CN107814996A - A kind of preparation method of crosslinkable polyethylene modified materials - Google Patents

Abstract

The invention relates to the field of crosslinkable polyethylene preparation, and discloses a preparation method of a crosslinkable polyethylene modified material. Including: (1) mixing the mixture containing polyethylene a, cross-linking agent, cross-linking auxiliary agent, antioxidant, lubricant and cross-linking stabilizer to make a cross-linkable polyethylene masterbatch; The total amount of the crosslinkable polyethylene masterbatch is based on the total content of the crosslinking agent and the crosslinking auxiliary agent is 12 to 27% by weight; (2) the crosslinkable polyethylene masterbatch, polyethylene b and the toughening component are respectively added into a twin-screw extruder for melt blending to obtain a crosslinkable polyethylene modified material; based on the total amount of the crosslinkable polyethylene modified material, the crosslinked The total content of additives and crosslinking assistants is 0.008-0.05% by weight. No cross-linking reaction occurs in the preparation process, and the obtained cross-linkable polyethylene modified material does not contain any gel.

Description

A kind of preparation method of crosslinkable polyethylene modified material

technical field

The invention relates to the field of preparation of crosslinkable polyethylene, in particular to a preparation method of a crosslinkable polyethylene modified material.

Background technique

Cross-linkable polyethylene modified material is a composition usually containing polyethylene, cross-linking agent and auxiliary agent, antioxidant, lubricant, etc., which can be further processed and applied in the fields of sheet extrusion, foaming, rotational molding, etc. , thus receiving more and more attention. However, in the process of preparing the crosslinkable polyethylene modified material through mixing the above composition, due to the crosslinking agent and crosslinking aid contained in the composition, under the action of heat, shear and pressure, Cross-linking occurs easily in the composition, resulting in gel in the obtained modified material, which affects subsequent processing and use. Therefore, in industrial production, how to ensure that the composition is uniformly mixed in the process of extruding and kneading into a cross-linkable polyethylene modified material, but does not cause cross-linking in advance, and the obtained cross-linkable polyethylene modified The material does not contain gel and does not affect the subsequent processing operations, which is an urgent research and solution issue.

CN203919665U A kind of screw combination that is used to produce high-performance polypropylene filling composite material, comprises two mutually engaged screw rods of identical structure, and described two screw rods are to rotate in the same direction, and each described screw rod comprises spline shaft, fixed sleeve A threaded element and a kneading element arranged on the spline shaft, the threaded element includes a plurality of forward threaded blocks and a plurality of reverse threaded blocks distributed along the length direction of the splined shaft, the engaging element includes Seriously, multiple forward kneading blocks and multiple reverse kneading blocks distributed along the length direction of the Sohu spline shaft are characterized in that the forward threaded blocks include 56/56, 72/72, 96/96, 56/ 56A, 112/56SK, 112/112SK, the reverse thread block includes 56/28L, the forward kneading block includes K60°/5/56, K45°/5/56, K60°/4/56 , K30°/7/72, ZME16/32, the reverse kneading block includes K45°/5/36L, the threaded element and the kneading element on the spline shaft are arranged in sequence in the following order: 56 /56A, 112/56SK, 112/112SK, 112/56SK, 96/96, 72/72, 56/56, K30°/7/72, K45°/5/56, K60°/4/56, 56/ 56, 56/56, K90°/5/56, K45°/5/36L, 96/96, 96/96, 72/72, 56/56, 96/96, 96/96, 72/72, 56/ 56, 56/56, K45°/5/56, K60°/4/56, K90°/5/56, 56/56, 56/56, ZME16/32, ZME16/32, 56/56, 56/56 , K45°/5/56, K45°/5/56, K45°/5/56, K45°/5/36L, 56/56, 56/56, K45°/5/56, K45°/5/56 , K90°/5/56, 56/28L, 96/96, 96/96, 96/96, 72/72, 72/72, 56/56, 56/56, 56/56. The utility model discloses the combination of ZME special kneading block and other kneading blocks to improve the distribution and dispersion effect of composite materials in polypropylene, so that the final product can maintain good impact toughness and have excellent tensile strength. Mechanical properties such as strength and flexural strength, and can increase the output of composite materials and save energy. The invention mainly improves dispersion through serrated meshing blocks, belongs to strong shear combination, and is not suitable for processing and mixing of cross-linkable polyethylene modified materials.

CN102529062B discloses a screw assembly for extruding nylon without drying the nylon, including an extruder, which is characterized in that the extruder has two screw (1) combinations with the same structure, the screw ( 1) It includes a spline shaft (2) with a spline, a threaded element (3) and a kneading element (4), the inner holes of the threaded element (3) and the kneading element (4) have a The spline grooves (5) corresponding to the splines on the top are fixed by multiple different forward and reverse threaded elements (3) and multiple different forward and reverse kneading elements (4); the rotation of the two screws (1) The same, when transferring, the two screws (1) have a phase difference of 90°; each screw is: (A) solid conveying section, (B) melting section, (C) mixing section, (D) exhaust section And (E) the homogenization section has a total of 5 sections. The invention provides an energy-saving and low-cost screw combination for extruding and processing nylon without drying the nylon (polyamide PA) without drying treatment before processing. However, it is mainly designed for the combination of water-absorbing materials. This screw combination can fully volatilize the water in nylon (polyamide PA) and keep the mechanical properties of nylon stable. But it is not suitable for the processing and mixing of cross-linkable polyethylene modified materials.

CN105291402A discloses a screw combination for processing nano-powder master batches, including a twin-screw extruder, and a barrel arranged on the twin-screw extruder; two parallel screws (6 ), each screw rod (6) is equipped with a plurality of screw parts of different specifications; the screw rods (6) are symmetrically arranged in the machine barrel, and the direction of rotation is the same, and one end of the screw rod (6) is connected to the screw rod bearing (7), And the screw rod (6) is driven to rotate by the screw rod bearing (7); it is characterized in that: the screw rod (6) includes a splined shaft (6-1) with a spline, a threaded element (6-2) and a kneading Element (6-3); the inner hole of the threaded element (6-2) and the kneading element (6-3) has a spline groove (6-4) corresponding to the spline on the spline shaft (6-1) ; A plurality of different forward and reverse screw elements (6-2) and a plurality of different forward and reverse kneading elements (6-3) are arranged on the spline shaft (6-1) in sequence, and the spline shaft ( The two ends of 6-1) fix the arranged threaded elements (6-2) and kneading elements (6-3), and one end of the screw (6) is provided with a spline groove (6-4) notch matching Screw head (6-5), the other end of screw rod (6) is fixedly connected by screw bearing (7); The outer diameter of this screw head (6-5) is less than the outer diameter of this screw rod (6). But it is not suitable for the processing and mixing of cross-linkable polyethylene modified materials.

CN104448461A discloses a preparation method of cross-linkable polyethylene, which includes (a) adding an antioxidant into a screw extruder by means of gravity metering feeding under purified conditions, and plasticizing after contacting with low-density polyethylene. granulation, filtration, and then granulation by underwater granulation to obtain polyethylene clean granules; (b) transporting the polyethylene clean granules to a height where the subsequent steps can be fed by gravity by means of water particle transport dehydrated and dried; (c) under the action of self-weight, preheat the dehydrated and dried polyethylene clean particles; (d) under purification conditions, use the gravity metering feeding method to mix the crosslinking agent with the preheated polyethylene Clean particles are mixed and infiltrated.

