A PVC material double-reinforced by polytetrafluoroethylene and basalt fiber, and a preparation method and application thereof

Abstract

The application relates to a PVC material reinforced by polytetrafluoroethylene and basalt fiber and a preparation method and application thereof. The preparation method of the PVC material reinforced by polytetrafluoroethylene and basalt fiber comprises the following steps: adding raw material components into a screw extruder, melting, blending, and extruding, so that the PVC material is obtained; the raw material components comprise polyvinyl chloride, polytetrafluoroethylene and basalt fiber with a mass ratio of 100:(3-4):(5-7); the melting temperature of the polytetrafluoroethylene is greater than or equal to 335 DEG C; and the screw rotation speed of the screw extruder is greater than or equal to 300 r / min. The PVC material prepared by the preparation method has high toughness (high elongation at break and high impact strength) and good plastic deformation resistance (high yield stress).

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of plastic processing, more particularly, to a PVC material reinforced by polytetrafluoroethylene and basalt fiber and a preparation method and application thereof. BACKGROUND

[0002] Plastic pipes are widely used in the fields of construction, water conservancy, heating delivery, gas delivery, etc. Compared with traditional concrete and metal pipes, plastic pipes have the advantages of low density, good corrosion resistance, simple installation, energy saving, long service life, etc. The Ministry of Construction has stipulated that plastic pipes are an advanced technology that can be widely used in various fields. The sharp rise in oil prices has led to a significant increase in the cost of downstream plastic materials, and it is necessary to find raw materials for plastic pipes from other channels to reduce costs. As one of the important raw materials for plastic pipes, polyvinyl chloride (PVC) resin can be made from coal, so from the aspects of raw material manufacturing and pipe forming processing, PVC pipes made of polyvinyl chloride as the main raw material have more promotion and research value than pipes made of other materials.

[0003] The prominent problem in the field of PVC pipe preparation is that polyvinyl chloride has obvious brittleness, which limits its application. The methods to improve the brittleness of PVC pipes are chemical modification and physical modification. Currently, the chemical modification of polyvinyl chloride mainly includes grafting and copolymerization. Although the method of chemical modification has certain effectiveness, it has high technical difficulty, is difficult to operate, and has high cost, which is not conducive to large-scale promotion. The physical modification mainly uses the method of adding modifiers and additives to toughen, such as the Chinese patent entitled "a toughening agent, PVC pipe material and preparation method thereof". Although the existing physical modification technology has low technical difficulty, in order to obtain good results, a high amount of toughening agent must be added, which increases the cost to some extent.

[0004] In addition, the plastic deformation resistance is one of the key indicators of pipes. Pipes with good plastic deformation resistance can ensure accurate installation, orderly layout and safe operation. Conventional toughening agents can improve the impact strength of PVC materials, but it is difficult to significantly improve the plastic deformation resistance of the materials. SUMMARY

[0005] The primary object of the present application is to overcome the problems of high cost and poor toughening effect of the existing polyvinyl chloride toughening technology, and the difficulty of conventional toughening agents to significantly improve the plastic deformation resistance of PVC materials, and to provide a preparation method of a PVC material reinforced by polytetrafluoroethylene and basalt fiber.

[0006] A further object of the present application is to provide a PVC material reinforced by polytetrafluoroethylene and basalt fiber.

[0007] It is a further object of the present application to provide the use of the above-mentioned PVC material in the preparation of PVC pipes.

[0008] The above-mentioned objects of the present application are achieved by the following technical solutions.

[0009] A method for preparing a PVC material reinforced by polytetrafluoroethylene and basalt fiber, comprising the following steps:

[0010] The raw material components are added into a screw extruder, melted, blended, and extruded to obtain the PVC material;

[0011] The raw material components include polyvinyl chloride, polytetrafluoroethylene, and basalt fiber in a mass ratio of 100:(3-4):(5-7); the melting temperature of the polytetrafluoroethylene is ≥332℃;

[0012] The screw rotation speed of the screw extruder is ≥300 rpm.

[0013] The present application finds that, by adding a certain amount of polytetrafluoroethylene with a specific melting temperature and a certain amount of basalt fiber into polyvinyl chloride and melting and extruding at a certain screw rotation speed, a PVC material with good plastic deformation resistance (high yield stress), high toughness (high elongation at break and high impact strength) can be obtained. The principle is that the crystal structure of polytetrafluoroethylene with a high melting temperature (≥332℃) is complete, and the combination of shearing action caused by a certain screw rotation speed and melting can realize in-situ fiber formation of polytetrafluoroethylene, forming flexible polytetrafluoroethylene continuous long fibers in the PVC material, and the polytetrafluoroethylene continuous long fibers further form a three-dimensional network entanglement structure with the basalt fiber, and the network entanglement structure has a balance of rigidity and toughness, thereby not only giving the PVC material high toughness, but also giving the PVC material good plastic deformation resistance.

