Polyurea for endowing PVC hose with self-repairing performance as well as preparation method and application of polyurea

Abstract

The invention relates to polyurea capable of endowing a PVC (polyvinyl chloride) hose with self-repairing performance as well as a preparation method and application of the polyurea. The polyurea has the following structure, the preparation method comprises the following steps: carrying out addition polymerization reaction on diamine dihydrochloride containing disulfide bonds and diisocyanate by adopting solution polymerization; in the application, polyurea containing disulfide bonds and hydrogen bonds is mixed with a PVC material by adopting a twin-screw extrusion method in the hot working process, unsaturated bonds generated by high-temperature processing are mutually crosslinked with the disulfide bonds in the polyurea, and the comprehensive performance of the pipe is improved. According to the method, the self-repairing efficiency is larger than 40% within 3 h at the temperature of 80 DEG C, an additional repairing agent is not needed in the self-repairing process, the process complexity is greatly reduced, and meanwhile the environmental pollution risk caused by repairing agent leakage is avoided.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer materials, and specifically designs a preparation method of polyurea and application of the polyurea in the modification of polyvinyl chloride (PVC) hoses. Background Art

[0002] The material advantages of polyvinyl chloride (PVC) hoses stem from their unique physical and chemical properties. The presence of chlorine atoms in their molecular chains imparts excellent corrosion resistance to acids, alkalis, salts, and organic solvents. The material is lightweight and easy to install, with low processing costs and mature technology. Furthermore, PVC hoses possess excellent electrical insulation and aging resistance, demonstrating high cost-effectiveness and long lifespan in building pipelines, industrial fluid transportation, and agricultural irrigation. However, with technological advancements and increasingly complex application scenarios, the inherent performance flaws of PVC materials have become increasingly prominent.

[0003] Traditional PVC hoses, while enhanced with a certain degree of softness through the addition of large amounts of plasticizers, still suffer from insufficient toughness during long-term service, particularly under dynamic stress, where they are susceptible to structural failure due to the propagation of microcracks. This limits their reliability under complex operating conditions and poses a safety hazard for the transportation of hazardous materials. Furthermore, when large cracks or other damage develop during the use of these PVC hoses, the only solution is to replace them with new ones. This approach ignores the value of the undamaged parts, resulting in significant material waste and a complex, labor-intensive construction process.

[0004] Traditional modifications often struggle to balance this dynamic toughness and self-healing properties. Patent CN103554729A proposes improving the toughness and service life of PVC pipes by introducing thermoplastic polyurethane elastomers and leveraging the flexibility of linear polyurethane and the hydrogen bonding interactions within the polyurethane. However, because this simply replaces traditional rubber toughening with linear polyurethane, the properties improved by this type of modification are limited. While it can delay crack initiation, it cannot actively repair existing large-scale damage, limiting the material's service life under long-term cyclic loads or accidental impacts. Summary of the Invention

[0005] The present invention addresses the shortcomings of current PVC hoses, such as insufficient toughness under dynamic conditions and an inability to repair large cracks that have already formed. By providing a polyurea that imparts self-healing properties to PVC hoses, its preparation method, and application, the polyurea is characterized by disulfide bonds and hydrogen bonds. During preparation, solution polymerization is used to induce addition polymerization between diamine dihydrochloride containing disulfide bonds and diisocyanate. Excess triethylamine is added to react with the hydrogen chloride in the diamine dihydrochloride, improving its solubility. In application, the polyurea containing disulfide and hydrogen bonds is mixed with PVC during a heat treatment process using twin-screw extrusion. During high-temperature processing, PVC partially decomposes, producing unsaturated bonds. These unsaturated bonds cross-link with the disulfide bonds in the polyurea at high temperatures, effectively compatibly compatibly with PVC and improving the overall performance of the hose. The present invention achieves a self-healing efficiency exceeding 40% within 3 hours at 80°C. Compared to conventional encapsulated repair agent technologies, this self-healing process requires no additional repair agent, significantly reducing process complexity and avoiding the risk of environmental contamination caused by repair agent leakage.

[0006] The technical solution of the present invention is:

[0007] A polyurea that imparts self-repairing properties to a PVC hose, the polyurea having the following structure:

[0008]

[0009] Wherein, R is the alkyl portion in diisocyanate, and n is 1 to 10,000.

