Modified polyester composition and method for producing the same

Abstract

To provide a modified polyester composition including modified polyester and a filler, with improved characteristics such as impact strength, tensile strength, flexural modulus, and heat deflection temperature.SOLUTION: The modified polyester includes a polyester material, a nucleating agent, and an antioxidant. The polyester material includes a polymer of polyethylene terephthalate. The content of the nucleating agent in the modified polyester is 0.5 wt.% to 3 wt.%.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a modified polyester composition and a method for producing the same.

Background Art

[0002] With the increasing awareness of environmental protection, attention to the recycling of plastic products is on the rise. Currently, in many clothing items, polyethylene terephthalate (PET) is used as a fiber material in the manufacturing process, and polyoxymethylene (POM) or nylon is used for zippers and buttons. However, since PET is a different plastic material from POM and nylon, it is necessary to manually disassemble elements such as zippers and buttons during the recycling process to separate the PET material from the clothing, increasing the difficulty of recycling.

[0003] Since PET fibers are firmly bonded to zippers and buttons, effectively separating different plastic materials requires delicate and time-consuming manual work. Such a disassembly process not only increases labor costs but also reduces the efficiency and advantages of recycling. Furthermore, if these elements are not properly disassembled and sorted, different plastic materials may be mixed in, potentially further affecting the reuse of resources after recycling.

Summary of the Invention

Problems to be Solved by the Invention

[0004] The impact strength, tensile strength, flexural modulus, and heat distortion temperature of a polyester composition affect its applications. It is important to improve these properties of the polyester composition.

Means for Solving the Problems

[0005] At least one embodiment of the present invention provides a method for manufacturing a modified polyester composition including the following steps. Provide a polyester material. The polyester material includes a high molecular compound of polyethylene terephthalate and an oligomer of polyethylene terephthalate, and the intrinsic viscosity (IV) of the polyester material is 0.5 dL / g to 0.6 dL / g. Perform a heating and decompression process on the polyester material to reduce the oligomer of polyethylene terephthalate in the polyester material and increase the intrinsic viscosity of the polyester material to 0.6 dL / g to 0.92 dL / g. Mix a nucleating agent, an antioxidant, and a filler with the polyester material to increase the crystallinity of the polyester material and obtain a modified polyester composition including a modified polyester and a filler. The content of the nucleating agent in the modified polyester composition is 0.5% by weight to 3% by weight, and the crystallinity of the modified polyester at 23°C is 15% to 28%.

[0006] At least one embodiment of the present invention provides a modified polyester composition including a modified polyester and a filler. The modified polyester includes a polyester material, a nucleating agent, and an antioxidant. The polyester material includes a high molecular compound of polyethylene terephthalate. The intrinsic viscosity of the polyester material before mixing with the nucleating agent is 0.6 dL / g to 0.92 dL / g. The content of the nucleating agent in the modified polyester composition is 0.5% by weight to 3% by weight, and the crystallinity of the modified polyester at 23°C is 15% to 28%.

Effects of the Invention

[0007] The impact strength, tensile strength, flexural modulus, and heat distortion temperature of the polyester can be improved by the addition of the nucleating agent.

Modes for Carrying Out the Invention

[0008] Hereinafter, embodiments of the present invention will be described in detail. However, these embodiments are illustrative, and the present invention is not limited thereto.

[0009] In addition, in this specification, the range indicated as "from one numerical value to another numerical value" is a general expression to avoid listing all the numerical values within that range. Therefore, the description of a specific numerical range includes any numerical value within that range and any smaller numerical range defined by any numerical value within that range, as if any numerical value and the smaller numerical range were described in the specification.

[0010] The present invention provides a method for producing a modified polyester composition. First, a polyester material is prepared. In some embodiments, the polyethylene terephthalate (PET) in the polyester material may include virgin polyester resin, recycled polyester, or a combination thereof. Virgin polyester resin is usually an existing new polyester. Recycled polyester may include physical recycled polyester and / or chemical recycled polyester.

[0011] For example, the method for obtaining recycled polyester includes the collection of various polyester resin waste materials. The polyester resin waste materials are sorted according to their types, colors, and uses. Further, the polyester resin waste materials are compressed, packaged, and transported to a waste treatment plant.

[0012] In some embodiments, examples of the polyester resin waste materials include, but are not limited to, recycled PET bottles, film materials, fibers, etc. Other members (such as bottle caps, labels, adhesives, etc.) of the waste polyester resin material are removed. Next, the polyester resin waste materials are cut and crushed, and methods such as flotation are used to separate the bottle necks, liners, and bottle bodies made of different materials inside the PET bottles. Further, the crushed polyester resin waste materials are dried to obtain a recycled polyester processing material (recycled polyethylene terephthalate (r-PET)), which can facilitate the subsequent manufacturing process.

[0013] The recycled polyester material is further processed to obtain a recycled polyester resin. The recycled polyester resin may be a physical recycled polyester resin or a chemical recycled polyester resin.

