Composition for preparing PVC (polyvinyl chloride) pipe and preparation method of PVC pipe

Abstract

The invention provides a composition for preparing a PVC (polyvinyl chloride) pipe and a preparation method of the PVC pipe, and belongs to the technical field of PVC processing, the composition comprises the following components in parts by weight: 100 parts of PVC resin; 1 to 2.5 parts of a stabilizing agent; 5 to 10 parts of an acrylic ester silicon prepolymer; 20 to 30 parts of silicon copolymerized polycarbonate; 1-2 parts of an assistant cross-linking agent; 0.5 to 1.0 part of an initiator; 1.0 to 1.5 parts of a processing aid; 2-4 parts of a lubricant; and 2-3 parts of light calcium carbonate. The PVC pipe provided by the invention not only meets the performance requirements of high strength and temperature resistance, but also meets the requirement of low-temperature impact resistance of the pipe.

Description

Technical Field

[0001] The invention relates to the technical field of PVC material processing, in particular to a high-strength, high-low temperature toughness, heat-resistant PVC pipe composition and a preparation method of the PVC pipe. Background Art

[0002] Polyvinyl chloride (PVC) resin is widely used, but its Vicat softening temperature is only about 80℃, its heat deformation temperature is about 70℃, and its heat resistance is low, which limits its application in some fields that require strength, toughness, and heat resistance, such as PVC pipes' resistance to 60℃ hydrostatic pressure (a test item in PVC pressure-resistant pipes, divided into 20℃ and 60℃, the latter of which has strict requirements), low-temperature impact performance, etc. Internal pressure resistance (closely related to hydrostatic performance, good internal pressure resistance means good hydrostatic performance) is a very important performance indicator for evaluating the pressure resistance of PVC pipes, expressed as the hydrostatic burst time under a certain ring stress, reflecting the pressure that the pipe can withstand during use and the life of the pipe.

[0003] Strength and toughness are two opposite indicators. Generally speaking, if the strength of a material is high, its toughness will be poor, and vice versa, if the toughness is good, its strength will be low. Therefore, for pressure-resistant pipes that require both high strength and good toughness, a balance between rigidity and toughness must be achieved, and good low-temperature impact performance is required, which requires the material to have not only good room-temperature toughness, but also good low-temperature toughness.

[0004] The patent with publication number CN106243553A discloses a multifunctional protective pipe for power construction, which uses a variety of ingredients to mix with each other to form a new type of composite toughening and reinforcement system. The toughness, stiffness, and elastic modulus performance indicators are good, which greatly improves the anti-aging performance and performance of the product. It has the characteristics of corrosion resistance, antibacterial and flame retardant effects, and good insulation performance. However, this solution only adopts a multi-component blending method, which is a list of the properties of the material itself, and does not mention the heat resistance and low-temperature toughness of the pipe; the patent with publication number CN104140608A discloses a heat-resistant polyvinyl chloride pipe and its preparation method, which also adopts a multi-component blending method to improve the heat-resistant aging performance of the PVC pipe, and can still maintain a high tensile strength and elongation at break at a higher temperature, and has excellent wear resistance, chemical corrosion resistance, and environmental cracking resistance. This solution also does not mention the low-temperature toughness problem. Summary of the invention

[0005] The present invention uses acrylate silicon prepolymer to tightly combine PVC resin, auxiliary crosslinking agent TAIC and silicon copolymer polycarbonate with the PVC resin under the action of an initiator (crosslinking agent) to form a ternary copolymer. Due to the effect of silicon copolymerization, the melt viscosity and processing temperature of the polycarbonate resin are greatly reduced, the processing fluidity is improved, and the PVC resin is better integrated with the polyvinyl chloride resin. The acrylate silicon prepolymer and the silicon copolymer polycarbonate have good synergistic effect, which not only improves the strength and heat resistance of the PVC pipe, but also has excellent low-temperature toughness. At the same time, due to the presence of the acrylate silicon prepolymer, the compatibility of each component with the PVC resin is greatly improved, forming a three-dimensional crosslinked material with good rigidity-toughness balance, so that the PVC pipe has higher tensile strength and higher heat resistance. When no impact modifier is added or a small amount of impact modifier is added (generally, the low-temperature toughness of the material without adding the impact modifier will be very low, and the present invention can achieve higher low-temperature toughness without adding or adding a small amount of impact modifier), the PVC pipe still has excellent low-temperature toughness, and the strength of the material is further improved.

[0006] One of the objects of the present invention is to provide a composition for preparing PVC pipes.

