Pet composite material and preparation method therefor

Abstract

The present disclosure relates to a PET composite material and a preparation method therefor. The composite material comprises the following components in parts by mass: 50-100 parts of PET, 5-30 parts of an inorganic filler, and 5-30 parts of a PET copolyester. The PET copolyester is obtained by melting a waste pressure-sensitive adhesive product, adding an alcoholysis agent and a catalyst, and then performing polycondensation, wherein the waste pressure-sensitive adhesive product comprises a PET matrix and a pressure-sensitive adhesive layer, the pressure-sensitive adhesive layer comprises a copolyester elastomer, the copolyester elastomer is a copolymer of a carboxyl-terminated polyester and an amorphous carbon dioxide-based polyester diol, and the number-average molecular weight of the PET copolyester is 50,000 or below.

Description

PET composite materials and their preparation methods

[0001] This disclosure claims priority to Chinese Patent Application No. 2024105719325, filed on May 10, 2024, entitled "PET Composite Material and Preparation Method Thereof", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This disclosure belongs to the field of waste PET material recycling technology, specifically, this disclosure relates to a PET composite material and its preparation method. Background Technology

[0003] PET polyester film, as an important new material in current industrial intermediates and future strategic emerging industries, is a high-performance polymer film material widely used as a substrate for pressure-sensitive adhesive tapes. With the widespread application of pressure-sensitive tapes in packaging and other fields, the amount of waste pressure-sensitive tapes is increasing year by year, and the pollution and resource waste they cause are becoming increasingly prominent, becoming an issue that cannot be ignored now and in the future. Traditional PET pressure-sensitive tape recycling requires removing the adhesive layer adhering to the PET before it can be recycled, and the degumming process is often complex and cumbersome. The disposal of these waste PET tapes is also troublesome; in many places, incineration is even used. Incineration not only causes air pollution but also fails to achieve material recycling and wastes energy.

[0004] Patent application CN103374791A discloses a process for manufacturing nonwoven fabric from waste PET: pulverizing and drying recycled PET film; stirring the pulverized PET and adding ethylene-octanoic acid copolymer to form a mixture; feeding the mixture into a twin-screw extruder to extrude and plasticize it into granules, and subsequent processing. This process only involves the recycling of PET film and cannot be applied to the recycling of PET tape containing pressure-sensitive adhesive layers.

[0005] Patent application CN106009545A discloses a method for directly melting recycled waste PET to produce films, comprising the following steps: 1) crushing and decolorizing the waste PET, heating and melting it, adding PET, PBT, antioxidants, flame retardants, and chain extenders, raising the temperature to 290℃, and treating it for 160-170 seconds using microwave and ultrasonic combined action; 2) directly performing film pressing, in which hot pressing is performed first, followed by cold pressing, to obtain the finished film. This method requires crushing and decolorizing the PET, making the process complex, and it does not involve the treatment of the pressure-sensitive adhesive in the PET tape.

[0006] Patent application US20220152904A1 discloses a method for producing biaxially oriented polyester (BOPET) peeling using recycled PET. The method includes the following steps: pre-cleaning the recycled PET; performing a primary wash on the recycled PET with a solvent to remove contaminants; brushing the PET to remove dust and unwanted materials; removing impurities from the particles through a filtration process; decolorizing the particles through a clay bed; then performing glycolysis on the pre-cleaned PET to obtain monomers; and finally polycondensing the monomers in an autoclave. This method requires pre-cleaning the recycled PET, and the process is complex. For PET pressure-sensitive tape, the adhesive layer after cleaning is difficult to handle and can easily pollute the environment.

[0007] Patent application KR102611876B1 discloses the preparation of PET film using waste PET fragments. The process involves separating and washing the waste PET to remove inorganic particles, color sorting, drying, pulverizing, washing with a non-solvent solution, drying again and separating from metal particles, and then adding a molding modifier (TEP) to a mixing apparatus. The process involves melting and mixing the waste PET film, followed by processing it into recycled PET film. This method requires the treatment of waste PET, involves complex steps, and does not involve the recycling of pressure-sensitive adhesive in PET tape.

[0008] Furthermore, PET itself has a cold crystallization temperature point (Tcc), which is typically in the range of 136℃ to 147℃, failing to meet the mold temperature requirements of normal injection molding. While forcing the mold to be heated and kept at the PET's cold crystallization temperature range during injection molding can temporarily eliminate the influence of the Tcc, once the ambient temperature reaches the Tcc, secondary crystallization will occur due to the memory effect of the PET's Tcc. This can lead to stress cracking or direct melting, which is PET's most fatal weakness.

[0009] Therefore, if these waste PET substrates can be recycled and reused, while also lowering their cold crystallization temperature, it will be of great significance for energy conservation, environmental protection, and improving product performance. Summary of the Invention

[0010] Based on this, the present disclosure aims to overcome at least one defect of the conventional technology and provide a PET composite material, which is not only prepared from waste PET material, but also has excellent performance and can meet the performance requirements of PET products.

[0011] Another objective of this disclosure is to provide a method for preparing a PET composite material that can fully recycle waste PET film and PET pressure-sensitive tape, thus realizing the recycling of two major waste PET materials.