[0014] In some embodiments, the physically recycled polyester resin refers to a polyester resin obtained by physical recycling, including a conventionally physically recycled polyester resin and a physically recycled modified polyester resin. No functional additives are added during the recycling process to the conventionally physically recycled polyester resin, while functional additives (such as lubricants, colorants, weather-resistant modifiers, nucleating agents, and clouding agents) are added to the physically recycled modified polyester resin to produce physically recycled modified polyester resins with different functions.

[0015] In some embodiments, the method for manufacturing a chemically recycled polyester resin includes cutting a recycled polyester material (such as flakes of PET bottles) to achieve the effect of depolymerizing the recycled polyester material, and then putting the cut flakes into a chemical depolymerization solution to break the chains of polyester molecules in the recycled polyester material, thereby obtaining a polyester composition having shorter molecular chains and ester monomers such as bis-hydroxyethyl terephthalate (BHET) composed of diacid units and two diol units. Next, the oligomer mixture is separated and purified, and then the oligomer mixture is repolymerized to obtain a chemically recycled polyester resin. In some embodiments, in the process of chemical replication, functional additives (such as lubricants, colorants, weather-resistant modifiers, nucleating agents, and clouding agents) may also be added to the oligomer mixture, and then repolymerization is carried out to obtain chemically recycled modified polyester resins with different functions.

[0016] The polyester material made of virgin polyester resin and / or recycled polyester before modification contains a PET polymer compound and a PET oligomer, and the intrinsic viscosity is 0.5 dL / g to 0.6 dL / g. Further, the melting point of PET in the polyester material before modification is 242 °C to 252 °C. In some embodiments, the crystallinity of PET in the polyester material before modification at room temperature (about 23 °C) is 5% to 15%. In some embodiments, the cold crystallization temperature (Tcc) of the polyester material before modification is 160 °C to 185 °C, and the heat crystallization temperature (Thc) is 105 °C to 135 °C.

[0017] Next, the polyester material is modified to obtain a modified polyester. Specifically, the modification of the polyester material includes performing a heating and depressurization process on the polyester material, and mixing additives such as a nucleating agent, an antioxidant, and a filler into the polyester material. The details are as follows.

[0018] A heating and depressurization process is performed on the polyester material to reduce the PET oligomer in the polyester material. Thereby, adhesion imparting of the polyester material is performed. The method of adhesion imparting includes solid adhesion imparting and / or liquid adhesion imparting. For example, a polyester material containing a PET polymer compound and a PET oligomer is placed in a chamber, and the chamber is depressurized and heated to volatilize the PET oligomer. In some embodiments, the polyester material is heated to 190 °C to 220 °C, depressurized to 0.01 kPa to 0.05 kPa, and subjected to solid-phase polymerization for 6 hours to 10 hours. Due to the decrease in the oligomer content, the intrinsic viscosity of the polyester material can increase to 0.6 dL / g to 0.92 dL / g, preferably 0.8 dL / g to 0.92 dL / g.

[0019] A nucleating agent, an antioxidant, and a filler are mixed into a polyester material. Since the nucleating agent can increase the crystallization rate, the crystallinity of the resulting modified polyester can be increased. In some embodiments, the nucleating agent includes an organic nucleating agent, an inorganic nucleating agent, or a combination of both. The organic nucleating agent is selected from at least one of sodium benzoate, sodium montanate, a sodium salt copolymer of ethylene-methyl methacrylate (EMMA-sodium salt, also known as SURLYN), and other organic sodium salts. The inorganic nucleating agent is selected from at least one of talc powder, titanium dioxide, silicon dioxide, calcium carbonate, and other inorganic micronano powders. The particle size of the inorganic nucleating agent used as the nucleating agent is less than 2 μm. The average particle size of the inorganic nucleating agent is, for example, 500 nm to 1500 nm. In some embodiments, the content of the nucleating agent in the finally obtained modified polyester composition is 0.5 wt% to 3 wt%, preferably 1 wt% to 2 wt%.

[0020] In some embodiments, the antioxidant is selected from at least one of a hindered phenolic antioxidant, a phenolic antioxidant, a mixed antioxidant, and a phosphite antioxidant. In some embodiments, the content of the antioxidant in the finally obtained modified polyester composition is 0.1 wt% to 1 wt%, for example, 0.2 wt% to 0.8 wt%, or 0.4 wt% to 0.6 wt%.

[0021] In some embodiments, the filler is selected from at least one of materials such as glass fiber, carbon fiber, metal oxide, and silicon dioxide. In some embodiments, the content of the filler in the finally obtained modified polyester composition is 0.5 wt% to 50 wt%, for example, 10 wt% to 40 wt%, or 20 wt% to 30 wt%. In some embodiments, the filler is fibrous or granular. When the filler is granular, the average particle size is 5 μm to 50 μm.