[0007] A second object of the present invention is to provide a method for preparing a PVC pipe.

[0008] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are particularly adopted:

[0009] In a first aspect, the present invention provides a composition for preparing a PVC pipe, comprising the following components in parts by weight: 100 parts of PVC resin; 1-2.5 parts of stabilizer; 5-10 parts of acrylate silicon prepolymer; 20-30 parts of silicon copolymer polycarbonate; 1-2 parts of co-crosslinking agent; 0.5-1.0 parts of initiator; 1.0-1.5 parts of processing aid; 2-4 parts of lubricant; and 2-3 parts of light calcium carbonate.

[0010] The following is a detailed description of each component:

[0011] There is no particular limitation on the source of the PVC resin, which can be obtained commercially or prepared by methods known in the art (such as suspension polymerization).

[0012] Preferably, the average degree of polymerization of the PVC resin is 950-1050, and the apparent density is 0.58-0.65 g / mL.

[0013] The added amount of PVC resin is 100 parts.

[0014] The stabilizer includes but is not limited to an organotin stabilizer, a calcium zinc stabilizer, etc., and is preferably an organotin stabilizer.

[0015] Preferably, the organic tin stabilizer is a methyltin mercaptan stabilizer, and specifically, brand 1928 may be cited, but is not limited thereto.

[0016] The amount of stabilizer added is 1-2.5 parts, for example, 1 part, 1.2 parts, 1.5 parts, 1.6 parts, 1.8 parts, 2 parts, 2.2 parts, 2.4 parts, 2.5 parts, but not limited thereto.

[0017] The acrylate silicon prepolymer specifically includes the acrylate silicon prepolymer with the brand number 3826F2 produced by Guangzhou Silicon Carbon New Materials Co., Ltd., which has a molecular weight of 2000, contains R-OOCCH=CH2 functional groups at both ends of the molecular chain, and contains isocyanate functional groups with a functionality of 6, and has high cross-linking characteristics.

[0018] The added amount of the acrylate silicon prepolymer is 5-10 parts, for example, 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts, but not limited thereto.

[0019] The silicon copolymer polycarbonate (silicon copolymer PC) refers to silicon copolymer polycarbonate block copolymerized with polydimethylsiloxane. Due to the presence of organic silicon groups, the length of the structural unit is increased, the rigidity of the benzene ring is reduced, and the flexibility of the molecular chain is greatly increased. Specific examples include Yantai Wanhua products, but are not limited to these.

[0020] The addition amount of silicon copolymer polycarbonate is 20-30 parts, for example, 20 parts, 22 parts, 24 parts, 25 parts, 26 parts, 28 parts, 30 parts, but not limited thereto.

[0021] The auxiliary cross-linking agent includes but is not limited to triallyl isocyanurate (TAIC) and the like.

[0022] The amount of the auxiliary cross-linking agent added is 1-2 parts, for example, 1 part, 1.2 parts, 1.5 parts, 1.6 parts, 1.8 parts, 2 parts, but not limited thereto.

[0023] The initiator includes but is not limited to dicumyl peroxide (DCP), BPO, DBHP, bis 25, etc., preferably DCP.

[0024] The amount of the initiator added is 0.5-1 part, for example, 0.5 part, 0.6 part, 0.7 part, 0.8 part, 0.9 part, 1 part, but not limited thereto.

[0025] The processing aid includes but is not limited to acrylic acid ester copolymer (ACR) and the like, and specifically PA-20 can be cited, but is not limited thereto.

[0026] The added amount of the processing aid is 1-1.5 parts, for example, 1 part, 1.1 parts, 1.2 parts, 1.3 parts, 1.4 parts, 1.5 parts, but not limited thereto.

[0027] The lubricant includes but is not limited to paraffin, oxidized polyethylene wax, polyethylene wax, calcium stearate, etc., and is preferably a composite lubricant compounded with paraffin and oxidized polyethylene wax, and the mass ratio of paraffin to oxidized polyethylene wax is 1.5-2:1.

[0028] The amount of lubricant added is 2-4 parts, for example, 2 parts, 2.5 parts, 3 parts, 3.5 parts, 4 parts, but not limited thereto.

[0029] The mesh number of the light calcium carbonate is above 2000 meshes and is activated to be light activated calcium carbonate.

[0030] The added amount of light calcium carbonate is 2-3 parts, for example, 2 parts, 2.5 parts, 3 parts, but not limited to this.