Contents of the invention

The purpose of the present invention is to overcome the defect that crosslinking structure is contained in the obtained crosslinkable polyethylene material caused by premature initiation of crosslinking reaction when preparing crosslinkable polyethylene material in the prior art, and to provide a crosslinkable polyethylene material. The preparation method of polyethylene modified material.

In order to achieve the above object, the present invention provides a preparation method of cross-linkable polyethylene modified material, including: (1) will contain polyethylene a, cross-linking agent, cross-linking auxiliary agent, antioxidant, lubricant and cross-linking The mixed material of linking stabilizer is mixed, and crosslinkable polyethylene masterbatch is made; Based on the total amount of said crosslinkable polyethylene masterbatch, the total content of said crosslinking agent and crosslinking auxiliary agent is 12 to 27% by weight; (2) adding the cross-linkable polyethylene masterbatch, polyethylene b and toughening components into a twin-screw extruder respectively for melt blending to obtain a cross-linkable polyethylene modified material ; Based on the total amount of the cross-linkable polyethylene modified material, the total content of the cross-linking agent and cross-linking assistant is 0.8-3% by weight.

Through the above-mentioned technical scheme, through step-by-step preparation, the cross-linkable polyethylene masterbatch containing cross-linking agent and various auxiliary agents is firstly prepared, wherein the content of cross-linking agent and cross-linking auxiliary agent is high; Ethylene masterbatch is extruded with a large amount of polyethylene and toughening components for melt blending, reducing the content of crosslinking agents and crosslinking aids, which is more conducive to the uniform dispersion of various additives, and the melt blending process is It is carried out under the condition of cross-linking reaction, so as to effectively overcome the cross-linking structure in the obtained cross-linkable polyethylene modified material.

Further, in the twin-screw extruder for extrusion melt blending, the screw used has a specific screw combination, especially in the melting section of the screw, a specially set arrangement and combination of screw elements and kneading elements is adopted, The frictional heat of cross-linkable polyethylene masterbatch, polyethylene b, and toughening components in the extrusion process can be reduced, and the obtained cross-linkable polyethylene modified material does not contain any gel.

Other features and advantages of the present invention will be described in detail in the detailed description that follows.

Description of drawings

The accompanying drawings are used to provide a further understanding of the present invention, and constitute a part of the description, together with the following specific embodiments, are used to explain the present invention, but do not constitute a limitation to the present invention. In the attached picture:

Fig. 1 is the overall structural representation of screw rod;

Fig. 2 is the structural representation of screw element;

Fig. 3 is a structural schematic diagram of a kneading element.

Explanation of reference signs

1. Screw 2. Spline shaft 3. Thread element 4. Kneading element

5. Spline groove A, solid conveying section B, melting section C, mixing section

D. Exhaust section E. Homogenization section

Detailed ways

Specific embodiments of the present invention will be described in detail below. It should be understood that the specific embodiments described here are only used to illustrate and explain the present invention, and are not intended to limit the present invention.

Neither the endpoints nor any values of the ranges disclosed herein are limited to such precise ranges or values, and these ranges or values are understood to include values approaching these ranges or values. For numerical ranges, between the endpoints of each range, between the endpoints of each range and individual point values, and between individual point values can be combined with each other to obtain one or more new numerical ranges, these values Ranges should be considered as specifically disclosed herein.

The invention provides a preparation method of a crosslinkable polyethylene modified material, comprising: (1) mixing a compound containing polyethylene a, a crosslinking agent, a crosslinking auxiliary agent, an antioxidant, a lubricant and a crosslinking stabilizer mixing materials to make a cross-linkable polyethylene master batch; based on the total amount of the cross-linkable polyethylene master batch, the total content of the cross-linking agent and cross-linking auxiliary agent is 12 to 27% by weight (2) adding the cross-linkable polyethylene masterbatch, polyethylene b and toughening components into a twin-screw extruder respectively for melt blending to obtain a cross-linkable polyethylene modified material; Based on the total amount of the crosslinked polyethylene modified material, the total content of the crosslinking agent and the crosslinking assistant is 0.8-3% by weight.

In the preparation method provided by the invention, step (1) is used to obtain a crosslinkable polyethylene masterbatch containing various auxiliary agents such as crosslinking agents, and the content of various auxiliary agents in the crosslinkable polyethylene masterbatch The concentration is higher. The kneading temperature for preparing the cross-linkable polyethylene masterbatch is lower than the temperature at which the cross-linking agent and the cross-linking auxiliary agent undergo a cross-linking reaction, but it only needs to be able to melt the polyethylene a. Preferably, step (1) can first fully mix polyethylene a, cross-linking agent, cross-linking auxiliary agent, antioxidant, lubricant and cross-linking stabilizer in a high-speed mixer until the mixture is uniform, such as 3-5 minutes; then pass the mixture through a twin-screw extruder to realize the mixing, extrude and granulate to obtain a cross-linkable polyethylene masterbatch. Wherein, the temperature of each temperature section of the twin-screw extruder can preferably be set at 130-145° C., and the rotation speed of the screw can be 60-350 rpm. A conventional twin-screw extruder can be used, for example, the diameter of the screw is 36-96 mm, and the aspect ratio (ratio of screw length to diameter) is (36-48):1. In the process of extruding granulation to achieve mixing, the temperature of the twin-screw extruder does not suddenly increase or the current of the extruder does not increase suddenly, which can indicate that no crosslinking reaction occurs during the extrusion granulation process.

According to the present invention, preferably, in step (1), the polyethylene a is selected from high-density polyethylene and/or low-density polyethylene.

Preferably, the high-density polyethylene has a density of 0.94-0.965 g/cm ³ and a melt index (MI) of 1-20 g/10 min at 190°C under a load of 2.16 kg. The high-density polyethylene is a known material, and commercially available is 8007 (HDPE, melt index: 8.2 g/10 min, density: 0.963 g/cm ³ ) from Shenhua Baotou Coal-to-oil Co., Ltd.

Preferably, the low-density polyethylene has a density of 0.91-0.935 g/cm ³ and a melt index of 1-20 g/10 min at 190°C under a load of 2.16 kg. The low-density polyethylene is a known substance, and 2426H (LDPE, melt index 2.1 g/10 min, density 0.924 g/cm ³ ) is commercially available from Shenhua Baotou Coal-to-oil Co., Ltd.

According to the present invention, the cross-linkable polyethylene masterbatch with relatively high concentration of the sum of the cross-linking agent and cross-linking auxiliary agent can be obtained by feeding each component in step (1). Preferably, in step (1), relative to 100 parts by weight of the polyethylene a, the cross-linking agent is 20-25 parts by weight, the cross-linking auxiliary agent is 5-10 parts by weight, and the anti- The oxygen agent is 2-15 parts by weight, the lubricant is 5-15 parts by weight, and the cross-linking stabilizer is 1-5 parts by weight.

