CN112113066B - Pipeline outer wall anticorrosion and heat insulation layer and preparation method thereof - Google Patents

Abstract

The invention discloses an anticorrosion heat-insulation layer for the outer wall of a pipeline and a preparation method thereof, wherein the anticorrosion heat-insulation layer comprises an inner film, a main layer, an outer film and a coating layer from inside to outside, the main layer comprises a plurality of spatial net layers which are nested together, the compactness degree of each spatial net layer is reduced from inside to outside in sequence, and foaming substances are filled in each spatial net layer. The invention combines corrosion protection and heat preservation, realizes corrosion protection and heat preservation at the same time, forms an integrated structure, further avoids the problem that the connection of a heat preservation layer and an anticorrosive layer is not firm in the traditional construction, and in addition, the anticorrosive heat preservation layer has a spatial net structure and has better effects on pressure resistance, collision resistance and flexibility.

Description

Pipeline outer wall anticorrosion and heat insulation layer and preparation method thereof

Technical Field

The invention relates to the technical field of pipeline protection, in particular to an anticorrosive heat-insulating layer for an outer wall of a pipeline and a preparation method thereof.

Background

The corrosion prevention of the pipeline refers to measures for slowing down or preventing the pipeline from being corroded and deteriorated under the chemical and electrochemical actions of internal and external media or by the metabolic activity of microorganisms;

the anti-corrosion layers of steel pipelines which are more applied in China comprise petroleum asphalt, PE jackets and PE foam jackets, epoxy coal asphalt, coal tar enamel, epoxy powder, a three-layer composite structure, epoxy coal asphalt cold winding tapes (PF type), rubber plastic type epoxy coal asphalt cold winding tapes (RPC type) and the like, and the anti-corrosion measures are that the pipelines are purely subjected to anti-corrosion and lack heat insulation treatment, namely, along with the development, some pipelines need heat insulation during anti-corrosion, for example, petroleum is a complex mixture and is easy to corrode the pipelines, and the anti-corrosion is necessary, but finished product oil pipelines also need heat insulation under the anti-corrosion condition, and in northeast and winter, the pipelines can be frozen and cracked due to expansion and contraction of heat, so that stable supply is influenced;

in addition, when heat preservation is considered, the problem of actual stress of the pipeline is also considered, the pipeline is usually buried underground and can be extruded by the ground, if the deformation of the ground is large or the interior of the pipeline is locally extruded, the traditional heat preservation layer is difficult to deal with, and meanwhile, the traditional heat preservation layer is difficult to effectively connect with the anticorrosive coating.

Disclosure of Invention

Aiming at the technical defects, the invention aims to provide an anticorrosive heat-insulating layer for the outer wall of a pipeline and a preparation method thereof, wherein the anticorrosive heat-insulating layer is combined with heat insulation, and heat insulation is carried out while corrosion prevention is realized to form an integrated structure, so that the problem that the heat-insulating layer and the anticorrosive layer are not firmly connected in the traditional construction process is solved, and in addition, the anticorrosive heat-insulating layer has a spatial net structure and has excellent effects on pressure resistance, collision resistance and flexibility.

In order to solve the technical problems, the invention adopts the following technical scheme:

the invention provides an anticorrosion and heat-insulation layer for the outer wall of a pipeline, which comprises an inner film, a main layer, an outer film and a coating layer from inside to outside, wherein the main layer comprises a plurality of spatial net layers which are nested together, the compactness of each spatial net layer is reduced from inside to outside in sequence, and foaming substances are filled in each spatial net layer.

Preferably, the space net layer is formed by bending and interlacing filament yarns.

Preferably, at least one part of the space net layers of two adjacent layers is partially overlapped, and the overlapped parts are mutually staggered.

Preferably, the space net layer is prepared from the following raw materials in parts by weight:

50-80 parts of ABS rubber powder, 10-25 parts of a compatilizer, 10-20 parts of a coloring agent, 200-300 parts of nano silver particles, 200-300 parts of nano silicon dioxide particles and 100-200 parts of glass fiber sections;

the length of the glass fiber yarn section is smaller than the thickness of the space net layer, and the glass fiber yarn section is distributed in the space net layer in a disordered state.

