CN108373569B

CN108373569B - PVC-U (polyvinyl chloride-U) pipe with shape memory function and preparation method and application thereof

Info

Publication number: CN108373569B
Application number: CN201810119716.1A
Authority: CN
Inventors: 曾富财; 汪磊; 李白千; 郑立贤; 刘在福
Original assignee: Rifeng Enterprise Foshan Co Ltd; Rifeng Enterprise Group Co Ltd; Rifeng Technology Co Ltd
Current assignee: Rifeng Enterprise Foshan Co Ltd; Rifeng Enterprise Group Co Ltd; Rifeng Technology Co Ltd
Priority date: 2018-02-06
Filing date: 2018-02-06
Publication date: 2021-03-02
Anticipated expiration: 2038-02-06
Also published as: CN108373569A

Abstract

The invention provides a PVC-U pipe with a shape memory function, a preparation method and an application thereof, wherein the PVC-U pipe with the shape memory function is prepared from the following raw materials in parts by mass: 100 parts of polyvinyl chloride resin, 1.5-8.0 parts of heat stabilizer, 0.1-6.0 parts of lubricant, 0-8 parts of plasticizer, 0.5-8 parts of processing modifier, 1-10 parts of toughening agent, 0.02-5 parts of crosslinking agent, 0-6 parts of acid absorbent and 0-30 parts of filler. The PVC-U pipe has a good shape memory function, and is particularly suitable for repairing a damaged pipeline under the condition of micro-excavation or no-excavation. In addition, the PVC-U pipe is simple in preparation process and low in cost.

Description

PVC-U (polyvinyl chloride-U) pipe with shape memory function and preparation method and application thereof

Technical Field

The invention relates to the technical field of preparation of PVC-U pipes with shape memory functions, in particular to a PVC-U pipe with a shape memory function and a preparation method and application thereof.

Background

With the successive arrival of the service life of the pipelines in the urban underground pipe network, the pipeline repairing technology attracts more and more attention. The traditional pipeline repairing and replacing technology not only leads to high construction cost, but also brings serious interference and influence to residents in construction areas and community life.

The technology for repairing the lining of U-shaped plastic pipe based on shape memory principle is to press the extruded round plastic pipe (with round cross section) into U shape by a deforming device to reduce the diameter or reduce the diameter. After the pipe is penetrated into a damaged pipeline, the damaged pipeline is heated or hot water or steam is introduced to restore the shape of the pipe to be shaped for the first time, so that the repairing effect is achieved. The method can complete the pipeline repairing function only by micro-excavation or non-excavation, so that the method has the advantages of low comprehensive cost, simple construction, short construction period, small environmental influence, good construction safety and the like, and is beneficial to improving the management technical level of urban construction.

The PVC-U pipe (hard polyvinyl chloride pipe) has the characteristics of excellent physical and chemical properties, corrosion resistance, small fluid resistance, high strength and rigidity, light weight, durability and the like, so that the PVC-U pipe has remarkable advantages in the sewage discharge and drainage system repair of an underground pipe network. However, the common PVC-U pipe has the defects of poor toughness, easy cracking, low deformation recovery rate, low deformation speed, small deformation and the like, does not achieve an ideal deformation memory effect, and cannot finish pipeline repair through a U-shaped lining repair technology. Therefore, the PVC material or the pipe needs to be physically or chemically modified to improve the deformation memory function of the PVC-U pipe. Chinese patent application (publication number: CN03114031) discloses a method for manufacturing and using a flat pipe, which realizes that the pipe has the function of deformation memory by a method of crosslinking an extruded polyvinyl chloride pipe by an electron accelerator or gamma irradiation. However, in order to achieve the deformation memory effect, the PVC-U pipe has high crosslinking requirement, the gel degree reaches 60%, and special equipment is required to realize chemical crosslinking of molecular chains, so that the processing technology is very complex, and the application of the PVC-U deformation memory pipe in the non-excavation field is greatly limited.

Disclosure of Invention

The PVC-U pipe has a good shape memory function, and is particularly suitable for repairing damaged pipelines under the condition of micro-excavation or no-excavation. In addition, the PVC-U pipe is simple in preparation process and low in cost.

In order to achieve the purpose, the invention adopts the following technical scheme:

the invention provides a PVC-U pipe with a shape memory function, which is prepared from the following raw materials in parts by mass:

100 parts of polyvinyl chloride resin, 1.5-8.0 parts of heat stabilizer, 0.1-6.0 parts of lubricant, 0-8 parts of plasticizer, 0.5-8 parts of processing modifier, 1-10 parts of toughening agent, 0.02-5 parts of crosslinking agent, 0-6 parts of acid absorbent and 0-30 parts of filler.

Based on the formula system of the PVC-U pipe, the pipe with good shape memory function can be prepared.

In a preferred embodiment of the invention, the mass parts of the plasticizer are preferably > 0 and ≦ 8 parts; more preferably 0.5 to 5 parts by mass. The optimal mass part of the acid absorbent is more than 0 and less than or equal to 6, which is favorable for avoiding the obvious coloring phenomenon of the color of the pipe and avoiding the yellowing of the pipe; more preferably 0.5 to 5.5 parts by mass. Preferably, the filler is present in an amount of greater than 0 parts by mass and less than or equal to 30 parts by mass, more preferably 5 to 25 parts by mass. The crosslinking agent is more preferably 0.06 to 3 parts by mass. Based on the preferable use amount of the components, the product with better comprehensive properties such as better shape memory function, better deformation recovery rate, better low-temperature flexibility, no obvious coloring phenomenon, excellent mechanical property and the like can be obtained.

The invention is not particularly limited, and the required pigment can be added when preparing the PVC-U pipe according to the actual production requirement.

Preferably, the crosslinking agent of the PVC-U pipe material comprises one or more of an organic peroxide crosslinking agent, a dithiotetramethylthiuram crosslinking agent and a mercapto-s-triazine crosslinking agent.

According to the invention, through the optimization of the cross-linking agent, the cross-linking reaction is easier to control, the problem of thermal degradation in the cross-linking process of PVC is basically eliminated, the coloring phenomenon in the processing process is inhibited, and the apparent quality and physical properties of the pipe are improved. Preferably, when the crosslinking agent comprises an organic peroxide crosslinking agent, a monomer with a carbon-carbon double bond is further added into the crosslinking agent, so that the dosage of the organic peroxide crosslinking agent can be reduced, and the severe coloring phenomenon accompanied with peroxide crosslinking is eliminated. More preferably, the mass percentage of the monomer having a carbon-carbon double bond in the total mass of the organic peroxide crosslinking agent and the monomer having a carbon-carbon double bond is preferably 85% to 98%. Further preferably, the monomer with a carbon-carbon double bond is selected from one or more of diallyl phthalate (DAP), triallyl isocyanurate (TAIC), triallyl cyanurate (TAC) and N, N' -m-phenylene bismaleimide (HVA-2). In the PVC-U pipe material of the present invention, preferably, the organic peroxide crosslinking agent comprises dicumyl peroxide (DCP).