In the present invention, the crosslinking agent can be selected from dicumyl peroxide, benzoyl peroxide, dicumyl hydroperoxide, tert-butyl hydroperoxide, 2,5-dimethyl-2, 5-di-tert-butylperoxyhexane, 2,5-dimethyl-2,5-di-tert-butylperoxyhex-3-yne, diacyl peroxide, di-tert-butyl peroxide, alkanes at least one of hydroperoxide, dilauroyl peroxide, methyl ethyl ketone peroxide and cyclohexanone peroxide.

In the present invention, the crosslinking aid can be selected from poly-1,2-butadiene, diallyl terephthalate (DATP), divinylbenzene (DVB), triallyl cyanurate (TAC), triallyl cyanurate (TAP) and triallyl isocyanate (TAIC). Among them, the weight-average molecular weight of poly-1,2-butadiene is 7,000-90,000.

In the present invention, the antioxidant can be a conventional choice, preferably antioxidant 1010 and/or antioxidant 168. The antioxidant is a known substance, commercially available from Sinopharm Chemical Reagent Co., Ltd.

In the present invention, the lubricant may be a conventional choice, preferably polyethylene wax, for example, commercially available from Honeywell.

In the present invention, the crosslinking stabilizer is a free radical inhibitor, preferably a phenolic, quinone or aromatic hydrocarbon nitro compound polymerization inhibitor, more preferably selected from tri(2,2,6,6-tetramethylphosphite) At least one of 2,2-bis(4-tert-octylphenyl)-1-picrylhydrazine and nitroxide free radical piperidinol.

In the preparation method provided by the present invention, step (2) is used to dilute the crosslinkable polyethylene masterbatch, so that the concentration of various auxiliary agents contained therein, especially the concentration of crosslinking agent and crosslinking auxiliary agent, can be The obtained cross-linkable polyethylene modified material meets the composition requirements and can be suitable for use in further processing.

In the step (2) of the present invention, the cross-linkable polyethylene masterbatch, polyethylene b, and toughening components are preferably fed into the twin-screw extruder from different feeding ports at the same time. And the crosslinkable polyethylene masterbatch, polyethylene b and toughening component are fed according to a certain ratio, preferably, in step (2), relative to the described crosslinkable polyethylene masterbatch of 100 parts by weight, The polyethylene b is 500-1000 parts by weight, and the toughening component is 35-400 parts by weight. That is, the weight ratio of the polyethylene b: the toughening component: cross-linkable polyethylene masterbatch may be (5-10): (0.35-4):1.

According to the present invention, step (2) can be used to dilute the concentration of various auxiliary agents in the cross-linkable polyethylene masterbatch, especially cross-linking agent and cross-linking auxiliary agent, and the polyethylene b can be combined with the poly Ethylene a is selected from the same polyethylene, and polyethylene b and polyethylene a may be selected from different polyethylenes as required. Preferably, the polyethylene b is selected from high-density polyethylene and/or low-density polyethylene; preferably, the density of the high-density polyethylene is 0.94-0.965g/cm ³ , and the temperature at 190°C under a load of 2.16kg The melt index is 1-20g/10min; the density of the low-density polyethylene is 0.91-0.935g/cm ³ , and the melt index at 190°C under a load of 2.16kg is 1-20g/10min. The high-density polyethylene is a known material, and commercially available is 8007 (HDPE, melt index: 8.2 g/10 min, density: 0.963 g/cm ³ ) from Shenhua Baotou Coal-to-oil Co., Ltd. The known low-density polyethylene can be purchased commercially from Shenhua Baotou Coal Oil Co., Ltd. 2426H (LDPE, melt index 2.1g/10min, density 0.924g/cm ³ ).

According to the present invention, the toughening component can play a role in improving the toughness of the material, preferably, the toughening component is selected from linear low density polyethylene, ethylene-octene copolymer and ethylene-propylene-diene rubber at least one of .

Preferably, the linear low density polyethylene has a density of 0.91-0.935 g/cm ³ and a melt index of 1-20 g/10 min at 190°C under a load of 2.16 kg. The linear low-density polyethylene is a known substance, and 7042 (LLDPE, melt index 2g/10min, density 0.92g/cm ³ ) of Shenhua Baotou Coal Oil Co., Ltd., 8320 (LLDPE, melt index ) of Daqing Petrochemical Company can be purchased commercially. The body index is 20g/10min, and the density is 0.926g/cm ³ ).

Preferably, in the ethylene-octene copolymer, the content of the octenyl structure may be 20-30% by weight, and the number-average molecular weight of the ethylene-octene copolymer (POE) may be 7000-20000, and the melt The index is 2-7g/10min, and the density is 0.75-0.95g/cm ³ . The ethylene-octene copolymer is a known substance, and POE8200 from Dow Chemical Company is commercially available.

Preferably, the EPDM rubber is a terpolymer of ethylene, propylene and a non-conjugated diene, wherein the non-conjugated diene can be ethylidene norbornene (ENB) or dicyclopentadiene (DCPD) . The ratio of ethylene to propylene in the EPDM rubber is 80:20 to 50:50, and the ENB content is 0.5 to 10% by weight. The Mooney viscosity (125°C) of the EPDM rubber is 20-100. The EPDM rubber is a known material, and it is commercially available as a product of Dow Chemical Company.

In the preparation method provided by the present invention, further, the twin-screw extruder used in step (2) preferably has a specially designed screw combination, so that the crosslinkable polyethylene masterbatch, polyethylene b, toughening group During the melt blending process carried out in the twin-screw extruder, the screw meshing and shearing effect received is stable and uniform, and the frictional heat generated is less, so that the uniform melt blending of the materials can be completed without crosslinking agent and crosslinking agent. The auxiliary agent has a cross-linking reaction.

According to the present invention, preferably, in step (2), as shown in Figure 1, the screw combination in the twin-screw extruder includes two mutually meshing screws 1 with the same structure; the screw 1 includes a spline shaft 2 , threaded element 3 and kneading element 4; a plurality of different forward and reverse screw threaded elements 3 and multiple different forward and reverse rotated kneading elements 4 are set on the spline shaft 2 through the spline grooves 5 provided in the respective inner holes .

According to the invention, as shown in FIG. 2 , the threaded element 3 has an internal bore with a spline groove 5 . Preferably, the lead of the threaded element 3 is 44-96 mm, and the length of the threaded element 3 is 44-96 mm. In the present invention, X/Y can be used to indicate that the threaded element is a forward threaded element, X/YL indicates that the threaded element is a reversed threaded element, and X/YA indicates the initial threaded element; where X indicates the lead of the threaded element, and Y indicates The length of the threaded element.

According to the present invention, as shown in FIG. 3, the kneading element 4 has an inner hole with a spline groove 5, and the kneading element 4 can be composed of a plurality of kneading blocks. Multiple kneading blocks are arranged in dislocation. The external shape of the section of the vertical inner hole of the kneading block is approximately elliptical. Preferably, the dislocation angle of the kneading element 4 is 30-60°, the length of the kneading element 4 is 44-56 mm, and the number of kneading blocks of the kneading element 4 is 4-6. In the present invention, the forward kneading element can be represented by θ/n/m, and the reverse kneading element can be represented by θ/n/mL; wherein, θ represents the dislocation angle of the kneading element, n represents the number of kneading blocks, and m represents the entire The length of the kneading element.