[0012] The technical solution is as follows: A PET composite material, wherein the PET composite material, by mass, contains: 50-100 parts PET, 5-20 parts inorganic filler, and 5-30 parts PET copolyester; wherein the PET copolyester is obtained by melting waste pressure-sensitive adhesive product, adding an alcoholysis agent and a catalyst, and then vacuum polycondensing, wherein the waste pressure-sensitive adhesive product includes a PET matrix and a pressure-sensitive adhesive layer, the pressure-sensitive adhesive layer includes a copolyester elastomer, the copolyester elastomer is a copolymer of carboxyl-terminated polyester and non-crystalline carbon dioxide-based polyester diol, and the number average molecular weight of the PET copolyester is 20,000-50,000.

[0013] This disclosure also relates to a method for preparing the above-mentioned PET composite material, including the following steps:

[0014] (1) The waste pressure-sensitive adhesive product is melted, an alcoholysis agent and a catalyst are added, and then polycondensation is performed to obtain the PET copolyester;

[0015] (2) The components other than the PET copolyester are processed into a premelt; the PET copolyester obtained in step (1) is added to the premelt, and then melted, kept warm, and extruded to obtain the PET composite material.

[0016] The pressure-sensitive adhesive product disclosed herein has a PET matrix and a copolyester elastomer in the pressure-sensitive adhesive layer. This copolyester elastomer is a copolymer of carboxyl-terminated polyester and amorphous carbon dioxide-based polyester diol, a material with good degradation properties. By completely melting the pressure-sensitive tape at high temperature (i.e., both the base film and the pressure-sensitive adhesive layer are completely melted), and then adding a catalyst and alcoholysis agent, the pressure-sensitive tape undergoes alcoholysis into small molecule monomers, which are then polycondensed to form a new PET copolyester. Pressure-sensitive adhesive products containing this type of copolyester elastomer do not require peeling off the pressure-sensitive adhesive layer, nor do they require alcoholysis of PET into monomers or oligomers before reacting with the new components, greatly simplifying the chemical conversion process. Compared to PET material, the PET copolyester formed by polycondensation has a lower cold crystallization temperature, a lower hot crystallization temperature, and a lower glass transition temperature. This is because amorphous segments are introduced into this PET copolyester, resulting in a lower glass transition temperature, greater softness, and a reduced cold crystallization temperature. Melt-compositing this PET copolyester with PET can lower the cooling crystallization temperature of PET, eliminate the weaknesses of PET, reduce the steric hindrance of PET, and the resulting PET composite material has a molding temperature higher than the cold crystallization temperature. PET will not undergo secondary crystallization, which is beneficial for the processing of PET materials.

[0017] Details of one or more embodiments of this disclosure are set forth in the following description, and other features, objects, and advantages of this disclosure will become apparent from the specification and claims. The technical solutions described in this disclosure enable the recycling of waste PET and waste pressure-sensitive adhesive products. The recycling of waste pressure-sensitive adhesive products does not require prior degumming of the pressure-sensitive adhesive layer; the entire pressure-sensitive adhesive product can be directly recycled. Furthermore, the recycled PET composite material has a low crystallization temperature, eliminating the weaknesses of PET. After lowering the cold crystallization temperature of the PET composite material, the molding temperature is higher than the cold crystallization temperature, preventing secondary crystallization of PET and facilitating the processing of PET materials. The prepared PET composite material exhibits excellent mechanical properties. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this disclosure clearer, the following detailed description is provided in conjunction with specific embodiments.

[0019] In one embodiment of the PET composite material disclosed herein, the 50-100 parts of PET comprise waste PET, which mainly originates from beverage bottles, films, laminates, tapes, high-grade sheets, fibers, etc., as well as PET from medical supplies such as syringes and containers. Alternatively, the PET may not contain waste PET. The molecular weight of the PET is below 50,000, and may also be 45,000, 40,000, 35,000, 30,000, 25,000, 20,000, etc.

[0020] In one embodiment, the copolyester elastomer comprises a hard-segment carboxyl-terminated polyester and a biodegradable soft-segment amorphous carbon dioxide-based polyester diol. The soft-segment amorphous carbon dioxide-based polyester diol is... Carbon dioxide-based polyester diols, derived from a third type of carbon source, exhibit rapid degradation and high degradation rates. Since the soft-segment carbon dioxide-based polyester diol used is a non-crystalline diol with poor cohesion, it cannot be used in pressure-sensitive adhesives. Therefore, a biodegradable hard-segment carboxyl-terminated polyester with a specific molecular weight is introduced to increase its cohesive strength. Because the hard segment is also biodegradable, the hard segment portion can also degrade, thus making the copolyester elastomer obtained by polymerizing the hard-segment carboxyl-terminated polyester and the soft-segment non-crystalline carbon dioxide-based polyester diol completely biodegradable. The polyester is polymerized from C3-C7 diacids and C3-C7 diols, accounting for 10-30% by mass of the copolyester elastomer. The number-average molecular weight of the polyester is 1100-3000, the non-crystalline carbon dioxide-based polyester diol is a copolymer of polypropylene carbonate diol with a number-average molecular weight of 2000-3000, and the number-average molecular weight of the copolyester elastomer is 30000-50000.

[0021] Because the hard segment contains carboxyl groups, it can act as a physical crosslinking point to form a copolyester elastomer with the soft segment (carbon dioxide-based polyester diol), thereby improving the overall cohesive strength of the resin. This allows it to meet the bonding performance requirements of pressure-sensitive adhesives. To achieve the desired performance, the hard segment should account for more than 10% of the elastomer's mass. While increasing its content improves the cohesive properties of the copolyester elastomer, excessively high hard segment content leads to increased phase separation, resulting in decreased elastomer performance and consequently, reduced performance of the pressure-sensitive adhesive. Furthermore, excessively high hard segment content also increases the physical entanglement of the elastomer, thus decreasing its degradation rate. Therefore, the hard segment mass ratio should be controlled below 30%. Specifically, the hard segment percentage can be 12%, 14%, 16%, 18%, 20%, 22%, 24%, 26%, or 28%.