In the PVC-U pipe material, preferably, the mercapto-s-triazine cross-linking agent comprises 2-n-butylamino-4, 6-dimercapto-s-triazine. The cross-linking agent is preferably selected, active chlorine atoms on PVC molecular chains are respectively captured through the nucleophilic substitution effect of sulfydryl, and the multi-sulfydryl compound grafted on the PVC connects different PVC molecular chains through the sulfydryl to form a cross-linking network, so that the degradation and color change phenomena of the PVC are avoided, and the cross-linked PVC product with excellent mechanical properties can be obtained.

The PVC-U pipe disclosed by the invention is subjected to low-degree crosslinking by controlling the using amount of the crosslinking agent, wherein the using amount is preferably 0.02-5 parts based on 100 parts of polyvinyl chloride resin. In a further preferred scheme, the dosage of the cross-linking agent is more preferably controlled within 3-10%, and more preferably within 3-8% of the gel degree (or cross-linking degree) of the PVC-U pipe.

In the PVC-U pipe according to the present invention, the toughening agent is preferably selected from one or more of vinyl acetate monomer, alkyl acrylate monomer, and carbon monoxide (CO), and a block copolymer polymerized from ethylene monomer (i.e. ethylene), preferably a mixture of one or more of ethylene-vinyl acetate copolymer (EVA), ethylene-butyl acrylate copolymer (EBA), ethylene-methyl acrylate copolymer (EMA), ethylene-ethyl acrylate copolymer (EEA), ethylene-vinyl acetate-carbonyl copolymer (E/VA/CO), and ethylene-butyl acrylate-carbonyl copolymer (E/nBA/CO). The inventor of the application finds that the toughening agent is preferably adopted in the formula system of the invention, and a side group consisting of polar vinyl acetate or alkyl acrylate or carbonyl is introduced into an ethylene main chain, so that the regularity of the molecular chain is reduced, the crystallinity of ethylene on the main chain is reduced, and the distance between polymer macromolecular chains is increased, therefore, the toughening agent has excellent low-temperature performance and flexibility, good processing thermal stability and larger filler receptivity, and can endow PVC-U pipes with excellent low-temperature impact performance, bending crack resistance and environmental stress crack resistance; in addition, the toughening agent is preferably compounded with PVC and then is matched with other components to improve the freedom degree of movement of PVC molecular chains, so that the molecular chains are curled to recover to a thermodynamic equilibrium state, and the shape recovery capability of PVC is further improved.

The plasticizer of the PVC-U pipe can adopt corresponding raw materials commonly used in the field. In a preferred embodiment of the present invention, the plasticizer is preferably selected from one or more of epoxidized soybean oil, trioctyl trimellitate, butyl epoxystearate, dibutyl sebacate, and polytrimethylene adipate to improve the shape recovery of the resulting pipe.

The lubricant of the PVC-U pipe can adopt corresponding raw materials commonly used in the field. In a preferred embodiment of the present invention, the lubricant is preferably selected from one or more of a mixture of fatty alcohol, fatty acid ester, aromatic dicarboxylic acid ester, fatty acid polyol complex ester, fatty acid amide, ethylene-vinyl acetate copolymer wax, OP wax, S wax, E wax, carnauba wax, polyethylene oxide wax, hydrocarbon-based wax. The optimized lubricant is adopted, so that the fluidity of the PVC melt is improved by providing internal and external balanced lubricating capability while maintaining the physical properties, low precipitation degree and good metal stripping property, and further the comprehensive performance of the prepared pipe is improved.

The fatty acid ester is a mixture of one or more compounds formed by esterification reaction of fatty acid and monohydric alcohol or polyhydric alcohol; preferably, the fatty acid ester comprises one or more of butyl stearate, glyceryl monostearate, stearyl stearate, glyceryl monooleate, glyceryl dioleate, glyceryl ricinoleate and distearate adipate.

The fatty acid-polybasic alcohol acid composite ester is a compound formed by mixing and esterifying polyalcohol, polybasic acid and fatty acid; preferably, the fatty acid polyol complex ester comprises one or a mixture of two of adipic acid-pentaerythritol stearate (e.g. the product having the trade mark emeryl LOXIOL G70, germany), adipic acid-pentaerythritol oleate (e.g. the product having the trade mark emeryl LOXIOL G71, germany).

The fatty acid amides preferably include mono-fatty amides and di-fatty amides; preferably, the mono-fatty amide comprises a mixture of one or more of stearic acid amide, erucic acid amide, ricinoleic acid amide; preferably, the double fatty amide is one or a mixture of two of N, N '-ethylene bis stearamide and N, N' -ethylene bis ricinoleic acid amide.

The hydrocarbon-based wax preferably includes one or more of a homopolymeric polyethylene wax and a branched linear paraffin wax. The branched linear paraffin wax may be Rheolub RL-165, Rheolub RL-170, Rheolub RL-915, and the like, available from Honeywell, USA.

The processing modifier of the PVC-U pipe can adopt corresponding raw materials commonly used in the field. In a preferred embodiment of the present invention, the processing modifier is preferably selected from but not limited to a mixture of one or more of a copolymer of methacrylate and alkyl acrylate, a copolymer of methyl methacrylate-styrene-alkyl acrylate, a terpolymer of methacrylate-acrylonitrile-alkyl acrylate, polystyrene with a weight average molecular weight of 1000 to 10000Da, and poly alpha-methyl styrene, and the preferred processing modifier can improve the overall performance of the pipe.

The PVC-U pipe material of the invention can adopt corresponding raw materials commonly used in the field, such as one or a mixture of more selected from but not limited to SG-5, SG-4 and SG-3. In a preferred embodiment of the present invention, the polyvinyl chloride resin preferably has an average polymerization degree of 981-1370 and a K value of 66 to 72.

The PVC-U pipe material can adopt corresponding raw materials commonly used in the field, preferably, the acid absorbent. In a preferred embodiment of the present invention, the acid absorbent is preferably selected from one or more of magnesium oxide (MgO), zinc oxide (ZnO), and hydrotalcite.

The filler of the PVC-U pipe can adopt corresponding raw materials commonly used in the field. In a preferred embodiment of the present invention, the filler is preferably selected from one or more of white carbon, calcium carbonate, china clay, montmorillonite, zeolite, talcum powder and barium sulfate; the addition of the above-mentioned filler is preferable, and the shape recovery temperature can be adjusted by increasing or decreasing the amount of the inorganic filler to be added in addition to cost reduction.

The heat stabilizer of the PVC-U pipe can adopt corresponding raw materials commonly used in the field. In a preferred embodiment of the present invention, the heat stabilizer is preferably selected from one or more of calcium zinc composite stabilizer, organic tin stabilizer and magnesium aluminum zinc composite stabilizer; further preferably, the organic tin stabilizer is one or more of methyl tin mercaptide, butyl tin mercaptide and octyl tin mercaptide. The heat stabilizer preferably adopted by the invention can be from commercial products, is convenient for industrialization, has the characteristics of stability, no toxicity and no pollution, and accords with the trend of environmental development.

The PVC-U pipe can be prepared into a pipe with good memory deformation function, high deformation recovery rate and good comprehensive performance by the formula system.