Preferably, the coloring agent is carbon black or black color master batch, and the compatilizer is maleic anhydride grafted compatilizer.

Preferably, the inner membrane and the outer membrane are both polypropylene fiber cloth.

Preferably, the filament is a hollow structure.

A preparation method of an anticorrosion and heat-insulation layer of an outer wall of a pipeline specifically comprises the following steps:

s1: preparing a tubular inner die tube, coating a layer of inner film on the inner film, and then placing the inner film into an injection head of an extruder, wherein the injection head is of an annular structure, the extruder is provided with a plurality of injection heads with different inner diameters, a plurality of wire outlet ends are arranged on the inner ring of the injection head, and the inner die tube and the injection head are coaxial and can reciprocate in the axial direction of the inner die tube;

s2: drying the ABS rubber powder in a drying box, adding the ABS rubber powder into a reaction kettle after the drying is finished, starting a stirrer and a heater of the reaction kettle, stirring and heating the ABS rubber powder, and then adding a compatilizer for a certain time;

s3: increasing the rotating speed of the reaction kettle, adding nano silver particles, nano silicon dioxide particles and a coloring agent, and keeping for a certain time;

s4: increasing the rotating speed of the reaction kettle, adding a glass fiber section, and keeping for a certain time;

s5: feeding the mixture into an extruder, wherein the extruder ejects a strand silk structure through an ejection head, and meanwhile, an inner die tube generates axial displacement, the displacement speed of the inner die tube is less than the silk discharging speed of the ejection head, the strand silk forms a hollow structure under the action of the ejection head, and curls are generated under the extrusion of the ejection head and under the condition that the contact between the strand silk and an inner film is blocked, and the strand silk and the inner film are mutually adhered to form a first spatial mesh layer positioned at the innermost layer;

s6: after the first spatial mesh layer in the S5 is finished, standing for a period of time, moving the inner mold pipe to the next spray head, and covering the second spatial mesh layer according to S5, wherein the density of the second spatial mesh layer is lower than that of the first spatial mesh layer, and part of filaments of the second spatial mesh layer enter the first spatial mesh layer to form partial overlapping and form connection in a mutually staggered mode;

s7: therefore, after the inner mould pipe is completely covered by the upper space net layer and stands for a period of time, the inner mould pipe enters the next injector head to realize the covering of the subsequent space net layer, and a plurality of space net layers which have different densities and are mutually overlapped and connected are formed;

s8: after all the space net layers are covered, cooling the space net layers, then coating an outer film on the space net layers, sealing two ends of the inner film and the outer film, then injecting a foaming substance between the inner film and the outer film, and standing for a period of time to allow the foaming substance to be fully foamed and formed in the space net layers;

s9: after the foaming material is formed, a coating layer is coated on the outer membrane, and the inner mould pipe is taken down to complete the whole manufacturing work.

Preferably, in step S8, the injection of the foaming substance is performed in a multi-point manner, specifically as follows:

a plurality of injection points are arranged on the outer membrane in the circumferential direction and the axial direction, and foaming substances are simultaneously injected into the space mesh layer through pipelines inserted into the injection points.

Preferably, the cladding has the design ring on the adventitia, and the adventitia laminating is in after the foaming material shaping on the inner wall of design ring.

The invention has the beneficial effects that:

(1) the anticorrosion heat-insulation layer combines anticorrosion and heat insulation, realizes anticorrosion and heat insulation at the same time, and forms an integrated structure, thereby avoiding the problem that the connection between the heat-insulation layer and the anticorrosion layer is not firm in the traditional construction and the problem that the defects between the layers are easy to occur in the traditional layered construction;

(2) the main layer of the anticorrosion and heat-insulation layer has a spatial net structure, and can form a spatial net structure in the main layer

The space reticular structure can form a large number of gaps, and when the outside is pressed, the gaps and the strand silk form good buffer, so that the space reticular structure has excellent pressure resistance degree and collision resistance, and also has excellent flexibility, and can reduce the damage of the bending part, so that the application range of the space reticular structure is improved, and the space reticular structure can be used for a straight pipe and a bent pipe; simultaneously formed space net structure and strand hollow