According to the present invention, preferably, each screw 1 includes a solid conveying section A, a melting section B, a mixing section C, an exhaust section D and a homogenizing section E, which are sequentially divided from the driving end of the screw 1 toward the end.

In the present invention, the solid conveying section A is used for conveying materials from the feeding port (such as cross-linkable polyethylene masterbatch, polyethylene b, toughening components) and preventing overflow. In the solid conveying section, it is required that this section has a larger material holding space to adapt to the adjustment of the feeding amount and prevent the material from accumulating at the feeding port to generate overflow. In addition to the conveying function, the solid conveying section can also compact the loose powdery material or increase the filling degree of the granular material in the screw, so as to promote the melting and plasticizing of the material in the next section. Therefore, the volume of the groove of the threaded element 3 in this section changes from large to small along the driving end of the screw 1 to the end, and the thread lead of the threaded element 3 gradually changes from large to small. Preferably, the solid conveying section in the present invention adopts a medium screw groove, a large lead, and a forward thread. For example, in a preferred embodiment, the arrangement of the plurality of threaded elements 3 forming the solid conveying section is 56/56A, 96/96, 96/96, 72/72, 72/72 from the driving end to the end of the screw 1. , 56/56, 44/44.

In the present invention, the melting section B is used for fully melting and homogenizing the materials through heat transfer and frictional shearing. In this section, the material begins to melt and mix after undergoing certain compression through the solid conveying section A. There are two sources of heat to melt the material, one is the external heating provided by the barrel heating, and the other is the shear heat of the screw. The shear heat of the screw is generated by the high shear generated by the elements of this section. Preferably, said melting section B contains at least two sets of intermeshing sections, each section of intermeshing section contains at least 2 kneading elements 4; said intermeshing sections contain at least one threaded element 3; said melting section contains at least one anti-rotating Threaded element 3. The plastic particles can be melt-plasticized by means of the high shear of the kneading element 4 and the back-flow compression of the counter-rotating screw element 3 .

According to the present invention, preferably, the melting section contains at least two groups of meshing sections, each section of meshing section contains at least one kneading element 4; at least one screw element 3 is contained between the meshing sections; the melting section contains at least One reverse threaded element or one reverse kneading element.

Preferably, when the intermeshing section contained in the melting section contains reverse kneading elements, the number of immediately adjacent forward kneading elements is no more than one, which can provide a more suitable blending effect and prevent crosslinking.

Preferably, when the intermeshing section contained in the melting section does not contain reverse kneading elements, the number of forward kneading elements is not less than 2, which can provide a more suitable blending effect and prevent crosslinking.

In the present invention, a preferred embodiment of forming the melting section may be that the arrangement of a plurality of screw elements 3 and kneading elements 4 forming the melting section is 45 degrees from the solid conveying section A to the end of the screw 1. °/5/56, 45°/5/56, 45°/56/56, 44/44, 45°/5/56, 60°/4/56, 56/56, 44/44, 60°/4 /44, 45°/5/56L.

In the present invention, the mixing section C has a distributive and dispersive mixing function, so that the molten material is further refined and uniform. The material is in a molten state after passing through the melting section. The mixing of the components in the material starts from melting. micron scale. Since the particles in the material coming out of the melting section have basically been melted and plasticized, the particles entering the mixing section are mainly dispersed. In the kneading section, kneading elements 4 and screw elements 3 are arranged alternately to form a medium shear kneading zone to avoid shear overheating. For example, in a preferred embodiment, the arrangement of the plurality of screw elements 3 and kneading elements 4 forming the kneading section C is 56/56, 44/44, 44/44 from the melting section B to the end of the screw 1 , 44/44, 45°/5/44, 45°/5/44, 45°/5/44, 56/56, 56/56, 44/44, 44/44, 45°/5/44, 45 °/5/56, 56/56.

In the present invention, the exhaust section D is used to exhaust impurities such as water vapor and low molecular weight substances. In the exhaust section, the flow characteristic of the material is that the material in a completely molten state is suddenly decompressed after being compressed, and the volatile material is quickly volatilized under vacuum conditions and separates from the melt. Preferably, the exhaust section can use a threaded element 3 with a medium lead to form a low fullness and a thin melt zone, so that the material has an exposed free surface to facilitate gas discharge. For example, in a preferred embodiment, the arrangement of the plurality of threaded elements 3 constituting the exhaust section D is 56/56, 44/44, 44/44 from the mixing section C to the end of the screw 1 in sequence.

In the present invention, the homogenizing section E is used for conveying and pressurizing to establish a certain pressure so that the material at the die opening set at the outlet of the twin-screw extruder has a certain density and is convenient for material discharge. At the same time, the homogenizing section E further mixes the materials, and finally achieves the purpose of smooth extrusion and granulation. Preferably, the homogenizing section can achieve pressurization through the gradual change of the lead or the gradual change of the screw groove of the threaded element 3 . For example, in a preferred embodiment, the arrangement of the plurality of threaded elements 3 and kneading elements 4 that make up the homogenizing section E is 45°/5/44, 60°/ 4/44, 64/64, 64/64, 44/44, 44/44.

According to the present invention, preferably, the direction of rotation of the two screws 1 is the same; when rotating, the phases of the two screws 1 differ by a phase angle of 90°.

According to the present invention, preferably, the diameter of the screw 1 is 36-96 mm, and the aspect ratio is (36-48):1. In a preferred embodiment, the diameter of the screw 1 is 65 mm, and the aspect ratio is 36:1.

In the present invention, two screws 1 are placed in the barrel of the twin-screw extruder. A heating zone is covered outside the barrel. From the driving end of the screw 1 to the end, the heating zones are equidistantly arranged from the first heating zone to the ninth heating zone, as shown in FIG. 1 .

In the present invention, to realize the melt blending in step (2), the temperature of the heating zone of the twin-screw extruder can be set at 140-145°C. A preferred embodiment, according to the temperature setting of the heating zone from the first heating zone to the ninth heating zone is 140°C, 140°C, 145°C, 145°C, 145°C, 145°C, 145°C, 145°C, 145°C. The rotation speed of the screw 1 may be 100-300 rpm, preferably 200 rpm in one embodiment.

In the present invention, when the melt blending of step (2) is carried out, the melt temperature of the extrudate will be higher than the set temperature of the above-mentioned heating zone, but the method of using crosslinkable polyethylene masterbatch provided by the present invention is still It can be ensured that no cross-linked structure is formed in the finally obtained cross-linkable polyethylene modified material.

The preparation method provided by the present invention may also include cutting the molten melt extruded by the twin-screw extruder in step (2) through an underwater pelletizer, and then drying at 80-100°C for 2-4 hours to form a cross-linkable polymer. Vinyl modifiers.

In the present invention, when performing the melt blending of step (2), the shape of the extruded product extruded by the extruder and the gel content of the final crosslinkable polyethylene modified material can be observed to evaluate the present invention. The effect of the invented method. Wherein, the gel content of the cross-linkable polyethylene modified material can be measured by measuring the content of xylene insolubles to determine whether a cross-linked structure is formed in the cross-linkable polyethylene modified material. Preferably, the crosslinkable polyethylene modified material has a gel content of 0% by weight.