The invention provides a preparation method of the PVC-U pipe material, which comprises the following steps:

1) preparing the components in the raw materials into a PVC-U mixed material;

2) adding the PVC-U mixed material into an extruder to be extruded and molded into a PVC-U pipe;

preferably, when the PVC-U mixed material is prepared in the step 1), hot mixing is carried out firstly and then cold mixing is carried out, each raw material in the formula is added in the hot mixing process, the hot mixing is changed into cold mixing until the temperature is increased to 120-130 ℃, the cold mixing is carried out until the temperature is reduced to 50-60 ℃, the crosslinking agent and the acid absorbent are preferably added when the temperature is increased to 100-110 ℃ in the hot mixing process, and the rest raw materials are added in the hot mixing process at the temperature lower than 100 ℃. Further preferred specific operations for formulating a PVC-U blend include: the PVC-U mixed material is prepared by the steps of carrying out hot mixing on polyvinyl chloride resin, a heat stabilizer, a processing modifier, a toughening agent and a plasticizer, adding a filler and a lubricant for mixing when the hot mixing temperature is increased to 75-85 ℃, adding a crosslinking agent and an acid absorbent when the temperature is increased to 110 ℃ for processing, continuing mixing until the hot mixing temperature is increased to 120 ℃ for processing and 130 ℃, then converting into cold mixing, carrying out cold mixing until the cold mixing temperature is reduced to 50-60 ℃, and discharging. Further preferably, the hot mixing is performed in a high-speed mixing pot (or called hot mixing pot) in a high-speed mixing unit, the cold mixing is performed in a cold mixing pot in the high-speed mixing unit, and the high-speed mixing unit is a device well known in the art and is not described in detail herein. The hot mixing in the high-speed mixing pot is high-speed hot mixing, the stirring speed of the high-speed mixing pot is preferably 500-1000rpm in the high-speed hot mixing process, the cold mixing in the cold mixing pot is low-speed cold mixing, and the stirring speed of the cold mixing pot is preferably 50-100rpm in the low-speed cold mixing process. The optimized PVC-U mixed material operation is adopted, which is beneficial to better cooperative matching among all the components, and the product with better performance is prepared.

Preferably, the step 2) is carried out in a double-screw extruder, and the temperature of each zone of the double-screw extruder is 160-230 ℃ during extrusion molding; in a particular embodiment, the twin screw extruder body may be a conical twin screw extruder.

The PVC-U pipe with the shape memory function is particularly suitable for repairing damaged pipelines under the condition of micro-excavation or non-excavation.

The third aspect of the invention provides a method for processing a PVC-U pipe, which comprises the steps of heating the PVC-U pipe or the PVC-U pipe prepared by the preparation method to 90-130 ℃ to enable the PVC-U pipe to be in a high elastic state, pressing the PVC-U pipe to deform, cooling the deformed pipe to 20-70 ℃ to enable the deformed pipe to be in a glass state; a pipe that exhibits a glassy state that can retain its deformed shape at room temperature. The deformed pipe processed and prepared based on the method is very suitable for repairing the damaged pipeline under the condition of micro-excavation or no-excavation, and has convenient transportation and small occupied space; during construction, the steel plate can be heated (by heating methods such as introducing hot water or steam) to a high elastic state again, and the steel plate can be restored to the original shape, so that the construction is simple, the construction period is shortened, the environmental influence is small, and the construction safety is good.

Preferably, the cooling is to cool the PVC-U pipe heated to 90-130 ℃ with cooling water within 0-120s after the PVC-U pipe is pressed and deformed until the temperature of the PVC-U pipe is reduced to 20-70 ℃, so that the shape of the pipe after the pressing and deformation can be fixed and can be maintained at room temperature. Preferably, the cooling is carried out with cooling water at 5-20 ℃;

preferably, in the step 2) of the method, the prepared PVC-U pipe is a cylindrical pipe; the pressing is to deform the circular cross section of the cylindrical PVC-U tubing made by the aforementioned method, preferably to deform the circular cross section of the PVC-U tubing to a shape having an internal recess, more preferably to a U-shape or substantially U-shape.

The invention provides an application of the PVC-U pipe with the shape memory function or the PVC-U pipe with the shape memory function prepared by the preparation method in repairing pipelines. For example, for repair of damaged pipelines or for renovation and maintenance of pipelines.

The glassy state as used herein means: in a lower temperature environment, the chain segment motion is frozen, so that only the bond length and the bond angle of the main chain can be slightly changed, the material is in a rigid solid state, and has little deformation under the action of external force, and the material is similar to glass, so the state is called as a glass state. This concept is common general knowledge in the art.

The high elastic state referred to herein means: if the ambient temperature corresponding to the glass state of the material is continuously raised to a certain temperature, the molecular chain can continuously change conformation through the rotation in the single bond under the action of external force, the chain segment motion is excited, the deformation of the material is obviously increased, and the deformation is relatively stable in a subsequent certain temperature interval, and the state is called a high-elasticity state. This concept is common general knowledge in the art.

The glass transition temperature as used herein means: the transition from a glassy state to a highly elastic state is called the glass transition, and the corresponding transition temperature is called the glass transition temperature. This concept is common general knowledge in the art.

Based on the raw material formula system of the PVC-U pipe, the PVC-U pipe with the shape memory function can be prepared. The balanced design of the plasticizing system and the crosslinking system in the formula system can improve the plasticizing condition of resin in the extrusion process of the PVC-U pipe, and regulate and control the proportion of a shape-memorizing stationary phase and a reversible phase which can reversibly harden and soften along with the temperature change in a PVC molecular chain. Heating the extruded round pipe to be above the glass transition temperature to be in a high elastic state, and quickly cooling and shaping after deforming the round pipe through external force; if the temperature is heated to be higher than the glass-transition temperature again, the existence of the reversible phase and the fixed phase with proper proportion enables the molecular chain to move fully and freely, the fixed phase with enough strength supports the internal stress to drive the molecular chain to be curled and return to a thermodynamic equilibrium state, and the initial shape is macroscopically memorized. In a further preferred scheme, the toughening system of the formula system is optimally designed and matched with each component of the formula system, so that the low-temperature impact property and the stress cracking resistance of the pipe are improved, the deformation is favorably implemented, the deformation recovery rate can be further improved, and the PVC-U pipe is endowed with a better shape memory function.

The technical scheme provided by the invention has the following beneficial effects:

the PVC-U pipe with better deformation memory function can be prepared based on the PVC-U pipe formula system, the preparation process is simple, the cost is low, and the prepared PVC-U pipe with the shape memory function can realize the repair effect on the damaged pipeline under the condition of micro-excavation or no-excavation.

