A chlorinated polyvinyl chloride composition, a method for preparing the same, and use thereof

Abstract

The application provides a chlorinated polyvinyl chloride composition and a preparation method and application thereof, and relates to the technical field of polymer composites.The chlorinated polyvinyl chloride composition is prepared by adding polyol stabilizers, maleate organic tin stabilizers and calcium-zinc stabilizers into the chlorinated polyvinyl chloride, and the three kinds of thermal stabilizers are used in combination, so that the thermal stability, the processing thermal stability and the mechanical properties are improved, and the chlorinated polyvinyl chloride pipe material with high thermal stability and high mechanical properties is prepared, thereby meeting the production requirements.

Description

Technical Field

[0001] This invention relates to the field of polymer composite materials technology, and more specifically, to a chlorinated polyvinyl chloride composition, its preparation method, and its application. Background Technology

[0002] Chlorinated polyvinyl chloride (PVC-C) is a high-performance material obtained by chlorinating polyvinyl chloride (PVC). Compared to PVC, PVC-C has higher temperature resistance, rigidity, chemical corrosion resistance, flame retardancy, and smoke suppression properties, giving it significant advantages in multiple fields. Pipes made from PVC-C are not only high in strength, corrosion-resistant, and flame-retardant, but also unaffected by residual chlorine, making them less susceptible to bacterial growth, and possessing good hygiene and aging resistance. These advantages have led to the widespread application of PVC-C pipes in building water supply and drainage, chemical, and fire protection industries. However, due to the introduction of a large number of polar chlorine atoms into its molecular chain, PVC-C exhibits significantly enhanced molecular chain polarity, resulting in increased melt viscosity. It is also more prone to decomposition during processing, producing corrosive HCl gas, which not only corrodes and wears molds but also increases the difficulty of plasticizing PVC-C. Furthermore, the processing of PVC-C requires high temperatures, further increasing its processing difficulty. Therefore, to meet the processing requirements of PVC-C, the requirements for heat stabilizers and lubricants have become correspondingly more stringent.

[0003] PVC-C resin typically has a chlorine content exceeding 67%. This increased chlorine content leads to greater molecular chain polarity, resulting in decreased thermal stability and making it more prone to decomposition during processing than regular PVC resin. This produces HCl gas, affecting the plasticization of formulation materials and consequently impacting product quality. Liquid thiols (organotin compounds) are commonly used as stabilizers in PVC-C processing. However, this stabilizer presents two problems: firstly, it has a strong odor and requires relatively large amounts during processing, which can cause sulfidation contamination and discoloration of copper components, including copper sizing sleeves and fittings in pipe manufacturing equipment; secondly, while liquid organotin compounds provide good short-term stability during PVC-C processing, their long-term stability is poor, making them unsuitable for prolonged processing.

[0004] Existing technology discloses a heat-resistant and corrosion-resistant PVC-C filler ring composition, comprising organotin stabilizers and calcium-zinc stabilizers. This composition does not cause material smearing during extrusion production, is easy to process, and the produced filler rings exhibit excellent heat resistance, corrosion resistance, and superior physical and mechanical properties. Corrosion resistance refers to preventing the decomposition and corrosion of the screw and die during the extrusion process by PVC-C, reducing discoloration or surface unevenness of the equipment. However, the use of thiols-based organotin stabilizers presents a problem of contamination of copper components and has a short thermal stability time, making it difficult to meet the application requirements of chlorinated polyvinyl chloride pipes.

[0005] Therefore, in order to further improve the thermal stability of chlorinated polyvinyl chloride (PVC) pipes and prevent heat stabilizers from damaging the processing equipment and copper components of the pipes, it is necessary to provide a modified PVC composition and PVC pipes that have high thermal stability, do not cause component damage, and have good mechanical properties. Summary of the Invention

[0006] In order to overcome the shortcomings of the prior art, the primary objective of this invention is to provide a chlorinated polyvinyl chloride composition that, through the rational compounding of heat stabilizers, improves the processing thermal stability and mechanical properties of the chlorinated polyvinyl chloride composition, including tensile strength and hydraulic strength.

[0007] Another object of the present invention is to provide a method for preparing the above-mentioned chlorinated polyvinyl chloride composition.

