Injection molding grade PVC tube and its manufacturing method

Abstract

To provide an injection molding grade PVC tube and a method for manufacturing the same.SOLUTION: The injection molding grade PVC tube contains 100 pts.wt. of a PVC resin, 2 pts. to 8 pts.wt. of a thermal stabilizer, 1 pts.wt. to 20 pts.wt. of a first additive, and 0.7 pts.wt. to 15 pts.wt. of a second additive. The first additive contains a processing modifier and a heat-resistant agent, and a weight ratio (processing modifier: heat-resistant agent) of the processing modifier to the heat-resistant agent is 1:6.67 to 1:10. The second additive contains at least a lubricant, an antioxidant or a filler. All the PVC resin, the thermal stabilizer, the first additive and the second additive are in powder states. The injection molding grade PVC tube is formed by hot-melt extruding the PVC resin, the thermal stabilizer, the first additive and the second additive, and then subjecting it to direct injection molding.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to PVC tubing and methods of making the same, and more particularly to injection molding grade PVC tubing and methods of making the same. [Background technology]

[0002] Conventional injection molding grade tubes, which are mainly made of PVC resin (polyvinyl chloride resin), have a problem of insufficient heat resistance and cannot be used in high-temperature environments.

[0003] Conventional injection molding grade tubes made mainly of CPVC resin (chlorinated polyvinyl chloride resin) have excellent heat resistance. However, due to the large intermolecular force of CPVC resin and the high chlorine content, the melt viscosity of conventional injection molding grade tubes made of CPVC resin is too high, resulting in poor fluidity, difficulty in processing, and easy decomposition. In addition, the high processing torque required for conventional injection molding grade tubes made mainly of CPVC resin makes it impossible to use general PVC molding equipment, leading to production difficulties. Summary of the Invention [Problem to be solved by the invention]

[0004] The technical problem that the present invention aims to solve is to provide an injection-molding grade PVC tube and a manufacturing method thereof, which overcomes the shortcomings of the prior art, such as the poor heat resistance and processing difficulties of conventional injection-molding grade PVC tubes. [Means for solving the problem]

[0005] In order to solve the above technical problems, one technical means adopted by the present invention provides an injection molding grade PVC tube. The injection molding grade PVC tube contains 100 parts by weight of PVC resin with a degree of polymerization of 600 to 1000, 2 to 8 parts by weight of a heat stabilizer, 1 to 20 parts by weight of a first additive, and 0.7 to 15 parts by weight of a second additive, the heat stabilizer being selected from at least one of the group consisting of organotin, calcium zinc stabilizer, hydrotalcite stabilizer, and rare earth stabilizer, the first additive being a processing modifier which is a vinyl chloride graft copolymer, and an α-methylstyrene acrylonitrile copolymer. a heat resistant agent comprising a PVC resin, a heat stabilizer, a first additive, and a second additive, the weight ratio of which (the processing modifier:the heat resistant agent) is 1:6.67 to 1:10; the second additive comprises at least a lubricant, an antioxidant, or a filler; the PVC resin, the heat stabilizer, the first additive, and the second additive are all in a powder form; and the injection molding grade PVC tube is formed by hot melt extrusion of the PVC resin, the heat stabilizer, the first additive, and the second additive, followed by direct injection molding.

[0006] Preferably, the vinyl chloride graft copolymer comprises vinyl chloride, a first graft functional group and a second graft functional group, the first graft functional group being ethylene and vinylidene chloride, and the second graft functional group being vinyl acetate and vinyl tertiary carbonate.

[0007] Preferably, the vinyl chloride content is 65 wt% to 85 wt%, the first graft functional group content is 10 wt% to 15 wt%, and the second graft functional group content is 5 wt% to 15 wt%, with the total weight of the vinyl chloride graft copolymer being 100 wt%.

[0008] Preferably, the particle size of the first additive is 30 μm to 120 μm, the content of the processing modifier in the first additive is 0.5 parts by weight to 5 parts by weight, and the content of the heat resistance agent in the first additive is 0.5 parts by weight to 15 parts by weight.