In the present invention, when performing the melt blending in step (2), the current of the extruder can reflect the screw torque during the extrusion process, reflect whether the extrusion is difficult, and be proportional to the viscosity of the extrudate. When the current of the extruder is high, it can reflect that the viscosity of the extruded product is high, and the torque of the extruder screw is large, indicating that the extrusion of the material in the extruder needs to consume more energy. Compared with the current of the extruder under the same conditions Small materials are more difficult to process.

The present invention will be described in detail below by way of examples.

In the following examples, the gel content of the crosslinkable polyethylene modified material is measured by the method of measuring the content of xylene insoluble matter;

Materials in the following examples and comparative examples,

HDPE (DMDA 8007, melt index 8.3g/10min, density 0.963g/cm ³ ), Shenhua Baotou Coal Oil Co., Ltd.;

LLDPE (DMDA 7042, melt index 2g/10min, density 0.92g/cm ³ ), Shenhua Baotou Coal Oil Co., Ltd.;

LLDPE (8320, melt index 20g/10min, density 0.926g/cm ³ ), Daqing Petrochemical Company;

POE (8200, melt index is 5g/10min, density is 0.87g/cm ³ ), Dow Chemical Company;

The cross-linking agent is di-tert-butyl peroxide, J&K Scientific;

The cross-linking aid is triallyl isocyanurate (TAIC) (technical grade), J&K Scientific;

The cross-linking stabilizer is tris(2,2,6,6-tetramethylpiperidinyl nitroxide) phosphite, J&K Scientific;

Antioxidant 1010, Antioxidant 168: Sinopharm Chemical Reagent Co., Ltd.;

Polyethylene wax (A-C316A), Honeywell.

Example 1

(1) 50kg of high-density polyethylene powder (DMDA8007), 11.25kg of di-tert-butyl peroxide, 3.75kg of triallyl isocyanurate, 3kg of antioxidant 1010, and 3kg of antioxidant 168, 2kg of polyethylene wax (A-C316A), 2.5kg of tris(2,2,6,6-tetramethylpiperidinyl nitroxide) phosphite were mixed in a high mixer for 5 minutes, added The cross-linkable polyethylene masterbatch was prepared by extruding at 145°C with an extruder.

(2) Put 500kg of high-density polyethylene, 200kg of linear low-density polyethylene (DMDA7042), and 50kg of cross-linkable polyethylene masterbatch into three different weight loss scales, and mix high-density polyethylene, linear low-density polyethylene, The cross-linkable polyethylene masterbatch is fed into a 65-type (screw diameter 65mm) co-rotating parallel twin-screw extruder (Nanjing Ruiya Extrusion Machinery Equipment Co., Ltd., TSE65) according to the mass ratio of 10:4:1. To prepare cross-linkable polyethylene modified materials, the temperatures of the 9 heating zones of the extruder are 140°C, 140°C, 145°C, 145°C, 145°C, 145°C, 145°C, 145°C, 145°C , the speed of the extruder is 200rpm, the melt flowing out of the twin-screw extruder is pelletized by an underwater pelletizer, and sucked into the drying silo for drying at 80°C for 2 hours to obtain a cross-linkable polyethylene modified material.

The screw combinations used by the twin-screw extruder in step (2) are sequentially from the screw drive end to the end:

(solid conveying section A) 56/56A, 96/96, 96/96, 72/72, 72/72, 56/56, 44/44; (melting section B) 45°/5/56, 45°/5 /56, 45°/5/56, 44/44, 45°/5/56, 60°/4/56, 56/56, 44/44, 60°/4/44, 45°/5/56L; (Mixing section C) 56/56, 44/44, 44/44, 44/44, 45°/5/44, 45°/5/44, 45°/5/44, 56/56, 56/56 , 44/44, 44/44, 45°/5/44, 45°/5/56, 56/56; (exhaust section D) 56/56, 44/44, 44/44; (homogenization section E )45°/5/44, 60°/4/44, 64/64, 64/64, 44/44, 44/44.

The melt temperature flowing out of the extruder, the current of the extruder, the state of the extrudate, and the gel content of the obtained crosslinkable polyethylene modified material are shown in Table 1.

Comparative example 1

First, 11.25kg of di-tert-butyl peroxide, 3.75kg of triallyl isocyanurate, 3kg of antioxidant 1010, 3kg of antioxidant 168, 2kg of polyethylene wax (A-C316A), 2.5kg of tris(2,2,6,6-tetramethylpiperidinyl nitroxide) phosphite was added to the high mixer and mixed for 5 minutes as an auxiliary composition, and then added to the weight loss scale-1;

Send 550kg of high-density polyethylene to the loss-in-weight scale-2, and 200kg of linear low-density polyethylene (DMDA 7042) to the loss-in-weight scale-3;

The additive composition, high-density polyethylene, and linear low-density polyethylene are fed into a 65-type co-rotating parallel twin-screw extruder at a mass ratio of 0.51:11:4 to prepare a cross-linkable polyethylene master pellets, the temperature of the 9-stage heating zone of the extruder is 140°C, 140°C, 145°C, 145°C, 145°C, 145°C, 145°C, 145°C, 145°C, and the extruder speed is 200rpm. The melt of the screw extruder is pelletized by an underwater pelletizer, sucked into the drying silo and dried at 80°C for 2 hours to obtain a cross-linkable polyethylene modified material.

The screw combinations used by the twin-screw extruder in step (2) are sequentially from the screw drive end to the end:

(solid conveying section A) 56/56A, 96/96, 96/96, 72/72, 72/72, 56/56, 44/44; (melting section B) 45°/5/56, 45°/5 /56, 45°/5/56, 44/44, 45°/5/56, 60°/4/56, 56/56, 44/44, 60°/4/44, 45°/5/56L; (Mixing section C) 56/56, 44/44, 44/44, 44/44, 45°/5/44, 45°/5/44, 45°/5/44, 56/56, 56/56 , 44/44, 44/44, 45°/5/44, 45°/5/56, 56/56; (exhaust section D) 56/56, 44/44, 44/44; (homogenization section E )45°/5/44, 60°/4/44, 64/64, 64/64, 44/44, 44/44.

The melt temperature flowing out of the extruder, the current of the extruder, the state of the extrudate, and the gel content of the obtained crosslinkable polyethylene modified material are shown in Table 1.

Comparative example 2

(1) 50kg of high-density polyethylene powder (DMDA8007), 11.25kg of di-tert-butyl peroxide, 3.75kg of triallyl isocyanurate, 3kg of antioxidant 1010, and 3kg of antioxidant 168, 2kg of polyethylene wax (A-C316A), 2.5kg of tris(2,2,6,6-tetramethylpiperidinyl nitroxide) phosphite were mixed in a high mixer for 5 minutes, added The cross-linkable polyethylene masterbatch was prepared by extruding at 145°C with an extruder.