[0031] In some embodiments, the composition for preparing PVC pipes includes the following components by weight: 100 parts of PVC resin; 1-2.5 parts of organotin stabilizer; 5-10 parts of acrylate silicon prepolymer; 20-30 parts of silicon copolymer polycarbonate; 1-2 parts of co-crosslinking agent TAIC; 0.5-1.0 parts of initiator DCP; 1.0-1.5 parts of processing aid ACR; 2-4 parts of composite lubricant; 2-3 parts of light activated calcium carbonate.

[0032] In a second aspect, the present invention provides a method for preparing a PVC pipe, comprising the following steps: mixing the above composition for preparing a PVC pipe and then extruding it to obtain a PVC pipe.

[0033] In some embodiments, the specific steps include:

[0034] (1) PVC resin, stabilizer (organic tin stabilizer), processing aid (ACR), lubricant, and light calcium carbonate are weighed in proportion, added into a high-speed mixer, and mixed at a speed of 1200-1500 r / min (preferably 1500 r / min) for high-speed mixing, a mixing time of 5-10 minutes, and a mixing temperature of 100-110° C., and then acrylate silicon prepolymer, silicon copolymer polycarbonate, auxiliary crosslinking agent (TAIC), and initiator (DCP) are added, and the mixing is continued at a mixing speed of 700-1000 r / min (preferably 800 r / min) for 3-5 minutes until the materials are uniformly mixed, and the materials are discharged for standby use;

[0035] (2) extruding the mixed materials into granules in a twin-screw extruder at a temperature of 140-155° C., a feeding frequency of 20-25 Hz, and a main engine speed of 100-120 r / min, and finally pelletizing, cooling, and packaging to obtain a PVC pipe composition;

[0036] (3) The above composition is extruded into a pipe with a diameter of 32 in a 65-132 type conical twin-screw extruder. The pipe extrusion processing temperature is 170-190° C. During the pipe extrusion process, the material is fully cross-linked to obtain a PVC pipe.

[0037] Beneficial Effects

[0038] (1) The present invention uses acrylate silicon prepolymer to tightly combine PVC resin, auxiliary crosslinking agent TAIC and silicon copolymer polycarbonate with it under the action of an initiator to form a ternary copolymer. Due to the effect of silicon copolymerization, the melt viscosity and processing temperature of the polycarbonate resin are greatly reduced, and the processing fluidity is improved, so that it is better integrated with the polyvinyl chloride resin. The acrylate silicon prepolymer and the silicon copolymer polycarbonate have a good synergistic effect, which not only improves the strength and heat resistance of the PVC pipe, but also has excellent low-temperature toughness. At the same time, due to the presence of the acrylate silicon prepolymer, the compatibility of each component with the PVC resin is greatly improved, forming a three-dimensional cross-linked material with a good rigidity-toughness balance, so that the PVC pipe has higher tensile strength and higher heat resistance. In the case of no or less addition of impact modifier, it still has excellent low-temperature toughness, and the strength of the material is further improved.

[0039] (2) After the above modification, the PVC pipe of the present invention not only meets the performance requirements of high strength and temperature resistance, but also meets the requirements of low temperature impact resistance of the pipe.

[0040] The present invention has been described in detail above, but the above embodiments are only illustrative in nature and are not intended to limit the present invention. In addition, this article is not limited by any theory described in the above prior art or invention content or the following examples. DETAILED DESCRIPTION

[0041] The present invention is further described below in conjunction with examples. It should be noted that the following examples are provided for illustrative purposes only and do not constitute a limitation on the scope of protection claimed for the present invention.

[0042] Unless otherwise specified, the raw materials, reagents, methods, etc. used in the examples are conventional raw materials, reagents, methods in the art.

[0043] The raw materials involved in the embodiments and comparative examples are as follows:

[0044] The PVC resin comes from the chlor-alkali plant of Sinopec Qilu Branch, with an average degree of polymerization of 1000 and an apparent density of 0.62 g / mL.

[0045] The organic tin stabilizer is methyl tin mercaptan stabilizer, imported from the United States, brand 1928.

[0046] Acrylate silicon prepolymer was purchased from Guangzhou Silicon Carbon New Materials Co., Ltd. with a brand name of 3826F2 and a molecular weight of 2000.

[0047] Silicon copolymer polycarbonate was purchased from Yantai Wanhua, brand STC3711.

[0048] Polycarbonate was purchased from Yantai Wanhua, brand PC1105.

[0049] MBS resin was purchased from Japan Zhongyuan, brand MBS561.

