A recyclable blow molding grade thermoplastic polyester elastomer and a method of making the same

Abstract

The application discloses a recyclable blow molding grade thermoplastic polyester elastomer and a preparation method thereof, which is prepared from the following components according to weight parts: thermoplastic polyester elastomer 92-99 parts, isocyanate chain extender 1-3 parts, difunctional epoxy resin 0.8-2.4 parts, and antioxidant 0.1-0.8%. In the blow molding process, the chain extender dimer and the epoxy group become the source of chain extension slow release, part of the dimer decomposes into monomers, and the monomers are chain-extended again, and meanwhile the remaining epoxy groups also participate in chain extension. The loss of chain scission degradation at high temperature is made up, the melt index and other performance changes are still small, and 100% secondary material is independently used. Through 5 times of double screw extrusion test, the melt index of the thermoplastic polyester elastomer changes very little, which provides reliable guarantee for the separate multiple recycling of the blow molding grade thermoplastic polyester elastomer in the factory.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials technology, specifically relating to a reusable blow-molding grade thermoplastic polyester elastomer and its preparation method. Technical Background

[0002] Thermoplastic polyester elastomers (TPEEs) are block copolymers containing polyester hard segments and polyether ester soft segments. TPEEs possess the elasticity of rubber and the strength of engineering plastics. The soft segments give them elasticity, making them like rubber; the hard segments give them processability, making them like plastics. Compared to rubber, TPEEs have better processability and a longer service life; compared to engineering plastics, TPEEs also have high strength, but with better flexibility and dynamic mechanical properties. TPEEs exhibit high strength, high elasticity, oil resistance, acid and alkali resistance, high temperature resistance, radiation resistance, and excellent dynamic mechanical properties. They have a wide operating temperature range of -50℃ to 180℃ and a hardness range of 25D to 80D.

[0003] Currently, TPEE has become an irreplaceable high-performance new elastomer material, widely used in automotive, electronics, and railway industries. To adapt to market demands, broaden application areas, and meet diverse processing requirements, TPEE needs modification. For example, dust covers and engine air pipes used in automobiles require blow-molding grade TPEE, necessitating tackification modification. The common practice is to directly mix and extrude with chain extenders to increase tack, but the stability of product quality is difficult to guarantee. Solid-phase tackification is also used, but it is difficult to achieve blow-molding grade requirements.

[0004] Furthermore, blow molding grade TPEE generates secondary materials during processing. Due to degradation during processing, the viscosity and performance of these secondary materials decrease. Reprocessing entirely with secondary materials cannot meet the requirements of blow molding, and their performance is even less satisfactory. To reduce waste, factories must reuse secondary materials without compromising their performance to ensure consistent final product quality. Currently, blow molding grade TPEE on the market can only be partially added to virgin materials during processing to meet product quality requirements.

[0005] Therefore, we adopted new processes and formulations to solve the above-mentioned problems and developed a fully reusable blow-molding grade thermoplastic polyester elastomer. The secondary material generated from this blow-molding grade thermoplastic polyester elastomer can be reprocessed separately or partially added without affecting the processing performance and product performance. Summary of the Invention

[0006] The purpose of this invention is to provide a reusable blow-molding grade thermoplastic polyester elastomer material and its preparation method, so as to solve the problems mentioned in the background art.

[0007] This invention provides the following technical solution:

[0008] A reusable blow-molding grade thermoplastic polyester elastomer, characterized in that it is prepared from the following components in parts by weight:

[0009]

[0010] In a further embodiment, the isocyanate chain extender includes one of diphenylmethane diisocyanate (MDI), toluene diisocyanate (TDI), isophorone diisocyanate (IPDI), dicyclohexylmethane diisocyanate (HMDI), hexamethylene diisocyanate (HDI), cyclohexyldimethylene diisocyanate (HXDI), lysine diisocyanate (LDI), and tris(hexamethylene isocyanate) isocyanurate.

[0011] In a further embodiment, the bifunctional epoxy resin is one of the following: 3,4-epoxycyclohexylcarboxylic acid-3',4'-epoxycyclohexylmethyl ester, bis((3,4-epoxycyclohexyl)methyl)adipate, dicyclopentadiene diepoxide, tetrahydroindene diepoxide, vinylcyclohexene dioxide, (3,4,3',4'-diepoxy)bicyclohexane, diglycidyl tetrahydrophthalate, diglycidyl cyclohexane-1,2-dicarboxylic acid, 3,4-epoxycyclohexylmethyl-3',4'-epoxycyclohexylcarboxylic acid ester and caprolactone (molar ratio 1:1), or a polymer of 3,4-epoxycyclohexylmethyl-3',4'-epoxycyclohexylcarboxylic acid ester and caprolactone (molar ratio 1:3).

