PET (Polyethylene Terephthalate) composite material suitable for ultrasonic welding as well as preparation method and application of PET composite material

Abstract

The invention discloses a PET composite material suitable for ultrasonic welding and a preparation method and application thereof, and relates to the technical field of engineering plastics. The invention provides a PET (Polyethylene Terephthalate) composite material suitable for ultrasonic welding. The PET composite material comprises the following components in parts by weight: 55-85 parts of PET, 10-32 parts of copolymerized PET, 8-22 parts of a core-shell toughening agent, 0.1-5 parts of a lubricating agent and 1-6.5 parts of a chain extender, the molar ratio of the terephthalic acid-1, 4-cyclohexanedimethanol ester unit in the copolymerized PET is greater than 50%; the chain extender is carbodiimide. According to the PET composite material provided by the invention, under the synergism of all the components, the prepared toy product has the excellent performance that the toy product does not crack after being thrown for multiple times, and the service life can be remarkably prolonged.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of engineering plastics, and particularly relates to a PET composite material suitable for ultrasonic welding and a preparation method and application thereof. BACKGROUND

[0002] Polyethylene terephthalate (PET) has the characteristics of high strength, chemical corrosion resistance, light weight, low price and the like, and is widely used in packaging, textile, electronics, automobile and other fields. PET material has shown great potential and unique advantages in realizing low carbon. Under the background of the increasing global environmental awareness, recycled PET (rPET) has been widely concerned and applied in many fields due to its significant environmental advantages. Studies have shown that the energy consumption of rPET production is only 50%-70% of that of virgin PET, and each ton of rPET can reduce about 1.5 tons of carbon dioxide emissions. The characteristics of not containing bisphenol A, low carbon emission and recyclability make PET have increasingly prominent application potential in the toy industry, and gradually become an ideal alternative material to traditional plastics.

[0003] However, with the development of the toy industry, the structural design of toy products is becoming more and more complex, which puts higher requirements on the connection efficiency and reliability between different parts. The ultrasonic welding technology, as a clean and environmentally friendly, low energy consumption, short cycle and additive-free connection process, has been widely used in the toy industry. However, due to the repeated throwing behavior of children during the use of toys, the toy products after ultrasonic welding need to have the performance of not cracking after multiple throws. In the prior art, the toy products prepared by using PET material are prone to cracking at the welding position or the product body when impacted, which shortens the service life of the toy and cannot meet the actual use requirements.

[0004] Therefore, how to develop a PET composite material suitable for ultrasonic welding and a preparation method and application thereof, so that the toy products prepared based on the material have the performance of anti-cracking after multiple throws, thereby significantly prolonging the service life, has become a technical problem to be solved at present. SUMMARY

[0005] Based on this, the purpose of the present application is to overcome the shortcomings of the prior art and provide a PET composite material suitable for ultrasonic welding and a preparation method and application thereof.

[0006] To achieve the above object, the technical scheme adopted by the present application is: a PET composite material, comprising the following components by weight: PET 55-85 parts, copolymerized PET 10-32 parts, core-shell type toughening agent 8-22 parts, lubricant 0.1-5 parts, chain extender 1-6.5 parts; the mole percentage of terephthalic acid-1,4-cyclohexane dimethanol units in the copolymerized PET is > 50%; and the chain extender is a carbodiimide.

[0007] Preferably, the weight percentage content of the PET resin in the PET composite material is not less than 50%; In the system of the present application, PET provides rigid support for the matrix of the PET composite material, and the copolymerized PET with a specific content of terephthalic acid-1,4-cyclohexane dimethanol units can destroy the regularity of the PET molecular chain, reduce the crystallinity, and improve the material toughness. After the combination of PET and copolymerized PET, the material is given sufficient flexibility to absorb impact energy while maintaining the rigidity of PET. The core of the core-shell type toughening agent deforms to absorb energy when subjected to a thrown impact, and the shell layer forms a good interface with PET and copolymerized PET to further consume energy. The core-shell type toughening agent cooperates with PET and copolymerized PET to significantly improve the anti-cracking performance after multiple throws through multiple mechanisms such as matrix deformation and energy consumption of the toughening agent. The lubricant and the carbodiimide chain extender cooperate, on the one hand, the lubricant reduces the melt viscosity and improves the flowability of the composite material during ultrasonic welding, ensuring that the welding interface is fully fused; on the other hand, the carbodiimide chain extender reacts with the terminal carboxyl and terminal hydroxyl groups of PET to lengthen the molecular chain and improve the melt strength and the cohesive force of the welded part. The combination of the two not only ensures the efficiency and quality of ultrasonic welding, but also significantly improves the anti-cracking performance after multiple throws by enhancing the intermolecular force.