[0050] ACR is PA-20, purchased from Zibo Huaxing Additive Co., Ltd.

[0051] DCP was purchased from Shanghai Reagent Factory.

[0052] The composite lubricant is a compound of paraffin wax and oxidized polyethylene wax, and the compounding ratio is paraffin wax: oxidized polyethylene wax = 1.5-2:1.

[0053] Light calcium carbonate was purchased from Changzhou Calcium Carbonate Co., Ltd., with a mesh size of more than 2000 meshes and was activated.

[0054] Examples 1-6

[0055] The ingredients of the PVC pipe compositions of Examples 1-6 are shown in Table 1.

[0056] The preparation method of the embodiment is:

[0057] (1) PVC resin, organotin stabilizer, processing aid ACR, composite lubricant, and light activated calcium carbonate are weighed in proportion and added into a high-speed mixer for high-speed mixing at a mixing speed of 1500 r / min for a mixing time of 5-10 minutes and a mixing temperature of 110° C. At this time, acrylate silicon prepolymer, silicon copolymer polycarbonate, TAIC, and DCP are added and the mixing is continued at a mixing speed of 800 r / min for 3-5 minutes until the materials are evenly mixed, and the materials are discharged for standby use;

[0058] (2) extruding the mixed materials into pellets in a twin-screw extruder at a temperature of 155° C., a feeding frequency of 25 Hz, and a main engine speed of 100 r / min, and finally pelletizing, cooling, and packaging to obtain a PVC pipe composition;

[0059] (3) The above composition is extruded into a pipe with a diameter of 32 in a 65-132 conical twin-screw extruder. The extrusion temperature of the pipe is 180° C. The material is fully cross-linked during the extrusion process.

[0060] Table 1

[0061]

[0062]

[0063] Comparative Examples 1-5

[0064] The ingredients of the PVC pipe compositions of Comparative Examples 1-5 are shown in Table 2.

[0065] Compared with Example 3, Comparative Example 1 does not use acrylate silicon prepolymer and silicon copolymer polycarbonate, but uses ordinary MBS resin, and the other components are the same; Compared with Example 3, Comparative Example 2 does not use crosslinking, but only ordinary blending between components; Compared with Example 3, Comparative Example 3 does not use silicon copolymer polycarbonate, but uses general polycarbonate resin; Compared with Example 3, Comparative Example 4 only uses silicon copolymer polycarbonate without acrylate silicon prepolymer, and the other components are the same; Compared with Example 3, Comparative Example 5 only uses acrylate silicon prepolymer without adding silicon copolymer polycarbonate, and the other components are the same.

[0066] The preparation method of the comparative example is:

[0067] (1) PVC resin, organotin stabilizer, impact modifier, processing aid, lubricant, light activated calcium carbonate and other additives are weighed in proportion, added into a high-speed mixer, mixed at high speed, with a mixing speed of 1500 r / min, a mixing time of 5-10 minutes, and a mixing temperature of 110° C., and the materials are discharged for standby use;

[0068] (2) extruding the mixed materials into pellets in a twin-screw extruder at a temperature of 155° C., a feeding frequency of 25 Hz, and a main engine speed of 100 r / min, and finally pelletizing, cooling, and packaging to obtain a PVC pipe composition;

[0069] (3) The pipe composition is extruded into a pipe with a diameter of 32 in a 65-132 type conical twin-screw extruder at an extrusion temperature of 180°C.

[0070] Table 2

[0071]

[0072]

[0073] Performance Testing

[0074] The following tests were performed on the embodiments and comparative examples, and the results are shown in Tables 3 and 4.

[0075] Tensile strength: tested according to national standard GB / T1040-2006;

[0076] Elongation at break: Tested in accordance with national standard GB / T1040-2006;

[0077] Vicat softening temperature: According to the national standard GB / T1633-2000, B 50 Method testing;

[0078] 0℃ drop hammer impact test: tested in accordance with national standard GB / T 14152-2001;

[0079] -20℃ notched impact strength: tested in accordance with national standard GB / T 1043.1-2008, type A notch; hydrostatic burst: tested in accordance with international standard ISO 1452-2:2009.

