polyethylene terephthalate (PET) has higher environmental protection, is non-toxic, has high hygienic safety, and excellent mechanical properties, and is widely used in the fields of food packaging, etc. Using PET resin as the matrix material and adding inorganic fillers, environmentally friendly and non-toxic PET sheet materials, profiles, etc. with excellent comprehensive properties can be extruded and produced. For example, Chinese Patent with the publication number CN 106928668 A proposes a modified PET thick plate and an extrusion molding method thereof. The components are proportioned by mass percentage as follows: 80-120 parts of PET resin, 1-10 parts of processing modifier, 20-40 parts of plasticizer, 10-20 parts of filler, 6-10 parts of stabilizer, and 1-3 parts of lubricant. Among them, the filler is nano-active calcium carbonate with a particle size of 10-50 nm and treated with a silane coupling agent. According to its examples, the net content of the filler (filler) in the formula is only 8.47-9.86%.

[0003] Different from the high filling extrusion molding of PVC, due to the extremely low melt strength of PET itself, adding a high content of inorganic fillers in PET results in extremely poor die extrusion molding characteristics of the PET / filler composite melt. When extruded from the die of the head, the melt sag phenomenon is serious, and the PET / filler melt is in a divergent state like bean curd residue, and cannot be drawn (the melt flow is likely to break during drawing), resulting in difficulty in continuously extruding to obtain plate and profile products with complete shapes. On the other hand, due to the large brittleness of PET itself, as the filler content increases, the toughness of the obtained composite material is extremely low, making it difficult to meet the use requirements. This brings great difficulties to realizing the high filling extrusion molding of PET to replace traditional PVC high-filled composite materials. Summary of the Invention

[0004] In order to solve the above problems existing in the prior art, the present invention provides a PET high-filled extrusion composite material and a preparation method thereof. Through comprehensive melt strength modification (viscosity increasing modification), toughening modification, etc., continuous extrusion molding of PET under a high inorganic filler content is realized, and PET high-filled composite material extrusion products with low cost and excellent comprehensive properties are obtained.

[0005] To achieve the object of the invention, the present invention adopts the following technical solutions: A PET high-filled extrusion composite material 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 a 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 for the chain extender with a relatively low content is 100 parts by weight.

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

[0007] Adding a chain extender to PET causes a chain extension reaction during the extrusion process, increasing the melt viscosity and melt strength to some extent, but the improvement of the melt strength is limited; due to its small melt flow rate (MFR), the low-flow high-density polyethylene has a low melt fluidity, high melt strength, and excellent impact resistance. Adding a low-flow high-density polyethylene with a small melt flow rate (MFR) on the basis of the chain extension modification of PET 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 adding inorganic fillers, and can improve the toughness of the composite material to a certain extent (correspondingly, it will also cause a decrease in the flexural modulus and heat resistance, so its addition amount should not be too high). Since the viscosity of the low-flow 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, its improvement of 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), the 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, improve the melt strength of the composite, and enable the melt stretching operation during the continuous extrusion process of the composite system, thereby realizing the continuous and stable extrusion molding of the PET / inorganic filler composite system with a high filling content.

[0008] To improve the compatibility of the low-flow high-density polyethylene and ultra-high molecular weight polyethylene with the PET resin, an appropriate amount of a compatibilizer is added. To improve the interfacial bonding between the inorganic filler and PET, low-flow high-density polyethylene, and ultra-high molecular weight polyethylene, an appropriate amount of a coupling agent is added, thereby obtaining a PET high-filled extrusion composite material with excellent properties.

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

[0010] In a preferred embodiment of the present invention, the inorganic filler is at least one of, including but not limited to, calcium carbonate and talc powder, or is a carrier-free particle such as calcium carbonate or talc, or a masterbatch with a carrier content of less than 15%. Adding inorganic fillers can significantly reduce the cost of products and improve mechanical properties such as flexural modulus and heat resistance at the same time.

[0011] In a preferred embodiment of the present invention, the low-flow high-density polyethylene is selected from powder or pellet with 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 million 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 powder silane coupling agent or powder titanate coupling agent.

[0015] The present invention also provides a method for preparing the PET highly filled extrusion composite material, comprising the following steps:

[0016] First, the dried PET and the chain extender are mixed evenly in a certain proportion, then mixed evenly with other components, and 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 the PET highly filled extrusion composite material product.

