Chlorinated polyvinyl chloride composition as well as preparation method and application thereof

Abstract

The invention provides a chlorinated polyvinyl chloride composition as well as a preparation method and application thereof, and relates to the technical field of polymer composite materials. According to the invention, the polyol stabilizer, the maleate organic tin stabilizer and the calcium-zinc stabilizer are added into the chlorinated polyvinyl chloride, and the three heat stabilizers are compounded and combined, so that the heat stability is improved, the processing heat stability and the mechanical property are improved, and then the chlorinated polyvinyl chloride pipe with high heat stability and high mechanical property is prepared, and the production requirements are met.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer composite materials, and more particularly to a chlorinated polyvinyl chloride composition, a preparation method thereof, and an application thereof. Background Art

[0002] Chlorinated polyvinyl chloride (PVC-C) is a high-performance material derived from polyvinyl chloride (PVC) through chlorination. Compared to PVC, PVC-C offers superior heat resistance, rigidity, chemical resistance, flame retardancy, and smoke suppression properties, giving it significant advantages in a variety of applications. Pipes made from PVC-C are not only strong, corrosion-resistant, and flame-retardant, but are also unaffected by residual chlorine, hindering bacterial growth. They also exhibit excellent hygienic properties and aging resistance. These advantages have led to their widespread use in various fields, including building water supply and drainage, the chemical industry, and fire protection. However, due to the large number of polar chlorine atoms incorporated into PVC-C's molecular chain, this significantly increases its polarity and melt viscosity, making it more susceptible to decomposition during processing, producing corrosive HCl gas. This not only corrodes and wears molds but also complicates the plasticization of PVC-C. Furthermore, the high temperatures required for PVC-C processing further complicate its processing. Consequently, to meet the processing requirements of PVC-C, the requirements for heat stabilizers and lubricants have become increasingly stringent.

[0003] The chlorine content of PVC-C resin typically exceeds 67%. This increased chlorine content increases the polarity of its molecular chain, resulting in reduced thermal stability. It decomposes more readily during processing than PVC resin, generating HCl gas, which affects the plasticization of the formulated material and, in turn, product quality. Liquid thiolate-based organotin stabilizers are commonly used in PVC-C processing. However, these stabilizers present two issues during use. First, they have a strong odor and require relatively large amounts during processing. Long-term use can lead to sulfide contamination and discoloration of copper components, including copper sizing sleeves and fittings used in pipe production equipment. Second, while liquid organotin stabilizers provide good short-term stability for PVC-C during processing, they exhibit poor long-term stability and are unsuitable for applications requiring extended processing times.

[0004] The prior art discloses a heat-resistant and corrosion-resistant composition for PVC-C packing rings, comprising an organotin stabilizer and a calcium-zinc stabilizer. This composition does not form a thick layer during extrusion production, is easy to process, and produces packing rings with excellent heat resistance, corrosion resistance, and excellent physical and mechanical properties. Corrosion resistance refers to preventing PVC-C from decomposing and corroding the screw and mold during the extrusion process, reducing discoloration or surface unevenness of the equipment. However, the use of organotin thiolates poses a risk of contamination of copper components and a short thermal stability period, 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 pipes and prevent the heat stabilizer from damaging the processing equipment and copper components of the pipes, it is necessary to provide a modified chlorinated polyvinyl chloride composition and a chlorinated polyvinyl chloride pipe, which have high thermal stability, will not cause component damage, and have good mechanical properties. Summary of the Invention

[0006] In order to overcome the deficiencies of the prior art, the primary purpose of the present invention is to provide a chlorinated polyvinyl chloride composition, which improves the processing thermal stability and mechanical properties of the chlorinated polyvinyl chloride composition through the rational compounding of heat stabilizers, the mechanical properties 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 use of the above-mentioned 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 object, the present invention adopts the following technical solutions:

[0011] The present 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 anti-impact agent, 0.5-1 part of titanium dioxide;

[0013] The heat stabilizer is a polyol stabilizer, a maleate organic tin stabilizer and a calcium zinc stabilizer, and the mass ratio is 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 and bis(2-hydroxyethyl)amino(trihydroxymethyl)methane.

[0016] The invention adopts three heat stabilizers, namely, polyol stabilizer, maleate organic tin stabilizer and calcium zinc stabilizer, in combination and in a certain proportion to achieve modification of chlorinated polyvinyl chloride, improve thermal stability and increase mechanical properties of chlorinated polyvinyl chloride.