[0009] Preferably, the particle size of the second additive is 0.1 μm to 100 μm, and in the second additive, the content of the lubricant is 0.5 parts by weight to 3 parts by weight, the content of the antioxidant is 0.1 parts by weight to 2 parts by weight, and the content of the filler is 0.1 parts by weight to 3 parts by weight.

[0010] Preferably, the lubricant is selected from at least one of the group consisting of polyethylene wax, oxidized polyethylene wax, fatty acid-based lubricants, metal soap-based lubricants, and silicone-based lubricants.

[0011] Preferably, the antioxidant is selected from at least one of the group consisting of hindered phenol-based antioxidants and phosphite-based antioxidants.

[0012] Preferably, the injection molding grade PVC tube has a tensile strength of 50.6MPa to 51.4MPa, an impact strength of 30.4J / m to 31.3J / m, and a Vicat softening temperature of 85.8°C to 90.6°C.

[0013] In order to solve the above technical problems, another technical means adopted by the present invention provides a method for producing an injection molding grade PVC tube. The method for producing the injection molding grade PVC tube includes a preparation step of providing 100 parts by weight of a PVC resin having a degree of polymerization of 600 to 1000, 2 to 8 parts by weight of a heat stabilizer, 1 to 20 parts by weight of a first additive, and 0.7 to 15 parts by weight of a second additive; a mixing step of adding the PVC resin, the heat stabilizer, the first additive, and the second additive at a temperature of 100°C to 120°C, followed by mixing in a process of cooling to 35°C to 50°C to obtain a mixed PVC resin material; and a mixing step of hot-melting the mixed PVC resin material using an injection molding machine at a temperature of 170°C to 200°C, followed by injection molding to obtain an injection molding grade PVC tube. and an injection molding step of obtaining a tube, wherein the heat stabilizer is selected from at least one of the group consisting of organotin, calcium zinc stabilizers, hydrotalcite stabilizers, and rare earth stabilizers, the first additive comprises a processing modifier which is a vinyl chloride graft copolymer and a heat resistant agent which is an α-methylstyrene acrylonitrile copolymer, the weight ratio of the processing modifier to the heat resistant agent (the processing modifier:the heat resistant agent) is 1:6.67 to 1:10, the second additive comprises at least a lubricant, an antioxidant, or a filler, and the PVC resin, the heat stabilizer, the first additive, and the second additive are all in a powder form.

[0014] Preferably, the vinyl chloride graft copolymer comprises vinyl chloride, a first graft functional group and a second graft functional group, the first graft functional group being ethylene and vinylidene chloride, and the second graft functional group being vinyl acetate and vinyl tertiary carbonate.

[0015] Preferably, the vinyl chloride content is 65 wt% to 85 wt%, the first graft functional group content is 10 wt% to 15 wt%, and the second graft functional group content is 5 wt% to 15 wt%, with the total weight of the vinyl chloride graft copolymer being 100 wt%.

[0016] Preferably, the particle size of the first additive is 30 μm to 120 μm, the content of the processing modifier in the first additive is 0.5 parts by weight to 5 parts by weight, and the content of the heat resistance agent in the first additive is 0.5 parts by weight to 15 parts by weight.

[0017] Preferably, the particle size of the second additive is 0.1 μm to 100 μm, the content of the lubricant in the second additive is 0.5 parts by weight to 3 parts by weight, the content of the antioxidant is 0.1 parts by weight to 2 parts by weight, the content of the filler is 0.1 parts by weight to 3 parts by weight, the lubricant is selected from at least one of the group consisting of polyethylene wax, oxidized polyethylene wax, fatty acid-based lubricants, metal soap-based lubricants, and silicone-based lubricants, and the antioxidant is selected from at least one of the group consisting of hindered phenol-based antioxidants and phosphite-based antioxidants.