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

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0019] In the present invention, in the filling system of PET and inorganic fillers, based on the chain extension reaction of PET using a chain extender, low-flow high-density polyethylene is used to enhance the melt strength of PET, and ultra-high molecular weight polyethylene is further used to increase the viscosity of PET, significantly improving the melt strength of the PET filling system, thereby improving the extrusion molding characteristics (melt stretching ability) of the high-fill PET system and realizing the continuous extrusion molding of PET composites with high filler content. The addition of low-flow high-density polyethylene helps to improve the toughness of the composite system. The addition of a compatibilizer improves the interfacial compatibility between the organic components of low-flow high-density polyethylene and ultra-high molecular weight polyethylene and PET. The addition of a coupling agent improves the interfacial bonding force between the inorganic filler and PET, low-flow high-density polyethylene, and ultra-high molecular weight polyethylene, thereby obtaining an extruded product of an inorganic high-fill PET composite with good comprehensive performance. Description of the Drawings

[0020] The following is further described in conjunction with the drawings.

[0021] Figure 1 It is a state diagram of the extrusion molding of high-fill PET sheets. Detailed Embodiments

[0022] The following describes the detailed embodiments of the present invention in conjunction with the examples. However, the following examples are only used to illustrate the present invention in detail and do not limit the scope of the present invention in any way.

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

[0024] Among them, the PET resin can be either new material (the intrinsic viscosity of PET is greater than 0.8 dL / g, preferably the intrinsic viscosity is 0.85 dL / g or more) or recycled material (preferably PET bottle recycled material), or a mixture of the two. The extrusion molding characteristics and mechanical properties of the new material are better, while using PET recycled material or a mixture of PET new material and recycled material is beneficial to further reduce costs.

[0025] The chain extender is selected from one of epoxy-based chain extenders, anhydride-based, and isocyanate-based chain extenders. The chain extender can be in the form of powder or masterbatch. For PET new material and / or low PET content, the addition amount of the chain extender is taken as a smaller value, and for PET recycled material and / or high PET content, the addition amount of the chain extender is taken as a larger value.

[0026] The inorganic filler can be at least one of calcium carbonate and talcum powder, etc., and can also be a non-carrier particle such as calcium carbonate or talcum powder, or a masterbatch with a carrier content lower than 15%. Masterbatches with a relatively high carrier content, such as PE carrier filler masterbatch or PP carrier filler masterbatch, have an increased melt fluidity at the high temperature of PET processing, which adversely affects the melt strength of the composite system. Therefore, non-carrier particles or carrier filler masterbatches with a low carrier content are preferred.

[0027] The low-flow high-density polyethylene selects a powder or pellet with a melt flow rate (MFR) less than 0.1 g / 10 min (test conditions: 230 °C, load 5 kg). When the inorganic filler is a powder, the low-flow high-density polyethylene preferably selects a powder; when the inorganic filler is granular, the low-flow high-density polyethylene preferably selects a pellet, which is conducive to the mixing of materials. When the addition amount of the low-flow high-density polyethylene is too high, it may cause a significant decrease in the flexural modulus and thermal properties of the product.

[0028] The ultra-high molecular weight polyethylene selects a resin (powder) with a viscosity-average molecular weight of 1-3 million, preferably a viscosity-average molecular weight of 1-2 million. When the filler content increases, its dosage is appropriately reduced to avoid excessive increase in the melt viscosity of the composite system, resulting in an increase in extrusion resistance.

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

[0030] The coupling agent selects a silane coupling agent or a titanate coupling agent in powder form. The solid powder coupling agent is convenient for the mixing treatment between the coupling agent and the inorganic filler.

[0031] To maximize the uniform dispersion of the chain extender in the PET matrix resin to ensure a sufficient chain extension reaction, first premix the powdery chain extender with an appropriate amount of liquid paraffin and PET until uniform, then mix this mixture with talcum powder, low-flow high-density polyethylene, ultra-high molecular weight polyethylene, compatibilizer and coupling agent until uniform, and then directly feed it into a twin-screw extruder for extrusion. After water cooling or air cooling, it is pelletized by a pelletizer to obtain high-filled modified PET pellets. After drying, it is extruded and molded by a single-screw extruder, and its extrusion state is as Figure 1 shown.

[0032] If it is necessary to reduce the specific gravity of the product, extrusion foaming molding can be carried out by adding a chemical foaming agent or injecting a physical foaming agent on the above basis.

[0033] To analyze the melt flow rate of the PET modified pellets to indirectly characterize the melt strength of the material (usually, the lower the melt flow rate, the higher the melt strength), the test was carried out according to GB / T3862-2000. Sampling was carried out at the same time intervals during the test, and the average value of the obtained sample masses was calculated. The calculation formula is as follows:

[0034]

[0035] In the formula, MFR—the melt flow rate of the PET modified pellets, g / 10min;

[0036] m—the average mass, g;

[0037] t—the time interval, s.