[0008] The PET composite material provided by the present application has excellent performance of not cracking after multiple throws, and can significantly prolong the service life.

[0009] Preferably, the carbodiimide is at least one of a polymeric carbodiimide and a monomeric carbodiimide.

[0010] Preferably, the copolymerized PET is a copolymer composed of terephthalic acid (TPA), 1,4-cyclohexane dimethanol (CHDM), and ethylene glycol (EG).

[0011] Preferably, the test method for the mole ratio of terephthalic acid-1,4-cyclohexane dimethanol units in the copolymerized PET is nuclear magnetic hydrogen spectrum: 5-10 mg of dried sample is weighed and placed in a nuclear magnetic tube, then deuterated trifluoroacetic acid is added, the sample is allowed to completely dissolve, and the BURKER 400 MHz nuclear magnetic resonance spectrometer is used for testing, the mole ratio (%) of terephthalic acid-1,4-cyclohexane dimethanol units = S1 / (2.5*S2)*100%, S1 is the peak area of chemical shift δ=1.0-2.5ppm, and S2 is the peak area of chemical shift δ=8.25ppm.

[0012] Preferably, the copolymerized PET can be a commercially available product or self-made, and the preparation method is referred to Chinese patent application CN103570924A.

[0013] Preferably, the preparation method of the copolymerized PET is as follows: TPA, EG and CHDM are mixed and stirred in a 10L polymerization reactor according to a certain proportion, and the amount of CHDM monomer is adjusted at a fixed proportion to prepare copolymerized PET with different contents of terephthalic acid-1,4-cyclohexane dimethanol units.

[0014] Preferably, in the preparation process of the copolymerized PET, [EG+CHDM]:[TPA] is fixed at 1.2, a catalyst antimony acetate is added, and ester exchange reaction is carried out at 260-275℃, a reaction pressure of 0.8-2MPa for 2-3h, followed by polycondensation reaction at 275-285℃, a reaction pressure of 20-40Pa for 3-4h, to obtain the copolymerized PET.

[0015] Preferably, the mole ratio of terephthalic acid-1,4-cyclohexane dimethanol units in the copolymerized PET is 60%-65%.

[0016] Preferably, the PET composite material comprises the following components in parts by weight: PET 60-70 parts, copolymerized PET 20-30 parts.

[0017] Preferably, the weight ratio of the chain extender and the lubricant is chain extender: lubricant=(1-12):1.

[0018] Preferably, the weight ratio of the chain extender and the lubricant is chain extender: lubricant=(2-5):1.

[0019] The inventors found in actual experiments that when the weight ratio of the chain extender and the lubricant is within the above range, the chain extender is dominant, a molecular chain network with sufficient length and appropriate cross-linking degree can be formed, the lubricant can make the interfaces fully fuse, and the two cooperate to prepare a PET composite material with better anti-cracking performance.

[0020] Optionally, the weight fraction of the PET is one or a range value of any two of 55 parts, 60 parts, 61 parts, 65 parts, 68 parts, 70 parts, 80 parts, 85 parts; the weight fraction of the copolymerized PET is one or a range value of any two of 10 parts, 15 parts, 20 parts, 25 parts, 30 parts, 32 parts; the weight fraction of the core-shell type toughening agent is one or a range value of any two of 8 parts, 10 parts, 12 parts, 15 parts, 18 parts, 20 parts, 22 parts; the weight fraction of the lubricant is one or a range value of any two of 0.1 parts, 0.5 parts, 1 part, 1.5 parts, 2 parts, 2.5 parts, 3 parts, 3.5 parts, 4 parts, 4.5 parts, 5 parts; the weight fraction of the chain extender is one or a range value of any two of 1 part, 1.5 parts, 2 parts, 2.5 parts, 3 parts, 3.5 parts, 4 parts, 4.5 parts, 5 parts, 6 parts, 6.5 parts.

