阅读说明：本技术 一种自清洁防结垢结蜡的聚烯烃管材及其制备方法与应用 (polyolefin pipe material capable of self-cleaning, preventing scaling and waxing as well as preparation method and application thereof ) 是由 应淑妮 陈国贵 冯金茂 郑思珣 李蕾 于 2019-09-17 设计创作，主要内容包括：本发明涉及一种自清洁防结垢结蜡的聚烯烃管材及其制备方法与应用,聚烯烃管材包括管材内层与管材外层,管材内层的材质为含氟基团的聚烯烃改性材料与基体聚烯烃材料的共混材料,管材外层的材质为聚烯烃材料；本聚烯烃管材制备方法为：1)将含氟基团的聚烯烃改性材料与基体聚烯烃材料共混,得到共混材料；2)将共混材料与聚烯烃材料双层共挤,即得到防结垢结蜡的聚烯烃管材；本聚烯烃管材可用于制作钢丝缠绕管内管。与现有技术相比,本发明通过引入含氟基团链段降低管道内壁表面能,使管道具有防结垢、结蜡的功能,此外,含氟基团的引入还有利于提高管道的耐高温性以及耐腐蚀性,使本聚烯烃管材具有较为广阔的应用前景。(The invention relates to a polyolefin pipe material with self-cleaning, anti-scaling and wax-deposition functions and a preparation method and application thereof, wherein the polyolefin pipe material comprises a pipe material inner layer and a pipe material outer layer, the pipe material inner layer is made of a blend material of a polyolefin modified material containing fluorine groups and a matrix polyolefin material, and the pipe material outer layer is made of a polyolefin material; the preparation method of the polyolefin pipe comprises the following steps: 1) blending the polyolefin modified material containing the fluorine group with a matrix polyolefin material to obtain a blended material; 2) co-extruding the blending material and the polyolefin material in a double layer manner to obtain the anti-scaling and anti-waxing polyolefin pipe; the polyolefin pipe can be used for manufacturing an inner pipe of a steel wire winding pipe. Compared with the prior art, the invention reduces the surface energy of the inner wall of the pipeline by introducing the fluorine-containing group chain segment, so that the pipeline has the functions of scale prevention and wax deposition, and in addition, the introduction of the fluorine-containing group is also beneficial to improving the high temperature resistance and the corrosion resistance of the pipeline, so that the polyolefin pipe has wider application prospect.)

1. The polyolefin pipe material is characterized by comprising a pipe inner layer and a pipe outer layer, wherein the pipe inner layer is made of a blend material of a polyolefin modified material containing fluorine groups and a matrix polyolefin material, and the pipe outer layer is made of a polyolefin material.

2. A self-cleaning antifouling wax polyolefin pipe as claimed in claim 1, wherein the polyolefin modified material containing fluorine group comprises a polyolefin main chain segment and a fluorine group containing chain segment grafted on the polyolefin main chain segment.

3. A self-cleaning antiscaling wax-protected polyolefin pipe material according to claim 2, wherein said polyolefin main segment comprises one of low density polyethylene, linear low density polyethylene, medium density polyethylene, high density polyethylene, heat resistant polyethylene or ultra high molecular weight polyethylene;

the fluorine-containing group chain segment is one of functional groups generated by graft polymerization of fluorine-containing and double-bond reaction monomers, and comprises poly (trifluoroethyl acrylate), poly (hexafluorobutyl acrylate), poly (dodecafluoro heptyl methacrylate) and poly (perfluorodecyl ethylene).

4. The self-cleaning anti-scaling polyolefin pipe as claimed in claim 1, wherein the base polyolefin material in the blend material and the polyolefin material in the outer layer of the pipe are the same polyolefin material, and the polyolefin material comprises one of high density polyethylene, heat resistant polyethylene and ultra high molecular weight polyethylene.

5. the self-cleaning anti-scaling polyolefin pipe as claimed in claim 1, wherein the polyolefin modified material containing fluorine groups in the blended material is 5-100 wt%.

6. The self-cleaning anti-scaling polyolefin pipe material as claimed in claim 1, wherein the thickness ratio of the inner layer to the outer layer is 1 (0-10).

7. A process for the preparation of a self-cleaning antifouling waxed polyolefin pipe, as claimed in any one of claims 1 to 6, comprising:

1) Blending the polyolefin modified material containing the fluorine group with a matrix polyolefin material to obtain a blended material;

2) And co-extruding the blending material and the polyolefin material in a double layer manner to obtain the anti-scaling and anti-waxing polyolefin pipe.

8. use of a self-cleaning anti-fouling and wax-depositing polyolefin pipe material as claimed in any one of claims 1 to 6 for making an inner pipe of a wire-wound pipe.

