Polyvinyl chloride composition as well as preparation method and application thereof

Abstract

The invention discloses a polyvinyl chloride composition as well as a preparation method and application thereof, and belongs to the technical field of high polymer materials. The polyvinyl chloride composition comprises the following components in parts by weight: 100 parts of polyvinyl chloride resin; 4-6 parts of a stabilizer; 6-8 parts of a waxy external lubricant; 3-5 parts of an internal lubricant; 10 to 20 parts of maleic anhydride grafted linear low density polyethylene; and 1-3 parts of nano white carbon black. According to the polyvinyl chloride composition provided by the invention, through the synergistic effect of the maleic anhydride grafted linear low-density polyethylene and the nano white carbon black, the polyvinyl chloride composition also has excellent plasticizing degree when a large amount of a waxy external lubricant is added, no powder exists on the surface after plasticizing, and the mechanical property is not obviously reduced; meanwhile, the waxy external lubricant can be obviously separated out, and scaling is prevented.

Description

Technical Field

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

[0002] Drain pipes are an indispensable part of modern buildings. PVC has many advantages such as flame retardancy, good rigidity and low price, making it the main material for drain pipes. Since PVC is a polar material, it is easy to scale on the inner wall after long-term use and is difficult to clean, causing bacteria and viruses to breed in large numbers, thus affecting the indoor environment.

[0003] The existing PVC composite material used to prepare PVC drainage pipes generally consists of PVC resin, heat stabilizer and lubricant. The lubricant includes external lubricant and internal lubricant. The external lubricant is generally polyethylene wax, and the internal lubricant is generally stearic acid.

[0004] Wax lubricants are generally used as external lubricants in PVC compositions for preparing PVC water pipes, and the amount of wax lubricants used is generally within 2% of the PVC composition.

[0005] In order to prevent scaling of PVC drainage pipes, there is an existing technology that adds a large amount of wax external lubricant to PVC, so that the wax external lubricant precipitates on the surface of the PVC pipe. By utilizing the incompatibility principle of water and wax, impurities in the water are prevented from adhering to the surface of the PVC pipe, thereby avoiding scaling inside the PVC water pipe and reducing the growth of bacteria.

[0006] However, increasing the content of wax external lubricant will lead to poor plasticization degree of PVC, the appearance of powder on the surface after plasticization, and reduce the mechanical properties of PVC materials. Summary of the invention

[0007] The technical problem to be solved by the present invention is to overcome the defects and shortcomings of the existing polyvinyl chloride composition for preparing PVC drainage pipes, such as poor plasticization degree, powdery matter on the surface after plasticization and reduced mechanical properties, due to the synergistic effect of maleic anhydride grafted linear low-density polyethylene and nano-white carbon black. The polyvinyl chloride composition can have excellent plasticization degree even when a large amount of wax external lubricant is added, no powdery matter on the surface after plasticization, and no obvious reduction in mechanical properties. At the same time, the wax external lubricant can be precipitated to prevent scaling.

[0008] Another object of the present invention is to provide a method for preparing the polyvinyl chloride composition.

[0009] Another object of the present invention is to provide a PVC composite pipe.

[0010] The above-mentioned purpose of the present invention is achieved through the following technical solutions:

[0011] A polyvinyl chloride composition, comprising the following components by weight:

[0012]

[0013] The polyvinyl chloride composition of the present invention has a relatively high content of wax external lubricant, which is precipitated on the surface of the PVC pipe. The incompatibility principle of water and wax is utilized to prevent impurities in water from adhering to the surface of the PVC pipe, thereby avoiding scaling inside the PVC water pipe and reducing bacterial growth.