[0038] The following are the test methods for the properties of the molded products:

[0039] The flexural property test was carried out according to GB / T 9341-2008. The dimensions of the specimen were 80×10×4 mm, the span S = 64 mm, and the speed was 2 mm / min. For the non-standard specimens of the extruded sheet, since the sheet thickness h ranged from 1 to 3 mm, according to the requirements of the national standard, the sheet was cut into specimens for the flexural property test (h = 2 mm), and the span S1 = 16h, that is, 32 mm. Five standard specimens were selected for each group for the test, and the average value was taken to calculate the result.

[0040] The Vicat softening temperature is an important index to measure the heat resistance of the composite material. Using a heat distortion and Vicat softening point tester, according to the standard of GB / T1633-2018, the specimen size was length×width×thickness = 10×10×4 mm, and the Vicat softening temperature test was carried out on the standard specimen by the A50 method.

[0041] Example 1

[0042] PET with an intrinsic viscosity of 0.85 dL / g was selected as the matrix resin. By weight, 40 parts of PET, 0.3 part of chain extender, 50 parts of PP carrier talc masterbatch, 4 parts of low-flow high-density polyethylene with MFR = 0.04 g / 10 min (test conditions: 230 °C, load 5 kg), 3 parts of ultra-high molecular weight polyethylene with a molecular weight of 1.5 million, 2 parts of compatibilizer, and 1 part of coupling agent were used. After mixing evenly according to the aforementioned method, it was granulated by a Φ20 twin-screw extruder. After drying, the melt flow rate of the granulated material was tested to be 0.67 g / 10 min, and a sheet was extruded and formed using a Φ45 single-screw extruder. The temperatures of the twin-screw barrel in zones 1 to 5 were 160 °C, 230 °C, 250 °C, 260 °C, and 250 °C respectively, the head temperature was 250 °C, and the screw speed was 60 r / min; the temperatures of the single-screw barrel in zones 1 to 3 were 210 °C, 250 °C, and 260 °C respectively, the temperatures of the die in 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, and the PET high-filled sheet product was obtained. The performance test results are shown in Table 1. The flexural modulus was 2.92 GPa, and the Vicat softening point was 212.7 °C. The improvement ratios compared with the pure PET were 54.4% and 183.6% respectively.

[0043] Example 2

[0044] PET with an intrinsic viscosity of 0.85 dL / g was selected as the matrix resin. By weight, 26 parts of PET, 0.2 part of chain extender, 55 parts of calcium carbonate powder, 9 parts of low-flow high-density polyethylene with MFR = 0.04 g / 10 min (test conditions: 230 °C, load 5 kg), 3 parts of ultra-high molecular weight polyethylene with a molecular weight of 1.5 million, 3 parts of compatibilizer, and 4 parts of coupling agent were used. After mixing evenly according to the aforementioned method, it was granulated by a Φ20 twin-screw extruder. After drying, the melt flow rate of the granulated material was tested to be 0.67 g / 10 min, and a sheet was extruded and formed using a Φ45 single-screw extruder. The temperatures of the twin-screw barrel in zones 1 to 5 were 160 °C, 230 °C, 250 °C, 260 °C, and 255 °C respectively, the head temperature was 250 °C, and the screw speed was 60 r / min; the temperatures of the single-screw barrel in zones 1 to 3 were 210 °C, 255 °C, and 260 °C respectively, the temperatures of the die in 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, and the PET high-filled sheet product was obtained. The performance test results are shown in Table 1. The flexural modulus was 3.15 GPa, and the Vicat softening point was 223.5 °C.

[0045] Example 3

[0046] PET with an intrinsic viscosity of 0.85 dL / g was selected as the matrix resin. By weight, there were 24 parts of PET, 0.2 part of chain extender, 58 parts of carrier-free talc particles, 9 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 ultra-high molecular weight polyethylene with a molecular weight of 1.5 million, 3 parts of compatibilizer, and 4 parts of coupling agent. After mixing evenly by the aforementioned method, it was pelletized by a Φ20 twin-screw extruder. After drying, the melt flow rate of the pellets was tested to be 0.69 g / 10 min, and a sheet was extruded and formed using a Φ45 single-screw extruder. The temperatures of the twin-screw barrel in zones 1 to 5 were 160 °C, 230 °C, 250 °C, 265 °C, and 260 °C respectively, the head temperature was 250 °C, and the screw speed was 60 r / min; the temperatures of the single-screw barrel in zones 1 to 3 were 210 °C, 260 °C, and 260 °C respectively, the temperatures of the die in 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, and the PET high-filled sheet product was obtained. The performance test results are shown in Table 1. The flexural modulus was 3.36 GPa, and the Vicat softening point was 235.8 °C.