[0022] Furthermore, the molecular weight of the hard segment, soft segment, and copolyester elastomer also affects the performance of biodegradable copolyester elastomers. For the hard segment, the higher the molecular weight, the stronger the crystallinity and the stronger its ability to act as a physical crosslinking point. To meet performance requirements, the number average molecular weight of the hard segment should be above 1100. However, excessively high molecular weight leads to excessive crystallinity, resulting in too much microphase separation in the biodegradable copolyester elastomer, which in turn leads to a decrease in the performance of the biodegradable copolyester elastomer and consequently, a decrease in the performance of the subsequent pressure-sensitive adhesive. The number average molecular weight of the hard segment should be controlled below 3000. Specifically, the number average molecular weight of the hard segment can be 1200, 1400, 1600, 1800, 2000, 2200, 2400, 2600, 2800, or 2900. For soft segments, if the molecular weight is too low, the chain segments are too short, and the degradable copolyester elastomer loses its elasticity. Therefore, its number-average molecular weight is at least 2000. If the molecular weight is too high, it is equivalent to a decrease in the hard segment content, resulting in a decrease in the strength of the degradable copolyester elastomer and affecting its subsequent use as a pressure-sensitive adhesive matrix resin. The number-average molecular weight should be controlled below 3000. Specifically, the number-average molecular weight of soft segments can be 2100, 2200, 2300, 2400, 2500, 2600, 2700, 2800, or 2900. For copolyester elastomers, the molecular weight needs to be above 30000 to have the required cohesive strength. However, if the molecular weight is too high, it will lead to poor degradation performance. Therefore, it needs to be controlled below 50000. The number-average molecular weight of copolyester elastomers can be 32000, 34000, 36000, 38000, 40000, 42000, 44000, 46000, or 48000.

[0023] By controlling the molecular weight, segment content, and overall molecular weight of the soft and hard segments of the biodegradable copolyester elastomer, the copolyester elastomer can possess excellent cohesive strength and biodegradability. The biodegradable polyester pressure-sensitive adhesive also exhibits excellent adhesion and degradation properties. By mixing the biodegradable copolyester elastomer with tackifying resins, plasticizers, etc., the prepared biodegradable polyester pressure-sensitive adhesive has excellent initial tack, holding power, high peel strength, and high degradation rate, and it is not easy to leave residue after peeling.

[0024] In one embodiment, the carboxyl-terminated polyester is polymerized from a C3-C7 dicarboxylic acid and a C3-C7 diol.

[0025] In one embodiment, the carboxyl-terminated polyester is polybutylene succinate (PBS), and the amorphous carbon dioxide-based polyester diol is polypropylene carbonate diol (PPC). PBS and PPC are novel biodegradable polymeric materials. The degradation mechanism of PBS is as follows: first, hydrolysis of CO bonds, followed by further degradation under the action of enzymes. PBS is a crystalline substance that can act as a physical crosslinking point to form a copolyester elastomer with polycarbonate, thereby improving the overall cohesive strength of the resin and enabling its application in pressure-sensitive adhesives to meet the adhesive performance requirements. Furthermore, PBS is synthesized from biomass, a second type of carbon source, and exhibits good degradation performance. The PPC segment is... Basic diols, derived from a third type of carbon source, degrade rapidly and have a high degradation rate.

[0026] In one embodiment, the PET can be 70-90 parts, the inorganic filler can be 10-20 parts, and the PET copolyester can be 10-30 parts.

[0027] In one embodiment, the cooling crystallization temperature of the PET composite material is 90-135°C, which can be 105-130°C or 110-120°C, and the number average molecular weight of the PET copolyester is 15,000-50,000, which can be 20,000-45,000 or 30,000-40,000.

[0028] In one embodiment, the PET composite material further contains 0.2 to 1 part of dispersant, 0.2 to 1 part of antioxidant, and may also contain 0.1 to 10 parts of additives optionally selected in the art, such as flame retardants, toughening agents, coupling agents, lubricants, etc.

[0029] In one embodiment, the alcoholysis agent is one or more of methanol, ethanol, ethylene glycol, propylene glycol, butanediol and pentanediol, for example, butanediol, and the mass ratio of the alcoholysis agent to the pressure-sensitive adhesive product is (1-2):1, which can be (1.3-1.8):1.

[0030] In one embodiment, the catalyst is tetrabutyl titanate, tetraisopropyl titanate, or p-toluenesulfonic acid, and the amount of the catalyst is 0.01 to 1% of the mass of the pressure-sensitive adhesive product, which can be 0.3‰ to 1‰.

[0031] In one embodiment, the pressure-sensitive adhesive product is a biodegradable tape, stick, or roll.

[0032] In one embodiment, the inorganic filler is one or more of talc, titanium dioxide, heavy calcium titanate, wollastonite, mica, kaolin, potassium titanate whiskers, calcium carbonate whiskers, barium sulfate, and silicon dioxide. The content of the inorganic filler is 5 to 30 parts, or it can be 8 to 20 parts, or it can be 10 to 18 parts.

[0033] In one embodiment, the dispersant is a TA-based lubricating dispersant or an ethylene-acrylate copolymer.