[0017] Calcium zinc stabilizers are often used as heat stabilizers in the processing of PVC resins. Their excellent lubricity significantly promotes the uniform dispersion of the stabilizer during processing, effectively reduces agglomeration, and enhances the melt fluidity of the formulated material. Experimental results show that in the processing of PVC-C, although the heat stabilization effect of calcium zinc stabilizers is slightly inferior to that of organotin stabilizers, they can effectively compensate for the shortcomings of organotin stabilizers in terms of lubricity. When calcium zinc stabilizers are used as a compound component of organotin stabilizers, the two exhibit an excellent synergistic effect. In addition, the zinc soap and calcium soap in the molecular structure of the calcium zinc stabilizer act together with the organotin stabilizer on PVC-C through coordination reactions by replacing active chlorine and absorbing HCl and capturing HCl, respectively, effectively inhibiting its de-HCl reaction.

[0018] The polyol stabilizer used in the present invention is either tris(hydroxymethyl)aminomethane or bis(2-hydroxyethyl)amino(trihydroxymethyl)methane, a novel and environmentally friendly organic heat stabilizer. The stabilizer's molecular structure contains a hydroxyl group and an amino group. The amino group possesses a lone pair of electrons, exhibiting strong alkalinity. This property enables it to displace unstable Cl atoms on the PVC chain through nucleophilic substitution and effectively neutralizes HCl released during PVC thermal degradation, further enhancing the stabilization effect.

[0019] The present invention discloses a maleate organotin stabilizer and a dioctyltin maleate-styrene-methyl acrylate terpolymer heat stabilizer. The terpolymer makes the organotin stabilizer a polymeric heat stabilizer, ensuring that the stabilizer can be evenly dispersed in the resin matrix during processing to form a stable blend system. Moreover, by introducing styrene and methyl acrylate, the mechanical properties of PVC-C are significantly improved, thereby effectively reducing the defects of the product. During processing, the dioctyltin maleate-styrene-methyl acrylate terpolymer can form coordination bonds with unstable chlorine atoms in the PVC-C molecular structure, absorb hydrogen chloride decomposed from the PVC to generate maleic acid mono-tin derivatives. The generated mono-tin can, under high temperature conditions, react with conjugated polyenes on the PVC chain to block the conjugated polyenes, thereby inhibiting the thermal decomposition of the PVC and controlling discoloration.

[0020] The synergistic effect of polyol stabilizer, maleate organotin stabilizer and calcium zinc stabilizer significantly broadens the processing temperature range of PVC-C, which not only effectively reduces energy consumption but also significantly improves molding efficiency.

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

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

[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 thermal stabilizer comprises the following steps:

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

[0026] S2. Adding an initiator to the S1 mixture to cause a polymerization reaction;

[0027] S3. The reaction product is treated with toluene containing an ethanol solution of hydroquinone to obtain a dioctyltin maleate-styrene-methyl acrylate terpolymer thermal stabilizer.

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

[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, the maleate organotin stabilizer, and the calcium zinc stabilizer is 1:4:2.

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

[0033] The components are weighed according to the proportion, the mixture is heated at a high speed at 110-120° C., and the mixture is cooled to 35-40° C. to obtain the chlorinated polyvinyl chloride composition.

[0034] The use of the above-mentioned chlorinated polyvinyl chloride composition in the preparation of chlorinated polyvinyl chloride pipes also falls within the protection scope of the present invention.

[0035] The present invention also protects a chlorinated polyvinyl chloride pipe prepared from the chlorinated polyvinyl chloride composition.

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

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] The present invention provides a polyvinyl chloride composition, which improves the thermal stability and mechanical properties of polyvinyl chloride by jointly using a polyol stabilizer, a maleate organic tin stabilizer, and a calcium zinc stabilizer. The composition can be used to prepare chlorinated polyvinyl chloride pipes with good chemical stability, processing stability and mechanical properties. DETAILED DESCRIPTION

[0039] The present invention is further described below with reference to the examples. These examples are intended to illustrate the present invention only and are not intended to limit the scope of the present invention. Experimental methods in the following examples where specific conditions are not specified are generally performed in accordance with conventional conditions in the art or the conditions recommended by the manufacturer; the raw materials and reagents used, unless otherwise specified, are all commercially available from conventional markets. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention fall within the scope of protection claimed in the present invention.

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

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

[0042] Add the ingredients in the formula into the hot mixing tank of the high-speed mixing unit in proportion, start heating, and heat the mixed material to 110-120℃ under high-speed stirring;

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

[0044] Discharging the materials to obtain a uniformly mixed chlorinated polyvinyl chloride composition;

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

[0046] The above-mentioned chlorinated polyvinyl chloride composition is put into the extruder hopper. At an extrusion temperature of 175-198° C., the material is fully melted, sheared and plasticized, and then extruded through a die head, shaped, cooled and cut to obtain a PVC-C product.