The PVC-U pipe with the shape memory function is prepared based on the formula system, and the polyvinyl chloride resin is taken as a raw material, an optimized plasticizing system, a toughening system, a micro-crosslinking system and the like are assisted, and all the components are combined in a certain proportion, so that the polyvinyl chloride resin is fully plasticized under the action of shearing force and heat in the extrusion processing process, and the plasticizing degree is improved. Micro-crosslinking occurs in the plasticizing process, a system with a three-dimensional physical crosslinking network structure taking microcrystals as crosslinking points and a slightly crosslinked chemical crosslinking network structure coexisting is formed, and the system serves as a stable stationary phase. And based on the formula system of the invention, in the preparation process, due to slight chemical crosslinking, amorphous molecular chains still exist in a large amount and act as a reversible phase, and the amorphous molecular chains can become hard or soft along with the change of temperature. When the shaped pipe is heated to a high elastic state and stress is applied to deform the pipe, and then the pipe is rapidly cooled to freeze the polymer chain segment to a glass state, at the moment, the incomplete reversible deformation is necessarily frozen in the polymer chain in the form of internal stress. If the secondary formed deformed pipe is heated to a high elastic state, the incomplete reversible shape is completed under the drive of internal stress due to the existence of a fixed phase and a reversible phase with proper proportion, and the material is recovered to the original state under the macroscopic condition, so that the PVC-U pipe has an excellent shape memory function.

According to the invention, a proper amount of cross-linking agent is added into a formula system to carry out micro-cross-linking on the PVC material, so that the proportion of the stationary phase in a molecular structure is further improved, and the stability of the stationary phase is enhanced, thereby enabling the PVC-U pipe to have the advantages of large shape, high shape speed, high shape recovery rate and the like. Further, the cross-linking reaction is easier to control by optimizing the cross-linking agent, the problem of thermal degradation in the cross-linking process of PVC is basically eliminated, the coloring phenomenon in the processing process is inhibited, and the apparent quality and the physical property of the pipe are improved. In addition, the cross-linking degree of the formula system is very small, so special equipment is not needed for processing, the plasticity is good, and the reclaimed materials can be recycled. For some PE type shape memory pipes for repairing drainage pipelines in the market, as the requirement on the degree of crosslinking is very high and the processing difficulty is high, special equipment is required to realize the crosslinking of molecular chains, the processing technology is very complex, and simultaneously, as the degree of crosslinking is very high, the PE type shape memory pipes basically lose plasticity, so that reclaimed materials cannot be recycled; the present invention overcomes these disadvantages.

Drawings

FIG. 1 is a schematic cross-sectional view of a round PVC-U tube (before pressing) made in one embodiment;

FIG. 2 is a schematic cross-sectional view of a deformed "U" shaped PVC-U pipe (after pressing) in one embodiment.

Detailed Description

In order to better understand the technical solution of the present invention, the following examples are further provided to illustrate the present invention, but the present invention is not limited to the following examples.

The raw materials used in the examples or comparative examples of the present invention were all commercially available, and some of the raw materials used were as follows:

polyvinyl chloride resin: zhongtai chemical SG-5, SG-4, SG-3. Calcium zinc heat stabilizer: CZ-8601E-2, Chengjiang. Lubricant polyethylene oxide wax: innospec VISCOWAX 252, germany. Methacrylate-ethyl acrylate copolymer: rohm & Hass Paraloid K-120N, USA. Ethylene-vinyl acetate-carbonyl copolymer: DuPont Elvaloy 741, USA. Dicumyl peroxide (DCP): chemical agents of the national drug group, ltd. Diallyl phthalate (DAP): daiso Monoplex DAP, Japan. Octyl tin mercaptide: arkema T-890, France. Fatty alcohol: hubei prefers pentaerythritol. Epoxidized Soybean Oil (ESO): zilu petrochemical. Monooleic acid monoglyceride: emery LOXIOL G10, Germany. Methyl methacrylate-ethyl acrylate copolymer: rohm & Hass Paraloid K-125, USA. Ethylene-butyl acrylate-carbonyl copolymer (E/nBA/CO): DuPont Elvaloy HP441, usa. Dithiotetramethylthiuram (TMTD): industrial grade, zhengzhou double strength chemical products limited. OP wax: clariant ROWAX, Germany. Homopolymerized polyethylene wax: honeywell AC-316A, USA. Epoxy Butyl Stearate (EBST): golden brocade chemical company, ltd. Methyl methacrylate-styrene-butyl acrylate copolymer: kane Ace PA-100, Japan. Triallyl isocyanurate (TAIC): shanghai Fanglida Chemicals Ltd. Methyl tin mercaptide: SunAce SAK-MT9001 Singapore. N, N' -ethylene bis stearamide: KAOWAX EB-FF in Japan. Carnauba wax: brazil FONCEPI Carnauba Wax T3. Adipic acid-pentaerythritol stearate: emery LOXIOL G7, Germany. Trioctyl trimellitate (TOTM): zilu petrochemical. Ethylene-methyl acrylate copolymer (EMA): DuPont Elvaloy AC 1124, USA. Magnesium-aluminum-zinc composite heat stabilizer: guangdong Sendeli CZX-368B. Stearyl alcohol stearate: emery LOXIOL G30, Germany. Aromatic dicarboxylic acid ester (distearyl phthalate): emery LOXIOL G60, Germany. Hydrocarbon-based wax: honeywell Rheochem RL-165, USA. Poly a-methylstyrene: amoco Resin 18-210 in the United states. Ethylene ethyl acrylate copolymer (EEA): DuPont Elvaloy AC 2116, usa. 2-n-butylamino-4, 6-dimercapto-s-triazine (DB): guangzhou Qian exhibition chemical products, Inc. Fischer-Tropsch wax: lu' an LA-W60. CPE-135A, Shandong Nichidae. Glyceryl monostearate: emery LOXIOL G12, Germany. Ethylene-vinyl acetate copolymer wax (EVA wax): honeywell AC-400A, USA.

Example 1

The PVC-U pipe with the shape memory function is prepared, and the formula comprises the following components in parts by mass:

polyvinyl chloride resin SG-5: 100 parts of (A); calcium zinc heat stabilizer CZ-8601E-2: 3.5 parts; lubricant polyethylene oxide wax: 0.5 part; copolymer of processing modifier methacrylate and ethyl acrylate: 1.5 parts; ethylene-vinyl acetate-carbonyl copolymer (toughening agent): 6 parts of (1); 0.58 part of a crosslinking agent (wherein, dicumyl peroxide (DCP): 0.08 part, diallyl phthalate (DAP): 0.5 part); acid absorbent magnesium oxide: 3.0 parts of (B); calcium carbonate as filler: 20 parts of (1); 2.0 parts of pigment titanium dioxide.

The method for preparing the PVC-U pipe with the shape memory function specifically comprises the following steps:

(1) according to the proportion, polyvinyl chloride resin, a heat stabilizer, a processing modifier, a toughening agent and a plasticizer (0 part of plasticizer is added in the embodiment) are put into a high-speed mixing pot of a high-speed mixing unit (Zhang Hou Yili SRL-Z800/2500) to be subjected to high-speed hot mixing (the stirring speed is 660rpm), when the mixing temperature is raised to 80 ℃, filler, pigment and a lubricant are added, when the hot mixing temperature is raised to 105 ℃, a crosslinking agent and an acid absorbent are added, when the temperature is raised to 125 ℃, the mixture is put into a cold mixing pot, and when the temperature is raised to 55 ℃, the mixture is subjected to low-speed cold mixing (the stirring speed is 51rpm) to 55 ℃, and then the PVC-U mixed material.