[0012] In a further embodiment, the intrinsic viscosity of the thermoplastic polyester elastomer is 1.1-1.5 dl / g;

[0013] The antioxidant is pentaerythritol-based propyl dodecyl thioester. 4,4-Bis(α,α-dimethylbenzyl)diphenylamine At least one of the following: bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite (ULTRANOX 627A), pentaerythritol tetrakis(β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate) (1010), tris[2,4-di-tert-butylphenyl]phosphite (168), N,N'-bis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl)hexamethylenediamine (1098), pentaerythritol distearate phosphite (619), octadecyl (3,5-di-tert-butyl-4-hydroxyphenyl)propionate, tetramethylene (3,5-di-tert-butyl-4-hydroxyphenylpropionate) methyl ester, bis[ethyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)]2,2-oxalamide, and bis(octadecyltetraol) diphosphite.

[0014] Another objective of this invention is to provide a method for preparing the above-mentioned reusable blow-molding grade thermoplastic polyester elastomer, comprising the following steps:

[0015] S1: Add the saturated chain extender solution to the dried thermoplastic polyester elastomer at room temperature, and shake well to allow the thermoplastic polyester elastomer to fully absorb the saturated chain extender solution.

[0016] S2: After the absorbed thermoplastic polyester elastomer is heated and reacted under a protective atmosphere, excess solvent in the saturated solution of the chain extender is removed by vacuuming.

[0017] S3: Add bifunctional epoxy resin to step S2 to carry out an absorption reaction;

[0018] S4: The thermoplastic polyester elastomer after absorption reaction is mixed with an antioxidant and then added to a twin-screw extruder for extrusion granulation to obtain blow molding grade thermoplastic polyester elastomer.

[0019] In a further embodiment, the saturated solution of the chain extender refers to dissolving the chain extender in a solvent until it no longer dissolves; the solvent is an aprotic polar solvent.

[0020] Preferably, the aprotic polar solvent is dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide, or acetone.

[0021] In a further embodiment, the dried thermoplastic polyester elastomer refers to the thermoplastic polyester elastomer dried in a dehumidifying oven at 90-110℃, ensuring that its moisture content is less than 0.05wt%.

[0022] In a further embodiment, the heating reaction in step S2 refers to a full reaction at 50℃-70℃ for 4-8 hours;

[0023] The absorption reaction in step S3 is carried out at a temperature of 20-40℃ for 4-8 hours.

[0024] In a further embodiment, the granulation temperature of the twin-screw extruder in step S4 is 180-230℃, the screw speed is 50-200 r / min, and the feeding speed is 50-100 kg / h.

[0025] The twin-screw extruder is equipped with a vacuum pump, with a vacuum level of -0.08 MPa.

[0026] Compared with the prior art, the beneficial effects of the present invention are:

[0027] Since chain extenders readily react with moisture in the air, dissolving them in a solvent to form a saturated solution can prevent moisture in the air from contacting the chain extender. At the same time, the chain extender forms a more uniform solution, making it easier to diffuse and be absorbed into the thermoplastic polyester elastomer.

[0028] When the chain extender is drawn into TPEE, some of the chain extender undergoes a chain extension reaction. At 50-70℃, some of the chain extender easily forms dimers, which can decompose into monomeric chain extenders at high temperatures. Other chain extenders exist as monomers and are then extruded through a twin-screw extruder. The chain extender monomers and some dimers decompose into monomers and undergo a chain extension reaction with the thermoplastic polyester elastomer to obtain blow-molded thermoplastic elastomer. Some dimers remain in the blow-molded thermoplastic elastomer, and excess solvent is removed by vacuuming.

[0029] Chain extenders readily react with the hydroxyl groups in TPEE, while bifunctional epoxy resins readily react with the carboxyl groups in TPEE. In addition to reacting with the carboxyl groups, the remaining epoxy groups in the inhaled epoxy are coated in TPEE.