[0080] Table 3 Test results of pipe performance of Examples 1-6 of the present invention

[0081]

[0082] Table 4 Performance test results of comparative examples 1-5 of the present invention

[0083]

[0084]

[0085] It can be seen from the above data that in Comparative Example 1, due to the use of MBS instead of acrylate silicon prepolymer and silicon copolymer polycarbonate, the tensile strength is greatly reduced, the Vicat softening temperature is reduced (heat resistance is reduced), and the 60°C pipe hydrostatic pressure cannot meet the standard requirements. Comparative Example 2 is just ordinary blending without crosslinking, and the components are not entangled with each other, so the tensile strength is reduced and the elongation is reduced. Comparative Example 3 uses polycarbonate instead of silicon copolycarbonate resin. Since polycarbonate has strong rigidity and poor toughness, the elongation at break of the composition is greatly reduced, the impact performance is reduced, and the standard requirements for pipe hydrostatic pressure cannot be met. Comparative Example 4 does not use acrylate silicon prepolymer, resulting in poor compatibility of the composition system, so the elongation of the system is greatly reduced, the low-temperature drop hammer impact cannot meet the requirements, and the hydrostatic pressure performance cannot meet the requirements. Comparative Example 5 only uses acrylate silicon prepolymer without adding silicon copolycarbonate resin, so the heat resistance is reduced (low Vicat softening temperature), and the strength and elongation of the pipe are reduced. In conclusion, the strength, low-temperature impact strength and heat resistance of the pipe extruded from the composition of the present invention are significantly better than those of the comparative example.

[0086] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions described in the above embodiments may be modified, or some or all of the technical features thereof may be replaced by equivalents, without departing from the spirit and essence of the claims of the present invention; and these modifications or replacements are still within the scope defined by the claims of the present invention.

Claims

1. A composition for preparing PVC pipes, characterized in that: The composition comprises the following components in parts by weight: 100 parts of PVC resin; 1-2.5 parts of stabilizer; 5-10 parts of acrylate silicon prepolymer; 20-30 parts of silicon copolymer polycarbonate; 1-2 parts of co-crosslinking agent; 0.5-1.0 parts of initiator; 1.0-1.5 parts of processing aid; 2-4 parts of lubricant; and 2-3 parts of light calcium carbonate.

2. The composition for preparing PVC pipe according to claim 1, characterized in that: The average polymerization degree of the PVC resin is 950-1050, and the apparent density is 0.58-0.65 g / mL.

3. The composition for preparing PVC pipe according to claim 1, characterized in that: The stabilizer is an organic tin stabilizer, and the organic tin stabilizer is a methyl tin mercaptan stabilizer.

4. The composition for preparing PVC pipe according to claim 1, characterized in that: The acrylate silicon prepolymer is Guangzhou Silicon Carbon New Material 3826F2.

5. The composition for preparing PVC pipe according to claim 1, characterized in that: The silicon copolymer polycarbonate is Yantai Wanhua STC3711 。 6. The composition for preparing PVC pipe according to claim 1, characterized in that: The auxiliary cross-linking agent is TAIC.

7. The composition for preparing PVC pipe according to claim 1, characterized in that: The initiator is one or more selected from DCP, BPO, DBHP and bis(25), preferably DCP.

8. The composition for preparing PVC pipe according to claim 1, characterized in that: The processing aid is ACR, especially PA-20.

9. The composition for preparing PVC pipe according to claim 1, characterized in that: The lubricant is a composite lubricant of paraffin wax and oxidized polyethylene wax, and the mass ratio of the paraffin wax to the oxidized polyethylene wax is 1.5-2:

1.

10. A method for preparing a PVC pipe, characterized in that: The following steps are involved: The composition for preparing a PVC pipe according to any one of claims 1 to 9 is mixed and then extruded to obtain a PVC pipe; Preferably, the specific steps include: (1) PVC resin, stabilizer, processing aid, lubricant, and light calcium carbonate are weighed in proportion, added into a high-speed mixer, and mixed at a speed of 1200-1500 r / min for 5-10 minutes at a mixing temperature of 100-110° C., and then acrylate silicon prepolymer, silicon copolymer polycarbonate, co-crosslinking agent, and initiator are added, and the mixing is continued at a mixing speed of 700-1000 r / min for 3-5 minutes until the materials are uniformly mixed, and the materials are discharged for standby use; (2) extruding the mixed materials into granules in a twin-screw extruder at a temperature of 140-155° C., a feeding frequency of 20-25 Hz, and a main engine speed of 100-120 r / min, and finally pelletizing, cooling, and packaging to obtain a PVC pipe composition; (3) The above composition is extruded into a pipe with a diameter of 32 in a 65-132 type conical twin-screw extruder. The pipe extrusion processing temperature is 170-190° C. During the pipe extrusion process, the material is fully cross-linked to obtain a PVC pipe.

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