[0014] The present invention can have excellent plasticization degree even when a large amount of wax external lubricant is added through the synergistic effect of maleic anhydride grafted linear low-density polyethylene and nano-white carbon black, and there is no powder on the surface after plasticization, and the mechanical properties are not significantly reduced. The principle is as follows: polyethylene is a non-polar material and is not easy to scale itself, but polyethylene cannot be compatible with PVC because of its strong non-polarity. Maleic anhydride grafted linear low-density polyethylene can improve polarity due to the maleic anhydride group, so it has excellent compatibility with PVC. Therefore, the anti-scaling ability of PVC material can be improved by maleic anhydride grafted linear low-density polyethylene. Since PVC resin is a heat-sensitive plastic, although a stabilizer is added, excessively high temperature will still cause the PVC resin to decompose, so the temperature needs to be strictly controlled during the PVC processing process. At the same time, the PVC resin processing process that only adds a stabilizer and a lubricant will have a "slippery wall" phenomenon, which is difficult to fully plasticize. If a higher content of wax external lubricant is added, the PVC plasticization is more difficult. Therefore, in order to ensure the plasticization of PVC resin with a high content of waxy external lubricant, nano-silica with a large specific surface area is added to increase shearing. Nanoparticles can enter between PVC molecular chains, increase the shear friction between PVC molecular chains, and thus enhance the plasticization effect. In addition, maleic anhydride grafted linear low-density polyethylene has a high melt viscosity, which is also very helpful for the plasticization of PVC resin with a high content of waxy external lubricant.

[0015] Preferably, the waxy external lubricant is one or more of Fischer-Tropsch wax, EVA copolymer wax or paraffin wax.

[0016] More preferably, the Fischer-Tropsch wax is a non-polar wax, and the melting point of the Fischer-Tropsch wax may be higher than 110° C. Fischer-Tropsch wax with a higher melting point is less likely to migrate, which is beneficial for maintaining the durability of the anti-fouling performance. In a specific embodiment, the melting point of the Fischer-Tropsch wax may be 115° C.

[0017] EVA copolymer wax is a polar wax and has good compatibility with PVC.

[0018] The paraffin wax may be fully refined paraffin wax, and the melting point of the paraffin wax may be lower than 65° C. The paraffin wax with a lower melting point has good hydrophobicity, which is more conducive to preventing impurities in water from adhering to the surface of the PVC pipe and improving the anti-scaling performance. In a specific embodiment, the melting point of the paraffin wax may be 56° C.

[0019] More preferably, the waxy external lubricant is Fischer-Tropsch wax, EVA copolymer wax and paraffin wax.

[0020] The weight percentage of the Fischer-Tropsch wax in the waxy external lubricant is 40-80%.

[0021] The weight percentage of the EVA copolymer wax in the waxy external lubricant is 15-30%.

[0022] The weight percentage of paraffin in the waxy external lubricant is 5 to 30%.

[0023] More preferably, the weight percentage of paraffin in the waxy external lubricant is not higher than 25%, because the long-term migration resistance is poor after the content of the lower melting point paraffin is increased, and the anti-fouling performance will gradually deteriorate after the wax is lost.

[0024] Preferably, the internal lubricant is a stearic acid-based internal lubricant.

[0025] Preferably, the stabilizer is an organotin stabilizer.

[0026] In the maleic anhydride grafted linear low-density polyethylene, the mass grafting rate of maleic anhydride is 0.6-1.2 wt %.

[0027] In the maleic anhydride grafted linear low-density polyethylene, the mass grafting rate of maleic anhydride is higher, which is more conducive to improving the surface gloss of the material and also more conducive to improving the anti-fouling performance.

[0028] Preferably, the D90 particle size of nano-white carbon black is 300-350 nm, and the D97 particle size is 450-500 nm.

[0029] The present invention also protects a PVC composite pipe, comprising an outer layer and an inner layer, wherein the inner layer is prepared from any one of the polyvinyl chloride compositions described above, and the outer layer is a PVC layer.

[0030] The present invention also protects a PVC composite pipe, comprising an outer layer, a middle layer and an inner layer, wherein the inner layer is prepared from any one of the above-mentioned polyvinyl chloride compositions.

[0031] Preferably, the wall thickness of the outer layer is 10-15% of the total wall thickness, the wall thickness of the middle layer is 60-70% of the total wall thickness, and the wall thickness of the inner layer is 15-30% of the total wall thickness.