[0034] In one embodiment, the antioxidant is antioxidant 1010, antioxidant 168, or antioxidant 1076.

[0035] In one embodiment, the pressure-sensitive adhesive layer is a biodegradable pressure-sensitive adhesive layer, comprising, by weight: 20 to 80 parts of copolyester elastomer, which may be 30 to 70 parts, or more preferably 50 to 60 parts; 20 to 50 parts of tackifying resin; 1 to 10 parts of plasticizer; and optional additives.

[0036] In one embodiment, the tackifying resin is one or more of natural rosin, hydrogenated rosin, disproportionated rosin, esterified rosin, C5 petroleum resin, C9 petroleum resin, and terpene resin, and the content of the tackifying resin can be 30-50 parts, or more preferably 40-50 parts.

[0037] In one embodiment, the plasticizer is one or more of epoxidized soybean oil, flaxseed oil, castor oil, and palm oil.

[0038] In one embodiment, the additive includes an antioxidant, which is one or more of tris(2,4-di-tert-butylphenyl) phosphite, bis(2,4-di-tert-butylphenyl) pentaerythritol diphosphite, di(tridecyl)thiodipropionate, and pentaerythritol tetrakis{3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate}.

[0039] In one embodiment, the PET includes, but is not limited to, waste PET. There are no specific requirements for the molecular weight of the PET; it can be a conventional molecular weight in PET composite materials, or it can be 10,000 to 100,000, or 15,000 to 80,000, or 20,000 to 70,000, or 25,000 to 60,000, or 30,000 to 50,000, or 35,000 to 45,000.

[0040] In one embodiment, the tensile strength of the PET composite material is 120–160 MPa.

[0041] In one embodiment, the elongation at break of the PET composite material is 3 to 12%.

[0042] In one embodiment of the PET composite material preparation method disclosed herein, in step 1), waste pressure-sensitive adhesive product is melted at 260-280°C, stirred for 3-4 hours, and after adding alcoholysis agent and catalyst, vacuum polycondensation is performed for 1-6.5 hours to obtain the PET copolyester.

[0043] In one embodiment, in step (2), the PET copolyester obtained in step (1) is introduced from the die head and melt-blended with the pre-melt and extruded. The melt blending conditions are: temperature 200-240°C and extruder speed 100-500 rpm.

[0044] In one embodiment, the specific steps of melting and extruding the molten copolyester and pre-melt in a twin-screw extruder in step (2) are as follows: 10 to 30 parts of the PET copolyester obtained in step (1) are introduced from the die head, and 70 to 90 parts of the pre-melt are melt-blended and extruded in a twin-screw extruder. The melt blending conditions are: temperature 210 to 230°C, twin-screw extruder speed 200 to 400 rpm.

[0045] In one embodiment, the premixing conditions in step (2) are: temperature 25±5℃, twin-screw extrusion, speed 50~1500rpm, premixing time 3~10 minutes, and the speed can also be 80~200rpm.

[0046] In one embodiment, in step (2), after extrusion, the material is traction and cooled before being cut into granules or flakes. Example

[0047] The embodiments disclosed herein are for illustrative purposes only and should not be construed as limiting the scope of this disclosure.

[0048] For simplicity, this paper only explicitly discloses some numerical ranges. However, any lower limit can be combined with any upper limit to form an undefined range; and any lower limit can be combined with other lower limits to form an undefined range, just as any upper limit can be combined with any other upper limit to form an undefined range. Furthermore, although not explicitly stated, every point or individual value between the endpoints of a range is included within that range. Therefore, each point or individual value can serve as its own lower or upper limit and be combined with any other point or individual value, or with other lower or upper limits, to form an undefined range.

[0049] The foregoing description of this application is not intended to describe every disclosed implementation or method. Instead, the following description provides more specific examples of exemplary embodiments. Throughout the application, guidance is provided through a series of embodiments that can be used in various combinations. The examples listed are representative only and should not be construed as exhaustive.

[0050] Unless otherwise specified, the raw materials used in the following examples are all commercially available products.

[0051] The waste pressure-sensitive adhesive products described in the following examples are waste products from pressure-sensitive adhesive tapes manufactured by our company. The specific components of the pressure-sensitive adhesive tape are a PET matrix and a pressure-sensitive adhesive layer.

[0052] The preparation process of the pressure-sensitive adhesive tape 1 used in Examples 1 to 5, 8 to 9 is as follows:

[0053] (1) Preparation of carboxyl-terminated polybutylene succinate

[0054] Forty parts of 1,4-butanediol and 60 parts of succinic acid were added to a reaction vessel. The temperature was then raised to 165°C, and tetrabutyl titanate catalyst (0.3 wt% of the total mass of 1,4-butanediol and succinic acid) was added. The reaction was carried out for about 3 hours, followed by a further increase in temperature to 180°C for about 1 hour. Then, the mixture was heated to 205°C and subjected to vacuum polycondensation for 2 hours. The ester content was then tested. The tested acid value was 70.125 mg KOH / g (the calculated number-average molecular weight was 1600, calculated using the following formula:). (where y is the acid value), and after cooling to room temperature, carboxyl-terminated polybutylene succinate is obtained.