[0021] Optionally, the mole fraction of terephthalic acid-1, 4-cyclohexane dimethanol units in the copolymerized PET is one or a range value of any two of 51%, 53%, 55%, 58%, 60%, 61%, 65%, 70%.

[0022] Preferably, the core-shell type toughening agent is a rubber type graft copolymer with a core-shell structure; further preferably, the core-shell type toughening agent comprises at least one of methyl methacrylate-butadiene-styrene copolymer, silicone rubber graft copolymer, and acrylate graft copolymer. Among them, the methyl methacrylate-butadiene-styrene copolymer is M-732, with cross-linked butadiene / styrene as the core and grafted polymethyl methacrylate as the shell; the silicone rubber graft copolymer is S-2100, with cross-linked silicone and acrylate as the core and grafted polymethyl methacrylate as the shell; the acrylate graft copolymer is EXL-2330, with cross-linked butyl acrylate as the core and grafted polymethyl methacrylate as the shell.

[0023] Preferably, the core-shell type toughening agent is methyl methacrylate-butadiene-styrene.

[0024] Preferably, the PET composite material comprises at least one of the following (a)-(c): (a) the intrinsic viscosity of the PET is 0.6-1.0 dL / g, and the weight percentage of isophthalic acid (IPA) in the PET resin is <3%; (b) the intrinsic viscosity of the copolymerized PET is 0.6-1.0 dL / g; (c) the lubricant is at least one of ester lubricant, amide lubricant, and paraffin lubricant.

[0025] Optionally, the intrinsic viscosity of the PET is within the range of one or any two of 0.6 dL / g, 0.7 dL / g, 0.8 dL / g, 0.9 dL / g, and 1.0 dL / g; and the weight percentage of isophthalic acid (IPA) in the PET resin is within the range of one or any two of 0.2%, 0.5%, 0.8%, 1.0%, 1.5%, 1.8%, 2.0%, 2.5%, and 2.9%.

[0026] Optionally, the intrinsic viscosity of the copolymerized PET is within the range of one or any two of 0.6 dL / g, 0.7 dL / g, 0.8 dL / g, 0.9 dL / g, and 1.0 dL / g.

[0027] Preferably, the intrinsic viscosity of the PET and copolymerized PET is measured according to ISO 1628-5-2015, using a mixed solution of phenol and tetrachloroethane as the testing solvent. The weight percentage of isophthalic acid in the PET resin is measured by proton nuclear magnetic resonance spectroscopy. Specifically, the testing method is as follows: 5-10 mg of a dried sample is weighed and placed into an NMR tube. Deuterated trifluoroacetic acid is then added, and the sample is allowed to completely dissolve. The sample is then measured on a Burker 400 MHz NMR spectrometer. The isophthalic acid unit molar ratio (%) is calculated as S3 / (4*S4)*100%, where S3 is the peak area at a chemical shift of δ = 7.67 ppm, and S4 is the peak area at a chemical shift of δ = 8.25 ppm.

[0028] Preferably, the ester lubricant includes at least one of pentaerythritol stearate, montanic acid wax, glyceryl stearate, butyl stearate, and ethyl oleate; the amide lubricant includes at least one of ethylene bisstearamide (EBS), monostearamide, and oleamide; and the paraffin lubricant includes at least one of polyethylene wax and oxidized polyethylene wax.

[0029] Further preferably, the lubricant is montanic acid wax.

[0030] In addition, the present invention provides a method for preparing the PET composite material, comprising the following steps: (1) Weigh each component by weight; (2) After mixing the components, add them into an extruder for melting and kneading, and extrude and granulate to obtain the PET composite material.

[0031] Preferably, the melt extrusion is carried out in a twin-screw extruder; the temperature of each region of the twin-screw extruder is preferably set as follows: the temperature of the first region is 220-240°C, the temperature of the second region is 245-265°C, the temperature of the third region is 240-260°C, the temperature of the fourth region is 240-260°C, the temperature of the fifth region is 240-260°C, the temperature of the sixth region is 245-265°C, the temperature of the seventh region is 245-265°C, the temperature of the eighth region is 250-270°C, the temperature of the ninth region is 250-270°C, and the temperature of the tenth region is 250-270°C; the length-diameter ratio of the twin-screw extruder is 32-40:1, and the screw rotation speed is 250-350 rpm.