The structure of (3) forms a large number of gaps, can reduce heat transfer, and further has the effect of heat preservation; (3) the main layer of the anticorrosive heat-insulating layer adopts ABS rubber powder as the foundation, so that the strand silk has

The ABS rubber powder has better toughness, can effectively cope with bending in the using process, and simultaneously adds the nano silver particles and the nano silicon dioxide particles, so that on one hand, the mechanical strength of the ABS rubber powder is increased, on the other hand, the distribution area of the nano silver particles is larger by utilizing a spatial net structure, and further, the nano silver particles are combined with the small-size effect and the surface effect of the nano particles, the oxidation speed of the ABS rubber powder is improved, and further, the corrosion of some microorganisms to a pipeline is reduced;

(4) the invention also adds the glass fiber section on the basis of ABS rubber powder, which is beneficial to the aspect of the invention

The glass fiber yarns are combined with the ABS rubber, so that the strength of the strand silk is improved, and on the other hand, the glass fiber yarns are mixed with the ABS rubber, so that the glass fiber yarns are positioned on two interlaced strand silks in the yarn discharging process and then pass through gaps between the strand silks, a spatial net structure formed by the main layer is further enriched, and the strength of the net structure is improved;

(5) the invention injects foaming substance into the space net structure formed by the main layer to make the space net structure

The clearance of structure can be filled, on the one hand, can combine together with the foaming material and further improve space network structure's intensity and leakproofness, forms stronger interconnect through the foaming material simultaneously, and on the other hand, utilizes the foaming material further to improve the heat preservation effect.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

Fig. 1 is a schematic structural view of an anticorrosion and insulation layer of an outer wall of a pipeline provided by an embodiment of the invention.

Description of reference numerals: 1-inner membrane, 2-main layer, 201-space network layer and 3-outer membrane.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

As shown in figure 1, the invention provides an anticorrosion and insulation layer for the outer wall of a pipeline, which comprises an inner film 1, a main layer 2, an outer film 3 and a coating layer, wherein the inner film 1 and the outer film 3 are both polypropylene fiber cloth, and the coating layer is a cold winding belt;

the main layer 2 includes a plurality of spatial network layers 201 nested together, the spatial network layers 201 are formed by bending and interlacing yarn strips, and the degree of compactness of each spatial network layer 201 decreases from inside to outside, fig. 1 shows a schematic diagram of three spatial network layers 201, for convenience of illustrating the degree of compactness, fig. 1 shows filling lines with different proportions, it should be noted that the degree of compactness in the present invention refers to the degree of compactness of the distribution of the yarn strips of the spatial network layers 201, and it can also be considered that the larger the degree of compactness, the smaller the gaps formed by the spatial network layers 201.

Furthermore, in order to improve the clearance rate, the space net layer 201 can also have a hollow structure, and a large number of gaps are beneficial to improving the heat preservation effect;

because the space net layers 201 are formed by adopting the silk strips, a large number of gaps are formed in the space net layers 201, and the gaps can be utilized, so that two adjacent space net layers 201 can form partial overlapping, namely the silk strips of one layer can enter the other layer, and then the silk strips are bent to form staggering, so that the adjacent layers are mutually connected, the connection strength is improved, and the separation between the layers is reduced; in addition, a large number of gaps are formed, when the outside is pressed, good buffering can be formed through the gaps and the strand silk, the high pressure-resistant degree is achieved, the collision is resisted, meanwhile, the high flexibility is achieved, the damage of a bent part can be reduced, the overlapping and staggering between adjacent layers also enables the dislocation and the separation between the adjacent layers to be reduced during bending, the application range of the high pressure-resistant pipe is improved, the high pressure-resistant pipe can be used for a straight pipe and a bent pipe, meanwhile, the progressive arrangement is sequentially reduced from inside to outside in the compaction degree of each space net layer 201, the supporting strength which is closer to the inner layer is higher, and the pipe wall is protected better; in addition, the formed space net-shaped structure and the filament hollow structure form a large amount of gaps, so that the heat transfer can be reduced, and the heat preservation effect is further achieved;