[0055] (2) Preparation of copolyester elastomer

[0056] Eighteen parts of carboxyl-terminated polybutylene succinate and 82 parts of amorphous carbon dioxide-based polyester diol (polypropylene carbonate diol, molecular weight approximately 2500, hydroxyl value approximately 44.88 mg KOH / g) were added to a reactor. The temperature was then raised to 180°C, and 0.2 wt% tetrabutyl titanate catalyst (the total mass of carboxyl-terminated polybutylene succinate and amorphous carbon dioxide-based polyester diol) was added. The reaction was carried out for 2 hours, followed by a further reaction at 220°C for 3 hours. Vacuum polycondensation was then performed for 4 hours, and the mixture was cooled to room temperature to obtain a biodegradable copolyester elastomer. Molecular weight analysis of the biodegradable copolyester elastomer revealed a number-average molecular weight of approximately 35,000.

[0057] (3) Preparation of pressure-sensitive adhesive solution

[0058] 50 parts of biodegradable copolyester elastomer, 45 parts of tackifying resin rosin, 5 parts of plasticizer epoxidized soybean oil, and 0.15 parts of antioxidant tris(2,4-di-tert-butylphenyl) phosphite were mixed and stirred at 130°C for 3 hours. The mixture was then cooled to room temperature and chloroform solution was added to obtain a biodegradable pressure-sensitive adhesive solution with a solid content of 20 wt%.

[0059] (4) Preparation of pressure-sensitive tape

[0060] The biodegradable pressure-sensitive adhesive solution was coated onto a PET base film using a coating machine and kept at 80°C for 10 minutes to obtain a biodegradable pressure-sensitive adhesive tape 1 with a pressure-sensitive adhesive layer thickness of approximately 15 μm.

[0061] The preparation process of the pressure-sensitive tape 2 used in Example 6 is as follows:

[0062] (1) Preparation of carboxyl-terminated polybutylene succinate

[0063] 45 parts of 1,4-butanediol and 65 parts of succinic acid were added to a reactor, and the temperature was raised to 165°C. Tetrabutyl titanate, a catalyst at a total mass of 0.5 wt% of the combined 1,4-butanediol and succinic acid, was added, and the reaction proceeded for approximately 4 hours. The temperature was then raised to 180°C and reacted for approximately 2 hours, followed by vacuum polycondensation at 220°C for 4 hours. The ester content was then tested. The acid value was found to be 38.7 mg KOH / g (calculated as a number-average molecular weight of 2900). After cooling to room temperature, carboxyl-terminated polybutylene succinate was obtained.

[0064] (2) Preparation of copolyester elastomer

[0065] Eighteen parts of hard-segment polyester and 82 parts of soft-segment amorphous carbon dioxide-based polyester diol (polypropylene carbonate diol, molecular weight approximately 2500, hydroxyl value approximately 44.88 mg KOH / g) were added to a reactor. The temperature was then raised to 180°C, and 0.2 wt% of tetrabutyl titanate catalyst (the total mass of carboxyl-terminated polybutylene succinate and amorphous carbon dioxide-based polyester diol) was added. The reaction was carried out for 2 hours, followed by a further increase in temperature to 220°C and a reaction for 4 hours. Vacuum polycondensation was then performed for 6 hours, and the mixture was cooled to room temperature to obtain a biodegradable copolyester elastomer. The molecular weight of the biodegradable copolyester elastomer was measured, and the number average molecular weight was approximately 49,000.

[0066] (3) Preparation of pressure-sensitive adhesive solution: The same as step (3) in the preparation process of pressure-sensitive adhesive tape 1.

[0067] (4) Preparation of pressure-sensitive tape: The same as step (4) of the preparation process of pressure-sensitive tape 1.

[0068] The preparation process of the pressure-sensitive tape 3 used in Example 7 is as follows:

[0069] (1) Preparation of carboxyl-terminated polybutylene succinate: the same as step (1) of the preparation process of pressure-sensitive tape 1.

[0070] (2) Ten parts of carboxyl-terminated polybutylene succinate and 90 parts of soft-segment amorphous carbon dioxide-based polyester diol (polypropylene carbonate diol, molecular weight approximately 2500, hydroxyl value approximately 44.88 mg KOH / g) were added to a reactor. The temperature was then raised to 190°C, and 0.1 wt% of tetrabutyl titanate catalyst (the total mass of carboxyl-terminated polybutylene succinate and amorphous carbon dioxide-based polyester diol) were added. The reaction was carried out for 2 hours, then the temperature was raised to 210°C and the reaction was carried out for 3 hours. Vacuum polycondensation was then performed for 3 hours, and the mixture was cooled to room temperature to obtain a biodegradable copolyester elastomer. The molecular weight of the biodegradable copolyester elastomer was tested, and the number average molecular weight was found to be approximately 32000.

[0071] (3) Preparation of pressure-sensitive adhesive solution: The same as step (3) in the preparation process of pressure-sensitive adhesive tape 1.

[0072] (4) Preparation of pressure-sensitive tape: The same as step (4) of the preparation process of pressure-sensitive tape 1.

[0073] Example 1

[0074] A method for preparing PET composite materials using waste PET and pressure-sensitive adhesive tape includes the following steps:

[0075] (1) Waste pressure-sensitive adhesive tape 1 was melted at 260℃ and stirred for 3 hours. After adding alcoholysis agent and catalyst tetrabutyl titanate, it was vacuum polycondensed for 5 hours to obtain PET copolyester. The amount of alcoholysis agent was 150% of the mass of the pressure-sensitive adhesive tape. The amount of catalyst was 0.5‰ of the mass of the waste pressure-sensitive adhesive tape. The molecular weight of the prepared PET copolyester was determined to be approximately 28,000.