[0014] If the melting temperature of polytetrafluoroethylene is too low, the crystal structure of polytetrafluoroethylene is incomplete, it is difficult to form continuous polytetrafluoroethylene fibers during preparation, and further formation of a three-dimensional network entanglement structure is impossible, resulting in that the toughness cannot be improved, and the polytetrafluoroethylene and basalt fibers that cannot be entangled with each other also have certain degradation to the plastic deformation resistance of the material. If the amount of polytetrafluoroethylene is too much, the melt viscosity during preparation rises obviously, the melt mixing is difficult, the uniform distribution of the continuous polytetrafluoroethylene fibers and basalt fibers is not conducive, and thus the performance of the material cannot be improved or is deteriorated. If the amount of basalt fibers is too small, a relatively complete three-dimensional network entanglement structure cannot be formed, and the performance is poor or poor. If the amount of basalt fibers is too much, the relatively high rigidity of the basalt fibers has a certain degree of degradation to the toughness of the material. If the basalt fibers are not selected, but other fibrous fillers (such as glass fibers) are selected, the network entanglement structure formed is insufficient in rigidity, the rigidity and toughness balance cannot be achieved, and thus the performance of the material cannot be improved obviously. If the screw rotation speed of the screw extruder is too low, the in-situ fiber forming effect of polytetrafluoroethylene during preparation is not good, the continuous long fibers formed are insufficient, and the performance of the material cannot be improved obviously.

[0015] The preparation method of the present application does not need to add a toughening agent, a compatibilizer and a dispersant (such as a silane coupling agent), and can obviously improve the yield stress, elongation at break and impact strength of the PVC material under the condition that the amount of polytetrafluoroethylene is low (3-4 wt% of the polyvinyl chloride resin), the amount of addition is small, the production cost of the PVC material can be well controlled. In addition, the addition of polytetrafluoroethylene also has the effects of anti-dripping and flame retardation, and no additional flame retardant is needed, which improves the product added value while further reducing the cost. The preparation method has simple equipment, easy operation, low technical difficulty and good implementation.

[0016] In the present application, when the amount of polyvinyl chloride is 100 parts by weight, the amount of polytetrafluoroethylene can be 3, 3.2, 3.5, 3.6, 3.8 or 4 parts by weight, and the amount of basalt fibers can be 5, 5.5, 6, 6.5 or 7 parts by weight.

[0017] In the present application, the melting temperature of polytetrafluoroethylene can be measured by a differential scanning calorimeter (DSC).

[0018] Preferably, the viscosity number of the polyvinyl chloride is 105-140 mL / g; specifically, it can be 105 mL / g, 110 mL / g, 115 mL / g, 120 mL / g, 125 mL / g, 130 mL / g, 135 mL / g or 140 mL / g.

[0019] In the present application, the viscosity number of polyvinyl chloride can be measured by an Ubbelohde viscometer.

[0020] Preferably, the polytetrafluoroethylene is added into the screw extruder in the form of particles.

[0021] Preferably, the polytetrafluoroethylene has a density of 2.1-2.3 g / cm 3 .

[0022] Preferably, the basalt fiber has an average cross-sectional diameter of 10-25 μm.

[0023] Typically, the basalt fiber has an average length of 20-50 mm.

[0024] Preferably, the polytetrafluoroethylene has a melting temperature of 335-340℃; specifically, 335℃, 336℃, 337℃, 338℃, 339℃ or 340℃.

[0025] Typically, the raw material component further comprises a heat stabilizer; the heat stabilizer is used in an amount of 5-8 wt% of the polyvinyl chloride.

[0026] Preferably, the raw material component further comprises other auxiliary agents.

[0027] More preferably, the other auxiliary agents include, but are not limited to, antioxidants, lubricants, etc.

[0028] Preferably, before the raw material component is added into the screw extruder, the method further comprises a step of drying the raw material component.

[0029] Preferably, the screw extruder has a rotation speed of 300-600 revolutions per minute; more preferably, 400-500 revolutions per minute.

[0030] Preferably, the screw extruder has a screw length-diameter ratio of (30-40):1

[0031] Preferably, the screw extruder is a double-screw extruder.

[0032] Preferably, the screw extruder comprises one to six zones from the feeding port to the head, and the temperatures of the one to six zones are 160-170℃, 170-175℃, 175-180℃, 175-180℃, 178-183℃ and 175-180℃, respectively.

[0033] A polytetrafluoroethylene and basalt fiber double-reinforced PVC material is prepared by the above preparation method.

[0034] The application of the above PVC material in the preparation of PVC pipes is also within the protection scope of the present application.