[0008] Another object of the present invention is to provide the application of the above-described chlorinated polyvinyl chloride composition in the preparation of chlorinated polyvinyl chloride pipes.

[0009] Another object of the present invention is to provide a chlorinated polyvinyl chloride pipe prepared from the above-mentioned chlorinated polyvinyl chloride composition.

[0010] To achieve the above objectives, the present invention adopts the following technical solution:

[0011] This invention protects a polyvinyl chloride composition comprising the following components in parts by weight:

[0012] 80-110 parts of chlorinated polyvinyl chloride, 4-9.5 parts of heat stabilizer, 2-3 parts of lubricant, 5-10 parts of impact agent, and 0.5-1 part of titanium dioxide;

[0013] The heat stabilizer is a polyol stabilizer, a maleate organotin stabilizer, and a calcium-zinc stabilizer, in a mass ratio of 0.5–1.5:2.5–6:1–2.

[0014] The maleate organotin stabilizer is a dioctyltin maleate-styrene-methyl acrylate terpolymer heat stabilizer.

[0015] The polyol stabilizer is one or both of tris(hydroxymethyl)aminomethane or bis(2-hydroxyethyl)amino(tris(hydroxymethyl)methane).

[0016] This invention uses a combination of three heat stabilizers—polyol stabilizer, maleate organotin stabilizer, and calcium-zinc stabilizer—within a certain range of proportions to modify chlorinated polyvinyl chloride, improve its thermal stability, and enhance its mechanical properties.

[0017] Calcium-zinc stabilizers are commonly used as heat stabilizers in PVC resin processing. Their excellent lubrication properties significantly promote uniform dispersion of the stabilizer during processing, effectively reducing agglomeration and enhancing the melt flowability of the formulated materials. Experimental results show that, in PVC-C processing applications, although the heat stabilization effect of calcium-zinc stabilizers is slightly inferior to that of organotin stabilizers, it can effectively compensate for the shortcomings of organotin stabilizers in terms of lubrication. When calcium-zinc stabilizers are used as a compound component of organotin stabilizers, the two exhibit excellent synergistic effects. Furthermore, the zinc soaps and calcium soaps in the molecular structure of calcium-zinc stabilizers, through the substitution of active chlorine and absorption and capture of HCl, respectively, act synergistically with organotin stabilizers through coordination reactions on PVC-C, effectively inhibiting its deHCl reaction.

[0018] The polyol stabilizer used in this invention is one or both of tris(hydroxymethyl)aminomethane or bis(2-hydroxyethyl)amino(tris(hydroxymethyl)methane), which are novel and environmentally friendly organic heat stabilizers. The stabilizer's molecular structure contains a hydroxyl group and an amino group. The amino group possesses a lone pair of electrons, exhibiting strong basic properties. This property allows it to replace unstable Cl atoms on the PVC chain through nucleophilic substitution and to effectively neutralize the HCl released during the thermal degradation of PVC, thereby further enhancing the stabilizing effect.

[0019] The present invention relates to a maleate organotin stabilizer, which is a heat stabilizer based on a dioctyltin maleate-styrene-methyl acrylate terpolymer. The terpolymer makes the organotin stabilizer a high-molecular-weight heat stabilizer, ensuring that the stabilizer is uniformly dispersed in the resin matrix during processing, forming a stable blend system. Furthermore, by introducing styrene and methyl acrylate, the mechanical properties of PVC-C are significantly improved, thereby effectively reducing product defects. During processing, the dioctyltin maleate-styrene-methyl acrylate terpolymer can form coordinate bonds with unstable chlorine atoms in the PVC-C molecular structure, absorbing hydrogen chloride from PVC decomposition to generate a maleate monotin derivative. Under high-temperature conditions, the generated monotin derivative can add to conjugated polyenes on the PVC chain, blocking the conjugated polyenes and inhibiting PVC thermal decomposition and controlling discoloration.

[0020] The synergistic effect of polyol stabilizers, maleate organotin stabilizers, and calcium-zinc stabilizers significantly broadens the processing temperature range of PVC-C, effectively reducing energy consumption and significantly improving molding efficiency.

[0021] Preferably, the chlorinated polyvinyl chloride has a chlorine content of ≥67%.