[0076] (2) 80 parts of waste PET (PET film with a number average molecular weight of about 40,000), 15 parts of talc powder, 0.5 parts of dispersant TA100 and 0.5 parts of antioxidant 1010 were premixed to obtain a pre-melt. The premixing conditions were: temperature 25℃, twin-screw extrusion, speed about 100 rpm, and premixing time 5 minutes. 20 parts of the PET copolyester obtained in step (1) were melted at 280℃ and kept at that temperature for 15 minutes. The molten PET copolyester was introduced from the die head and melt-blended with the pre-melt in a twin-screw extruder. The melt-blending conditions were: temperature 220℃ and twin-screw extruder speed 300 rpm. After traction and cooling, the mixture was cut into granules to obtain copolyester-reinforced PET composite material.

[0077] Example 2

[0078] A method for preparing PET composite materials using waste PET and pressure-sensitive adhesive tape includes the following steps:

[0079] (1) Waste pressure-sensitive adhesive tape was melted at 270°C and stirred for 3.5 h. After adding alcoholysis agent and catalyst tetrabutyl titanate, it was vacuum polycondensed for 6.5 h to obtain PET copolyester. The amount of alcoholysis agent was 160% of the mass of the pressure-sensitive adhesive tape. The amount of catalyst was 0.3‰ of the mass of the waste pressure-sensitive adhesive tape. The molecular weight of the prepared PET copolyester was determined to be approximately 30,000.

[0080] (2) 80 parts of waste PET (PET film with a number average molecular weight of about 40,000), 15 parts of talc powder, 0.5 parts of dispersant TA100 and 0.5 parts of antioxidant 1010 were premixed to obtain a pre-melt. The premixing conditions were: temperature 25℃, twin-screw extrusion, speed about 100 rpm, and premixing time 3 to 10 minutes. 20 parts of the PET copolyester obtained in step (1) were melted at 260℃ and kept at that temperature for 10 minutes. The molten PET copolyester was introduced from the die head and melt-blended with the pre-melt in a twin-screw extruder. The melt-blending conditions were: temperature 270℃ and twin-screw extruder speed 300 rpm. After traction and cooling, the mixture was cut into granules to obtain copolyester-reinforced PET composite material.

[0081] Example 3

[0082] A method for preparing PET composite materials using waste PET and pressure-sensitive adhesive tape includes the following steps:

[0083] (1) The waste pressure-sensitive adhesive tape 1 was melted at 275°C and stirred for h. After adding alcoholysis agent and catalyst tetrabutyl titanate, it was vacuum polycondensed for 3.5 h to obtain PET copolyester. The amount of alcoholysis agent was 180% of the mass of the pressure-sensitive adhesive tape. The amount of catalyst was 1‰ of the mass of the waste pressure-sensitive adhesive tape. The molecular weight of the prepared PET copolyester was determined to be approximately 26,000.

[0084] (2) 80 parts of waste PET (PET film with a number average molecular weight of about 40,000), 15 parts of talc powder, 0.5 parts of dispersant TA100 and 0.5 parts of antioxidant 1010 were premixed to obtain a pre-melt. The premixing conditions were: temperature 25℃, twin-screw extrusion, speed about 100 rpm, and premixing time 7 minutes. 20 parts of the PET copolyester obtained in step (1) were melted at 270℃ and kept at that temperature for 20 minutes. The molten PET copolyester was introduced from the die head and melt-blended with the pre-melt in a twin-screw extruder. The melt-blending conditions were: temperature 220℃ and twin-screw extruder speed 300 rpm. After traction and cooling, the mixture was cut into granules to obtain copolyester-reinforced PET composite material.

[0085] Example 4

[0086] A method for preparing PET composite materials using waste PET and pressure-sensitive adhesive tape includes the following steps:

[0087] (1) Waste pressure-sensitive adhesive tape 1 was melted at 280℃ and stirred for 4 hours. After adding alcoholysis agent and catalyst tetrabutyl titanate, it was vacuum polycondensed for 5 hours to obtain PET copolyester. The amount of alcoholysis agent was 150% of the mass of the pressure-sensitive adhesive tape. The amount of catalyst was 0.5‰ of the mass of the waste pressure-sensitive adhesive tape. The molecular weight of the prepared PET copolyester was determined to be approximately 28,000.

[0088] (2) 90 parts of waste PET (PET film with a number average molecular weight of about 40,000), 20 parts of talc powder, 1 part of dispersant TA100 and 1 part of antioxidant 1010 were premixed to obtain a pre-melt. The premixing conditions were: temperature 25℃, twin-screw extrusion, speed about 100 rpm, and premixing time 3 to 10 minutes. 10 parts of the PET copolyester obtained in step (1) were melted at 280℃ and kept at that temperature for 5 minutes. The molten PET copolyester was introduced from the die head and melt-blended with the pre-melt in a twin-screw extruder. The melt-blending conditions were: temperature 220℃ and twin-screw extruder speed 300 rpm. After traction and cooling, it was cut into granules to obtain copolyester reinforced PET composite material.

[0089] Example 5

[0090] A method for preparing PET composite materials using waste PET and pressure-sensitive adhesive tape includes the following steps:

[0091] (1) Waste pressure-sensitive adhesive tape 1 was melted at 260℃ and stirred for 3.5h. After adding alcoholysis agent and catalyst tetrabutyl titanate, it was vacuum polycondensed for 5h to obtain PET copolyester. The amount of alcoholysis agent was 150% of the mass of the pressure-sensitive adhesive tape. The amount of catalyst was 0.5‰ of the mass of the waste pressure-sensitive adhesive tape. The molecular weight of the prepared PET copolyester was determined to be approximately 27,000.