[0018] Preferably, the injection molding grade PVC tube has a tensile strength of 50.6MPa to 51.4MPa, an impact strength of 30.4J / m to 31.3J / m, and a Vicat softening temperature of 85.8°C to 90.6°C. Effect of the Invention

[0019] As advantageous effects of the present invention, the injection molding grade PVC tube and its manufacturing method according to the present invention have the following technical features: "the first additive comprises a processing modifier which is a vinyl chloride graft copolymer and a heat resistant agent which is an α-methylstyrene acrylonitrile copolymer, the weight ratio of the processing modifier to the heat resistant agent (the processing modifier:the heat resistant agent) is 1:6.67 to 1:10, and the second additive comprises at least a lubricant, an antioxidant or a filler" and "the PVC resin, the heat stabilizer, the first additive and the second additive are all in a powder form", thereby improving the poor heat resistance and processing difficulty of conventional injection molding grade PVC tubes. [Brief description of the drawings]

[0020] [Figure 1]1 is a flow chart of a method for making injection molding grade PVC tubing according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] In order to better understand the features and technical contents of the present invention, please refer to the following detailed description of the present invention and the accompanying drawings, which are provided for reference and explanation only and are not intended to limit the scope of the present invention.

[0022] Hereinafter, the "injection molding grade PVC tube and its manufacturing method" according to the embodiment of the present invention will be described in detail with reference to certain specific embodiments, and those skilled in the art will be able to understand the advantages and effects of the present invention based on the contents disclosed in this specification. The present invention can be implemented or applied in other different specific embodiments, and various modifications and changes can be made to each detail in this specification based on different perspectives and applications without departing from the concept of the present invention. In addition, as described in advance, the accompanying drawings of the present invention are simple schematic illustrations and are not drawn based on actual size. The technical contents of the present invention will be described in more detail based on the following embodiments, but the disclosed contents do not limit the protection scope of the present invention.

[0023] It should be understood that, although the present specification may use the terms "first", "second", "third" and the like to describe various elements or signals, these elements or signals are not limited by these terms. These terms are mainly used to distinguish one element from another element or one signal from another signal. In addition, the term "or" used in the present specification may include any one or more combinations of the associated listed items according to actual circumstances.

[0024] [Injection molding grade PVC tube] In an embodiment of the present invention, there is provided an injection molding grade PVC tube comprising 100 parts by weight of PVC resin, 2 to 8 parts by weight of a heat stabilizer, 1 to 20 parts by weight of a first additive, and 0.7 to 15 parts by weight of a second additive.

[0025] The PVC resin, the heat stabilizer, the first additive, and the second additive are all in a powder state. The particle size of the first additive is 30 μm to 120 μm, and the particle size of the second additive is 0.1 μm to 100 μm. In other words, each component of the injection molding grade PVC tube according to this embodiment may be in a powder state. It is not appropriate for other PVC tubes containing components in other states (for example, liquids) to correspond to the injection molding grade PVC tube according to this embodiment.

[0026] The injection molding grade PVC tube is formed by hot melt extruding the PVC resin, the heat stabilizer, the first additive and the second additive, and then directly injection molding. It should be noted that the conventional PVC tube is usually produced by extrusion, granulation and injection molding in this order. In contrast, the injection molding grade PVC tube of the present invention does not need to go through the extrusion granulation process, which simplifies the process.

[0027] The degree of polymerization of the PVC resin is 600 to 1000. It is worth noting that if the degree of polymerization of the PVC resin is too high (e.g., exceeds 1000), the components contained in the injection molding grade PVC tube will have poor fluidity after mixing and hot melting, leading to difficulties in processing.

[0028] In addition, conventional injection molding grade tubes mainly made of CPVC resin have excellent heat resistance. However, because the intermolecular force of CPVC resin is large and the chlorine content is high, the melt viscosity of conventional injection molding grade tubes made of CPVC resin is too high, resulting in poor fluidity, difficulty in processing, and easy decomposition. In contrast, the injection molding grade PVC tube according to the present embodiment does not need to contain CPVC resin, and it is not appropriate for conventional injection molding grade tubes containing CPVC resin to correspond to the injection molding grade PVC tube according to the present embodiment.

[0029] The heat stabilizer is selected from at least one of the group consisting of organotin, calcium zinc stabilizer, hydrotalcite stabilizer, and rare earth stabilizer. Preferably, the heat stabilizer is butyltin maleate.