[0035] Compared with the prior art, the present application has the following beneficial effects:

[0036] The PVC material prepared by the preparation method has high toughness (high elongation at break and high impact strength) and good plastic deformation resistance (high yield stress). DETAILED DESCRIPTION

[0037] In order to more clearly and completely describe the technical solutions of the present application, the present application is further described in detail below through specific examples. It should be understood that the specific examples described herein are only used to explain the present application and are not used to limit the present application, and various changes can be made within the scope of the present application.

[0038] Example 1

[0039] The present embodiment provides a preparation method of a PVC material double-strengthened by polytetrafluoroethylene and basalt fiber, comprising the following steps:

[0040] 1) Dry the polyvinyl chloride granules, the polytetrafluoroethylene granules and the basalt fiber in a drying machine at 60 degrees Celsius for 2 hours, respectively; wherein the viscosity number of the polyvinyl chloride granules is 120 mL / g; the melting temperature of the polytetrafluoroethylene granules is 337 degrees Celsius (manufacturer is Mitsubishi, model is A3800); the average diameter of the cross section of the basalt fiber is 15 microns, and the average length is 35 mm;

[0041] 2) After the dried polyvinyl chloride granules, the polytetrafluoroethylene granules and the basalt fiber are weighed according to the mass ratio of 100:3:6, they are then put into a double-screw extruder (Nanjing May-75) at one time, melted, blended and extruded, and thus the PVC material is obtained; wherein the temperature of the double-screw extruder is set from the feeding port to the head as 160 degrees Celsius, 170 degrees Celsius, 180 degrees Celsius, 180 degrees Celsius, 183 degrees Celsius and 175 degrees Celsius; the rotating speed of the double-screw extruder is 400 revolutions per minute, and the length-diameter ratio of the screw is 32:1.

[0042] Example 2

[0043] The present embodiment provides a preparation method of a PVC material double-strengthened by polytetrafluoroethylene and basalt fiber, which is different from example 1 in that in the first step, the polytetrafluoroethylene granules (manufacturer is Mitsubishi, model is A3800) are replaced by another kind of polytetrafluoroethylene granules, and the melting temperature of the other kind of polytetrafluoroethylene granules is 339 degrees Celsius (manufacturer is 3M, model is TF-1645).

[0044] Example 3

[0045] The present embodiment provides a preparation method of a PVC material double-strengthened by polytetrafluoroethylene and basalt fiber, which is different from example 1 in that in the first step, the viscosity number of the polyvinyl chloride granules is 130 mL / g.

[0046] Example 4

[0047] The present example provides a method for preparing a PVC material reinforced by both polytetrafluoroethylene and basalt fiber, which is different from example 1 in that in the first step, the average diameter of the cross section of the basalt fiber is 20 μm.

[0048] Example 5

[0049] The present example provides a method for preparing a PVC material reinforced by both polytetrafluoroethylene and basalt fiber, which is different from example 1 in that in the second step, the dried PVC granules, polytetrafluoroethylene granules and basalt fiber are weighed according to a mass ratio of 100:4:5.

[0050] Example 6

[0051] The present example provides a method for preparing a PVC material reinforced by both polytetrafluoroethylene and basalt fiber, which is different from example 1 in that in the second step, the screw rotation speed of the twin-screw extruder is 500 rpm.

[0052] Comparative Example 1

[0053] The present comparative example provides a method for preparing a PVC material, which is different from example 1 in that in the first step, the melting temperature of the polytetrafluoroethylene granules is 325°C (manufacturer: DuPont, model: MP1400).

[0054] Comparative Example 2

[0055] The present comparative example provides a method for preparing a PVC material, which is different from example 1 in that in the second step, no polytetrafluoroethylene granules are added.

[0056] Comparative Example 3

[0057] The present comparative example provides a method for preparing a PVC material, which is different from example 1 in that in the second step, the dried PVC granules, polytetrafluoroethylene granules and basalt fiber are weighed according to a mass ratio of 100:6:6.

[0058] Comparative Example 4

[0059] The present comparative example provides a method for preparing a PVC material, which is different from example 1 in that in the second step, the dried PVC granules, polytetrafluoroethylene granules and basalt fiber are weighed according to a mass ratio of 100:3:2.

[0060] Comparative Example 5

[0061] The present comparative example provides a method for preparing a PVC material, which is different from example 1 in that in the second step, the dried PVC granules, polytetrafluoroethylene granules and basalt fiber are weighed according to a mass ratio of 100:3:10.

[0062] Comparative Example 6

[0063] The present comparative example provides a preparation method of the PVC material, different from Example 1, in the second step, the screw rotation speed of the twin-screw extruder is 200 rpm.

[0064] Comparative Example 7

[0065] The present comparative example provides a preparation method of the PVC material, different from Example 1, in the second step, the basalt fiber is replaced by glass fiber.