[0032] Preferably, the middle layer is a PVC layer, and the outer layer is prepared by blending polyvinyl chloride resin and polymethyl methacrylate powder with an average particle size of 74 to 149 μm.

[0033] PMMA powder has good weather resistance, better compatibility with PVC, and bright colors, which can be adjusted to be close to the color of the building.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] The invention provides a polyvinyl chloride composition, which can have excellent plasticization degree even when a wax external lubricant is added in a large amount through the synergistic effect of maleic anhydride grafted linear low-density polyethylene and nano-white carbon black, has no powdery matter on the surface after plasticization, and has no obvious reduction in mechanical properties, and at the same time, the wax external lubricant can be obviously precipitated to prevent scaling. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is an appearance picture with good plasticization and obvious wax precipitation.

[0037] Figure 2 This is an appearance picture with a good degree of plasticization and wax precipitation on the surface.

[0038] Figure 3 This is an appearance picture with a general degree of plasticization and no obvious wax precipitation.

[0039] Figure 4 This is an appearance picture with poor plasticization, no wax precipitation, and visible powder particles.

[0040] Figure 5 This is the appearance of an overly plasticized product.

[0041] Figure 6 It is a schematic diagram of the structure of the device used in the anti-scaling performance test. DETAILED DESCRIPTION

[0042] The present invention is further described below in conjunction with specific embodiments, but the embodiments do not limit the present invention in any form. Unless otherwise specified, the raw materials and reagents used in the embodiments of the present invention are conventionally purchased raw materials and reagents.

[0043] Polyvinyl chloride resin, type VIII suspension polyvinyl chloride resin, brand name SG-8.

[0044] Stabilizer: tin methyl mercaptan.

[0045] External lubricant 1, Fischer-Tropsch wax, melting point is 115°C. The manufacturer is Shaanxi Future Cleaning Chemicals Co., Ltd., brand name is WL-115.

[0046] External lubricant 2: EVA copolymer wax. The manufacturer is BASF, the brand is EVA3.

[0047] External lubricant 3: paraffin wax, melting point is 56°C. The manufacturer is PetroChina Daqing Refining and Chemical Company, brand number is 56# fully refined.

[0048] Internal lubricant, stearic acid.

[0049] Maleic anhydride grafted linear low density polyethylene 1, manufacturer is Coase Chemical, brand: TDS-W1L.

[0050] The mass grafting rate of maleic anhydride was 0.8 wt %, and the melt mass flow rate of the maleic anhydride grafted linear low density polyethylene at 190° C. and 2.16 kg was 1.7 g / 10 min.

[0051] Maleic anhydride grafted linear low-density polyethylene 2 was customized by Coase Chemical, and the difference from maleic anhydride grafted linear low-density polyethylene 1 was that the mass grafting rate of maleic anhydride was 1.1 wt%.

[0052] Nano-silica gel 1, D90 particle size is 300-350nm, D97 particle size is 450-500nm.

[0053] Ordinary white carbon black 2, 1500 mesh.

[0054] The specific content of the wax external lubricant composition is shown in Table 1 below.

[0055] Table 1 Wax external lubricant composition of each embodiment (by weight percentage)

[0056] Group Fischer-Tropsch wax EVA copolymer wax paraffin Waxy external lubricant composition 1 60％ 30％ 10％ Waxy external lubricant composition 2 80％ 15％ 5％ Waxy external lubricant composition 3 40％ 30％ 30％

[0057] Examples 1 to 6

[0058] A polyvinyl chloride composition, comprising the following components by weight:

[0059] Polyvinyl chloride resin; stabilizer; waxy external lubricant; internal lubricant; maleic anhydride grafted linear low-density polyethylene; nano-silica gel.

[0060] The specific content of each component is shown in Table 2 below.

[0061] Table 2 Composition of polyvinyl chloride composition of each embodiment (by weight)

[0062]

[0063] The preparation method of the above polyvinyl chloride composition is as follows:

[0064] The components are put into a high-speed mixer and stirred to 120-125 degrees, and then stirred at a low speed in a low-speed mixer and cooled to 50-60 degrees, and the dry mixture is discharged to obtain a polyvinyl chloride composition.