[0030] The first additive includes a processing modifier and a heat-resistant agent. The processing modifier is a vinyl chloride graft copolymer, and the heat-resistant agent is an α-methylstyrene acrylonitrile copolymer. By setting the weight ratio of the processing modifier to the heat-resistant agent (the processing modifier:the heat-resistant agent) to 1:6.67 to 1:10, the injection molding grade PVC tube has high heat resistance and is easy to process. In other words, if the weight ratio of the processing modifier to the heat-resistant agent is too high or too low, the injection molding grade PVC tube cannot obtain the desired heat resistance and processability. In this embodiment, the content of the processing modifier is 0.5 parts by weight to 5 parts by weight, and the content of the heat-resistant agent is 0.5 parts by weight to 15 parts by weight.

[0031] More specifically, the vinyl chloride graft copolymer includes vinyl chloride, a first graft functional group and a second graft functional group, the first graft functional group being ethylene and vinylidene chloride, and the second graft functional group being vinyl acetate and vinyl tertiary carbonate.

[0032] More specifically, the content of the vinyl chloride is 65wt% to 85wt%, the content of the first graft functional group is 10wt% to 15wt%, and the content of the second graft functional group is 5wt% to 15wt%, where the total weight of the vinyl chloride graft copolymer is 100wt%. In addition, in the first graft functional group of this embodiment, the weight ratio of the ethylene to the vinylidene chloride (the ethylene:the vinylidene chloride) is 1:0.5 to 1:3, and in the second graft functional group, the weight ratio of the vinyl acetate to the tertiary vinyl carbonate (the vinyl acetate:the tertiary vinyl carbonate) is 1:0.2 to 1:4.

[0033] In this embodiment, the vinyl chloride graft copolymer may be SRC manufactured by Zhong Plastic Union New Material Technology Hubei Co., Ltd., and the heat-resistant agent may be, for example, Blendex 587S manufactured by Compton, USA, POLYB H810 or POLYMER NR-188 manufactured by Hannanotech, but the present invention is not limited thereto.

[0034] The second additive contains at least a lubricant, an antioxidant, or a filler. In the second additive of this embodiment, the content of the lubricant is 0.5 to 3 parts by weight, the content of the antioxidant is 0.1 to 2 parts by weight, and the content of the filler is 0.1 to 3 parts by weight.

[0035] Preferably, the lubricant is selected from at least one of the group consisting of polyethylene wax, oxidized polyethylene wax, fatty acid lubricant, metal soap lubricant, and silicone lubricant, the antioxidant is selected from at least one of the group consisting of hindered phenol antioxidant and phosphite ester antioxidant, and the filler is selected from at least one of the group consisting of ground calcium carbonate, light calcium carbonate, nano calcium carbonate, talc powder, carbon black, and organic pigment. In order to comply with the relevant standards and requirements, it is preferable that the specific gravity of the filler is less than 1.47.

[0036] In this embodiment, the injection molding grade PVC tube has a tensile strength of 50.6 MPa to 51.4 MPa, an impact strength of 30.4 J / m to 31.3 J / m, and a Vicat softening temperature of 85.8° C. to 90.6° C. The Vicat softening temperature is the temperature at which a thermoplastic is softened over 1 mm when placed in a liquid heat transfer medium, subjected to a constant load, and constantly increased in temperature. 2 It is the temperature at which an indenter of 1 mm is pressed into the sample, and is an indicator of the heat resistance of the material, as well as the physical and mechanical properties of the reaction products under heated conditions.

[0037] [Manufacturing method for injection molding grade PVC tube] As shown in Figure 1, an embodiment of the present invention provides a method for producing an injection molding grade PVC tube. The injection molding grade PVC tube may be obtained by carrying out the method for producing an injection molding grade PVC tube, but the present invention is not limited thereto.

[0038] The method for producing the injection molding grade PVC tube includes a preparing step S110, a mixing step S120, and an injection molding step S130.