(2) Extruding a pipe: the PVC-U mixed material is added into a conical twin-screw extruder and extruded into a cylindrical pipe (or a round pipe) with the nominal outer diameter of 110mm, wherein the temperature of each zone of the extruder is 160 ℃ and 230 ℃. The tube obtained in the step is the PVC-U tube with the shape memory function. Next, it is press-deformed by step (3).

(3) Folding into a U shape: heating the extruded round pipe (or called as a cylindrical pipe) to 110 ℃ to enable the pipe to be in a high-elasticity state, pressing the pipe to deform, pressing to enable the round cross section of the round pipe to be deformed into a U shape, and rapidly cooling the deformed pipe by using cooling water at 15 ℃ within 30s after deformation until the temperature of the pipe is reduced to below 50 ℃ to enable the pipe to be in a glass state, so that the deformed U shape of the pipe can be stored at room temperature. The tubing before and after deformation is shown schematically in figures 1 and 2, respectively.

Example 2

polyvinyl chloride resin SG-5: 100 parts of (A); octyl tin mercaptide T-890: 2.0 parts of (B); lubricant fatty alcohol: 0.5 part; lubricant mono-glycerol monooleate: 0.2 part; plasticizer Epoxidized Soybean Oil (ESO): 2 parts of (1); processing modifier methyl methacrylate-ethyl acrylate copolymer: 0.8 part; toughener ethylene-butyl acrylate-carbonyl copolymer (E/nBA/CO): 5 parts of a mixture; crosslinker tetramethylthiuram dithionate (TMTD): 2.5 parts; acid absorbent (3.0 parts of magnesium oxide; 2.0 parts of zinc oxide); calcium carbonate as filler: 15 parts of pigment titanium dioxide and 2.0 parts of pigment titanium dioxide.

The specific steps of the method for preparing the PVC-U pipe with the shape memory function in this embodiment are the same as those of embodiment 1, and are not described herein again.

Example 3

polyvinyl chloride resin SG-5: 80 parts of a mixture; polyvinyl chloride resin SG-3: 20 parts of (1); calcium zinc heat stabilizer CZ-8601E-2: 3.8 parts; lubricant OP wax: 0.8 part; 0.1 part of lubricant homopolymerized polyethylene wax; plasticizer butyl epoxy stearate (EBST): 0.5 part; processing modifier methyl methacrylate-styrene-butyl acrylate copolymer: 1.2 parts; toughening agent ethylene-vinyl acetate-carbonyl copolymer (E/VA/CO): 4 parts of a mixture; 1.6 parts of a crosslinking agent (DCP: 0.1 parts; triallyl isocyanurate (TAIC): 1.5 parts); acid absorbent zinc oxide: 2 parts of (1); filler talc powder: 8 parts of pigment titanium dioxide and 2.0 parts of pigment titanium dioxide.

Example 4

The composition for preparing the PVC-U pipe with the shape memory function comprises the following components in parts by mass:

polyvinyl chloride resin SG-5: 100 parts of (A); heat stabilizer methyl tin mercaptide SAK-MT 9001: 1.5 parts; lubricant N, N' -ethylene bis stearamide: 0.5 part; lubricant carnauba wax: 0.3 part; lubricant adipic acid-pentaerythritol stearate: 0.5 part; plasticizer trioctyl trimellitate (TOTM): 2 parts of (1); processing modifier methyl methacrylate-styrene-butyl acrylate copolymer: 2.0 parts of (B); toughener ethylene-methyl acrylate copolymer (EMA): 6 parts of (1); 0.86 parts of crosslinking agent (DCP: 0.06 parts; 0.8 parts of diallyl phthalate (DAP)); acid absorbent magnesium oxide: 5 parts of a mixture; filling white carbon black: 10 parts of (A); 2.0 parts of pigment titanium dioxide.

Example 5

polyvinyl chloride resin SG-5: 60 parts; polyvinyl chloride resin SG-4: 40 parts of a mixture; magnesium-aluminum-zinc composite heat stabilizer CZX-368B: 3.6 parts; lubricant distearyl phthalate: 0.3 part; lubricant hydrocarbon-based wax: 0.2 part; plasticizer trioctyl trimellitate (TOTM): 4 parts of a mixture; processing modifier poly-a-methylstyrene: 1.6 parts; toughener ethylene-ethyl acrylate copolymer (EEA): 8 parts of a mixture; crosslinker 2-n-butylamino-4, 6-dimercapto-s-triazine (DB): 1.8 parts; acid absorbent magnesium oxide: 5.5 parts; calcium carbonate as filler: 18 parts of a mixture; 2.0 parts of pigment titanium dioxide.

Comparative example 1

The comparative example is compared by adopting a preparation formula system of a common PVC-U drainage pipe.

The raw material formula comprises the following components in parts by mass:

polyvinyl chloride resin SG-5: 100 parts of (A); calcium zinc heat stabilizer CZ-8601E-2: 3.5 parts; lubricant fischer-tropsch wax: 0.5 part; processing modifier methyl methacrylate-ethyl acrylate terpolymer: 2.0 parts of (B); calcium carbonate as filler: 20 parts of pigment titanium dioxide and 2.0 parts of pigment titanium dioxide.

The preparation method specifically comprises the following steps:

(1) and (2) putting the polyvinyl chloride resin, the heat stabilizer and the processing modifier into a high-speed mixing pot of a high-speed mixing unit according to the proportion, carrying out high-speed hot mixing, adding the filler, the pigment and the lubricant when the temperature of the mixed materials is increased to 80 ℃, transferring into a cold mixing pot after the temperature is increased to 125 ℃, carrying out low-speed cold mixing until the temperature is 55 ℃, and discharging to obtain the PVC-U mixed material.

(2) Extruding a pipe: adding the PVC-U mixed material into a conical double-screw extruder to be extruded into a round pipe with the nominal outer diameter of 110mm, wherein the temperature of each zone of the extruder is 160-230 ℃.

(3) Folding into a U shape: heating the extruded round pipe to 115 ℃ to enable the pipe to be in a high-elasticity state, pressing the pipe to deform, deforming the circular cross section of the pressed round pipe into a U shape, and quickly cooling the deformed pipe by using cooling water at 15 ℃ within 30s after deformation until the temperature of the pipe is reduced to 50 ℃ to be in a glass state, so that the U-shaped pipe can be stored at room temperature.

Example 6

The raw material formula comprises the following components in parts by mass:

polyvinyl chloride resin SG-5: 60 parts; polyvinyl chloride resin SG-4: 40 parts of a mixture; magnesium-aluminum-zinc composite heat stabilizer CZX-368B: 3.6 parts; lubricant distearyl phthalate: 0.3 part; lubricant hydrocarbon-based wax: 0.2 part; plasticizer trioctyl trimellitate (TOTM): 4 parts of a mixture; processing modifier poly-a-methylstyrene: 1.6 parts; toughening agent CPE-135A: 8 parts of a mixture; crosslinker 2-n-butylamino-4, 6-dimercapto-s-triazine (DB): 1.8 parts; acid absorbent magnesium oxide: 5.5 parts; calcium carbonate as filler: 23 parts of pigment titanium dioxide and 2.0 parts of pigment titanium dioxide.