[0065] A PVC composite pipe comprises an outer layer, an intermediate layer and an inner layer, wherein the inner layer is made of the above-mentioned polyvinyl chloride composition, the intermediate layer is a PVC layer, and the outer layer is made of a mixture of polyvinyl chloride resin and polymethyl methacrylate powder with an average particle size of 74 to 149 μm. The wall thickness of the outer layer is 10% of the total wall thickness, the wall thickness of the intermediate layer is 60% of the total wall thickness, and the wall thickness of the inner layer is 30% of the total wall thickness.

[0066] Comparative Examples 1 to 4

[0067] A polyvinyl chloride composition, comprising the following components by weight:

[0068] Polyvinyl chloride resin; stabilizer; waxy external lubricant; internal lubricant; maleic anhydride grafted linear low-density polyethylene; nano-silica gel.

[0069] The specific content of each component is shown in Table 3 below.

[0070] Table 3 Composition of polyvinyl chloride compositions of various comparative examples (by weight)

[0071]

[0072] The preparation method of the polyvinyl chloride composition is the same as that of the embodiment, which will not be described again here.

[0073] Results

[0074] Processing performance evaluation: The polyvinyl chloride composition dry blend prepared in the examples and comparative examples was plasticized for 10 minutes at 190°C and 45 rpm using a rheometer to obtain a melt. The equilibrium temperature and equilibrium torque when the melt reached equilibrium are shown in Table 1 below. The appearance of the rheological residue was observed:

[0075] Figure 1 It is an appearance picture with good plasticization degree (75% ≤ gelation degree ≤ 85%) and obvious wax precipitation, and the appearance grade is level one.

[0076] Figure 2 It is an appearance picture with a good degree of plasticization (70% ≤ degree of gelation < 75%) and wax precipitation on the surface. The appearance grade is level 2.

[0077] Figure 3 It is an appearance picture with a general degree of plasticization (60% ≤ degree of gelation < 70%) and no obvious wax precipitation. The appearance grade is level three.

[0078] Figure 4It has a poor degree of plasticization (gelation degree < 60%), no wax precipitation, and visible powder particles. The appearance grade is level four.

[0079] Figure 5 This is an appearance picture of a product with too high a degree of plasticization (gelation degree > 85%), and the appearance grade is level five.

[0080] The polyvinyl chloride composition melts prepared in the examples and comparative examples were pressed into test specimens on a specimen mold of a flat vulcanizer and tested as follows:

[0081] (1) Density: The test standard is GB / T1033.1-2008.

[0082] (2) Anti-scaling performance: The test method is as follows: 1. The polyvinyl chloride compositions of each embodiment and comparative example are rheologically pressed into a sample of 20 mm wide × 200 mm long × 4 mm thick. The sample weighs between 21 and 23 g under the material of the present invention. 2. The test sample is marked with a weight a and fixed on a device filled with muddy water (such as Figure 6 3. After continuous rotation for 72 hours, take out the sample, dry it at room temperature for 24 hours, and measure the sample weight b. 4. Put the weighed sample into another same device filled with clean water, rotate it for another 24 hours, take out the sample, dry it at room temperature for 24 hours, and measure the sample weight c. Calculate the values ​​of (ba) / a and (ca) / a respectively. The lower the value, the more wax is precipitated on the surface of the material and the better the anti-scaling performance.

[0083] (3) Gloss: Cut a thin slice of the rheological residue and place it under a colorimeter to measure the L value.

[0084] The PVC composite pipes prepared in the examples and comparative examples were tested as follows:

[0085] (4) Vicat softening temperature: test standard GB / T 8802-2001.

[0086] (5) Tensile yield stress: The test standard is GB / T 8804.2-2003.

[0087] (6) Elongation at break: The test standard is GB / T 8804.2-2003.