[0047] Example 4

[0048] PET with an intrinsic viscosity of 0.85 dL / g was selected as the matrix resin. By weight, there were 45 parts of PET, 0.5 part of chain extender, 40 parts of calcium carbonate powder, 7 parts of low-flow high-density polyethylene with an MFR of 0.04 g / 10 min (test conditions: 230 °C, load 5 kg), 4 parts of ultra-high molecular weight polyethylene with a molecular weight of 1.5 million, 1 part of compatibilizer, and 3 parts of coupling agent. After mixing evenly by the aforementioned method, it was pelletized by a Φ20 twin-screw extruder. After drying, the melt flow rate of the pellets was tested to be 0.63 g / 10 min, and a sheet was extruded and formed using a Φ45 single-screw extruder. The temperatures of the twin-screw barrel in zones 1 to 5 were 160 °C, 230 °C, 250 °C, 260 °C, and 250 °C respectively, the head temperature was 250 °C, and the screw speed was 60 r / min; the temperatures of the single-screw barrel in zones 1 to 3 were 210 °C, 250 °C, and 260 °C respectively, the temperatures of the die in 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, and the PET high-filled sheet product was obtained. The performance test results are shown in Table 1. The flexural modulus was 3.05 GPa, and the Vicat softening point was 218.3 °C.

[0049] Example 5

[0050] PET bottle recycled material was selected as the matrix resin. By weight, 42 parts of PET recycled material, 1.2 parts of chain extender, 40 parts of calcium carbonate powder, 8 parts of low-flow high-density polyethylene with MFR = 0.04 g / 10 min (test conditions: 230 °C, load 5 kg), 4 parts of ultra-high molecular weight polyethylene with a molecular weight of 1.5 million, 2 parts of compatibilizer, and 4 parts of coupling agent. After mixing evenly according to the aforementioned method, it was pelletized by a Φ20 twin-screw extruder. After drying, the melt flow rate of the pellets was measured to be 1.02 g / 10 min, and a sheet was extruded and formed using a Φ45 single-screw extruder. The temperatures of the twin-screw barrel in zones 1 to 5 were 160 °C, 230 °C, 250 °C, 260 °C, and 250 °C respectively, the head temperature was 250 °C, and the screw speed was 60 r / min; the temperatures of the single-screw barrel in zones 1 to 3 were 210 °C, 250 °C, and 260 °C respectively, the temperatures of the die in 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, and the PET high-filled sheet product was obtained. The performance test results are shown in Table 1, with a flexural modulus of 2.52 GPa and a Vicat softening point of 202.6 °C.

[0051] Example 6

[0052] PET (new material) with an intrinsic viscosity of 0.85 dL / g and PET bottle recycled material were selected as the matrix resin. By weight, 20 parts of PET new material, 15 parts of PET recycled material, 0.8 part of chain extender, 45 parts of calcium carbonate powder, 9 parts of low-flow high-density polyethylene with MFR = 0.04 g / 10 min (test conditions: 230 °C, load 5 kg), 5 parts of ultra-high molecular weight polyethylene with a molecular weight of 1.5 million, 2 parts of compatibilizer, and 4 parts of coupling agent. After mixing evenly according to the aforementioned method, it was pelletized by a Φ20 twin-screw extruder. After drying, the melt flow rate of the pellets was measured to be 0.86 g / 10 min, and a sheet was extruded and formed using a Φ45 single-screw extruder. The temperatures of the twin-screw barrel in zones 1 to 5 were 160 °C, 230 °C, 250 °C, 260 °C, and 250 °C respectively, the head temperature was 250 °C, and the screw speed was 60 r / min; the temperatures of the single-screw barrel in zones 1 to 3 were 210 °C, 250 °C, and 260 °C respectively, the temperatures of the die in 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, and the PET high-filled sheet product was obtained. The performance test results are shown in Table 1, with 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 0.85dL / g was selected as the base resin, PET was 45 parts by weight, PP carrier talc masterbatch was 50 parts by weight, and coupling agent was 5 parts. After uniform mixing, granulation was performed by Φ20 twin-screw extrusion, and the twin-screw barrel temperature zones 1 to 5 were 160℃, 230℃, 250℃, 260℃, and 250℃, respectively, the head temperature was 250℃, and the screw speed was 60r / min. After drying, the melt flow rate of the pellets tested was 29.8g / 10min, and sheet extrusion was performed using a Φ45 single-screw extruder. The twin-screw barrel temperature zones 1 to 5 are 160°C, 230°C, 250°C, 260°C, and 250°C, the die head temperature is 250°C, and the screw speed is 60r / min; the single-screw barrel temperature zones 1 to 3 are 210°C, 250°C, and 260°C, the mold temperature zones 1 to 3 are 260°C, 240°C, and 225°C, and the screw speed is 15r / min. During extrusion, it was found that the material flow had a serious melt hammer phenomenon, and it was in a bean curd-like divergent state, and it was completely impossible to form.