(1) Putting the polyvinyl chloride resin, the heat stabilizer, the processing modifier, the toughening agent and the plasticizer into a high-speed mixing pot of a high-speed mixing unit (Zhang Jia Jong Yili SRL-Z800/2500) according to the proportion, carrying out high-speed hot mixing, adding the filler, the pigment and the lubricant when the temperature of the mixed material is raised to 80 ℃, adding the crosslinking agent and the acid absorbent when the temperature of the hot mixed material is raised to 105 ℃, transferring the mixed material into a cold mixing pot when the temperature is raised to 125 ℃, carrying out low-speed cold mixing until the temperature is 55 ℃, and discharging to obtain the PVC-U mixed material.

(2) Extruding a pipe: the PVC-U mixed material is added into a conical twin-screw extruder and extruded into a cylindrical pipe (or a round pipe) with the nominal outer diameter of 110mm, wherein the temperature of each zone of the extruder is 160 ℃ and 230 ℃.

(3) Folding into a U shape: heating the extruded round pipe to 110 ℃ to enable the pipe to be in a high-elasticity state, pressing the pipe to deform, pressing to enable the round cross section of the round pipe to be deformed into a U shape, rapidly cooling the deformed pipe by using cooling water at 15 ℃ within 30s after deformation until the temperature of the pipe is reduced to 50 ℃ and the pipe is in a glass state, and storing the U-shaped pipe at room temperature.

Comparative example 2

No cross-linking agent was added during the preparation of the PVC-U blend for comparison.

The raw material formula comprises the following components in parts by mass:

polyvinyl chloride resin SG-5: 100 parts of (A); calcium zinc heat stabilizer CZ-8601E-2: 3.5 parts; lubricant fatty alcohol: 0.5 part; plasticizer trioctyl trimellitate (TOTM): 1 part; copolymer of processing modifier methacrylate and ethyl acrylate: 1.5 parts; toughening agent ethylene-vinyl acetate copolymer: 5.0 parts of (B); acid absorbent magnesium oxide: 3.0 parts of (B); calcium carbonate as filler: 8 parts of pigment titanium dioxide and 2.0 parts of pigment titanium dioxide.

The preparation method specifically comprises the following steps:

(1) and (2) putting the polyvinyl chloride resin, the heat stabilizer, the processing modifier, the toughening agent and the plasticizer into a high-speed mixing pot of a high-speed mixing unit according to the proportion, adding the filler and the lubricant when the temperature of the mixed materials rises to 80 ℃, transferring the mixed materials into a cold mixing pot after the temperature rises to 120 ℃, performing low-speed cold mixing until the temperature reaches 50-60 ℃, and discharging to obtain the PVC-U mixed material.

(3) Folding into a U shape: heating the extruded round pipe to 110 ℃ to enable the pipe to be in a high-elasticity state, pressing the pipe to deform, deforming the circular cross section of the pressed round pipe into a U shape, rapidly cooling the deformed pipe by using cooling water at 15 ℃ within 30s after deformation until the temperature of the pipe is reduced to 50 ℃ and the pipe is in a glass state, and storing the U-shaped pipe at room temperature.

Example 7

In the preparation of the PVC-U blend of this example, the crosslinking agent was compared with the acid absorbent using DCP and monomers without double bonds.

The raw material formula comprises the following components in parts by mass:

polyvinyl chloride resin SG-5: 100 parts of (A); calcium zinc heat stabilizer CZ-8601E-2: 3.5 parts; lubricant glyceryl monostearate: 0.4 part; ethylene-vinyl acetate copolymer wax (EVA wax): 0.6; copolymer of processing modifier methacrylate and ethyl acrylate: 1.5 parts; ethylene-vinyl acetate-carbonyl copolymer (toughening agent): 6 parts of (1); plasticizer trioctyl trimellitate (TOTM): 1 part; crosslinking agent peroxide dicumyl benzene (DCP): 0.08 part; calcium carbonate as filler: 20 parts of (1); 2.0 parts of pigment titanium dioxide.

(1) Putting the polyvinyl chloride resin, the heat stabilizer, the processing modifier, the toughening agent and the plasticizer into a high-speed mixing pot of a high-speed mixing unit (Zhang Jia Jong Yili SRL-Z800/2500) according to the proportion, carrying out high-speed hot mixing, adding the filler, the pigment and the lubricant when the temperature of the mixed material is raised to 80 ℃, adding the crosslinking agent when the temperature of the hot mixed material is raised to 105 ℃, transferring the mixed material into a cold mixing pot when the temperature is raised to 125 ℃, carrying out low-speed cold mixing until the temperature is 55 ℃, and discharging to obtain the PVC-U mixed material.

Comparative example 3

In the preparation process of the PVC-U mixed material of the comparative example, excessive cross-linking agent is added for comparison.

The raw material formula comprises the following components in parts by mass:

polyvinyl chloride resin SG-5: 100 parts of (A); calcium zinc heat stabilizer CZ-8601E-2: 3.5 parts; lubricant stearyl stearate: 0.5 part; copolymer of processing modifier methacrylate and ethyl acrylate: 1.5 parts; ethylene ethyl acrylate copolymer (EEA) (toughener): 4 parts of a mixture; plasticizer butyl epoxy stearate (EBST): 0.5 part; crosslinker 2-n-butylamino-4, 6-dimercapto-s-triazine (DB): 12 parts of (1); acid absorbent magnesium oxide: 3.0 parts of (B); filling montmorillonite: 15 parts of (1); 2.0 parts of pigment titanium dioxide.

(2) Extruding a pipe: the PVC-U mixed material is added into a conical twin-screw extruder and extruded into a cylindrical pipe (or a round pipe) with the nominal outer diameter of 110mm, wherein the temperature of each zone of the extruder is 160 ℃ and 230 ℃. Because the crosslinking degree is higher, the current of the extruder host rises quickly in the extrusion process, the feeding speed can only be set very small, the extrusion speed is very small, and the processing difficulty is very large.

(3) Folding into a U shape: heating the extruded round pipe to 110 ℃ to enable the pipe to be in a high-elasticity state, pressing the pipe to deform, deforming the circular cross section of the pressed round pipe into a U shape, and quickly cooling the deformed pipe by using cooling water at 15 ℃ within 30s after deformation until the temperature of the pipe is reduced to 50 ℃, so that the U-shaped pipe can be stored at room temperature.

Randomly selecting the round PVC-U pipe products with the nominal outer diameter of 110mm, which are prepared in the preparation step (2) in the above examples and comparative examples, and carrying out a correlation performance test; the U-shaped tubes manufactured in the manufacturing step (3) in the above examples and comparative examples were randomly selected, after the deformation recovery was performed by the oven heating method, the outer diameter of the tube after the deformation recovery was measured and compared with the outer diameter of the original shape (the outer diameter of the tube manufactured in the manufacturing step (2)), and the outer diameter change rate was calculated, and the specific test results are shown in the test data in tables 1 and 2 below.