[0022] Preferably, the lubricant is one or more of polyethylene wax, oxidized polyethylene wax, or paraffin.

[0023] Preferably, the impact-resistant agent is one or more of chlorinated polyethylene, acrylate copolymer, or methyl methacrylate-butadiene-styrene terpolymer.

[0024] Preferably, the preparation process of the dioctyltin maleate-styrene-methyl acrylate terpolymer heat stabilizer includes the following steps:

[0025] S1. Dioctyltin maleate, styrene, and methyl acrylate are mixed evenly in an organic solvent under an inert atmosphere;

[0026] S2. Add an initiator to the S1 mixture to initiate a polymerization reaction;

[0027] S3. Treat the reaction product with toluene containing hydroquinone ethanol solution to obtain a heat stabilizer of dioctyltin maleate-styrene-methyl acrylate terpolymer.

[0028] Preferably, the molar ratio of dioctyltin maleate, styrene, and methyl acrylate is 1 to 1.5:3:1.

[0029] Preferably, the initiator is azobisisobutyronitrile.

[0030] Preferably, the polymerization reaction is carried out at 65–75°C for 24–30 hours.

[0031] Preferably, the mass ratio of the polyol stabilizer, maleate organotin stabilizer, and calcium-zinc stabilizer is 1:4:2.

[0032] This invention also protects a method for preparing a chlorinated polyvinyl chloride composition, comprising the following steps:

[0033] Weigh each component according to the specified ratio, mix them at high speed at 110-120°C, and cool them to 35-40°C to obtain the chlorinated polyvinyl chloride composition.

[0034] The application of the above-mentioned chlorinated polyvinyl chloride composition in the preparation of chlorinated polyvinyl chloride pipes is also within the scope of protection of this invention.

[0035] The present invention also protects a chlorinated polyvinyl chloride pipe, which is prepared from the above-mentioned chlorinated polyvinyl chloride composition.

[0036] When the compound of the present invention is applied to the processing of PVC-C pipes, the pipe processing process is as follows: the above-mentioned uniformly mixed compound is put into the hopper of an extruder, and after the material is fully melted, sheared and plasticized at an extrusion temperature of 175 to 198°C, it is extruded through a die, shaped, cooled and cut to obtain PVC-C products.

[0037] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0038] This invention provides a polyvinyl chloride composition that improves the thermal stability and mechanical properties of polyvinyl chloride by using a combination of polyol stabilizers, maleate organotin stabilizers, and calcium-zinc stabilizers. This composition can be used to prepare chlorinated polyvinyl chloride pipes with good chemical stability, processing stability, and mechanical properties. Detailed Implementation

[0039] The present invention is further illustrated below with reference to specific embodiments. These embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Experimental methods in the following embodiments that do not specify specific conditions are generally performed under conventional conditions in the art or as recommended by the manufacturer; the raw materials and reagents used, unless otherwise specified, are all commercially available from the conventional market. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention are within the scope of protection claimed by the present invention.

[0040] The chlorinated polyvinyl chloride compositions, chlorinated polyvinyl chloride pipes, and maleate organotin stabilizers of the various embodiments and comparative examples of the present invention were prepared through the following process:

[0041] S1. Preparation of chlorinated polyvinyl chloride composition.

[0042] Add the ingredients in the formula to the hot mixing cylinder of the high-speed mixer in proportion, start heating, and heat the mixture to 110-120°C under high-speed stirring.

[0043] When the material reaches 110-120℃, transfer the material to a cold mixing tank and continue to stir and cool at low speed until the material temperature drops to 35-40℃.

[0044] The material is discharged to obtain a uniformly mixed chlorinated polyvinyl chloride composition;

[0045] S2. Prepare the corresponding chlorinated polyvinyl chloride pipes.

[0046] The above-mentioned chlorinated polyvinyl chloride composition is fed into the hopper of an extruder. At an extrusion temperature of 175-198°C, the material is fully melted, sheared, and plasticized. After being extruded through a die, shaped, cooled, and cut, PVC-C products are obtained.