[0039] In the preparation step S110, 100 parts by weight of PVC resin, 2 to 8 parts by weight of heat stabilizer, 1 to 20 parts by weight of a first additive, and 0.7 to 15 parts by weight of a second additive are prepared. The degree of polymerization of the PVC resin is 600 to 1000. The heat stabilizer is selected from at least one of the group consisting of organotin, calcium zinc stabilizer, hydrotalcite stabilizer, and rare earth stabilizer. The first additive contains a processing modifier which is a vinyl chloride graft copolymer and a heat resistant agent which is an α-methylstyrene acrylonitrile copolymer, and the weight ratio of the processing modifier to the heat resistant agent (the processing modifier:the heat resistant agent) is 1:6.67 to 1:10. The second additive contains at least a lubricant, an antioxidant, or a filler. The PVC resin, the heat stabilizer, the first additive, and the second additive are all powder-like. The particle size of the first additive is 30 μm to 120 μm, and the particle size of the second additive is 0.1 μm to 100 μm.

[0040] In the mixing step S120, the PVC resin, the heat stabilizer, the first additive, and the second additive are added at a temperature of 100° C. to 120° C., and then the mixture is mixed in the process of cooling to 35° C. to 50° C. to obtain a mixed PVC resin material. Specifically, in the mixing step S120, the PVC resin, the heat stabilizer, the first additive, and the second additive are mixed at a temperature of 100° C. to 120° C. for 600 to 800 seconds, and then the mixture is introduced into a cooling tube and mixed in the process of cooling to 35° C. to 50° C. for 300 to 500 seconds to obtain the PVC resin material.

[0041] In the injection molding step S130, the mixed PVC resin material is hot-melted using an injection molding machine at a temperature of 170°C to 200°C, and then injection molded to obtain an injection molding grade PVC tube. The manufacturing method for the injection molding grade PVC tube may further include other steps after the injection molding step S130. For example, the manufacturing method may include a pressure holding step, a cooling and shaping step, and a gate trimming step, but the present invention is not limited thereto.

[0042] Specifically, the vinyl chloride graft copolymer includes vinyl chloride, a first graft functional group, and a second graft functional group, the first graft functional group being ethylene and vinylidene chloride, and the second graft functional group being vinyl acetate and tertiary vinyl carbonate. The vinyl chloride content is 65wt% to 85wt%, the first graft functional group content is 10wt% to 15wt%, and the second graft functional group content is 5wt% to 15wt%, with the total weight of the vinyl chloride graft copolymer being 100wt%.

[0043] The content of the processing modifier is 0.5 to 5 parts by weight, and the content of the heat resistance agent is 0.5 to 15 parts by weight.

[0044] In the second additive, the lubricant is selected from at least one of the group consisting of polyethylene wax, oxidized polyethylene wax, fatty acid-based lubricants, metal soap-based lubricants, and silicone-based lubricants. The antioxidant is selected from at least one of the group consisting of hindered phenol-based antioxidants and phosphite-based antioxidants, and the filler is selected from at least one of the group consisting of heavy calcium carbonate, light calcium carbonate, nano calcium carbonate, talc powder, carbon black, and organic pigments.

[0045] The injection molding grade PVC tube has a tensile strength of 50.6MPa to 51.4MPa, an impact strength of 30.4J / m to 31.3J / m, and a Vicat softening temperature of 85.8°C to 90.6°C.

[0046] [Measurement of experimental data] The composition of each component, tensile strength, impact strength, Vicat softening temperature, gel time and gel torque of the film removing liquid according to Examples 1 to 4 and Comparative Examples 1 and 2 are as shown in the following Table 1. The measurement methods are described below.

[0047] Tensile strength: According to ASTM D638, the tensile strength of a plastic material is obtained by performing a tensile test on the plastic material.

[0048] Measurement of impact strength: Based on the notched Izod bending impact test according to ASTM D256, it expresses the characteristic values ​​of impact strength and notch sensitivity at high deformation rates in the form of energy values ​​related to thickness. The measurements are usually carried out under normal climatic conditions of 23°C / 50% relative humidity to measure the impact strength and notched impact strength of plastics.

[0049] Vicat softening temperature: The heat resistance temperature can be measured using a Vicat heat distortion temperature tester in accordance with GB / T1633 "Determination of thermoplastic Vicat softening temperature (VST)", GB8802 "Determination of Vicat softening temperature of unplasticized polyvinyl chloride (PVC-U) pipes and fittings" and ASTM1525.