[0066] Performance test

[0067] The PVC materials of each example and comparative example are added into a single-screw extruder to prepare PVC pipes, and performance tests are carried out. The yield stress and elongation at break are tested according to GB / T 8804.1-2003. The notched impact strength is tested according to GB / T 1043-1993. The test results are shown in Table 1 below.

[0068] Table 1

[0069] Yield stress Elongation at break Notched impact strength Example 1 59.6 MPa 30.1％ 12.3 KJ / m 2 ]] Example 2 60.2 MPa 29.8％ 12.0 KJ / m 2 ]] Example 3 60.5 MPa 30.0％ 12.8 KJ / m 2 ]] Example 4 61.5 MPa 28.8％ 12.1 KJ / m 2 ]] Example 5 61.9 MPa 29.7％ 12.3 KJ / m 2 ]] Example 6 60.8 MPa 30.1％ 12.5 KJ / m 2 ]] Comparative Example 1 54.3 MPa 18.2％ 7.5 KJ / m 2 ]] Comparative Example 2 58.7 MPa 18.1％ 7.3 KJ / m 2 <!-- 4 -->]]> Comparative Example 3 45.6 MPa 28.3％ 11.8 KJ / m 2 ]]> Comparative Example 4 41.3 MPa 23.3％ 10.8 KJ / m 2 ]] Comparative Example 5 59.5 MPa 12.0％ 5.8 KJ / m 2 ]]> Comparative Example 6 52.6 MPa 25.3％ 10.3 KJ / m 2 ]] Comparative Example 7 51.4 MPa 26.8％ 10.7 KJ / m 2 ]]

[0070] From Table 1, it can be seen that:

[0071] The PVC pipes prepared from the PVC materials prepared by the preparation methods of Examples 1-6 have a yield stress of more than 59 MPa, an elongation at break of more than 28%, and an impact strength of more than 12 KJ / m 2 The above shows that the PVC pipes prepared from the PVC materials prepared by the preparation method of the present application have good plastic deformation resistance and good toughness.

[0072] The melting temperature of the polytetrafluoroethylene selected in Comparative Example 1 is too low, the toughness of the PVC pipe prepared from the PVC material is not obviously improved, and the yield stress is poor. In Comparative Example 2, no polytetrafluoroethylene is added, the toughness of the PVC pipe prepared from the PVC material is not good. In Comparative Example 3, too much polytetrafluoroethylene is added, the toughness is not good, and the yield stress is poor. In Comparative Example 4, too little basalt fiber is added, the toughness of the PVC pipe prepared from the PVC material is not good, and the yield stress is poor. In Comparative Example 5, too much basalt fiber is added, the toughness of the PVC pipe prepared from the PVC material is poor. In Comparative Example 6, the screw rotation speed of the screw extruder is too low, and each performance is not good. In Comparative Example 7, glass fiber is selected, and each performance is not good.

[0073] Obviously, the above embodiments of the present application are merely exemplary but not intended to limit the embodiments of the present application. Based on the above description, any other variations or changes can be made by those skilled in the art without departing from the spirit and principles of the present application. It is not necessary to list all the embodiments here. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the present application shall fall within the scope of the claims of the present application.

Claims

1. A method for preparing a PVC material dual-reinforced with polytetrafluoroethylene and basalt fiber, characterized in that, Includes the following steps: The raw material components are added to a screw extruder, melted, blended, and extruded to obtain the PVC material. The raw material components include polyvinyl chloride, polytetrafluoroethylene and basalt fiber in a mass ratio of 100:(3~4):(5~7); the melting temperature of the polytetrafluoroethylene is 332~340℃; The screw speed of the screw extruder is 300~600 rpm; The raw material components also include a heat stabilizer; the amount of the heat stabilizer is 5-8 wt% of polyvinyl chloride.

2. The preparation method according to claim 1, characterized in that, The viscosity of the polyvinyl chloride is 105~140mL / g.

3. The preparation method according to claim 1, characterized in that, The basalt fiber has an average cross-sectional diameter of 10~25μm.

4. The preparation method according to claim 1, characterized in that, The average length of the basalt fibers is 20-50 mm.

5. The preparation method according to claim 1, characterized in that, The raw material components also include other additives.

6. The preparation method according to claim 1, characterized in that, Before adding the raw material components to the screw extruder, the process also includes a step of drying the raw material components.

7. The preparation method according to claim 1, characterized in that, The screw extruder is a twin-screw extruder.

8. The preparation method according to claim 1, characterized in that, The screw extruder includes six zones from the feed port to the die head, with temperatures of 160-170℃, 170-175℃, 175-180℃, 175-180℃, 178-183℃, and 175-180℃ respectively.

9. A PVC material dual-reinforced with polytetrafluoroethylene and basalt fiber, characterized in that, It is prepared by any of the preparation methods described in claims 1 to 8.

10. The use of the PVC material of claim 9 in the preparation of PVC pipes.