in addition, in order to further improve the heat preservation effect and the connection strength, foaming substances, specifically, foaming glue, are filled in each space net layer 201; namely, the space net layer 201 formed by the main layer 2 is injected with foaming substances, so that the gap of the space net layer 201 is filled, on one hand, the space net layer 201 can be combined with the foaming substances to further improve the strength of the space net layer 201, and meanwhile, stronger interconnection is formed by the foaming substances, and on the other hand, the heat preservation effect is further improved by the foaming substances;

the space net layer 201 is prepared from the following raw materials in parts by weight:

50-80 parts of ABS rubber powder, 10-25 parts of a compatilizer, 10-20 parts of a coloring agent, 200-300 parts of nano silver particles, 200-300 parts of nano silicon dioxide particles and 100-200 parts of glass fiber sections;

wherein the coloring agent is carbon black or black color master batch, and the compatilizer is maleic anhydride grafted compatilizer;

the length of the glass fiber yarn section is smaller than the thickness of the space net layer 201, specifically, in the actual manufacturing process, the length of the glass fiber yarn section also needs to refer to the gap formed by the space net layer 201, it needs to be noted that the thickness of the space net layer 201 is larger than the gap formed by the space net layer 201, for example, the length of the glass fiber yarn section can be 1-1.5 times of the average gap of the space net layer 201, and the arrangement improves the strength of the yarn strip itself by combining the glass fiber yarn and the ABS rubber; on the other hand, be unordered mode after the glass fiber silk adds and arrange to make partly glass fiber silk be in on two crisscross strand silks, and then pass in the clearance between strand silks and strand silks, make glass fiber form the effect similar to the bridge, connect the strand silks of clearance both sides, further richen the space network structure that main layer 2 formed, improve this network structure's intensity.

Aiming at the anticorrosion and heat-insulation layer, the anticorrosion and heat-insulation layer is prefabricated, namely manufactured by a factory and then installed on site, and the preparation method of the anticorrosion and heat-insulation layer is as follows:

s1: preparing a tubular inner die tube, coating a layer of inner film 1 on the inner film, and then placing the inner film into an injection head of an extruder, wherein the injection head is of an annular structure, the extruder is provided with a plurality of injection heads with different inner diameters, a plurality of circumferentially distributed filament outlet ends are arranged on the injection head inner ring, and the inner die tube and the injection head are coaxial and can reciprocate in the axial direction of the inner die tube;

s2: drying the ABS rubber powder in a drying box at the drying temperature of about 85 ℃, adding the ABS rubber powder into a reaction kettle after drying is finished, starting a stirrer and a heater of the reaction kettle at the stirring speed of about 150rpm, stirring and heating the ABS rubber powder, and then adding a compatilizer for 10-15 minutes;

s3: the rotating speed of the reaction kettle is increased to 200-250rpm, and the nano silver particles, the nano silicon dioxide particles and the coloring agent are added and kept for 20-30 minutes;

s4: the rotating speed of the reaction kettle is increased to 270-300rpm, and the glass fiber section is added and kept for 20-30 minutes;

s5: feeding the mixture into an extruder, wherein the extruder ejects a strand silk structure through an ejection head, and meanwhile, an inner die tube generates axial displacement, the displacement speed of the inner die tube is less than the silk discharging speed of the ejection head, the strand silk forms a hollow structure under the action of the ejection head, and curls are generated under the extrusion of the ejection head and under the condition that the contact between the strand silk and an inner film is blocked, and the strand silk and the inner film are mutually adhered to form a first spatial mesh layer 201 positioned at the innermost layer;

s6: after the first spatial mesh layer 201 in S5 is finished, standing for 3-5 minutes, moving the inner mold pipe to the next spray head, and covering the second spatial mesh layer 201 according to S5, wherein the density of the second spatial mesh layer 201 is lower than that of the first spatial mesh layer 201 (which can be realized by the speed of filament discharge and the moving speed of the inner mold pipe), and a part of filaments of the second spatial mesh layer 201 enter the first spatial mesh layer 201 to form partial overlapping and form connection by interlacing with each other;