Table 1:

table 2:

the results of the above table 1 and table 2 tests show that:

1) the common PVC-U pipe of the comparative example 1 has poor toughness, poor low-temperature impact property, low shape recovery rate and incomplete deformation recovery;

2) compared with the embodiment 6, the embodiments 1-5 and 7 adopt the preferred toughening agent in the formula system, so that the low-temperature impact performance is better; in example 6, the low-temperature impact performance is poor, and the deformation recovery rate is also affected; in addition, the deformation-recovery process is repeated for many times according to the performance detection method, the surface of the PVC-U pipe in example 6 (without the preferred toughening agent of the invention) is subjected to stress cracking after being deformed for 2-3 times, so that the deformation cannot be recovered again, and the deformation-recovery process is repeated for many times by using the preferred toughening agent, so that the pipe cannot crack and can still be recovered again.

3) In the comparative example 2, a crosslinking system is not added for mild crosslinking, the stationary phase strength in a PVC molecular chain is not enough, and the deformation recovery rate of the obtained product is poor;

4) in example 7, the monomer with double bond and the acid absorbent are not added in the DCP crosslinking process, the color of the pipe is obviously colored, the pipe is yellowed, and the crosslinking efficiency is also influenced. The deformation recovery rate of the obtained product is slightly worse than that of the product obtained in the embodiment 1-5, and the mechanical property is also influenced to a certain extent;

5) comparative example 3 has a higher degree of crosslinking, significantly increases the processing difficulty, increases the brittleness of the pipe, and increases the degree of crosslinking, decreases the reversible phase ratio in the molecular chain, increases the degree of restriction on the movement of the molecular chain, prolongs the time for the pipe to return to the original shape at the same temperature, and decreases the deformation recovery rate at the same temperature and time.

The experimental results show that the PVC-U pipe prepared by the embodiment of the invention has better shape recovery rate; the product prepared by the embodiment adopting the preferred scheme has good low-temperature poor flexibility and mechanical property, has the shape recovery rate of more than 97 percent, and has an excellent shape memory function. The PVC-U pipe with the shape memory function obtained by the scheme is particularly suitable for repairing the damaged pipeline under the condition of micro-excavation or non-excavation, and has the advantages of being beneficial to shortening the construction period, reducing the comprehensive cost, reducing the influence on the construction environment and the like.

The performance testing method referred to in table 1 is described below:

1. -10 ℃ drop impact: measured according to GB/T14152-2001, wherein the test temperature is (-10 +/-1) DEG C, the hammer head of the drop hammer is d90 type, the mass of the drop hammer is 0.5Kg, and the drop height is 2 m.

2. Density: measured according to GB/T1033.1-2008;

3. vicat softening temperature: measured according to GB/T8802-2001;

4. tensile yield strength: measured according to GB/T8804.2-2003;

5. longitudinal retraction rate: measured according to GB/T6671-2001;

6. normal temperature hydraulic strength: according to GB/T6111-2003, the test conditions are as follows: the temperature is 20 ℃, the test pressure is started from 0.5MPa, the test time is 1h, the pressure is increased once every 0.1MPa until the pipe is cracked or leaked, and the previous group of data when the pipe is cracked or leaked is taken as the measured value of the hydraulic strength.

7. Shape recovery rate: taking a sheet sample from the pipe obtained in the preparation step 2),making two scales as L₀The sample is dipped in methyl silicone oil with the temperature of 95 ℃, is kept at the constant temperature for 5min, is bent into a U shape, is rapidly cooled by cooling water with the temperature of 10 ℃ to ensure that the shape is fixed, and the distance of the measured marked line is L₁. Placing the sample with the fixed shape into 110 deg.C silicone oil again, maintaining the temperature for 20min to recover the shape of the sample, and measuring the distance L between the standard lines₂When the shape recovery ratio R is (L)₂-L₁)/(L₀-L₁)×100％。

8. Gel content G (i.e. gel degree): the sample was placed in a soxhlet extractor and extracted with tetrahydrofuran for 5h to remove the non-gel fraction. The extracted sample was dried in a vacuum oven at 70 ℃ for 2 h. G is expressed as the percentage of the mass of the starting sample (mass without plasticizer, filler and pigment) by the formula: g ═ m₀-m₁)/m₀X 100% of formula (II)₁For the net weight of the extracted sample (excluding the mass of fillers and pigments according to the formulation), m₀Starting sample mass (minus plasticizer, filler and pigment mass by formula).

9. The change rate of the outer diameter of the pipe: carrying out outer diameter R on the pipe obtained in the preparation step 2)₀Measuring (with the minimum outer diameter point), preparing a U-shaped pipe according to the method in the preparation step 3), then placing a section of the U-shaped pipe with the diameter of 300 and 500mm in a 110 ℃ oven, keeping the temperature for 20min to recover the shape, and measuring the outer diameter R₁(in terms of outer diameter minimum point), the outer diameter change rate is (R)_0-R₁)/R₀×100％。

The specific embodiments described herein are merely illustrative of the spirit of the invention. Various modifications or additions may be made to the described embodiments or alternatives may be employed by those skilled in the art without departing from the spirit or ambit of the invention as defined in the appended claims.

While the invention has been described in detail and with reference to specific embodiments thereof, it will be apparent to one skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope thereof.

Claims

1. The PVC-U pipe with the shape memory function is characterized by being prepared from the following raw materials in parts by mass:

100 parts of polyvinyl chloride resin, 1.5-8.0 parts of heat stabilizer, 0.1-6.0 parts of lubricant, 0-4 parts of plasticizer, 0.5-8 parts of processing modifier, 1-10 parts of toughening agent, 0.02-5 parts of crosslinking agent, 0-6 parts of acid absorbent, and more than 0 and less than or equal to 30 parts of filler;

wherein the crosslinking agent comprises one or more of an organic peroxide crosslinking agent, a dithio-tetramethyl thiuram crosslinking agent and a mercapto-s-triazine crosslinking agent;

when the crosslinking agent comprises an organic peroxide crosslinking agent, a monomer with a carbon-carbon double bond is also added into the crosslinking agent; in the total mass of the organic peroxide crosslinking agent and the monomer with the carbon-carbon double bond, the mass percentage of the monomer with the carbon-carbon double bond is 85-98%; the monomer with the carbon-carbon double bond is selected from one or more of diallyl phthalate, triallyl isocyanurate, triallyl cyanurate and N, N' -m-phenylene bismaleimide;

and the dosage of the cross-linking agent is that the gel degree of the PVC-U pipe reaches 3-10%;

the toughening agent is a block copolymer formed by polymerizing one or more of vinyl acetate monomer, alkyl acrylate monomer and carbon monoxide with ethylene monomer.

2. The PVC-U pipe with the shape memory function according to claim 1, wherein the mass part of the plasticizer is more than 0 and less than or equal to 4; the mass part of the acid absorbent is more than 0 and less than or equal to 6; the mass part of the filler is 5-25; the mass portion of the cross-linking agent is 0.06-3.