[0032] Further, the present application provides the application of the PET composite material in the field of toys. Specifically, the present application provides the application of the PET composite material in the preparation of toy parts with complex shapes, such as toy cars, toy airplanes, cartoon dolls, or ornaments, etc.

[0033] The present application provides a toy comprising the PET composite material. Compared with the prior art, the PET composite material provided by the present application has the beneficial effects that: under the synergistic effect of various components, the toy product prepared by the PET composite material has the excellent performance of not cracking after multiple throws, and the service life can be significantly prolonged. DETAILED DESCRIPTION

[0034] For the purpose of better illustrating the present application, technical solutions and advantages, the present application will be further described in conjunction with specific examples. The purpose is to understand the content of the present application in detail, rather than to limit the present application. All other examples obtained by the ordinary skilled in the art without making creative efforts fall within the protection scope of the present application. The experimental reagents and instruments designed in the examples and comparative examples are common reagents and instruments unless otherwise specified, and can be obtained from commercial channels. In the examples and comparative examples, the experimental methods used are conventional methods unless otherwise specified; and the raw materials used in parallel experiments are the same batch of raw materials unless otherwise specified.

[0035] The raw materials used in the present application will be further described, but are not limited to the following raw materials: PET-1: PETBG80, intrinsic viscosity 0.80 dL / g, IPA content 1.3-1.5%, Sinopec Yizheng Chemical Fibre Co., Ltd.; PET-2: PETFG600, intrinsic viscosity 0.68 dL / g, IPA content 0%, Sinopec Yizheng Chemical Fibre Co., Ltd.; PET-3: PETCR-8839, intrinsic viscosity 0.80 dL / g, IPA content 0.2-0.5%, Huarun Chemical Technology Co., Ltd. Co-PET-1: self-made, intrinsic viscosity 0.7 dL / g, the mole ratio of 1,4-cyclohexanedimethanol terephthalate units in the copolymer PET is 65%; The preparation method is as follows: TPA, EG and CHDM are mixed and stirred in a 10 L polymerization reactor in a certain proportion, and different CHDM contents of the copolymer PET are prepared by adjusting the amount of monomers. In the preparation process of the copolymer PET, the mole ratio [EG+CHDM]:[TPA] is fixed at 1.2, and the amount of CHDM accounts for 60% of the total amount of diol monomers (EG+CHDM) in moles; add catalyst antimony acetate, carry out ester exchange reaction at 270℃ and reaction pressure 1.5 MPa for 2.5 h, and then carry out polycondensation reaction at 280℃ and reaction pressure 20 Pa for 3.5 h to prepare the copolymer PET.