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

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

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

[0050] S2. After the reactants are completely dissolved in the toluene solvent, add azobisisobutyronitrile to the flask. Then, continue to raise the temperature to 70°C under a nitrogen atmosphere to allow polymerization to proceed. Maintain magnetic stirring throughout the polymerization process to ensure uniform reaction. The polymerization reaction lasts for 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. The product is then precipitated with methanol. After multiple dissolution and precipitation steps, the resulting product is dried in a vacuum drying oven for 7 hours to obtain a dioctyltin maleate-styrene-methyl acrylate terpolymer thermal stabilizer.

[0052] Test indicators:

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

[0054] The materials were mixed using torque rheology, and the rheological information of the samples was recorded. Specifically, the materials were weighed in proportion, added to a small mixer and mixed at high speed for 2 to 3 minutes, and then 78 to 80 g of the mixed materials were weighed; the mixed materials were added to the HAAKE torque rheometer, and the materials were quickly introduced into the mixing chamber and compacted with a plunger. The temperature was set to 182 to 186 ° C and the speed was 25 rpm. During the mixing process, the torque value of the plasticization peak was recorded, and the time when the rheological curve began to rise was observed (when the rheological curve of the PVC-C mixed material rose, it indicated that the material began to decompose). This time was the dynamic thermal stability time of the mixed material.

[0055] (2) Tensile strength

[0056] The tensile strength is characterized by the tensile yield stress. The formulation of the embodiment or comparative example is put into the extruder hopper. At an extrusion temperature of 175-198°C, the material is fully melted, sheared and plasticized, and then extruded through a die, shaped, cooled, and cut to obtain a PVC-C product. The pipe is tested in accordance with "GB / T 39380.1-2021 Chlorinated polyvinyl chloride (PVC-C) piping systems for water spray fire extinguishing Part 1: Pipes". The tensile yield stress requirement is ≥55 MPa, and the tensile speed is 5 mm / min. The specific test method is based on GB / T 8804.2-2003.

[0057] (3) Hydraulic performance

[0058] The hydraulic performance is characterized by the hydrostatic strength. The formulation of the embodiment or comparative example is put into the extruder hopper. At an extrusion temperature of 175-198°C, the material is fully melted, sheared and plasticized, and then extruded through a die, shaped, cooled, and cut to obtain a PVC-C product. The pipe is tested for hydrostatic strength in accordance with "GB / T 39380.1-2021 Chlorinated polyvinyl chloride (PVC-C) piping systems for water spraying fire extinguishing - Part 1: Pipes". The test conditions are 23°C, 1000 hours, and a hoop stress of 31.1 MPa. No leakage or cracking is required to meet the requirements.

[0059] Some of the reagents selected in the embodiments and comparative examples of the present invention are described as follows:

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

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

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

[0063] Polyol stabilizer 3#: pentaerythritol;

[0064] Maleate organotin stabilizer: dioctyltin maleate-styrene-methyl acrylate terpolymer;

[0065] dioctyltin maleate;

[0066] Calcium zinc stabilizer.

[0067] Table 1 Chlorinated polyvinyl chloride compositions provided by Examples 1 to 9

[0068]

[0069] Table 2 Chlorinated polyvinyl chloride compositions provided by Comparative Examples 1 to 5

[0070]

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

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

[0073]

[0074]

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

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

[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 the technical solutions of the present invention may be modified or replaced by equivalents 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 It includes the following components calculated 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 anti-impact agent, 0.5-1 part of titanium dioxide; The heat stabilizer is a polyol stabilizer, a maleate organic tin stabilizer and a calcium zinc stabilizer, and the mass ratio is 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 and bis(2-hydroxyethyl)amino(trihydroxymethyl)methane.

2. The chlorinated polyvinyl chloride composition according to claim 1, characterized in that The mass ratio of the polyol stabilizer, the maleate organic tin stabilizer and the calcium zinc stabilizer is 0.5-1.5:3.0-5.0:1.5-2.

5.

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

2.

4. 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 comprises the following steps: S1. Dioctyltin maleate, styrene, and methyl acrylate are mixed in an organic solvent under an inert atmosphere; S2. Adding an initiator to the S1 mixture to cause a polymerization reaction; S3. The reaction product is treated with toluene containing an ethanol solution of hydroquinone to obtain a dioctyltin maleate-styrene-methyl acrylate terpolymer thermal stabilizer.

5. 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.

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

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

8. The method for preparing the chlorinated polyvinyl chloride composition according to any one of claims 1 to 7, characterized in that: The following steps are involved: The components are weighed according to the proportions, the mixture is heated at 110-120° C., and the mixture is cooled to obtain the chlorinated polyvinyl chloride composition.

9. Use of the chlorinated polyvinyl chloride composition according to any one of claims 1 to 7 in the preparation of chlorinated polyvinyl chloride pipes.

10. A chlorinated polyvinyl chloride pipe, characterized in that: The chlorinated polyvinyl chloride composition is prepared from any one of claims 1 to 7.

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