CN102617911A - Reclaimed high-density polyethylene/polypropylene composite material prepared through reaction extruding - Google Patents

Abstract

The present invention relates to a kind of HDPE/PP compound material that utilizes reclaimed material to prepare by reaction extrusion, prepares by the following method: first dry the reclaimed HDPE material (PP content 5～30%), according to reclaimed material: crosslinking agent: assistant Cross-linking agent=(97.5～99.85):(0.05～0.5):(0.1～2), add the ingredients into the high-speed mixer and mix them, then add them into the feeding port of the twin-screw extruder, and extrude at a speed of 120～300rpm , the extrusion temperature is 140-210°C, and the pellets are obtained by cutting with a pelletizer. In the present invention, by adding a co-crosslinking agent into the pipe system prepared by cross-linking recycled HDPE, the degradation reaction of PP in the presence of peroxide is suppressed, thereby reducing the melt index of the material and improving the compatibility between the two properties, obtaining a material suitable for pipe extrusion and improving the mechanical properties of the material.

Description

Recycled high-density polyethylene/polypropylene composites prepared by reactive extrusion

technical field

The invention relates to a HDPE/PP composite material prepared by using recycled materials through reaction extrusion, and belongs to the field of modification of recycled polymer composite materials.

Background technique

The recycling of HDPE products can solve the problem of white pollution to a certain extent and relieve the pressure of plastic waste on the environment. On the other hand, with the rapid development of urban construction, the demand for HDPE pipes is increasing rapidly, which also intensifies the consumption of petroleum resources. If the recycled HDPE can be used to produce pipes, on the one hand, it can turn "waste" into treasure and save costs, and on the other hand, it can greatly relieve the dual pressure on the environment and energy. The research on the preparation of pipe special materials by using recycled HDPE has been reported in the patent CN101805472A.

However, recycled HDPE often contains small amounts of PP. When peroxide crosslinking modification is carried out on recycled materials, PP molecular chains are prone to breakage, which increases the melt index of the system, which is not conducive to the extrusion of pipes. On the other hand, the introduction of PP tends to make the material brittle, which reduces the mechanical properties of the material, especially the impact strength and elongation at break. It has been reported in the literature that adding a co-crosslinking agent during the crosslinking process of PP can reduce its melt index and improve its mechanical properties. The present invention considers adding a cross-linking assistant in the process of cross-linking modification of recycled materials. On the one hand, the PP in the system can be cross-linked without degradation, reducing the melt index of the material; on the other hand, due to the cross-linking process Inhibiting the further degradation of PP, so that PP free radicals can combine with PE free radicals to form PE-g-PP graft copolymers, improve the compatibility of the two, and improve the mechanical properties of the blend, thereby obtaining Tube material that meets performance requirements.

Patent CN101863091A reports on the recovery of HDPE and PP packaging materials. In the report, the waste plastic packaging materials are recycled and re-granulated to realize the recycling of resources. Patent reports on PP crosslinking mainly focus on radiation crosslinking (CN1142514) and silane crosslinking (CN101158423), and materials with excellent mechanical properties and high temperature resistance are obtained through crosslinking. There is also a patent report (CN101805472A) utilizing reclaimed HDPE to carry out cross-linking modification to prepare pipe special materials. However, there is no report on how to overcome the influence of the presence of PP on the crosslinking reaction and final properties when the recycled HDPE containing PP is crosslinked and modified.

Contents of the invention

The purpose of the present invention is to solve the problem that the melting index rises and the performance declines due to the raw material containing PP in the process of reducing its melt index, improving its performance and widening its application range by using peroxide cross-linking modification to recycle HDPE. Adding a co-crosslinking agent in the crosslinking system can improve the melt index and mechanical properties of the system, so as to obtain materials with a wider range of applications.

The present invention is achieved through the following technical solutions.

A reclaimed high-density polyethylene/polypropylene composite material prepared by reactive extrusion, characterized in that the reclaimed high-density polyethylene/polypropylene composite material is prepared through the following steps:

(1) The recovered HDPE containing 5-30% PP is dried as reclaimed material, according to the following weight and number ratio, reclaimed material: cross-linking agent: co-cross-linking agent=(97.5-99.85): (0.05-0.5) : (0.1～2) carry out batching, then add batching into high-speed mixer and mix; The drying of recycled materials is selected to dry at 80 ℃ for 4h, and the high-speed mixing time is 10min;

(2) Add the homogeneously mixed material obtained in step (1) into the feeding port of the twin-screw extruder;

(3) Use a twin-screw extruder to extrude. The temperature of the extruder is set at 140-210° C., and the extrusion speed is 120-300 rpm. The obtained product is obtained by cooling in a water tank, drying with a blower, and cutting with a pelletizer. The required cross-linked HDPE/PP composite material;

Among them, HDPE: ρ = 0.94g/cm ³ , M _n = 21000, M _w = 228000; PP: ρ = 0.91g/cm ³ , M _n = 44000, M _w = 188000,

The crosslinking agent adopts one or more of peroxide, vinyl siloxane, allyl siloxane,

The auxiliary cross-linking agent adopts allyl type auxiliary cross-linking agent.