[0036] Co-PET-2: self-made, intrinsic viscosity 0.73 dL / g, the mole ratio of 1,4-cyclohexanedimethanol terephthalate units in the copolymer PET is 60%; wherein, the only difference between the preparation method and Co-PET-1 is that the amount of CHDM accounts for 55% of the total amount of diol monomers (EG+CHDM) in moles; Co-PET-3: self-made, intrinsic viscosity 0.78 dL / g, the mole ratio of 1,4-cyclohexanedimethanol terephthalate units in the copolymer PET is 51%; wherein, the only difference between the preparation method and Co-PET-1 is that the amount of CHDM accounts for 45% of the total amount of diol monomers (EG+CHDM) in moles; Co-PET-4: self-made, intrinsic viscosity 0.81 dL / g, the mole ratio of 1,4-cyclohexanedimethanol terephthalate units in the copolymer PET is 40%; wherein, the only difference between the preparation method and Co-PET-1 is that the amount of CHDM accounts for 35% of the total amount of diol monomers (EG+CHDM) in moles; Co-PET-5: self-made, intrinsic viscosity 0.79 dL / g, the mole ratio of 1,4-cyclohexanedimethanol terephthalate units in the copolymer PET is 25%; wherein, the only difference between the preparation method and Co-PET-1 is that the amount of CHDM accounts for 20% of the total amount of diol monomers (EG+CHDM) in moles; Co-PET-6: intrinsic viscosity 0.80 dL / g, the mole ratio of 1,4-cyclohexanedimethanol terephthalate units in the copolymer PET is 65%, grade PCTG DN011, American Eastman Chemical; Core-shell toughening agent-1: methyl methacrylate-butadiene-styrene copolymer, M-732, Japan Nippon Gohsei; Core-shell toughening agent-2: acrylate graft copolymer, with crosslinked butyl acrylate as core and grafted polymethyl methacrylate as shell, EXL-2330, Rohm & Haas; Core-shell toughening agent-3: silicone rubber graft copolymer, with crosslinked silicone and acrylate as core and grafted polymethyl methacrylate as shell, S-2100, Mitsubishi Rayon Co., Ltd.; Toughening agent-4: ethylene-methyl methacrylate copolymer, Elvaloy AC resin 1125, DuPont; Lubricant-1: montanic acid wax, WARADUR GSM, Germany Vokabel; Lubricant-2: pentaerythritol stearate, LOXIOL P861 / 3.5, Germany Emery; Lubricant-3: oxidized polyethylene wax, PED 521, manufacturer Clariant; Chain extender-1: polymeric carbodiimide, Hymax 213, Longrich New Materials; Chain extender-2: monomeric carbodiimide, Stabilizer 7000, manufacturer LaSalle Technologies, Germany; Chain extender-3: copolymer containing epoxy functional groups, ADR-4468, BASF; Chain extender-4: 1,3-bis(4,5-dihydro-2-oxazolyl)benzene, Aladdin, B152626-500G; Examples and comparative examples The present application provides a PET composite material suitable for ultrasonic welding, the components and weight parts of the PET composite material are shown in Tables 1-2, and a preparation method of the PET composite material, comprising the following steps: (1) weighing each component by weight parts; (2) mixing each component and then adding to an extruder for melt mixing, extruding and granulating to obtain the PET composite material suitable for ultrasonic welding; the melt extrusion is carried out in a twin-screw extruder; the temperature of each region of the twin-screw extruder is preferably set as follows: the temperature of the first region is 230°C, the temperature of the second region is 250°C, the temperature of the third region is 255°C, the temperature of the fourth region is 255°C, the temperature of the fifth region is 260°C, the temperature of the sixth region is 260°C, the temperature of the seventh region is 260°C, the temperature of the eighth region is 260°C, the temperature of the ninth region is 260°C, and the temperature of the tenth region is 265°C; the length-diameter ratio of the twin-screw extruder is 36:1, and the screw rotation speed is 300 revolutions / minute.

[0037] Performance test (1) Welding drawing force: the material is placed in an injection molding machine, the injection molding temperature is 270 DEG C, the injection molding is a special sample for ultrasonic welding, then the ultrasonic welding sample is welded, the welding time is 0.25 s, the welding pressure is 1 kg / cm 2 , the hardening time is 0.5 s. After welding, the tensile strength is tested by a universal tensile testing machine at a tensile rate of 10 mm / min, 6 samples of each material are prepared for testing, and the average value is obtained; (2) Izod impact strength: the PET composite material is tested according to standard ISO 180-2023, the pendulum energy is 2.75 J; (3) throwing performance: the material is placed in an injection molding machine, the injection molding temperature is 270 DEG C, the injection molding is a toy sample with a length of 6 cm, a width of 4 cm and a height of 6 cm, the height is 1 m, the fixed thrust is 10 N, the number of repeated throwing cracks of a single product is recorded, if the test is still not cracked after 50 times, the throwing cracking number is > 50, and the test is stopped.

[0038] Table 1

[0039] Table 2

[0040] From the above table, it can be seen that the PET composite material prepared in the embodiment of the application has excellent performance of not cracking after multiple throwing, the throwing cracking number is > 37 times under the condition of height 1 m and fixed thrust 10 N, which can significantly prolong the service life.

[0041] From the comparison of examples 1-6, comparative examples 1-2, it can be seen that the selection of the specific copolymerized PET, core-shell toughening agent, chain extender and lubricant in the application makes the IPA content in the PET have little effect on the final performance, so that most of the PET can have good throwing performance. When the mole ratio of terephthalic acid-1, 4-cyclohexane dimethanol ester units in the copolymerized PET is > 60%, the PET has excellent throwing cracking number > 50 times.