s7: therefore, after the inner mould pipe is completely covered by the upper space mesh layer 201 and stands for 3-5 minutes, the inner mould pipe enters the next injector head to realize the covering of the subsequent space mesh layer 201, and a plurality of space mesh layers 201 which have different densities and are mutually overlapped and connected are formed;

s8: after all the space net layers 201 are completely covered, cooling the space net layers to room temperature, then coating the outer film 3 on the space net layers, sealing two ends of the inner film 1 and the outer film 2, then injecting foaming substances between the inner film 1 and the outer film 2, and standing for a period of time to allow the foaming substances to be fully foamed and formed in the space net layers 201; when injecting the foaming substance, a plurality of injection points may be provided in both the circumferential direction and the axial direction of the outer membrane 3, and the foaming substance is simultaneously injected into the space network layer 201 through pipes inserted into these injection points; in addition, in order to ensure the regular size of the outer membrane 3 after foaming, a plurality of axially extending shaping rings are arranged on the outer membrane 3, when the outer membrane 3 is attached to the inner wall of the shaping rings after foaming materials are formed, the positioning rings can be combined together in a semi-ring mode and are coated on the outer membrane 3, and injection points are arranged on the corresponding positioning rings for the foaming materials to enter;

s9: after the foaming material is formed, a layer of coating layer is coated on the outer film 3, the inner mold pipe is taken down, the whole manufacturing work is completed, and the inner mold pipe is also aligned together in a semi-ring mode for being convenient to take out.

With respect to the above-described preparation method and the composition of the spatial network layer, we present a number of examples, in particular as follows:

example 1: in parts by weight

50 parts of ABS rubber powder, 10 parts of compatilizer, 10 parts of coloring agent, 200 parts of nano silver particles, 200 parts of nano silicon dioxide particles and 100 parts of glass fiber yarn segments;

example 2: in parts by weight

65 parts of ABS rubber powder, 20 parts of compatilizer, 15 parts of coloring agent, 250 parts of nano silver particles, 250 parts of nano silicon dioxide particles and 150 parts of glass fiber yarn segments;

example 3: in parts by weight

80 parts of ABS rubber powder, 25 parts of compatilizer, 20 parts of coloring agent, 300 parts of nano silver particles, 300 parts of nano silicon dioxide particles and 200 parts of glass fiber yarn sections;

preparing an anti-corrosion heat-insulation layer with the length of 3m, the inner diameter of 200mm and the outer diameter of 400mm according to the preparation method, and performing a bending resistance experiment, a compression resistance experiment and a heat conduction experiment;

wherein, the bending resistance test method comprises the following steps: the method adopts a suspension experiment mode, namely, two ends of the section of the anti-corrosion heat-insulation layer are placed on two supporting points, the same weight is applied to the middle part, and the distance between the weight and the ground is compared; wherein, a plurality of weights with different weights are required to be arranged for carrying out a plurality of groups of experiments; in addition, in order to reduce the influence of deformation of the hanging part during hanging, the contact area between the hanging part and the section of the anti-corrosion heat-insulation layer is increased as much as possible during hanging, for example, a section of rubber pad can be sleeved, and a heavy object is hung on the rubber pad;

the compression resistance test method comprises the following steps: placing the same weight at different positions of the section of the anti-corrosion heat-insulation layer, and observing or measuring the depth of the concave surface; wherein, a plurality of weights with different weights are required to be arranged for carrying out a plurality of groups of experiments;

the heat conduction experimental method comprises the following steps: taking an experimental pipeline, introducing hot water into the experimental pipeline, and measuring the temperature of the outer surface of the section of the anti-corrosion heat-insulation layer after a certain time;

specifically, three weights with different weights are set in the bending resistance test, wherein the weights are respectively 2kg, 4kg and 6 kg; three weights with different weights are arranged in the compression resistance experiment, wherein the weights are respectively 2kg, 4kg and 6 kg:

bending strength: example 1< example 2< example 3

Compressive strength: example 1< example 2< example 3

Heat conductivity: the difference between the three embodiments is small, the difference is within 3 ℃, and the embodiment 3 is slightly better;

for the above experimental results: the difference between the bending strength and the compressive strength is mainly reflected in the addition amount of the nano particles and the glass fiber filament segments and the foaming adhesive, because the addition of the nano particles and the glass fiber filament segments can increase the strength of the filament strands and the connection strength between the filament strands, the corresponding strength is further improved after the addition amount is increased, but it needs to be noted that the excessive addition also influences the molding of the filament strands, and therefore the addition amount needs to be within a reasonable interval range.

For this reason, according to the above examples 1 to 3, we also respectively perform the following comparative experiments, and the corrosion-resistant insulating layer obtained by the comparative experiments still has the following growth: the length is 3m, the inner diameter is 200mm, the outer diameter is 400mm, and the experimental conditions are the same as those in examples 1-3, and in order to fully embody the present invention, we selected the following comparison based on example 1:

comparative example 1:

on the basis of the embodiment 1, the addition of the nano silver particles and the nano silicon dioxide particles is cancelled, and other preparation steps are the same as the embodiment 1;

compared to example 1:

bending strength: example 1 outperformed comparative example 1; when 2kg of the powder is placed, the difference between the powder and the powder is small, and the difference is 3 mm; when the tea is placed for 6kg, the difference between the tea and the tea is large, and the difference is 22 mm;

compressive strength: example 1 outperformed comparative example 1; when the mixture is placed for 2kg, the difference between the two is not large, and the error is 2 mm; when the tea is placed for 6kg, the difference between the tea and the tea is large, and the difference is 15 mm;

heat conductivity: the difference between the two is small and is at 3 ℃;

comparative example 2:

on the basis of the embodiment 1, the addition of the glass fiber is eliminated, and other preparation steps are the same as the embodiment 1;

compared to example 1:

bending strength: example 1 outperformed comparative example 1; when 2kg of the powder is placed, the difference between the powder and the powder is small, and the difference is 2 mm; when the tea is placed for 6kg, the difference between the tea and the tea is large, and the difference is 34 mm;

compressive strength: example 1 outperformed comparative example 1; when the mixture is placed for 2kg, the difference between the two is not large, and the error is 2 mm; when the tea is placed for 6kg, the difference between the tea and the tea is large, and the difference is 35 mm;

heat conductivity: the difference between the two is not large and is 2 ℃;

comparative example 3:

on the basis of the embodiment 1, the addition of a foaming substance is cancelled, and other preparation steps are the same as the embodiment 1;

compared to example 1:

bending strength: example 1 outperformed comparative example 1; when the container is placed for 2kg, the difference between the two is large, and the difference is 16 mm; when the rice is placed for 6kg, the difference between the rice and the rice is large, and the difference is 51 mm;

compressive strength: example 1 outperformed comparative example 1; when the sample is placed for 2kg, the difference between the two samples is large, and the error is 11 mm; when the tea is placed for 6kg, the difference between the tea and the tea is large, and the difference is 42 mm;

heat conductivity: the difference between the two is large and is 12 ℃;

in conclusion, the strength of the anti-corrosion heat-insulation layer can be improved clearly by adding the glass fibers, the nano silicon dioxide particles and the nano silver particles, the strength is further improved by adding the foaming substance, and the heat insulation effect is further improved by adding the foaming substance.

Claims (7)

1. The anticorrosion and heat-insulation layer for the outer wall of the pipeline is characterized by comprising an inner film, a main layer, an outer film and a coating layer from inside to outside, wherein the main layer comprises a plurality of spatial net layers which are nested together, the compactness of each spatial net layer is reduced from inside to outside in sequence, and foaming substances are filled in each spatial net layer;

the space net layer is formed by bending and interlacing silk strips;

at least one part of the space net layers of two adjacent layers are overlapped, and the overlapped parts are mutually staggered;

the space net layer is prepared from the following raw materials in parts by weight:

50-80 parts of ABS rubber powder, 10-25 parts of a compatilizer, 10-20 parts of a coloring agent, 200-300 parts of nano silver particles, 200-300 parts of nano silicon dioxide particles and 100-200 parts of glass fiber sections;

the length of the glass fiber yarn section is smaller than the thickness of the space net layer, and the glass fiber yarn section is distributed in the space net layer in a disordered state.