[0050] Measurement of gel time and gel torque: The method for measuring the plastic speed was to carry out a rheological test using a torque rheometer (HAAKE PolyLab OS) at a specific temperature (170°C to 200°C) and a specific rotation speed (45 rpm to 60 rpm), and the measured gel time and balance torque of the compound were used as the basis for the productivity of the compound.

[0051] [Table 1]

[0052] [Consideration of measurement results] Comparing Example 1 with Comparative Example 1, in Example 1, the vinyl chloride graft copolymer was used instead of the ACR processing aid to promote gelation, which not only maintained the gelation time but also reduced the processing torque, thereby reducing the load on the machine, improving the processability of injection molding, and slightly increasing the Vicat softening temperature.

[0053] Comparison of Example 1 with Comparative Example 2 and Example 2 shows that in Example 1, the ACR processing aid and toughening agent for promoting gelation were replaced with vinyl chloride graft copolymer, improving the impact resistance, and adding vinyl chloride graft copolymer to the formulation achieved both gelation and toughening functions.

[0054] Comparing Examples 3 and 4 with Comparative Examples 1 and 2, it was found that by adding the vinyl chloride graft copolymer and the heat stabilizer simultaneously, the same plasticizing function was maintained, the impact strength was improved, and the Vicat softening temperature of the injection molding grade PVC was significantly improved.

[0055] [Advantageous Effects of the Embodiments] As advantageous effects of the present invention, the injection molding grade PVC tube and its manufacturing method according to the present invention have the following technical features: "the first additive comprises a processing modifier which is a vinyl chloride graft copolymer and a heat resistant agent which is an α-methylstyrene acrylonitrile copolymer, the weight ratio of the processing modifier to the heat resistant agent (the processing modifier:the heat resistant agent) is 1:6.67 to 1:10, and the second additive comprises at least a lubricant, an antioxidant or a filler" and "the PVC resin, the heat stabilizer, the first additive and the second additive are all powdery" and thus improve the poor heat resistance and processing difficulty of conventional injection molding grade PVC tubes.

[0056] The above disclosure is merely a preferred embodiment of the present invention, and the scope of the claims of the present invention is not limited thereto. Therefore, all equivalent technical modifications made by utilizing the contents of the specification and drawings of the present invention are included in the scope of the claims of the present invention. [Explanation of symbols]

[0057] S110…Preparation process S120…Mixing process S130…Injection molding process

Claims

1. An injection molding grade PVC tube comprising 100 parts by weight of a PVC resin having a degree of polymerization of 600 to 1000, 2 to 8 parts by weight of a heat stabilizer, 1 to 20 parts by weight of a first additive, and 0.7 to 15 parts by weight of a second additive, the heat stabilizer is selected from at least one of the group consisting of organotin, calcium zinc stabilizers, hydrotalcite stabilizers, and rare earth stabilizers; The first additive includes a processing modifier which is a vinyl chloride graft copolymer and a heat resistant agent which is an α-methylstyrene acrylonitrile copolymer, and the weight ratio of the processing modifier to the heat resistant agent (the processing modifier:the heat resistant agent) is 1:6.67 to 1:10; the vinyl chloride graft copolymer comprises vinyl chloride, a first graft functional group and a second graft functional group, the first graft functional group being ethylene and vinylidene chloride, the second graft functional group being vinyl acetate and vinyl ester of versatic acid; The second additive includes at least a lubricant, an antioxidant, or a filler; the PVC resin, the heat stabilizer, the first additive, and the second additive are all in a powder form; The injection molding grade PVC tube is formed by hot melt extruding the PVC resin, the heat stabilizer, the first additive and the second additive, and then directly injection molding the PVC tube.

2. 2. The injection molding grade PVC tube of claim 1, wherein the vinyl chloride content is 65 wt % to 85 wt %, the first graft functional group content is 10 wt % to 15 wt %, and the second graft functional group content is 5 wt % to 15 wt %, where the total weight of the vinyl chloride graft copolymer is 100 wt %.

3. 2. The injection molding grade PVC tube of claim 1, wherein the particle size of the first additive is 30 μm to 120 μm, the content of the processing modifier in the first additive is 0.5 parts by weight to 5 parts by weight, and the content of the heat resistance agent in the first additive is 0.5 parts by weight to 15 parts by weight.