[0010] The method for preparing the polyurea that imparts self-repairing properties to the PVC hose comprises the following steps:

[0011] S1: Dissolve diamine dihydrochloride and triethylamine in a solvent and stir for 0.5-1.5 h to obtain a clear solution;

[0012] The molar ratio of triethylamine to diamine dihydrochloride is (5-15):1; the mass ratio of solvent to triethylamine is (2-10):1;

[0013] The diamine dihydrochloride is cystamine dihydrochloride;

[0014] The solvent is a ketone solvent, an aromatic hydrocarbon solvent or other organic solvent; specifically one or more of methyl ethyl ketone, acetone, N,N-dimethylformamide, N,N-dimethylacetamide, ethyl acetate, toluene, dimethyl sulfoxide, dichloromethane, tetrahydrofuran and dioxane;

[0015] S2: Add diisocyanate to the clear solution obtained in S1, raise the temperature to 30-80°C, and react for 18-30 hours; remove the solvent to obtain a white powdery product PUS, which is polyurea that imparts self-healing properties to the PVC hose;

[0016] Wherein, the molar ratio of the diisocyanate to the diamine dihydrochloride in S1 is (0.9-1.1):1;

[0017] The diisocyanate includes aliphatic diisocyanate, aromatic diisocyanate or alicyclic diisocyanate;

[0018] Specifically, hexamethylene diisocyanate (HDI), lysine diisocyanate (LDI), toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), isophorone diisocyanate (IPDI) or dicyclohexylmethane diisocyanate (HMDI).

[0019] The specific structure is as shown below;

[0020]

[0021] The application of the polyurea imparting self-repairing properties to the PVC hose is used in the preparation of the PVC hose;

[0022] The specific steps include:

[0023] The polyvinyl chloride resin, the prepared light yellow powdered polyurea, the compatibilizer, the antioxidant, the heat stabilizer, and the lubricant are added to a high-speed mixer in proportion, premixed at 100-120° C. for 40-50 minutes, and cooled to 30-40° C. to form a premix for standby use; the premix is ​​fed into a granulator for granulation, and the granules are transferred to the barrel of an extruder; the temperature of the feeding section of the extruder is controlled at 100-120° C., the temperature of the compression section is controlled at 120-140° C., the temperature of the metering section is controlled at 140-160° C., the temperature of the die is controlled at 150-160° C., and the speed of the extruder screw is controlled at 30-35 r / min; after cooling, shaping, pulling, and cutting, a PVC hose with self-repairing properties is obtained;

[0024] The mass ratio of polyvinyl chloride resin: prepared light yellow powdered polyurea: compatibilizer: antioxidant: heat stabilizer: plasticizer is (80-120): (10-30): (3-8): (1-3): (1-3): (25-15).

[0025] The polyvinyl chloride is a powder material with a particle size of 10 to 30 μm;

[0026] The compatibilizer is maleic anhydride grafted PVC, the antioxidant is antioxidant 1010, the heat stabilizer is dibutyltin dilaurate, and the plasticizer is dioctyl phthalate.

[0027] The essential features of the present invention are:

[0028] The present invention addresses the difficulties of traditional modification in balancing toughness and self-healing properties. Diisocyanate and diamine hydrochloride are polymerized through solution to introduce a monomer containing dynamic disulfide bonds into polyurea. This dynamic bond can cross-link with the double bonds generated during thermal processing, thereby contributing to the compatibility of PVC and polyurea. In addition, this dynamic disulfide bond, together with the dynamic hydrogen bonds in the polyurea, constitutes a dynamic cross-linking network. Compared with traditional toughening modification, the presence of these multiple dynamic bonds not only provides the composite PVC hose with excellent mechanical strength, but also gives the material self-healing properties under thermal action.

[0029] The beneficial results of the present invention are:

[0030] The present invention introduces dynamic disulfide bonds into the polyurea backbone through solution polymerization, and combines them with the urea hydrogen bonds in the polyurea to form a multiple dynamic cross-linking network. (1) During high-temperature processing, the double bonds generated by partial decomposition of PVC undergo in-situ cross-linking with the disulfide bonds in the dynamic polyurea, significantly reducing the polarity difference between the two phases. Combined with the polar adsorption effect of the compatibilizer maleic anhydride grafted PVC, the interfacial bonding strength is significantly improved. Compared with pure physical blending in other materials, the chemical cross-linking strategy of the present invention significantly improves the uniformity of the material. Compared with the simple addition of plasticizers, the tensile strength can be increased from 12.2MPa to 15.5MPa; (2) The three-dimensional interpenetrating network of the dynamic polyurea is uniformly embedded in the PVC matrix through twin-screw high shear dispersion, while maintaining the rigidity of PVC, the elongation at break is increased from 310% to 422%; (3) The synergistic effect of multiple dynamic bonds makes the material self-healing efficiency greater than 40% within 3 hours at 80°C. Compared with traditional encapsulation repair agent technology, this self-repair process does not require external stimulation or additional repair agents, greatly reducing the process complexity, while avoiding the risk of environmental pollution caused by leakage of repair agents.