Technical Field

The invention belongs to the technical field of pipes, and relates to a polyolefin pipe with self-cleaning, anti-scaling and wax-deposition functions, and a preparation method and application thereof.

Background

In the process of oilfield water injection and crude oil transportation, due to the changes of environmental conditions such as pressure, temperature and the like and the adsorption effect of a fluid medium and the surface of a pipe, wax and inorganic salt in a transportation medium can be deposited on the pipe wall to form a wax scaling layer, so that the flow area is reduced, and the transportation resistance is increased. The wax precipitation and the scale formation reduce the circulation area of the pipeline, increase the friction resistance, reduce the conveying capacity of the pipeline, even block the pipeline in serious conditions, and cause great economic loss. In addition, the heating in the north is mainly central heating, and the quality of water in the north is relatively poor, will be at the pipeline inner wall scale deposit after operation a period to can lead to the water resistance to increase and influence the heating effect, generally just need wash once 3-5 years, waste time and energy and cost money, seriously influence user experience and feel.

The solid-liquid interface theory considers that the surface energy of the material is an important factor for initiating wax precipitation and scaling. Reducing the surface energy of the pipe material can reduce the degree of fouling of the inner wall of the pipe. Therefore, in the investigation process, the modification of the inner wall of the pipe is proposed, so that the inner wall of the pipe forms lower surface energy, the hydrophobic-oleophobic performance is realized, and the problems of scaling and wax deposition of the pipe are fundamentally solved.

High molecular materials with low surface energy are the primary consideration, while the surface energy of fluorine-containing materials is the lowest among the polymeric materials. However, the conventional fluorine-containing modifier has low molecular weight and poor compatibility with polyolefin matrix. Although it can migrate to the surface, to some extent, reduce the surface energy. But because the bonding force between the polyolefin and the polyolefin is weak, the polyolefin can be gradually taken away along with the liquid conveying in the pipeline and the scraping of impurities in the liquid, and the continuous action effect of the polyolefin is influenced.

disclosure of Invention

The invention aims to overcome the defects in the prior art and provide a polyolefin pipe with self-cleaning, anti-scaling and anti-waxing functions, a preparation method and application thereof.

The purpose of the invention can be realized by the following technical scheme:

The polyolefin pipe comprises an inner layer and an outer layer, wherein the inner layer is made of a blend material of a polyolefin modified material containing fluorine groups and a matrix polyolefin material, and the outer layer is made of a polyolefin material.

Further, the polyolefin modified material containing the fluorine group comprises a polyolefin main chain segment and a fluorine-containing group chain segment grafted on the polyolefin main chain segment.

the main chain segment is a polyolefin chain segment, has good compatibility with a matrix polyolefin material in the blending material, and is favorable for the entanglement of the main chain segment and the chain segment in the matrix polyolefin material due to the long chain length of the main chain segment, so that the binding force of the two materials in the blending material is improved; the fluorine-containing group chain segment is grafted on the polyolefin main chain segment as a functional chain segment, and the fluorine-containing group chain segment with smaller surface energy can be gathered to the surface of the blending material, namely to the surface of the inner layer of the pipe, so that the surface energy of the inner wall of the pipe is reduced; in addition, the fluorine-containing group chain segment which cannot be migrated to the surface in the blending material can be anchored between the main chain segment and the matrix polyolefin material chain segment in the matrix polyolefin material, so that the entanglement between the two chain segments is enhanced, and the bonding force between the fluorine-containing group polyolefin modified material and the matrix polyolefin material is further improved.

Further, the polyolefin main chain segment comprises one of Low Density Polyethylene (LDPE), Linear Low Density Polyethylene (LLDPE), Medium Density Polyethylene (MDPE), High Density Polyethylene (HDPE), heat-resistant Polyethylene (PERT) or ultrahigh molecular weight polyethylene (UHMWPE);

the fluorine-containing group chain segment comprises one of functional groups generated by graft polymerization of fluorine-containing and double-bond reaction monomers such as poly (trifluoroethyl acrylate), poly (hexafluorobutyl acrylate), poly (dodecafluoro heptyl methacrylate), poly (perfluorodecyl ethylene) and the like.

Further, the base polyolefin material in the blended material and the polyolefin material in the outer layer of the pipe are the same polyolefin material, and the polyolefin material comprises one of high-density polyethylene, heat-resistant polyethylene and ultrahigh molecular weight polyethylene.

further, the mass percentage of the polyolefin modified material containing fluorine groups in the blending material is 5-100 wt%.

Further, the thickness ratio of the inner layer of the pipe to the outer layer of the pipe is 1 (0-10), wherein the preferable thickness ratio is 1 (3-6), the thickness ratio can be properly adjusted according to application requirements, and a core die used for extruding the inner layer is subjected to mirror polishing and coated with a polytetrafluoroethylene coating to ensure sufficient low roughness.