4. 2. The injection molding grade PVC tube of claim 1, wherein the particle size of the second additive is 0.1 μm to 100 μm, and in the second additive, the content of the lubricant is 0.5 parts by weight to 3 parts by weight, the content of the antioxidant is 0.1 parts by weight to 2 parts by weight, and the content of the filler is 0.1 parts by weight to 3 parts by weight.

5. 2. The injection molding grade PVC tubing of claim 1, wherein the lubricant is selected from at least one of the group consisting of polyethylene wax, oxidized polyethylene wax, fatty acid-based lubricants, metal soap-based lubricants, and silicone-based lubricants.

6. 2. The injection molding grade PVC tube of claim 1, wherein the antioxidant is selected from at least one of the group consisting of hindered phenol antioxidants and phosphite antioxidants.

7. 2. The injection molding grade PVC tube of claim 1 having a tensile strength of 50.6 MPa to 51.4 MPa, an impact strength of 30.4 J / m to 31.3 J / m, and a Vicat softening temperature of 85.8°C to 90.6°C.

8. A preparation step of providing 100 parts by weight of a PVC resin having a degree of polymerization of 600-1000, 2-8 parts by weight of a heat stabilizer, 1-20 parts by weight of a first additive, and 0.7-15 parts by weight of a second additive; a mixing step of adding the PVC resin, the heat stabilizer, the first additive and the second additive at a temperature of 100°C to 120°C, and then continuously mixing them during cooling to 35°C to 50°C to obtain a mixed PVC resin material; and an injection molding step of hot-melting the mixed PVC resin material using an injection molding machine at a temperature of 170°C to 200°C, and then injection molding the mixed PVC resin material to obtain an injection molding grade PVC tube, The heat stabilizer is selected from at least one of the group consisting of organotin, calcium zinc stabilizers, hydrotalcite stabilizers, and rare earth stabilizers; the first additive comprises a processing modifier which is a vinyl chloride graft copolymer and a heat resistant agent which is an α-methylstyrene acrylonitrile copolymer, the vinyl chloride graft copolymer comprises vinyl chloride, a first graft functional group and a second graft functional group, the first graft functional group being ethylene and vinylidene chloride, and the second graft functional group being vinyl acetate and vinyl ester of versatic acid; The weight ratio of the processing modifier to the heat resistant agent (the processing modifier:the heat resistant agent) is 1:6.67 to 1:10; The second additive includes at least a lubricant, an antioxidant, or a filler; A method for producing an injection molding grade PVC tube, wherein the PVC resin, the heat stabilizer, the first additive and the second additive are all in a powder form.

9. 9. The method for producing injection molding grade PVC tubing according to claim 8, wherein the vinyl chloride content is 65 wt % to 85 wt %, the first graft functional group content is 10 wt % to 15 wt %, and the second graft functional group content is 5 wt % to 15 wt %, where the total weight of the vinyl chloride graft copolymer is 100 wt %.

10. 9. The method for producing an injection molding grade PVC tube according to claim 8, wherein the particle size of the first additive is 30 μm to 120 μm, the content of the processing modifier in the first additive is 0.5 parts by weight to 5 parts by weight, and the content of the heat resistance agent in the first additive is 0.5 parts by weight to 15 parts by weight.

11. The particle size of the second additive is 0.1 μm to 100 μm, the content of the lubricant in the second additive is 0.5 parts by weight to 3 parts by weight, the content of the antioxidant is 0.1 parts by weight to 2 parts by weight, and the content of the filler is 0.1 parts by weight to 3 parts by weight, The lubricant is selected from at least one of the group consisting of polyethylene wax, oxidized polyethylene wax, fatty acid-based lubricants, metal soap-based lubricants, and silicone-based lubricants; 9. The method for producing an injection molding grade PVC tube according to claim 8, wherein the antioxidant is selected from at least one of the group consisting of hindered phenol-based antioxidants and phosphite-based antioxidants.

12. 9. The method of claim 8, wherein the injection molding grade PVC tube has a tensile strength of 50.6 MPa to 51.4 MPa, an impact strength of 30.4 J / m to 31.3 J / m, and a Vicat softening temperature of 85.8°C to 90.6°C.

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