[0031] By introducing multiple dynamic bonds and chemical compatibilization strategies, the present invention overcomes the technical bottlenecks of poor compatibility between modified materials and PVC, insignificant toughening effect, and no self-repairing performance. It successfully develops a functional PVC hose with both high mechanical strength and self-repairing properties, providing a long-life, low-maintenance cost solution for the medical, industrial and intelligent equipment fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is the XPS graph of the S element in the polyurea PUS obtained in Example 1. DETAILED DESCRIPTION

[0033] The present invention systematically illustrates the technical solution through specific implementation methods. The examples shown are only representative implementation methods of the present invention and are not an exhaustive list of implementation methods of the technical solution. Based on the technical principles disclosed by the present invention, any implementation method implemented by practitioners familiar with the technology in this field through equivalent substitution or conventional technical means without expending creative work shall fall within the scope of protection of the patent claims of the present invention.

[0034] Reaction formula of the present invention is as follows:

[0035]

[0036] Wherein, n=1~10000.

[0037] The polyurea of ​​the present invention is used in PVC hoses to impart high toughness and self-repairing properties to the hoses. Examples 1 to 4 are used in the preparation of self-repairing PVC hoses.

[0038] Example 1

[0039] (1) Synthesis of PUS: Dissolve cystamine dihydrochloride (90 g, 0.4 mol) in 2 L of DMF, add triethylamine (400 g, 4 mol) and stir for 1 h to obtain a clear solution. Then, add IPDI (88.8 g, 0.4 mol) dropwise. Heat the reaction solution to 40°C and react for 24 h. After the reaction is complete, remove the solvent. Finally, obtain the white powder product PUS in a yield of approximately 68%.

[0040] like Figure 1 As shown, S(2p 1 / 2 ) and S(2p 3 / 2 ) are shown at 164.50 eV and 163.38 eV, indicating that SS bonds are successfully introduced into polyurea.

[0041] (2) Preparation of PVC-PUS 110-10 Hose: Add polyvinyl chloride resin (110 parts, powder, powder particle size is 20μm), PUS (10 parts), maleic anhydride grafted PVC (4 parts), antioxidant 1010 (2 parts), dibutyltin dilaurate (2 parts), dioctyl phthalate (20 parts) in proportion to a high-speed mixer, premix at a speed of 100r / min at 110℃ for 40min, and cool to 35℃ to form a premix. The premix is ​​sent to a granulator for granulation, and the pellets (about 3-5mm) are transferred to the extruder barrel. The extruder feeding section temperature is set to 110℃, the compression section temperature is set to 130℃, the metering section temperature is set to 150℃, the die temperature is set to 160℃, the extruder screw speed is set to 30r / min, and feeding is started after the temperature stabilizes; after cooling with tap water, shaping, pulling, and cutting, a PVC hose with self-repairing properties is obtained, named PVC-PUS. 110-10.

[0042] The parts mentioned are all parts by mass.

[0043] Example 2

[0044] The other steps were the same as in Example 1, except that polyvinyl chloride resin (110 parts) and PUS (10 parts) were replaced with polyvinyl chloride resin (105 parts) and PUS (15 parts) to prepare PVC-PUS. 105-15 ;

[0045] Example 3

[0046] The other steps were the same as in Example 1, except that polyvinyl chloride resin (110 parts) and PUS (10 parts) were replaced with polyvinyl chloride resin (100 parts) and PUS (20 parts) to prepare PVC-PUS 100-20 ;

[0047] Example 4

[0048] The other steps were the same as in Example 1, except that polyvinyl chloride resin (110 parts) and PUS (10 parts) were replaced with polyvinyl chloride resin (95 parts) and PUS (25 parts) to prepare PVC-PUS. 95-25 ;

[0049] Example 5

[0050] The other steps were the same as in Example 1, except that polyvinyl chloride resin (110 parts) and PUS (10 parts) were replaced with polyvinyl chloride resin (90 parts) and PUS (30 parts) to prepare PVC-PUS. 90-30 .

[0051] Comparative Example 1

[0052] Preparation of PVC hose: Polyvinyl chloride resin (120 parts), compatibilizer (4 parts), antioxidant (2 parts), heat stabilizer (2 parts), and plasticizer (20 parts) are added to a high-speed mixer in appropriate proportions. Premix at 110°C for 40 minutes and cool to 35°C to form a premix. The premix is ​​pelletized, extruded, cooled and shaped, pulled, and cut to obtain a PVC hose, designated PVC.

[0053] In order to verify the properties of the materials obtained in Examples 1 to 5 and Comparative Example 1, relevant characterization and performance tests were performed.

[0054] (1) Tensile strength

[0055] The tensile strength of the materials prepared in Examples 1 to 5 and Comparative Example 1 was tested according to the method specified in GB / T1040.2-2006. The specific data are shown in Table 1.