[0047] The chlorinated polyvinyl chloride (PVC) pipe has an outer diameter of 26.8 mm and a wall thickness of 2.3 mm, which conforms to the national standard GB / T 39380.1-2021 Chlorinated polyvinyl chloride (PVC-C) piping systems for fire sprinkler systems - Part 1: Pipes.

[0048] Preparation of maleate organotin stabilizers: dioctyltin maleate-styrene-methyl acrylate terpolymer:

[0049] S1. Dioctyltin maleate, styrene, and methyl acrylate were added to a 500 mL three-necked flask in a molar ratio of 1:3:1. Then, 160 mL of toluene solvent was added to the flask. The reaction mixture was magnetically stirred at 50 °C for 25 min under nitrogen protection.

[0050] S2. After the reactants are completely dissolved in toluene, azobisisobutyronitrile (AIBN) is added to the flask. Then, under nitrogen protection, the temperature is raised to 70°C to continue the polymerization reaction. Magnetic stirring is maintained throughout the polymerization process to ensure uniform reaction. The polymerization time is 26 hours.

[0051] S3. After the polymerization reaction is complete, the product in the three-necked flask is poured into toluene containing a hydroquinone ethanol solution. Then, the product is precipitated using methanol. After multiple dissolutions and precipitations, the resulting product is dried in a vacuum drying oven for 7 hours to obtain a heat stabilizer for the dioctyltin maleate-styrene-methyl acrylate terpolymer.

[0052] Test metrics:

[0053] (1) Dynamic thermal stability time and plasticizing peak torque value

[0054] Torque rheology was used to perform intensive mixing of materials, and the rheological information of the samples was recorded. Specifically, the materials were weighed according to the ratio and added to a small mixer for high-speed mixing for 2-3 minutes. Then, 78-80g of the mixture was weighed out and added to the HAAKE torque rheometer. The material was quickly introduced into the mixing chamber and compacted with a plunger. The temperature was set to 182-186℃ and the rotation speed was 25rpm. During the intensive mixing process, the torque value of the plasticizing peak was recorded, and the time when the rheological curve began to rise (when the rheological curve of the PVC-C mixture rises, it indicates that the material has begun to decompose) was observed. This time is the dynamic thermal stability time of the mixture.

[0055] (2) Tensile strength

[0056] Tensile strength is characterized by tensile yield stress. The formulation of the example or comparative example is fed into the extruder hopper. After the material is fully melted, sheared and plasticized at an extrusion temperature of 175-198°C, it is extruded through the die, shaped, cooled and cut to obtain PVC-C products. The pipes are tested according to GB / T 39380.1-2021 Chlorinated polyvinyl chloride (PVC-C) piping systems for water sprinkler fire extinguishing - Part 1: Pipes. The tensile yield stress requirement is ≥55MPa, and the tensile speed is 5mm / min. The specific test method is based on GB / T 8804.2-2003.

[0057] (3) Hydraulic performance

[0058] Hydraulic performance is characterized by hydrostatic strength. The formulation materials of the examples or comparative examples are fed into the extruder hopper. After the material is fully melted, sheared and plasticized at an extrusion temperature of 175-198°C, it is extruded through the die, shaped, cooled and cut to obtain PVC-C products. The hydrostatic strength of the pipes is tested according to GB / T 39380.1-2021 Chlorinated Polyvinyl Chloride (PVC-C) Piping Systems for Sprinkler Fire Extinguishing Part 1: Pipes. The test conditions are 23°C, 1000h, and a ring stress of 31.1MPa. The requirement is that there is no leakage and no cracking to meet the requirements.

[0059] The reagents used in the various embodiments and comparative examples of this invention are described below:

[0060] Chlorinated polyvinyl chloride: chlorine content is 68%;

[0061] Polyol stabilizer 1#: Tris(hydroxymethyl)aminomethane;

[0062] Polyol stabilizer 2#: bis(2-hydroxyethyl)amino(tris(hydroxymethyl)methane;

[0063] Polyol stabilizer #3: Pentaerythritol;

[0064] Organotin maleate stabilizer: Dioctyltin maleate-styrene-methyl acrylate terpolymer;

[0065] Dioctyltin maleate;

[0066] Calcium and zinc stabilizers.

[0067] Table 1 shows the chlorinated polyvinyl chloride compositions provided in Examples 1-9.