[0042] From the comparison of examples 1, examples 7-8 and comparative example 3, it can be seen that the selection of the specific core-shell toughening agent in the application makes the prepared PET composite material have good throwing performance. Compared with other core-shell toughening agents, when the core-shell toughening agent is methyl methacrylate-butadiene-styrene, the PET has excellent throwing cracking number > 50 times. Compared with non-core-shell toughening agents, the core-shell toughening agent has good compatibility with the PET matrix due to its rigid shell, is more uniformly dispersed and has strong interfacial bonding, has less decrease in rigidity under the same toughening effect, and is more conducive to ultrasonic wave transmission.

[0043] It can be seen from the comparison of Example 1, Example 9-10 that when the lubricant is lignoceric acid wax, the inner lubrication and outer lubrication can be better balanced, the flowability of the composite material during ultrasonic welding is improved, the shear force acting on the polymer is weakened, the crystallization temperature is reduced, the interface after welding is fully fused, and the throwing performance is better. It can be seen from the comparison of Example 1, Example 17 and Comparative Examples 4-5 that when the chain extender is carbodiimide, the throwing performance is good. When other types of chain extenders are selected, overcrosslinking is prone to occur, the flowability of the system decreases, the system is brittle, and it is not conducive to ultrasonic welding.

[0044] It can be seen from the comparison of Example 1, Example 11-14 that when the weight ratio of the chain extender and the lubricant is 2-5:1, the throwing performance is better, and the throwing cracking times are greater than 50, which is an excellent performance.

[0045] It can be seen from the comparison of Example 1, Example 15-16, and Comparative Examples 6-7 that when the content of PET is 60-70 parts and the content of copolymerized PET is 20-30 parts, the throwing performance is better, and the throwing cracking times are greater than 50, which is an excellent performance.

[0046] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present application and do not limit the protection scope of the present application. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present application.

Claims

1. A PET composite material, characterized in that: The invention comprises the following components in parts by weight: 55-85 parts of PET, 10-32 parts of copolymerized PET, 8-22 parts of a core-shell toughener, 0.1-5 parts of a lubricant, and 1-6.5 parts of a chain extender; the molar proportion of 1,4-cyclohexanedimethanol terephthalate units in the copolymerized PET is greater than 50%; and the chain extender is a carbodiimide.

2. The PET composite material according to claim 1, wherein The molar proportion of 1,4-cyclohexanedimethanol terephthalate units in the copolymerized PET is 60%-65%.

3. The PET composite material according to claim 1 or 2, wherein: The invention comprises the following components in parts by weight: 60-70 parts of PET and 20-30 parts of copolymerized PET.

4. The PET composite material according to claim 1 or 2, wherein: The weight ratio of the chain extender to the lubricant is chain extender:lubricant=(1-12):

1.

5. The PET composite material according to claim 4, wherein The weight ratio of the chain extender to the lubricant is chain extender:lubricant=(2-5):

1.

6. The PET composite material according to claim 1, wherein The core-shell toughening agent is a rubber-type graft copolymer with a core-shell structure; and / or the core-shell toughening agent includes at least one of methyl methacrylate-butadiene-styrene copolymer, silicone rubber graft copolymer, and acrylate graft copolymer.

7. The PET composite material according to claim 1, wherein Including at least one of the following (a)-(c): (a) the intrinsic viscosity of the PET is 0.6-1.0 dL / g, and the weight percentage of isophthalic acid in the PET resin is less than 3%; (b) the intrinsic viscosity of the copolymerized PET is 0.6-1.0 dL / g; (c) The lubricant is at least one of an ester lubricant, an amide lubricant, and a paraffin lubricant.

8. A method for preparing the PET composite material according to any one of claims 1 to 7, characterized in that: The steps include: (1) Weigh each component by weight; (2) After mixing the components, add them into an extruder for melting and kneading, and extrude and granulate to obtain the PET composite material.

9. Use of the PET composite material according to any one of claims 1 to 7 in the field of toys.

10. A toy, characterized in that: The PET composite material comprises the PET composite material according to any one of claims 1 to 7.

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