[0088] The specific test results of each embodiment are described in Table 4 below:

[0089] Table 4

[0090]

[0091]

[0092] The specific test results of each comparative example are described in Table 5 below:

[0093] Table 5

[0094] project Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Equilibrium temperature℃ 192.4 195.9 209.2 196.8 Balance torque℃ 15.1 17.2 23.5 18.1 Appearance grade Level 3 Level 3 Level 5 Level 4 <![CDATA[Density g / cm 3 > 1.392 1.373 1.35 1.353 (ba) / a 4.3％ 2.7％ 2.3％ 2.9％ (ca) / a 3.8％ 2.0％ 1.8％ 2.0％ Glossiness (L value) 79.7 80.6 90.3 81.5 Vicat softening temperature℃ 79.5 79.8 80.3 78.6 Tensile yield stress MPa 33.8 37.5 39.9 37.4 Elongation at break % 57.1 82.6 90.2 79.3

[0095] It can be seen from the above data that the PVC composition of the present invention has a higher lubricant content, has excellent plasticization degree through maleic anhydride grafted linear low-density polyethylene LLDPE and nano-white carbon black, and has good gloss on the melt surface, no powder, and obvious oily matter when touched by hand, thereby preventing scaling of water pipes.

[0096] It can be seen from the examples and comparative example 1 that the appearance grade of comparative example 1 is level 3, which is unqualified. This may be because there is no maleic anhydride grafted linear low-density polyethylene LLDPE and nano-white carbon black. Due to the excessive content of wax lubricant and stearic acid lubricant, the plasticization is poor, which is manifested as powdery matter after plasticization, and the equilibrium temperature and equilibrium torque are low, resulting in no obvious wax precipitation on the melt surface. The tensile yield stress and elongation at break in the mechanical properties are both too poor.

[0097] It can be seen from the example and comparative example 2 that the amount of maleic anhydride grafted linear low-density polyethylene LLDPE added is too little, the appearance grade is level three, which is unqualified, and the anti-fouling performance is too poor.

[0098] It can be seen from the examples and comparative example 3 that the amount of nano-white carbon black added is too much, the anti-scaling performance is still poor, and the plasticization degree is too high, the color is yellowish, and the appearance grade is level five and unqualified.

[0099] It can be seen from the embodiment and comparative example 4 that when the nano-white carbon black is replaced with ordinary micron-level white carbon black, the anti-scaling performance is still poor, and the plasticization is poor, the surface is dull, and the appearance grade is level four and unqualified.

[0100] In addition, compared with Example 4, Example 1 has better processability.

[0101] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A polyvinyl chloride composition, characterized in that By weight, it includes the following components:

2. The polyvinyl chloride composition according to claim 1, characterized in that The wax external lubricant is one or more of Fischer-Tropsch wax, EVA copolymer wax or paraffin wax.

3. The polyvinyl chloride composition according to claim 1, characterized in that The internal lubricant is a stearic acid internal lubricant.

4. The polyvinyl chloride composition according to claim 1, characterized in that The stabilizer is an organotin stabilizer.

5. The polyvinyl chloride composition according to claim 1, characterized in that: In the maleic anhydride grafted linear low-density polyethylene, the mass grafting rate of maleic anhydride is 0.6-1.2 wt %.

6. The polyvinyl chloride composition according to claim 1, characterized in that: The D90 particle size of nano-silica is 300-350nm, and the D97 particle size is 450-500nm.

7. A PVC composite pipe, characterized in that: It comprises an outer layer and an inner layer, wherein the inner layer is prepared from the polyvinyl chloride composition according to any one of claims 1 to 6, and the outer layer is a PVC layer.

8. A PVC composite pipe, characterized in that: It comprises an outer layer, a middle layer and an inner layer, wherein the inner layer is prepared from the polyvinyl chloride composition according to any one of claims 1 to 6.

9. The PVC composite pipe according to claim 8, characterized in that: The wall thickness of the outer layer is 10-15% of the total wall thickness, the wall thickness of the middle layer is 60-70% of the total wall thickness, and the wall thickness of the inner layer is 15-30% of the total wall thickness.

10. The PVC composite pipe according to claim 8, wherein the middle layer is a PVC layer, and the outer layer is prepared by blending polyvinyl chloride resin and polymethyl methacrylate powder with an average particle size of 74 to 149 μm.

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