[0068]

[0069] Table 2 shows the chlorinated polyvinyl chloride compositions provided in Comparative Examples 1-5.

[0070]

[0071] The test results of the examples and comparative examples are shown in Table 3:

[0072] Table 3 Test results of the examples and comparative examples

[0073]

[0074]

[0075] As can be seen from Table 3, the chlorinated polyvinyl chloride pipes prepared by the chlorinated polyvinyl chloride compositions of Examples 1 to 9 of the present invention all have excellent thermal stability and maintain excellent mechanical properties, among which Example 1 has the best overall performance.

[0076] Comparative Example 1 uses pentaerythritol instead of polyol stabilizer, resulting in a lack of amino groups in the system, which leads to the inability to effectively capture and neutralize the released chlorine atoms during the thermal decomposition of PVC-C. Comparative Example 2 does not add polyol stabilizer, resulting in poor thermal stability. Comparative Example 3 does not add maleate organotin stabilizer, resulting in a significant decrease in the thermal stability of the chlorinated PVC composition and poor mechanical properties of the product. Comparative Example 4 does not add calcium-zinc stabilizer, resulting in high melt viscosity during processing and significant shear heat effect during processing, leading to poor dynamic thermal stability. Comparative Example 5 uses dioctyltin maleate instead of maleate organotin stabilizer, making it difficult to utilize the excellent stability and the improvement effect on the mechanical properties of PVC-C of the dioctyltin maleate-styrene-methyl acrylate terpolymer.

[0077] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A chlorinated polyvinyl chloride composition, characterized in that, Includes the following components by weight: 80-110 parts of chlorinated polyvinyl chloride, 4-9.5 parts of heat stabilizer, 2-3 parts of lubricant, 5-10 parts of impact agent, and 0.5-1 part of titanium dioxide; The heat stabilizer is a polyol stabilizer, a maleate organotin stabilizer, and a calcium-zinc stabilizer, in a mass ratio of 0.5~1.5:2.5~6:1~2; The maleate organotin stabilizer is a dioctyltin maleate-styrene-methyl acrylate terpolymer heat stabilizer. The polyol stabilizer is one or both of tris(hydroxymethyl)aminomethane or bis(2-hydroxyethyl)amino(tris(hydroxymethyl)methane).

2. The chlorinated polyvinyl chloride composition according to claim 1, characterized in that, The mass ratio of the polyol stabilizer, maleate organotin stabilizer, and calcium zinc stabilizer is 1:4:

2.

3. The chlorinated polyvinyl chloride composition according to claim 1, characterized in that, The preparation process of the dioctyltin maleate-styrene-methyl acrylate terpolymer heat stabilizer includes the following steps: S1. Dioctyltin maleate, styrene, and methyl acrylate are mixed evenly in an organic solvent under an inert atmosphere; S2. Add an initiator to the S1 mixture to initiate a polymerization reaction; S3. Treat the reaction product with toluene containing hydroquinone ethanol solution to obtain a heat stabilizer of dioctyltin maleate-styrene-methyl acrylate terpolymer.

4. The chlorinated polyvinyl chloride composition according to claim 1, characterized in that, The lubricant is one or more of polyethylene wax, oxidized polyethylene wax, or paraffin wax.

5. The chlorinated polyvinyl chloride composition according to claim 1, characterized in that, The lubricant is polyethylene wax and oxidized polyethylene wax.

6. The chlorinated polyvinyl chloride composition according to claim 1, characterized in that, The impact-resistant agent is one or more of chlorinated polyethylene, acrylate copolymer, or methyl methacrylate-butadiene-styrene terpolymer.

7. A method for preparing the chlorinated polyvinyl chloride composition according to any one of claims 1 to 6, characterized in that, Includes the following steps: Weigh each component according to the specified ratio, heat and mix at 110~120℃, and cool to obtain the chlorinated polyvinyl chloride composition.

8. The use of the chlorinated polyvinyl chloride composition according to any one of claims 1 to 6 in the preparation of chlorinated polyvinyl chloride pipes.

9. A chlorinated polyvinyl chloride pipe, characterized in that, It is prepared from the chlorinated polyvinyl chloride composition according to any one of claims 1 to 6.

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