[0092] (2) 70 parts of waste PET (PET film with a number average molecular weight of about 40,000), 10 parts of talc powder, 0.2 parts of dispersant TA100 and 0.2 parts of antioxidant 1010 were premixed to obtain a pre-melt. The premixing conditions were: temperature 25℃, twin-screw extrusion, speed about 100 rpm, and premixing time 3 minutes. 30 parts of the PET copolyester obtained in step (1) were melted at 260℃ and kept at that temperature for 5 minutes. The molten PET copolyester was introduced from the die head and melt-blended with the pre-melt in a twin-screw extruder. The melt-blending conditions were: temperature 220℃ and twin-screw extruder speed 300 rpm. After traction and cooling, the mixture was cut into granules to obtain copolyester reinforced PET composite material.

[0093] Example 6

[0094] A method for preparing PET composite materials using waste PET and pressure-sensitive adhesive tape includes the following steps:

[0095] (1) Waste pressure-sensitive adhesive tape 2 was melted at 260℃ and stirred for 3 hours. After adding alcoholysis agent and catalyst tetraisopropyl titanate, it was vacuum polycondensed for 5 hours to obtain PET copolyester. The amount of alcoholysis agent was 150% of the mass of the pressure-sensitive adhesive tape. The amount of catalyst was 0.5‰ of the mass of the waste pressure-sensitive adhesive tape. The molecular weight of the prepared PET copolyester was determined to be approximately 30,000.

[0096] (2) 80 parts of waste PET (PET film with a number average molecular weight of about 35,000), 15 parts of talc, 0.5 parts of TA100 and 0.5 parts of antioxidant 168 were premixed to obtain a pre-melt. The premixing conditions were: temperature 30℃, twin-screw extrusion, speed about 80 rpm, and premixing time 3 to 10 minutes. 20 parts of the PET copolyester obtained in step (1) were melted at 260℃ and kept at that temperature for 10 minutes. The molten PET copolyester was introduced from the die head and melt-blended with the pre-melt in a twin-screw extruder. The melt-blending conditions were: temperature 230℃ and twin-screw extruder speed 200 rpm. After traction and cooling, the mixture was cut into granules to obtain copolyester-reinforced PET composite material.

[0097] Example 7

[0098] A method for preparing PET composite materials using waste PET and pressure-sensitive adhesive tape includes the following steps:

[0099] (1) Waste pressure-sensitive adhesive tape 3 was melted at 265°C and stirred for 4 hours. After adding alcoholysis agent and catalyst tetrabutyl titanate, it was vacuum polycondensed for 5 hours to obtain PET copolyester. The amount of alcoholysis agent was 150% of the mass of the pressure-sensitive adhesive tape. The amount of catalyst was 0.5‰ of the mass of the waste pressure-sensitive adhesive tape. The molecular weight of the prepared PET copolyester was determined to be approximately 34,000.

[0100] (2) 80 parts of waste PET (PET film with a number average molecular weight of about 45,000), 15 parts of talc, 0.5 parts of dispersant TA100 and 0.5 parts of antioxidant 168 were premixed to obtain a pre-melt. The premixing conditions were: temperature 20℃, twin-screw extrusion, speed about 200 rpm, and premixing time 4 minutes. 20 parts of the PET copolyester obtained in step (1) were melted at 265℃ and kept at that temperature for 5 minutes. The molten PET copolyester was introduced from the die head and melt-blended with the pre-melt in a twin-screw extruder. The melt-blending conditions were: temperature 210℃ and twin-screw extruder speed 400 rpm. After traction and cooling, the mixture was cut into granules to obtain copolyester-reinforced PET composite material.

[0101] Example 8

[0102] A method for preparing PET composite materials using waste PET and pressure-sensitive adhesive tape is disclosed. This embodiment is largely the same as Embodiment 1, except that the vacuum polycondensation time in this embodiment is 2 hours, and the molecular weight of the prepared PET copolyester is approximately 18,000.

[0103] Example 9

[0104] A PET composite material, which is largely the same as Example 1, except that the molecular weight of the waste PET in this example is about 20,000.

[0105] Comparative Example 1

[0106] A PET composite material, which is largely the same as Example 1, except that the vacuum polycondensation time of Comparative Example 1 is 9 hours, and the molecular weight of the prepared PET copolyester is about 56,000.

[0107] Comparative Example 2

[0108] An unmodified waste PET, the waste PET being the same as the waste PET of Example 1.

[0109] The mechanical properties of the composite materials prepared in Examples 1 to 9 and Comparative Examples 1 to 2 were tested. The tensile, bending and impact properties were tested in accordance with GB / T 1040-2006, and the tensile rate for the tensile property test was 50 mm / min.

[0110] The test results are shown in Table 1.

[0111]

[0112] The glass transition temperature, melting point, and crystallization temperature of the PET composite materials prepared in Examples 1-9 and Comparative Examples 1-2 were tested using differential thermal analysis. The cold crystallization temperature test conditions were as follows: heating from room temperature to 280°C at a rate of 10°C / min and holding at that temperature for 5 min; then cooling from 280°C to 80°C at a rate of -5°C / min, with the sample slice weight <10 mg. The test results are shown in Table 2.