Preferably, the crosslinking agent is dicumyl peroxide or benzoyl peroxide.

Preferably, the auxiliary crosslinking agent is triallyl cyanurate or triallyl isocyanurate.

As a preference, the recycled HDPE is selected from recycled materials containing 5% PP.

Beneficial effect

The present invention overcomes the problems of increased melt index and decreased mechanical properties caused by PP in recycled materials by adding a crosslinking assistant to the system for preparing pipes by crosslinking HDPE recycled materials, thereby obtaining materials suitable for pipe extrusion, and The mechanical properties of the material are improved, and the "waste" is truly turned into treasure. While relieving the environmental pressure, it also reduces the pressure on petroleum energy.

The advantages of this patent will be illustrated by specific examples.

Detailed ways

Example 1:

Dispensing according to the following components: recycled material (from beverage bottle caps, wherein PP content is 5%): dicumyl peroxide (DCP): triallyl isocyanurate (TAIC) = 100: 0.25 : 0.5.

The recycled materials, DCP and TAIC were mixed with a high-speed mixer at a speed of 500 rpm for 10 minutes at room temperature, and then added to the feeding port of the twin-screw extruder for extrusion.

The mixture is extruded at a speed of 150rpm. The temperature settings of each section of the extruder are: the first section is 140°C, the second section is 160°C, the third section is 170°C, the fourth section is 180°C, and the fifth section is 200°C. The sixth section is 210°C, the seventh section is 210°C, and the machine head is 200°C.

In this example, the performance comparison of materials before and after adding auxiliary crosslinking agent is shown in Table 1.

Table 1

performance Does not contain co-crosslinking agent system Add auxiliary crosslinking agent system Elongation at break (%) 464±10 890±15 Tensile strength (MPa) 20±0.5 23.5±0.7 Notched impact strength (KJ/m ² ) 25±0.5 38±0.8 Bending strength (MPa) 18±0.4 23.7±0.5 Flexural modulus (MPa) 400±9.8 500±12.1 Density(g/m ³ ) 0.95 0.96 Melt index (g/10min) 1.3 0.7

Embodiment two:

Dispensing according to the following components: recycled material (from beverage bottle caps, wherein PP content is 5%): DCP: TAIC = 100: 0.25: 1.

The recycled materials, DCP and TAIC were mixed with a high-speed mixer at a speed of 500 rpm for 10 minutes at room temperature, and then added to the feeding port of the twin-screw extruder for extrusion.

The mixture is extruded at a speed of 150rpm. The temperature settings of each section of the extruder are: the first section is 140°C, the second section is 160°C, the third section is 170°C, the fourth section is 180°C, and the fifth section is 200°C. The sixth section is 210°C, the seventh section is 210°C, and the machine head is 200°C.

In this example, the performance comparison of the materials before and after adding auxiliary crosslinking agent is shown in Table 2.

Table 2

performance Does not contain co-crosslinking agent system Add auxiliary crosslinking agent system Elongation at break (%) 464±10 1068±15 Tensile strength (MPa) 20±0.5 24±0.7 Notched impact strength (KJ/m ² ) 25±0.5 42±1.2 Bending strength (MPa) 18±0.4 25±0.6 Flexural modulus (MPa) 400±9.8 600±11.2 Density(g/m ³ ) 0.95 0.97 Melt index (g/10min) 1.3 0.5

Embodiment three:

Dosing according to the following components: recycled material (from beverage bottle caps, wherein the PP content is 5%): benzoyl peroxide (BPO): TAIC = 100: 0.: 25: 0.5.

The recycled material, BPO and TAIC were mixed with a high-speed mixer at a speed of 500 rpm for 10 minutes at room temperature, and then added to the feeding port of the twin-screw extruder for extrusion.