[0056] (2) Self-repair performance test

[0057] At least three samples were cut into two sections using a razor blade. The cut sections were squeezed together and fixed. The samples were placed in an 80°C forced air oven for 3 hours. The tensile strength was then tested according to the method specified in GB / T 1040.2-2022. The specific data are shown in Table 1.

[0058] Table 1 Performance of PUS modified PVC hose in the present invention

[0059]

[0060] In the present invention, by adding polyurea containing disulfide bonds and hydrogen bonds, not only the toughness of the PVC hose is significantly improved (tensile strength and elongation at break are improved), but also the PVC hose is given very good self-repairing properties. After optimization, the repair rate can reach more than 40%.

[0061] The embodiments listed in the present invention are only used to illustrate several preferred technical solutions, and are not a restrictive description of the scope of protection. The above embodiments are intended to provide exemplary technical guidance, rather than an exhaustive limitation. Under the inspiration of the technical solution of the present invention, relevant technical personnel, without departing from the core design concept of the present invention, make adaptive adjustments through equivalent replacement, structural deformation or process improvement, including but not limited to adjustment, supplementation or optimization of the composition ratio, implementation steps or technical parameters, which should be deemed to fall within the scope of protection of the claims of the present invention.

[0062] Matters not covered by the present invention are known technologies.

Claims

1. A polyurea that imparts self-repairing properties to a PVC hose, characterized by: The polyurea has the following structure: Wherein, R is the alkyl portion in diisocyanate, and n is 1 to 10,000.

2. The method for preparing polyurea for imparting self-repairing properties to PVC hose according to claim 1, characterized in that: The following steps are involved: S1: dissolving diamine dihydrochloride and triethylamine in a solvent and stirring for 0.5-1.5 h to obtain a reaction solution; The molar ratio of triethylamine to diamine dihydrochloride is (5-15):1; the mass ratio of solvent to triethylamine is (2-10):1; The solvent is a ketone solvent, an aromatic hydrocarbon solvent or other organic solvent; S2: adding diisocyanate to the reaction solution obtained in S1, raising the temperature to 30-80° C. and reacting for 18-30 hours to obtain polyurea that imparts self-repairing properties to the PVC hose; Wherein, the molar ratio of the diisocyanate to the diamine dihydrochloride in S1 is (0.9-1.1):1; The diisocyanate includes aliphatic diisocyanate, aromatic diisocyanate or alicyclic diisocyanate.

3. The method for preparing polyurea for imparting self-repairing properties to PVC hose according to claim 2, characterized in that: The diamine dihydrochloride is cystamine dihydrochloride; The solvent is one or more of methyl ethyl ketone, acetone, N,N-dimethylformamide, N,N-dimethylacetamide, ethyl acetate, toluene, dimethyl sulfoxide, dichloromethane, tetrahydrofuran and dioxane.

4. The method for preparing polyurea for imparting self-repairing properties to PVC hose according to claim 2, wherein: The diisocyanate is hexamethylene diisocyanate (HDI), lysine diisocyanate (LDI), toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), isophorone diisocyanate (IPDI) or dicyclohexylmethane diisocyanate (HMDI).

5. The use of the polyurea for imparting self-repairing properties to a PVC hose as claimed in claim 1, characterized in that: Used for the preparation of PVC hoses.

6. The use of polyurea for imparting self-repairing properties to PVC hoses as claimed in claim 5, characterized in that: The steps include: The polyvinyl chloride resin, the prepared light yellow powdered polyurea, the compatibilizer, the antioxidant, the heat stabilizer, and the lubricant are added to a high-speed mixer in proportion, premixed at 100-120° C. for 40-50 minutes, and cooled to 30-40° C. to form a premix for standby use; the premix is ​​fed into a granulator for granulation, and the granules are transferred to the barrel of an extruder; the temperature of the feeding section of the extruder is controlled at 100-120° C., the temperature of the compression section is controlled at 120-140° C., the temperature of the metering section is controlled at 140-160° C., the temperature of the die is controlled at 150-160° C., and the speed of the extruder screw is controlled at 30-35 r / min; after cooling, shaping, pulling, and cutting, a PVC hose with self-repairing properties is obtained; The mass ratio of polyvinyl chloride resin: prepared light yellow powdered polyurea: compatibilizer: antioxidant: heat stabilizer: plasticizer is (80-120): (10-30): (3-8): (1-3): (1-3): (25-15).

7. The use of polyurea for imparting self-repairing properties to PVC hoses as claimed in claim 6, characterized in that: The polyvinyl chloride is a powder material with a particle size of 10 to 30 μm.

8. The use of polyurea for imparting self-repairing properties to PVC hoses as claimed in claim 6, characterized in that: The compatibilizer is maleic anhydride grafted PVC, the antioxidant is antioxidant 1010, the heat stabilizer is dibutyltin dilaurate, and the plasticizer is dioctyl phthalate.

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