[0022] In some embodiments, a nucleating agent, an antioxidant, a filler, and an unmodified polyester material can be added to a twin-screw extruder and mixed to obtain a modified polyester composition after extrusion. In some embodiments, the nucleating agent, the antioxidant, and the filler are mixed with the polyester material at 260°C to 280°C. In some embodiments, other additives such as a lubricant, a dye, and a color masterbatch can also be mixed with the polyester material.

[0023] In some embodiments, the crystallinity of the modified polyester composition at 23°C is 15% to 28%. In some embodiments, the cold crystallization temperature (Tcc) of the modified polyester composition is 190°C to 210°C, and the heat crystallization temperature (Thc) is 100°C to 130°C. In some embodiments, the tensile strength of the modified polyester composition is 60 MPa to 90 MPa. In some embodiments, the melting point of the modified polyester composition is 245°C to 255°C.

[0024] To prove that the modified polyester composition presented by the present invention has excellent heat resistance and excellent mechanical strength, Table 1 shows the mechanical properties and thermal properties of some examples and comparative examples. Here, the method for manufacturing the modified polyester composition includes performing solid-phase polymerization on the polyester material so as to increase the intrinsic viscosity of the polyester material to 0.6 dL / g to 0.92 dL / g, and mixing a nucleating agent and / or a filler into the polyester material.In Comparative Example 3 and Example 2, the filler is spherical (talcum powder) with a particle size of about 5 μm. In Example 3, the glass fiber is fibrous (or rod-shaped) with a fiber diameter of about 10 μm to 13 μm. In Example 1, a sodium organic benzoate nucleating agent was added. In Example 2 and Example 3, mainly an inorganic talcum powder nucleating agent was added. An impact strength test was carried out according to ASTM D256 standard. The value obtained indicates the total energy that can be endured when the test sample is damaged. The larger the value, the more the test sample can withstand a greater impact strength (or the resistance strength of the test sample). A tensile strength test was carried out according to ASTM D638 standard. The value obtained indicates the total energy that the test sample can endure against tensile deformation. The larger the value, the more the test sample can withstand a greater tensile strength. The flexural modulus was measured according to ASTM D790 standard test method. The value obtained represents the resistance of the test piece to flexural strain and deformation. The larger the value, the higher the flexural strength of the test piece. The heat distortion temperature (HDT) was carried out according to ASTM D648 standard. It is a parameter representing the relationship between heat and strain of the test sample and is an index for measuring the heat resistance of the polymer. In the process of the HDT test, a certain load is applied to the polymer, the temperature rises at a certain speed, and reaches the temperature corresponding to the specified strain.

[0025]

Table 1

[0026] From Comparative Example 2 and Example 1, it can be seen that the addition of the nucleating agent improves the impact strength, tensile strength, flexural modulus and heat distortion temperature of the polyester. Also, from Example 1 to Example 3, it can be seen that the addition of the filler improves the flexural modulus and heat distortion temperature of the polyester. Here, Example 3 with the addition of glass fiber is preferred.

Industrial Applicability

[0027] The modified polyester composition of the present invention can be applied to hard plastic products such as zippers and buttons.

Claims

1. providing a polyester material, the polyester material comprising a polyethylene terephthalate polymer and a polyethylene terephthalate oligomer, the intrinsic viscosity of the polyester material being 0.5 dL / g to 0.6 dL / g; subjecting the polyester material to a heating and decompression process, including performing solid-state polymerization under conditions of 190° C. to 220° C. and 0.01 kPa to 0.05 kPa, to reduce the oligomers of polyethylene terephthalate in the polyester material and increase the intrinsic viscosity of the polyester material to 0.6 dL / g to 0.92 dL / g; and after the heating and depressurizing steps, mixing a nucleating agent, an antioxidant, and a filler with the polyester material to increase the crystallinity of the polyester material to obtain a modified polyester composition containing the polyester material, the nucleating agent, and the antioxidant, and the filler, wherein the modified polyester composition has a nucleating agent content of 0.5% by weight to 3% by weight, an antioxidant content of 0.1% by weight to 1% by weight, and a crystallinity of the modified polyester at 23° C. of 15% to 28%.

2. A method for producing a modified polyester composition as described in claim 1, wherein the content of the filler in the modified polyester composition is 0.5% by weight to 50% by weight.

3. The method of claim 1 , wherein the nucleating agent comprises an organic nucleating agent, an inorganic nucleating agent, or a combination of both.

4. 4. The method for producing a modified polyester composition according to claim 3, wherein the organic nucleating agent is selected from at least one of sodium benzoate, sodium montanate, and a sodium salt copolymer of ethylene-methyl methacrylate, the inorganic nucleating agent is selected from at least one of talcum powder, titanium dioxide, silicon dioxide, and calcium carbonate, and the filler is selected from at least one of glass fiber, carbon fiber, metal oxide, and silicon dioxide.

5. The method for producing the modified polyester composition according to claim 1, wherein the nucleating agent, the antioxidant, and the filler are mixed into the polyester material at 260°C to 280°C.

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