[0055] Comparative Example 2

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

[0057] Comparative Example 3

[0058] PET with an intrinsic viscosity of 0.85 dL / g was selected as the matrix resin, with 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 MFR = 0.04 g / 10 min (test conditions: 230 °C, load 5 kg), 2 parts of compatibilizer, and 3 parts of coupling agent. After mixing evenly, it was pelletized by a Φ20 twin-screw extruder. The temperatures of the twin-screw barrel in zones 1 to 5 were 160 °C, 230 °C, 250 °C, 260 °C, and 250 °C respectively, the head temperature was 250 °C, and the screw speed was 60 r / min. After drying, the melt flow rate of the pellets was tested to be 2.95 g / 10 min, and a Φ45 single-screw extruder was used for sheet extrusion molding. The temperatures of the twin-screw barrel in zones 1 to 5 were 160 °C, 230 °C, 250 °C, 260 °C, and 250 °C respectively, the head temperature was 250 °C, and the screw speed was 60 r / min; the temperatures of the single-screw barrel in zones 1 to 3 were 210 °C, 250 °C, and 260 °C respectively, the temperatures of the die in zones 1 to 3 were 260 °C, 240 °C, and 225 °C respectively, and the screw speed was 15 r / min. Melt stretching could basically be achieved, but the extrusion process was unstable and sometimes fractures occurred. The test results of the sheet properties are shown in Table 1. The flexural modulus was 1.28 GPa, and the Vicat softening point was 128.5 °C. Compared with the pure material, the flexural modulus decreased by 30.0%; compared with Example 1, the flexural modulus decreased by 56.2%, and the Vicat softening point decreased by 39.6%.

[0059] Table 1 Test Results of PET Sheet Properties

[0060]

[0061]

[0062] From the examples, comparative examples, and Table 1, it can be seen that the present invention improves the melt strength and melt viscosity of the PET / inorganic filler system, and improves the extrusion molding characteristics of the high-fill system through chain extension reaction, adding low-flow high-density polyethylene and ultra-high molecular weight polyethylene, thereby realizing the continuous and stable extrusion molding of PET / inorganic filler composites with high filling content and obtaining excellent physical and mechanical properties. This is of great significance for replacing traditional PVC high-fill composites.

[0063] The above examples are only partial examples of the present invention, not all examples. Those skilled in the art can modify according to the above examples, and these examples are still covered by the claims of the present invention. Any replacement or modification according to the technical solution of the present invention should be covered within the protection scope 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 chain extender, 40-60 parts by weight of inorganic filler, 4-9 parts by weight of low-fluidity high-density polyethylene, 1-6 parts by weight of ultra-high molecular weight polyethylene, 1-5 parts by weight of compatibilizer and 1-6 parts by weight of coupling agent; except for the chain extender with a relatively low content, the total amount of all other components is 100 parts by weight.

2. The PET high-filling 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 a characteristic viscosity greater than 0.8dL / g, and the recycled material is preferably PET bottle recycled material.

3. The PET high-filling extruded composite material according to claim 1, characterized in that: The chain extender is selected from one of epoxy chain extenders, acid anhydride chain extenders and isocyanate chain extenders.

4. The PET high-filling extruded composite material according to claim 1, characterized in that: The inorganic filler is at least one of calcium carbonate and talcum powder, or a carrier-free particle including but not limited to calcium carbonate and talcum powder, or a masterbatch with a carrier content of less than 15%.

5. The PET high-filling extruded composite material according to claim 1, characterized in that: 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.

6. The PET high-filling 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 1-3 million; more preferably, the viscosity average molecular weight is 1-2 million; preferably, it is a powder.

7. The PET high-filling extruded composite material according to claim 1, characterized in that: The compatibilizer is selected from polyolefin elastomer grafted with glycidyl methacrylate (POE-g-GMA) or polyolefin elastomer grafted with maleic anhydride (POE-g-MAH).

8. 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.

9. The method for preparing a PET highly filled extruded composite material according to any one of claims 1 to 8, characterized in that: The following steps are involved: First, the dried PET and the 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 a PET high-filling extruded composite material product.

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

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