(2) Put 500kg of high-density polyethylene, 200kg of linear low-density polyethylene (DMDA7042), and 50kg of cross-linkable polyethylene masterbatch into three different weight loss scales, and mix high-density polyethylene, linear low-density polyethylene, The cross-linkable polyethylene masterbatch is fed into a 65-type (screw diameter 65mm) co-rotating parallel twin-screw extruder (Nanjing Ruiya Extrusion Machinery Equipment Co., Ltd., TSE65) according to the mass ratio of 10:4:1. To prepare cross-linkable polyethylene modified materials, the temperatures of the 9 heating zones of the extruder are 140°C, 140°C, 145°C, 145°C, 145°C, 145°C, 145°C, 145°C, 145°C , the speed of the extruder is 200rpm, the melt flowing out of the twin-screw extruder is pelletized by an underwater pelletizer, and sucked into the drying silo for drying at 80°C for 2 hours to obtain a cross-linkable polyethylene modified material.

The screw combinations used by the twin-screw extruder in step (2) are sequentially from the screw drive end to the end:

(solid conveying section A) 56/56A, 96/96, 96/96, 72/72, 72/72, 56/56, 44/44; (melting section B) 56/56, 60°/5/56, 56/56, 44/44, 45°/5/56, 60°/4/56, 56/56, 44/44, 60°/4/44, 45°/5/56L; (mixing section C) 56/56, 44/44, 44/44, 44/44, 44/44, 45°/5/44, 45°/5/44, 56/56, 56/56, 44/44, 44/44, 45°/5/44, 45°/5/56, 56/56; (exhaust section D) 56/56, 44/44, 44/44; (homogenization section E) 45°/5/44, 60 °/4/44, 64/64, 64/64, 44/44, 44/44.

The melt temperature flowing out of the extruder, the current of the extruder, the state of the extrudate, and the gel content of the obtained crosslinkable polyethylene modified material are shown in Table 1.

Example 2

(1) 50kg high-density polyethylene (DMDA 8007) powder, 10kg di-tert-butyl peroxide, 5kg triallyl isocyanurate, 2kg antioxidant 1010, 2kg antioxidant 168 , 4.5kg of polyethylene wax (A-C316A), 2kg of tris(2,2,6,6-tetramethylpiperidinyl nitroxide) phosphite were mixed in a high mixer for 5 minutes, added to extrude Extrude at 140°C to prepare cross-linkable polyethylene masterbatch.

(2) Put 500kg of high-density polyethylene, 100kg of linear low-density polyethylene (8320), and 50kg of cross-linkable polyethylene masterbatch into three different weight loss scales, and mix high-density polyethylene, linear low-density polyethylene, The cross-linkable polyethylene masterbatch is fed into the 65-type co-rotating parallel twin-screw extruder according to the mass ratio of 10:2:1 for extrusion to prepare the cross-linkable polyethylene modified material. The 9th section of the extruder The temperature of the heating zone is 140°C, 140°C, 145°C, 145°C, 145°C, 145°C, 145°C, 145°C, 145°C, the speed of the extruder is 200rpm, and the melt flowing out of the twin-screw extruder passes through The pellets were pelletized by an underwater pelletizer, sucked into the drying silo and dried at 80°C for 2 hours to obtain a cross-linkable polyethylene modified material.

The screw combinations used by the twin-screw extruder in step (2) are sequentially from the screw drive end to the end:

(solid conveying section A) 56/56A, 96/96, 96/96, 72/72, 72/72, 56/56, 44/44; (melting section B) 45°/5/56, 45°/5 /56, 56/56, 44/44, 45°/5/56, 60°/4/56, 56/56, 44/44, 60°/4/44, 45°/5/56L; (mixing Section C) 56/56, 44/44, 44/44, 44/44, 44/44, 45°/5/44, 45°/5/44, 56/56; (Exhaust Section D) 56/56 , 44/44, 44/44, 45°/5/44, 45°/5/56, 56/56, 56/56, 44/44, 44/44; (homogenizing section E) 45°/5/ 44, 60°/4/44, 64/64, 64/64, 44/44, 44/44.

The melt temperature flowing out of the extruder, the current of the extruder, the state of the extrudate, and the gel content of the obtained crosslinkable polyethylene modified material are shown in Table 1.

Comparative example 3

First, 10kg of di-tert-butyl peroxide, 5kg of triallyl isocyanurate, 2kg of antioxidant 1010, 2kg of antioxidant 168, 4.5kg of polyethylene wax (A-C316A), 2kg Tris(2,2,6,6-tetramethylpiperidinyl nitroxide radical) phosphite was added to a high mixer and mixed for 5 minutes as an auxiliary composition, and then added to the weight loss scale-1;

Send 550kg of high-density polyethylene to the loss-in-weight scale-2, and 100kg of linear low-density polyethylene (8320) to the loss-in-weight scale-3;

The auxiliary composition, high-density polyethylene, and linear low-density polyethylene are fed into a 65-type co-rotating parallel twin-screw extruder according to a mass ratio of 0.51:11:2 to prepare cross-linkable polyethylene masterbatches. The temperature of the 9-stage heating zone of the extruder is 140°C, 140°C, 145°C, 145°C, 145°C, 145°C, 145°C, 145°C, 145°C, and the extruder speed is 200rpm. The melt out of the machine is pelletized by an underwater pelletizer, sucked into the drying silo and dried at 80°C for 2 hours to obtain a cross-linkable polyethylene modified material.

The screw combinations used by the twin-screw extruder in step (2) are sequentially from the screw drive end to the end:

(solid conveying section A) 56/56A, 96/96, 96/96, 72/72, 72/72, 56/56, 44/44; (melting section B) 45°/5/56, 45°/5 /56, 45°/5/56, 44/44, 45°/5/56, 60°/4/56, 56/56, 60°/4/44, 60°/4/44, 45°/5 /56L; (mixing section C) 56/56, 44/44, 44/44, 44/44, 45°/5/44, 45°/5/44, 45°/5/44, 56/56, 56/56, 44/44, 44/44, 45°/5/44, 45°/5/56, 56/56; (exhaust section D) 56/56, 44/44, 44/44; (both Paragraph E) 45°/5/44, 60°/4/44, 64/64, 64/64, 44/44, 44/44.

The melt temperature flowing out of the extruder, the current of the extruder, the state of the extrudate, and the gel content of the obtained crosslinkable polyethylene modified material are shown in Table 1.

Example 3

(1) With 50kg high-density polyethylene powder (DMDA 8007), 11.25kg of di-tert-butyl peroxide, 3.75kg of triallyl isocyanurate, 3kg of antioxidant 1010, 3kg of antioxidant Agent 168, 2.5kg of polyethylene wax (A-C316A), 2kg of phosphite tris (2,2,6,6-tetramethylpiperidinyl nitroxide) ester, put into a high mixer and mix for 5min, Put into an extruder and extrude at 135°C to prepare cross-linkable polyethylene masterbatch.

(2) Put 300kg of high-density polyethylene, 17.5kg of ethylene-octene copolymer (POE8200), and 50kg of cross-linkable polyethylene masterbatch into three different weight loss scales, and mix high-density polyethylene, ethylene-octene The copolymer and cross-linkable polyethylene masterbatch are fed into the 65-type co-rotating parallel twin-screw extruder according to the mass ratio of 6:0.35:1 for extrusion to prepare cross-linkable polyethylene modified materials. The extruder The temperature of the 9-stage heating zone is 140°C, 140°C, 145°C, 145°C, 145°C, 145°C, 145°C, 145°C, 145°C, and the speed of the extruder is 200rpm. The melt is granulated by an underwater pelletizer, sucked into a drying silo for 2 hours at 80°C, and obtained a cross-linkable polyethylene modified material.