3. The PVC-U pipe with the shape memory function according to claim 2, wherein the plasticizer is 0.5 to 4 parts by mass; the acid absorbent accounts for 0.5 to 5.5 parts by mass.

4. The PVC-U pipe with shape memory function according to claim 1, characterized in that the organic peroxide crosslinking agent comprises dicumyl peroxide;

the mercapto-s-triazine cross-linking agent comprises 2-n-butylamino-4, 6-dimercapto-s-triazine.

5. The PVC-U tube with a shape memory function according to claim 1, wherein the cross-linking agent is used in an amount such that the PVC-U tube has a gel degree of 3-8%.

6. The PVC-U pipe with shape memory function according to claim 1, wherein the toughening agent is a mixture of one or more of ethylene-vinyl acetate copolymer (EVA), ethylene and butyl acrylate copolymer (EBA), ethylene-methyl acrylate copolymer (EMA), ethylene-ethyl acrylate copolymer (EEA), ethylene-vinyl acetate-carbonyl copolymer (E/VA/CO) and ethylene-butyl acrylate-carbonyl copolymer (E/nBA/CO).

7. The PVC-U pipe with a shape memory function according to claim 1, wherein the plasticizer is selected from one or more of epoxidized soybean oil, trioctyl trimellitate, butyl epoxystearate, dibutyl sebacate, and polytrimethylene adipate.

8. The PVC-U pipe with a shape memory function according to claim 1, wherein the lubricant is selected from a mixture of one or more of fatty alcohol, fatty acid ester, aromatic dicarboxylic acid ester, fatty acid polyol complex ester, fatty acid amide, ethylene-vinyl acetate copolymer wax, OP wax, S wax, E wax, carnauba wax, polyethylene oxide wax, hydrocarbon-based wax;

the fatty acid ester is a mixture of one or more of compounds formed by esterification reaction of fatty acid and monohydric alcohol or polyhydric alcohol;

the fatty acid-polybasic alcohol acid composite ester is a compound formed by mixing and esterifying polyalcohol, polybasic acid and fatty acid;

the fatty acid amide includes one or more of a mono-fatty amide and a di-fatty amide.

9. The PVC-U pipe with a shape memory function according to claim 8, wherein the fatty acid ester comprises one or more of butyl stearate, glyceryl monostearate, stearyl stearate, glyceryl monooleate, glyceryl dioleate, glyceryl ricinoleate, and distearyl adipate;

the fatty acid-polybasic alcohol acid composite ester comprises one or a mixture of two of adipic acid-pentaerythritol stearate and adipic acid-pentaerythritol oleate;

the mono-fatty amide comprises one or more of stearic acid amide, erucic acid amide and ricinoleic acid amide; the double fatty amide comprises one or a mixture of two of N, N '-ethylene bis stearamide and N, N' -ethylene bis ricinoleic acid amide;

the hydrocarbon-based wax includes one or more of a homopolymeric polyethylene wax and a linear paraffin wax with a branched chain.

10. The PVC-U pipe with the shape memory function of claim 1, wherein the processing modifier is selected from one or more of a copolymer of methacrylate and alkyl acrylate, a copolymer of methyl methacrylate-styrene-alkyl acrylate, a terpolymer of methacrylate-acrylonitrile-alkyl acrylate, polystyrene with the weight average molecular weight of 1000-10000 Da, and poly-alpha-methyl styrene.

11. The PVC-U tubing with shape memory function according to claim 1, wherein the polyvinyl chloride resin is selected from one or more of SG-5, SG-4 and SG-3;

the acid absorbent is one or a mixture of more of magnesium oxide (MgO), zinc oxide (ZnO) and hydrotalcite;

the filler is selected from one or a mixture of more of white carbon black, calcium carbonate, argil, montmorillonite, zeolite, talcum powder and barium sulfate;

the heat stabilizer is one or a mixture of more of calcium-zinc composite stabilizer, organic tin stabilizer and magnesium-aluminum-zinc composite stabilizer.

12. The PVC-U tube with shape memory function as claimed in claim 11, wherein the polyvinyl chloride resin has an average degree of polymerization of 981-1370 and a K value of 66-72.

13. The PVC-U pipe with a shape memory function according to claim 11, wherein the organotin stabilizer is a mixture of one or more of methyltin mercaptide, butyltin mercaptide, and octyltin mercaptide.

14. A method for preparing a PVC-U pipe with shape memory according to any of claims 1 to 13, characterized in that it comprises the following steps:

1) preparing the components in the raw materials into a PVC-U mixed material;

2) adding the PVC-U mixed material into an extruder to be extruded and molded into a PVC-U pipe.

15. The method for preparing the PVC-U compound according to claim 14, wherein the specific operation of preparing the PVC-U compound in the step 1) comprises the following steps: the PVC-U mixed material is prepared by hot mixing of polyvinyl chloride resin, a heat stabilizer, a processing modifier, a toughening agent and a plasticizer, adding a filler and a lubricant for mixing when the hot mixing temperature is increased to 75-85 ℃, adding a crosslinking agent and an acid absorbent when the hot mixing temperature is increased to 110 ℃, continuously mixing until the hot mixing temperature is increased to 120-130 ℃, then converting into cold mixing, and cold mixing until the cold mixing temperature is reduced to 50-60 ℃.

16. The method of claim 15, wherein the hot mixing is performed in a high-speed mixer set in a high-speed mixer kettle and the cold mixing is performed in a high-speed mixer set in a cold mixer kettle.

17. The method as claimed in claim 14, wherein the step 2) is carried out in a twin-screw extruder, and the temperature of each zone of the twin-screw extruder during the extrusion molding is 160 ℃ to 230 ℃.

18. A method of processing a PVC-U pipe, characterized in that the PVC-U pipe according to any one of claims 1 to 13 or the PVC-U pipe obtained by the method according to any one of claims 14 to 17 is heated to 90 to 130 ℃ to be in a high elastic state, and the PVC-U pipe is pressed to be deformed, and the deformed pipe is cooled to 20 to 70 ℃ to be in a glassy state.

19. The process for producing PVC-U pipe according to claim 18, wherein the cooling step is carried out by cooling the PVC-U pipe heated to 90-130 ℃ with cooling water within 0-120s after the PVC-U pipe is deformed by pressing until the temperature of the PVC-U pipe is reduced to 20-70 ℃.

20. The process for the manufacture of PVC-U tubing according to claim 19, wherein the cooling is performed with cooling water at 5-20 ℃.

21. The method of processing PVC-U tubing of claim 18, wherein the pressing is to deform the circular cross section of the cylindrical PVC-U tubing.

22. The method of processing PVC-U tubing of claim 21, wherein the pressing is such that the circular cross section of the PVC-U tubing is deformed into a shape having an internal recess.

23. The method of processing PVC-U tubing of claim 21, wherein the pressing is to deform the circular cross section of the PVC-U tubing into a U-shape.

24. Use of a PVC-U pipe with shape memory according to any of claims 1 to 13 or a PVC-U pipe with shape memory according to the production process according to any of claims 14 to 17 or a PVC-U pipe with shape memory according to any of claims 18 to 23 for repairing pipes.