The mixture is extruded at a speed of 150rpm. The temperature settings of each section of the extruder are: the first section is 140°C, the second section is 160°C, the third section is 170°C, the fourth section is 180°C, and the fifth section is 200°C. The sixth section is 210°C, the seventh section is 210°C, and the machine head is 200°C.

In this example, the performance comparison of materials before and after adding auxiliary crosslinking agent is shown in Table 3.

table 3

performance Does not contain co-crosslinking agent system Add auxiliary crosslinking agent system

Elongation at break (%) 500±11 1000±12.5 Tensile strength (MPa) 21.2±0.5 24.5±0.6 Notched impact strength (KJ/m ² ) 27±0.6 40±0.9 Bending strength (MPa) 19±0.4 24±0.5 Flexural modulus (MPa) 450±10 550±11.3 Density(g/m ³ ) 0.96 0.97 Melt index (g/10min) 1.0 0.62

Embodiment four:

The ingredients are distributed according to the following components: recycled material (from beverage bottle caps, wherein the PP content is 10%): DCP: triallyl cyanurate (TAC) = 100: 0.25: 0.5.

The recycled materials, DCP and TAC were mixed with a high-speed mixer at a speed of 500 rpm for 10 minutes at room temperature, and then added to the feeding port of the twin-screw extruder for extrusion.

The mixture is extruded at a speed of 150rpm. The temperature settings of each section of the extruder are: the first section is 140°C, the second section is 160°C, the third section is 170°C, the fourth section is 180°C, and the fifth section is 200°C. The sixth section is 210°C, the seventh section is 210°C, and the machine head is 200°C.

In this example, the performance comparison of materials before and after adding auxiliary crosslinking agent is shown in Table 4.

Table 4

performance Does not contain co-crosslinking agent system Add auxiliary crosslinking agent system Elongation at break (%) 442±10 910±12 Tensile strength (MPa) 18±0.5 23.7±0.6 Notched impact strength (KJ/m ² ) 23±0.5 41±0.9 Bending strength (MPa) 16±0.4 24.3±0.5 Flexural modulus (MPa) 380±9.6 610±10.2

Density(g/m ³ ) 0.95 0.97 Melt index (g/10min) 1.4 0.6

It can be seen from the above examples that adding a cross-linking agent to the system of peroxide modified recycled bottle cap materials not only reduces the melt index of the system, but also facilitates the extrusion processing of pipe materials, and improves the quality of the material. The mechanical properties of the material, especially the toughness of the material are greatly improved, so that the material with excellent performance can be obtained.

Claims (4)

1. the recovery high density polyethylene(HDPE)/PP composite material of preparation is extruded in a reaction, it is characterized in that described recovery high density polyethylene(HDPE)/PP composite material prepares through following steps:

5～30% polyacrylic high density polyethylene(HDPE)s that contain that (1) will reclaim carry out drying as reclaimed materials; By following ratio of weight and number; Reclaimed materials: linking agent: additional crosslinker=(97.5～99.85): (0.05～0.5): prepare burden (0.1～2), and the adding high-speed mixer of will preparing burden then mixes; The drying of reclaimed materials is selected 80 ℃ of dry 4h down, and the mixed at high speed time is 10min;

(2) material that mixes that step (1) is obtained adds in the charging opening of twin screw extruder;

(3) utilize twin screw extruder to extrude; The temperature of forcing machine is set to 140～210 ℃; Extruded velocity is 120～300rpm, successively through tank cooling, hair dryer dry up, the dicing machine cutting obtains required crosslinked high density polyethylene(HDPE)/PP composite material;

Wherein, high density polyethylene(HDPE): ρ=0.94g/cm ³, M _n=21000, M _w=228000; Vestolen PP 7052: ρ=0.91g/cm ³, M _n=44000, M _w=188000,

Said linking agent is to be selected from superoxide, vinylsiloxane, the allyl group silica one or more,

Described additional crosslinker is the allylic additional crosslinker.

2. the recovery high density polyethylene(HDPE)/PP composite material of preparation is extruded in reaction as claimed in claim 1, it is characterized in that, described linking agent adopts Di Cumyl Peroxide 99 or Lucidol.

3. the recovery high density polyethylene(HDPE)/PP composite material of preparation is extruded in reaction as claimed in claim 1, it is characterized in that, described additional crosslinker adopts triallyl cyanurate or iso-cyanuric acid triallyl ester.

4. the recovery high density polyethylene(HDPE)/PP composite material of preparation is extruded in reaction as claimed in claim 1, it is characterized in that, described reclaimed materials is for containing 5% polyacrylic high density polyethylene(HDPE) reclaimed materials.