The screw combinations used by the twin-screw extruder in step (2) are sequentially from the screw drive end to the end:

(solid conveying section A) 56/56A, 96/96, 96/96, 72/72, 72/72, 56/56, 44/44; (melting section B) 45°/5/56, 45°/5 /56, 45°/5/56, 44/44, 45°/5/56, 60°/4/56, 56/56, 44/44, 60°/4/44, 45°/5/56L; (Mixing section C) 56/56, 44/44, 44/44, 44/44, 45°/5/44, 45°/5/44, 45°/5/44, 56/56, 56/56 , 44/44, 44/44, 45°/5/44, 45°/5/56, 56/56; (exhaust section D) 56/56, 44/44, 44/44; (homogenization section E )45°/5/44, 60°/4/44, 64/64, 64/64, 44/44, 44/44.

The melt temperature flowing out of the extruder, the current of the extruder, the state of the extrudate, and the gel content of the obtained crosslinkable polyethylene modified material are shown in Table 1.

Comparative example 4

First 11.25kg of di-tert-butyl peroxide, 3.75kg of triallyl isocyanurate, 3kg of antioxidant 1010, 3kg of antioxidant 168, 2.5kg of polyethylene wax (A-C316A), 2kg of phosphorous acid Tris(2,2,6,6-tetramethylpiperidinyl nitroxide radical) ester was added to a high mixer and mixed for 5 minutes as an auxiliary composition, and then added to weight loss scale 1;

Send 350kg of high-density polyethylene to the weight loss scale 2, and add 17.5kg of ethylene-octene copolymer (POE8200) to the weight loss scale 3;

The auxiliary agent composition, high-density polyethylene, and ethylene-octene copolymer are fed into a 65-type co-rotating parallel twin-screw extruder according to the mass ratio of 0.51:7:0.35 for extrusion to prepare cross-linkable polyethylene master pellets, the temperature of the 9-stage heating zone of the extruder is 140°C, 140°C, 145°C, 145°C, 145°C, 145°C, 145°C, 145°C, 145°C, and the extruder speed is 200rpm. The melt of the screw extruder is pelletized by an underwater pelletizer, sucked into the drying silo and dried at 80°C for 2 hours to obtain a cross-linkable polyethylene modified material.

The screw combinations used by the twin-screw extruder in step (2) are sequentially from the screw drive end to the end:

(solid conveying section A) 56/56A, 96/96, 96/96, 72/72, 72/72, 56/56, 44/44; (melting section B) 45°/5/56, 45°/5 /56, 45°/5/56, 44/44, 45°/5/56, 60°/4/56, 56/56, 44/44, 60°/4/44, 45°/5/56L; (Mixing section C) 56/56, 44/44, 44/44, 44/44, 45°/5/44, 45°/5/44, 45°/5/44, 56/56, 56/56 , 44/44, 44/44, 45°/5/44, 45°/5/56, 56/56; (exhaust section D) 56/56, 44/44, 44/44; (homogenization section E )45°/5/44, 60°/4/44, 64/64, 64/64, 44/44, 44/44.

The melt temperature flowing out of the extruder, the current of the extruder, the state of the extrudate, and the gel content of the obtained crosslinkable polyethylene modified material are shown in Table 1.

Comparative example 5

(1) With 50kg high-density polyethylene powder (DMDA 8007), 11.25kg of di-tert-butyl peroxide, 3.75kg of triallyl isocyanurate, 3kg of antioxidant 1010, 3kg of antioxidant Agent 168, 2.5kg of polyethylene wax (A-C316A), 2kg of phosphite tris (2,2,6,6-tetramethylpiperidinyl nitroxide) ester, put into a high mixer and mix for 5min, Put into an extruder and extrude at 135°C to prepare cross-linkable polyethylene masterbatch.

(2) Put 300kg of high-density polyethylene, 17.5kg of ethylene-octene copolymer (POE8200), and 50kg of cross-linkable polyethylene masterbatch into three different weight loss scales, and mix high-density polyethylene, ethylene-octene The copolymer and cross-linkable polyethylene masterbatch are fed into the 65-type co-rotating parallel twin-screw extruder according to the mass ratio of 6:0.35:1 for extrusion to prepare cross-linkable polyethylene modified materials. The extruder The temperature of the 9-stage heating zone is 140°C, 140°C, 145°C, 145°C, 145°C, 145°C, 145°C, 145°C, 145°C, and the speed of the extruder is 200rpm. The melt is granulated by an underwater pelletizer, sucked into a drying silo for 2 hours at 80°C, and obtained a cross-linkable polyethylene modified material.

The screw combinations used by the twin-screw extruder in step (2) are sequentially from the screw drive end to the end:

(solid conveying section A) 56/56A, 96/96, 96/96, 72/72, 72/72, 56/56, 44/44; (melting section B) 45°/5/56, 45°/5 /56, 45°/5/56, 44/44, 45°/5/56, 60°/4/56, 56/56, 60°/4/44, 60°/4/44, 45°/5 /56L; (Mixing Section C) 56/56, 44/44, 44/44, 44/44, 45°C/5/44, 45°/5/44, 45°/5/44, 56/56, 56/56, 44/44, 44/44, 45°/5/44, 45°/5/56, 56/56; (exhaust section D) 56/56, 44/44, 44/44; (both Paragraph E) 45°/5/44, 60°/4/44, 64/64, 64/64, 44/44, 44/44.

The melt temperature flowing out of the extruder, the current of the extruder, the state of the extrudate, and the gel content of the obtained crosslinkable polyethylene modified material are shown in Table 1.

Table 1

Table 1 shows the melt temperature, extruder current when the cross-linkable polyethylene masterbatch, polyethylene and toughening components are extruded in a twin-screw extruder equipped with screws with different combinations of shear flights. , the extruded form of the extrudate and the gel content of the obtained cross-linkable polyethylene modified material.

It can be seen from the results in Table 1 that Examples 1-3 can ensure that the shape of the extruded product is completely melted, that is, the obtained crosslinkable polyethylene modified material can be melted well and mixed uniformly. Under this premise, the melt temperatures of the extrudates in Examples 1-3 were all lower than those of the comparative examples, and the gel content of the extrudates was 0% by weight, indicating that no crosslinking occurred during the extrusion process. Further observation of the current value of the extruder shows that when the above-mentioned good melting is achieved in the embodiment, the viscosity of the extruded product is not high, and the processing difficulty is not great.

However, in Comparative Examples 1-4, the shape of the extrudate cannot be melted well, or even cross-linked, which cannot provide good melting of the cross-linkable polyethylene modified material, and the mixing effect will be poor.

Comparative Example 1 corresponds to Example 1, but the feeding method of various materials is to directly feed and extrude polyethylene, cross-linking agent, cross-linking auxiliary agent, antioxidant, lubricant, cross-linking stabilizer, etc. Table 1 shows that a fully molten extrudate was not obtained. The feeding method in Comparative Example 1 enables materials of different physical states to be melt-blended in an extruder, without pre-prepared masterbatch form. Since some additives are in liquid state and some materials are solid powder or granules, the mixture is uneven and the shear becomes weak during extrusion, resulting in poor melting state. In addition, there is a loss of material.