2. The anticorrosive and heat-insulating layer for the outer wall of the pipeline as claimed in claim 1, wherein the thread strips are of hollow structure.

3. The pipe outer wall anticorrosion and insulation layer of claim 1, wherein the coloring agent is carbon black or black color master batch, and the compatilizer is maleic anhydride grafted compatilizer.

4. The anticorrosive and heat-insulating layer for the outer wall of the pipeline as claimed in claim 1, wherein the inner membrane and the outer membrane are both polypropylene fiber cloth.

5. The preparation method of the anti-corrosion and heat-insulation layer for the outer wall of the pipeline as claimed in claim 1 is characterized by comprising the following steps:

s1: preparing a tubular inner die tube, coating a layer of inner film on the inner film, and then placing the inner film into an injection head of an extruder, wherein the injection head is of an annular structure, the extruder is provided with a plurality of injection heads with different inner diameters, a plurality of wire outlet ends are arranged on the inner ring of the injection head, and the inner die tube and the injection head are coaxial and can reciprocate in the axial direction of the inner die tube;

s2: drying the ABS rubber powder in a drying box, adding the ABS rubber powder into a reaction kettle after the drying is finished, starting a stirrer and a heater of the reaction kettle, stirring and heating the ABS rubber powder, and then adding a compatilizer for a certain time;

s3: increasing the rotating speed of the reaction kettle, adding nano silver particles, nano silicon dioxide particles and a coloring agent, and keeping for a certain time;

s4: increasing the rotating speed of the reaction kettle, adding a glass fiber section, and keeping for a certain time;

s5: feeding the mixture into an extruder, wherein the extruder ejects a strand silk structure through an ejection head, and meanwhile, an inner die tube generates axial displacement, the displacement speed of the inner die tube is less than the silk discharging speed of the ejection head, the strand silk forms a hollow structure under the action of the ejection head, and curls are generated under the extrusion of the ejection head and under the condition that the contact between the strand silk and an inner film is blocked, and the strand silk and the inner film are mutually adhered to form a first spatial mesh layer positioned at the innermost layer;

s6: after the first spatial mesh layer in the S5 is finished, standing for a period of time, moving the inner mold pipe to the next spray head, and covering the second spatial mesh layer according to S5, wherein the density of the second spatial mesh layer is lower than that of the first spatial mesh layer, and part of filaments of the second spatial mesh layer enter the first spatial mesh layer to form partial overlapping and form connection in a mutually staggered mode;

s7: therefore, after the inner mould pipe is completely covered by the upper space net layer and stands for a period of time, the inner mould pipe enters the next injector head to realize the covering of the subsequent space net layer, and a plurality of space net layers which have different densities and are mutually overlapped and connected are formed;

s8: after all the space net layers are covered, cooling the space net layers, then coating an outer film on the space net layers, sealing two ends of the inner film and the outer film, then injecting a foaming substance between the inner film and the outer film, and standing for a period of time to allow the foaming substance to be fully foamed and formed in the space net layers;

s9: after the foaming material is formed, a coating layer is coated on the outer membrane, and the inner mould pipe is taken down to complete the whole manufacturing work.

6. The method for preparing an anticorrosion and insulation layer on the outer wall of a pipeline as claimed in claim 5, wherein in step S8, the injection of the foaming substance is performed in a multipoint manner, specifically as follows:

a plurality of injection points are arranged on the outer membrane in the circumferential direction and the axial direction, and foaming substances are simultaneously injected into the space mesh layer through pipelines inserted into the injection points.

7. The method for preparing the anticorrosion and insulation layer for the outer wall of the pipeline as claimed in claim 5, wherein the outer film is coated with a sizing ring, and the outer film is attached to the inner wall of the sizing ring after the foaming substance is molded.

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