The preparation method of the self-cleaning anti-scaling wax polyolefin pipe comprises the following steps:

1) Blending the polyolefin modified material containing the fluorine group with a matrix polyolefin material to obtain a blended material;

2) And carrying out double-layer co-extrusion molding on the blending material and the polyolefin material to obtain the anti-scaling and anti-waxing polyolefin pipe.

Wherein, the matrix polyolefin material is a conventional commercial material, and the polyolefin modified material containing fluorine groups is a commercial material, or is prepared by adopting a method reported by a currently published literature, or is prepared by adopting the following steps:

1) placing the powder of the polyolefin main chain segment (such as LDPE powder, MDPE powder and the like) in a plasma device, performing vacuum treatment under the vacuum degree of 200mTorr, introducing helium or argon with the pressure of 250 and 1250mTorr as protective gas, then performing glow discharge with the treatment power of 10-250W (preferably 50-250W), namely plasma treatment, adjusting the plasma treatment condition to generate a large amount of free radicals on the surface of the polyolefin powder, and obtaining the powder of the polyolefin main chain segment with the surface containing the free radicals after treating for 10-600 s;

2) Placing the polyolefin main chain segment powder with the surface containing the free radicals in the air for 5-1440min, and converting the surface free radicals into surface peroxides by oxygen in the air so as to obtain the polyolefin main chain segment powder with the surface containing the peroxides;

3) Adding polyolefin main chain segment powder with surface containing peroxide as a free radical initiator into a solution of a polymerization monomer of a fluorine-containing group segment (such as poly (trifluoroethyl acrylate), poly (hexafluorobutyl acrylate) and the like), carrying out free radical polymerization of the polymerization monomer at 50-100 ℃ under the protection of nitrogen or argon, and reacting for 2-24h to obtain polymer powder, wherein the addition amount of the polyolefin main chain segment powder with surface containing peroxide is 5-95% of the mass of the polymerization monomer, the concentration of the polymerization monomer solution is 0.1-1g/mL, and the solvent is one of 1, 4-dioxane, toluene, xylene, N-methylpyrrolidone, N-methylacetamide, N-dimethylformamide or N, N-dimethylacetamide;

4) And washing and drying the polymer powder in sequence to obtain the polyolefin modified material with the surface grafted with the fluorine-containing group chain segment.

In addition, in the step 3), the free radical polymerization reaction comprises a common free radical polymerization reaction or a living free radical polymerization reaction;

When the free radical polymerization reaction is common free radical polymerization reaction, polyolefin powder with surface containing peroxide is directly added into a solvent containing a polymerization monomer as a free radical initiator;

When the free radical polymerization reaction is a living free radical polymerization reaction, the polyolefin powder with the surface containing peroxide is firstly reacted with diisopropyl xanthate or dithiobenzoic anhydride to form xanthate or dithioester on the surface of the polyolefin powder, and then the xanthate or dithioester is added into a solvent containing a polymerization monomer. The polyolefin powder containing xanthate or dithioester on the surface can be used as a chain transfer agent of living radical polymerization, namely a RAFT agent, so that the acrylic polymer can be grafted by means of RAFT polymerization.

The inner layer blending material can be directly extruded by an extruder with a high-dispersion screw, and in order to improve the dispersion effect, the double-screw granulation can be firstly carried out, and then the double-layer extrusion of the pipe extruder is carried out.

As a preferable technical scheme, in the blending process of the step 1) and the double-layer co-extrusion molding process of the step 2), conventional modified materials such as color master batches, antioxidants, extrusion modifiers and the like can be added according to needs.

The polyolefin pipe material with the self-cleaning function and the anti-scaling and anti-waxing function can be used for manufacturing an inner pipe of a steel wire winding pipe.

The invention introduces the long-chain polyethylene modified material with fluorine-containing graft, ensures the full combination with the matrix resin, endows the matrix material with lower surface energy, realizes the hydrophobic and oleophobic effects, and is finally applied to the fields needing scale prevention and wax deposition, such as crude oil transportation, heating, bittern transportation, inorganic and organic raw material transportation, and the like. In addition, the melting point of the fluorine-containing graft modified polyethylene material is slightly higher than that of the polyethylene material, so that the high temperature resistance can be improved to a certain extent; the fluorine-containing material can also block gases such as H2S, O2 and the like to a certain extent, and further enhances the corrosion resistance of equipment.