Comparative Example 2 corresponds to Example 1, wherein although the masterbatch is made earlier, the intermeshing section where the melting section begins in the screw combination used does not contain a reverse kneading element, but only contains a forward kneading element (60°/5/ 56) Different from Example 1 (containing three kneading elements), the combination of screws in the melting section is different, and as a result, the effect of melt blending is weakened, and complete melting of the material cannot be completed.

The corresponding embodiment 2 of various material feeding amounts in comparative example 3, but the feeding method of various materials is direct feeding, and uses the screw combination that is different from embodiment 2 in comparative example 3, is strong shear combination (60 °/4 /44, 60°/4/44, 45°/5/56L), which will increase the melt temperature and cause crosslinking.

The amount of material feeding in Comparative Example 4 corresponds to Example 3, but the feeding method is different, no masterbatch is made, polyethylene and various additives are directly fed into the extruder, and white infusibles can be found in the extruded product. That is to say, the shearing of the elastomer under this screw combination is relatively weak, and the elastomer cannot be effectively sheared and melted.

The material feeding amount and feeding method in comparative example 5 correspond to embodiment 3, but adjust thread combination, use strong shear combination (60 °/4/44, 60 °/4/44, 45 °/5/56L), extrude The resulting extrudate has a rough surface and is partially crosslinked.

In the embodiment, the feeding method of the present invention is adopted, by first making a cross-linkable polyethylene masterbatch, then melt blending with polyethylene and toughening components, and combining with adjusting the thread combination of the melting section, the cross-linkable polyethylene can be prepared. In the process of polyethylene modification, there can be a larger safe processing range, the shear heat is greatly reduced, and the volatilization of additives is less, and the cross-linkable polyethylene modification with a gel content of 0 and no cross-linking structure can be obtained. sexual material. The cross-linked polyethylene with high cross-linking degree can be prepared by using the cross-linkable polyethylene modified material.

Claims (10)

1. a kind of preparation method of crosslinkable polyethylene modified materials, including：

(1) will be mixed containing polyethylene a, crosslinking agent, crosslinking coagent, antioxidant, lubricant and the compound of cross-linked stable agent Refining, is made crosslinkable polyethylene masterbatch；On the basis of the total amount of the crosslinkable polyethylene masterbatch, the crosslinking agent and crosslinking help The total content of agent is 12~27 weight %；

(2) the crosslinkable polyethylene masterbatch, polyethylene b and toughening element are separately added into double screw extruder and melted Blending, obtains crosslinkable polyethylene modified materials；On the basis of the total amount of the crosslinkable polyethylene modified materials, the crosslinking agent and The total content of crosslinking coagent is 0.8~3 weight %.

2. preparation method according to claim 1, wherein, in step (1), relative to the polyethylene of 100 parts by weight A, the crosslinking agent are 20~25 parts by weight, and the crosslinking coagent is 5~10 parts by weight, and the antioxidant is 2~15 parts by weight, The lubricant is 5~15 parts by weight, and the cross-linked stable agent is 1~5 parts by weight.

3. preparation method according to claim 1 or 2, wherein, in step (1), the polyethylene a is selected from high-density polyethylene Alkene and/or low density polyethylene (LDPE)；Preferably, the density of the high density polyethylene (HDPE) is 0.94~0.965g/cm³, in 2.16kg Melt index when load is lower 190 DEG C is 1~20g/10min；The density of the low density polyethylene (LDPE) is 0.91~0.935g/ cm³, at 2.16 kg load 190 DEG C when melt index be 1~20g/10min.

4. preparation method according to claim 1, wherein, in step (2), relative to the described cross-linking of 100 parts by weight Polyethylene master batch, the polyethylene b are 500~1000 parts by weight, and the toughening element is 35~400 parts by weight.

5. the preparation method according to claim 1 or 4, wherein, in step (2), the polyethylene b is selected from high-density polyethylene Alkene and/or low density polyethylene (LDPE)；Preferably, the density of the high density polyethylene (HDPE) is 0.94~0.965g/cm³, in 2.16kg Melt index when load is lower 190 DEG C is 1~20g/10min；The density of the low density polyethylene (LDPE) is 0.91~0.935g/ cm³, at 2.16 kg load 190 DEG C when melt index be 1~20g/10min.

6. according to the preparation method described in any one in claim 1-5, wherein, the toughening element is selected from linea low density At least one of polyethylene, ethylene-octene copolymer and ethylene propylene diene rubber；The crosslinking agent is selected from peroxidating diisopropyl Benzene, benzoyl peroxide, di-isopropylbenzene hydroperoxide, TBHP, 2,5- dimethyl -2,5- di-tert-butyl peroxides Hexane, 2,5- dimethyl -2,5- di-tert-butyl peroxides -3- alkynes, diacyl peroxide, di-tert-butyl peroxide, alkane At least one of base hydrogen peroxide, dilauroyl peroxide, methyl ethyl ketone peroxide and cyclohexanone peroxide；The crosslinking coagent Selected from poly 1,2-butadiene, diallyl p phthalate, divinylbenzene, TAC, cyanuric acid triolefin At least one of propyl ester and triallyl isocyanate；The cross-linked stable agent is selected from (the 2,2,6,6- tetramethyls of phosphorous acid three Piperidine NO free radical) ester, at least one in 2,2- bis- (4- t-octyls phenyl) -1- picryls hydrazine and NO free radical piperidine alcohols Kind.

7. preparation method according to claim 1, wherein, in step (2), the screw combinations in the double screw extruder Including intermeshing two root architectures identical screw rod (1)；

Screw rod (1) includes splined shaft (2), screwing element (3) and kneading member (4)；

The screwing element (3) of multiple positive and negative rotations of difference and the kneading member (4) of multiple positive and negative rotations of difference pass through respective endoporus The spline (5) carried is sleeved on splined shaft (2)；

Every screw rod (1) includes solid conveying section (A), the melt zone divided successively towards end from the driving end of screw rod (1) (B), mixing section (C), exhaust section (D) and homogenizing zone (E).

8. preparation method according to claim 7, wherein, the helical pitch of screwing element (3) is 44~96mm, screwing element (3) length is 44~96mm；The error angle of kneading member (4) is 30~60 °, and the length of kneading member (4) is 44~56mm, The number of the kneading block of kneading member (4) is 4~6；

Preferably, the melt zone contains at least two groups of engaged sections, and every section of engaged section contains at least one kneading member (4)；

Contain at least one screwing element (3) between the engaged section；

The melt zone contains at least one reverse-flight elements or a reverse kneading member.

9. the preparation method according to claim 7 or 8, wherein, the steering of two screw rods (1) is identical；During rotation, two spiral shells The phase of bar (1) differs 90 ° of phase angles；Preferably, a diameter of 36~96mm of screw rod (1), draw ratio (36~48)：1.

10. according to the preparation method described in any one in claim 1-9, wherein, the crosslinkable polyethylene modified materials Gel content is 0 weight %.