[0113]

[0114] The molecular weight of the PET copolyester in Comparative Example 1 is 56,000. Since its molecular weight is much higher than 50,000, the carbonate in the PET copolyester with a large molecular weight will form more intramolecular hydrogen bonds, resulting in greater polarity. At the same time, the combination of a larger molecular weight makes the cold crystallization temperature exceed the cold crystallization temperature of conventional waste PET.

[0115] Obviously, the above embodiments of this disclosure are merely examples for clearly illustrating the technical solutions of this disclosure, and are not intended to limit the specific implementation of this disclosure. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the claims of this disclosure should be included within the protection scope of the claims of this disclosure.

Claims

1. A PET composite material, characterized in that, The PET composite material contains, by weight, the following: 50-100 parts PET, 5-30 parts inorganic filler and 5-30 parts PET copolyester; The PET copolyester is obtained by melting waste pressure-sensitive adhesive products, adding alcoholysis agents and catalysts, and then polycondensing. The waste pressure-sensitive adhesive products include a PET matrix and a pressure-sensitive adhesive layer. The pressure-sensitive adhesive layer includes a copolyester elastomer, which is a copolymer of carboxyl-terminated polyester and amorphous carbon dioxide-based polyester diol. The number average molecular weight of the PET copolyester is below 50,000.

2. The PET composite material according to claim 1, characterized in that, The 50-100 parts of PET include waste PET, wherein the polyester in the copolyester elastomer is polymerized from C3-C7 diacids and C3-C7 diols, accounting for 10-30% by mass of the copolyester elastomer, the number average molecular weight of the polyester is 1100-3000, the non-crystalline carbon dioxide-based polyester diol is a copolymer of polypropylene carbonate diol, the number average molecular weight of which is 2000-3000, and the number average molecular weight of the copolyester elastomer is 30000-50000.

3. The PET composite material according to claim 1 or 2, characterized in that, The PET composite material, by weight, contains: 70-90 parts of PET, and / or 10-20 parts of inorganic filler, and / or 10-30 parts of PET copolyester, and / or a cooling crystallization temperature of 90-135°C, and / or a number-average molecular weight of 15,000-50,000 for the PET copolyester, and / or a tensile strength of 120-160 MPa for the PET composite material, and / or an elongation at break of 3%-12%.

4. The PET composite material according to any one of claims 1-3, characterized in that, The PET composite material further contains 0.2 to 1 part dispersant, and / or 0.2 to 1 part antioxidant, and / or the number average molecular weight of the PET copolyester is 20,000 to 50,000, and / or the molecular weight of the PET in the PET composite material is 35,000 to 45,000.

5. The PET composite material according to any one of claims 1-4, characterized in that, The copolyester elastomer is a copolymer of polybutylene succinate and polypropylene carbonate diol, wherein the alcoholysis agent is one or more of methanol, ethanol, ethylene glycol, propylene glycol, butanediol, and pentanediol, and the mass ratio of the alcoholysis agent to the pressure-sensitive adhesive product is (1-2):1; the catalyst is tetrabutyl titanate, tetraisopropyl titanate, or p-toluenesulfonic acid, and the mass of the catalyst is 0.01-1% of the mass of the pressure-sensitive adhesive product; the pressure-sensitive adhesive product is a biodegradable tape, stick, or roll; the inorganic filler is one or more of talc, titanium dioxide, heavy calcium titanate, wollastonite, mica, kaolin, potassium titanate whiskers, calcium carbonate whiskers, barium sulfate, and silicon dioxide.

6. The PET composite material according to any one of claims 1-5, characterized in that, The pressure-sensitive adhesive layer in the waste pressure-sensitive adhesive product, by weight, comprises: 20–80 parts copolyester elastomer; 20-50 parts of tackifying resin; 1 to 10 parts plasticizer; And optional additives.

7. The PET composite material according to any one of claims 1-6, characterized in that, The tackifying resin is one or more of natural rosin, hydrogenated rosin, disproportionated rosin, esterified rosin, C5 petroleum resin, C9 petroleum resin, and terpene resin; the plasticizer is one or more of epoxidized soybean oil, linseed oil, castor oil, and palm oil; the additives include antioxidants, which are one or more of tris(2,4-di-tert-butylphenyl) phosphite, bis(2,4-di-tert-butylphenyl) pentaerythritol diphosphite, di(tridecyl)thiodipropionate, and pentaerythritol tetrakis{3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate}.

8. A method for preparing a PET composite material as described in any one of claims 1-7, characterized in that, Includes the following steps: (1) The waste pressure-sensitive adhesive product is melted, an alcoholysis agent and a catalyst are added, and then polycondensation is performed to obtain the PET copolyester; (2) The components other than the PET copolyester are processed into a premelt; the PET copolyester obtained in step (1) is added to the premelt, and then melted, kept warm, and extruded to obtain the PET composite material.

9. The method for preparing the PET composite material according to claim 8, characterized in that, In step 1), the waste pressure-sensitive adhesive product is melted at 260-280°C, stirred for 3-4 hours, and then an alcoholysis agent and catalyst are added. After vacuum polycondensation for 1-6.5 hours, the PET copolyester is obtained.

10. The method for preparing the PET composite material according to claim 8 or 9, characterized in that, In step (2), the PET copolyester obtained in step (1) is introduced from the die head and melt-blended with the pre-melt and extruded. The melt blending conditions are: temperature 200-240℃, and extruder speed 100-500rpm.

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