Compared with the prior art, the invention has the following characteristics:

1) the invention introduces the low surface energy modified layer as the inner wall of the pipeline, improves the surface performance of the inner wall of the pipeline (in the hydrophobic performance test, the contact angle is increased from 87.7 degrees to 98.4 degrees, so that the pipeline has the functions of self-cleaning, anti-scaling and wax deposition;

2) The modified material is a polyolefin material grafted and modified by a fluorine-containing group chain segment, and the fluorine-containing group chain segment can be migrated and concentrated on the surface of the inner wall of the pipeline, so that the surface energy of the inner wall of the pipeline is reduced; the fluorine-containing group chain segment which is not transferred to the surface can be anchored between the polyolefin main chain segment and the matrix polyolefin material chain segment, so that the bonding force of the two materials in the blending material is improved;

3) The introduction of the fluorine-containing group is beneficial to improving the melting point of the material, and the melting point of the HDPE subjected to grafting modification can be increased from 136.4 ℃ to 141.0 ℃ in a performance test. Therefore, the temperature resistance of the inner layer material of the pipe can be improved to a certain extent. Due to the introduction of the fluorine-containing group, the gas barrier effect is achieved to a certain extent, and the corrosion resistance of the equipment is improved.

Drawings

FIG. 1 is a schematic structural diagram of a self-cleaning anti-fouling and wax-deposition polyolefin pipe in example 1;

FIG. 2 is an enlarged view of a portion of FIG. 1 at A;

FIG. 3 is a graph showing the results of a contact angle test of a water drop on the surface of an HDPE pellet of the polyethylene modified material without the addition of fluorine-containing groups in example 1;

FIG. 4 is a graph showing the contact angle test results of water drops on the surface of a pressed sheet of the fluorine group-containing polyethylene modified material and the HDPE blend material in example 1;

FIG. 5 is a graph showing the results of a first water drop rolling test performed on the surface of an HDPE pellet of example 1 to which a fluorine group-containing polyethylene modified material is not added;

FIG. 6 is a graph showing the results of a second water drop rolling test performed on the surface of an HDPE pellet of example 1 without a fluorine-containing group-containing polyethylene modified material;

FIG. 7 is a graph showing the results of a first water drop rolling test performed on the surface of a pellet of a fluorine-containing group-containing polyethylene modified material and HDPE blend material in example 1;

FIG. 8 is a graph showing the results of a second water drop rolling test performed on the surface of a pellet of the fluorine-containing group-containing polyethylene modified material and HDPE blend material of example 1;

FIG. 9 is a graph showing the results of melting point and enthalpy of fusion tests for HDPE of example 1 in FIG. 8.

FIG. 10 is a graph showing the melting point and enthalpy of fusion test results for the fluorinated grafted HDPE of example 1.

the notation in the figure is:

1-inner layer of pipe, 2-outer layer of pipe, 3-segment containing fluorine group, and 4-main segment of polyolefin.

Detailed Description

the invention is described in detail below with reference to the figures and specific embodiments. The present embodiment is implemented on the premise of the technical solution of the present invention, and a detailed implementation manner and a specific operation process are given, but the scope of the present invention is not limited to the following embodiments.

The outer layer material of the polyolefin pipe in each of the following examples was a commercially available polyethylene material. The inner layer material is prepared by the following steps:

1) Placing the powder of the polyolefin main chain segment (such as LDPE powder, MDPE powder and the like) in a plasma device, performing vacuum treatment under the vacuum degree of 200mTorr, introducing helium or argon with the pressure of 250 and 1250mTorr as protective gas, then performing glow discharge with the treatment power of 10-250W (preferably 50-250W), namely plasma treatment, adjusting the plasma treatment condition to generate a large amount of free radicals on the surface of the polyolefin powder, and obtaining the powder of the polyolefin main chain segment with the surface containing the free radicals after treating for 10-600 s;

2) Placing the polyolefin main chain segment powder with the surface containing the free radicals in the air for 5-1440min, and converting the surface free radicals into surface peroxides by oxygen in the air so as to obtain the polyolefin main chain segment powder with the surface containing the peroxides;

3) adding polyolefin main chain segment powder with surface containing peroxide as a free radical initiator into a solution of a polymerization monomer of a fluorine-containing group segment (such as poly (trifluoroethyl acrylate), poly (hexafluorobutyl acrylate) and the like), carrying out free radical polymerization of the polymerization monomer at 50-100 ℃ under the protection of nitrogen or argon, and reacting for 2-24h to obtain polymer powder, wherein the addition amount of the polyolefin main chain segment powder with surface containing peroxide is 5-95% of the mass of the polymerization monomer, the concentration of the polymerization monomer solution is 0.1-1g/mL, and the solvent is one of 1, 4-dioxane, toluene, xylene, N-methylpyrrolidone, N-methylacetamide, N-dimethylformamide or N, N-dimethylacetamide;

4) and washing and drying the polymer powder in sequence to obtain the polyolefin modified material with the surface grafted with the fluorine-containing group chain segment.