[0030] During blow molding, the chain extender dimer and epoxy groups become the source of slow-release chain extension. Some dimers decompose into monomers, which then further extend the chain, while the remaining epoxy groups also participate in chain extension. This compensates for losses due to chain breakage and degradation at high temperatures, resulting in minimal changes in melt flow index and other properties, enabling 100% reuse of the recycled material. Through five twin-screw extrusions, the melt flow index and other properties of the thermoplastic polyester elastomer show minimal changes, resolving the risk of unused recycled material and performance degradation that often occurs when factories add a portion of the recycled material to the virgin material. This provides a reliable guarantee for factories to reuse blow-molded grade thermoplastic polyester elastomer multiple times. Detailed Implementation

[0031] To facilitate understanding of the present invention, a more comprehensive description will be given below with reference to specific embodiments. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of the present invention.

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. Unless otherwise specified, "parts" in the description refers to parts by weight.

[0033] The specific information of the raw materials used in the following examples and comparative examples is as follows:

[0034] Component A: The preparation method of TPEE is as follows:

[0035] 18 parts of dimethyl terephthalate, 14 parts of 1,4-butanediol, 16 parts of polyether ester polyol, 0.1 parts of 4,4'-bis(α,α-dimethylbenzyl)diphenylamine antioxidant, 0.25 parts of tetrabutyl titanate catalyst, and 0.3 parts of triphenyl phosphite anti-yellowing agent were added to a polymerization reactor. Polycondensation reaction was carried out at 250℃. Based on the change of stirring current in the reactor, a polyester elastomer matrix with an intrinsic viscosity of 1.3 dl / g was prepared.

[0036] Component B: Saturated MDI solution. MDI was dissolved in N,N-dimethylacetamide (DMAC) until it no longer dissolved, to prepare an 80% saturated solution. The diphenylmethane diisocyanate (MDI) was purchased from Nantong Ruifeng Petrochemical Co., Ltd.; the solvent was N,N-dimethylacetamide, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0037] Component C: Diphenylmethane diisocyanate (MDI)

[0038] Component D: The epoxy chain extender is diglycidyl tetrahydrophthalate, purchased from Jiangsu Taiter New Material Technology Co., Ltd.

[0039] Component E: Antioxidant 1 and Antioxidant 2 are compounded in a weight ratio of 2:1, wherein Antioxidant 1 is 4,4'-bis(α,α-dimethylbenzyl)diphenylamine, brand name Naugard N445, purchased from Kojuya Co., Ltd.; Antioxidant 2 is pentaerythritol distearate (619) phosphite, purchased from Kojuya Co., Ltd.

[0040] All materials are commercially available, commonly used products.

[0041] It is understood that the above raw materials and reagents are merely examples of some specific embodiments of the present invention, making the technical solution of the present invention clearer, and do not mean that the present invention can only use the above reagents. The specific scope shall be determined by the claims.

[0042] Any range described in this invention includes the endpoint, any value between the endpoints, and any subrange consisting of the endpoint or any value between the endpoints.

[0043] The weight parts of each component added and the reaction conditions in Comparative Examples 1-5 and Examples 1-3 are shown in Table 1. The preparation methods are as follows:

[0044] S1: Prepare a saturated MDI solution: Dissolve MDI in N,N-dimethylacetamide (DMAC) until it no longer dissolves;

[0045] S2: Weigh out the dried thermoplastic polyester elastomer and saturated MDI liquid according to the weight parts and put them into a sealed kettle for thorough mixing and absorption;

[0046] S3: Heat to an internal temperature of 60°C under nitrogen protection and react for 6 hours; then remove DMAC by vacuum.

[0047] S4: Add diglycidyl tetrahydrophthalate to S3 and reabsorb the reaction at 30°C for 6 hours;

[0048] S5: After the fully reacted TPEE is mixed with an antioxidant, it is extruded and granulated in a twin-screw extruder to obtain blow-molding grade thermoplastic polyester elastomer, and then its melt index is tested.

[0049] S6: Then, the dried S5 material is added back into the twin-screw extruder and extruded again, and its melt index is measured; then it is extruded four times in a row, for a total of five times, and the melt index of the material after each extrusion is measured.

[0050] Table 1 shows the amount of each component added in Comparative Examples 1-5 and Examples 1-3.

[0051]

[0052] The melt flow index of the blow-molding grade thermoplastic polyester elastomer materials prepared in the above comparative examples and embodiments was tested. The melt flow index (230℃, 10KG) g / 10min is shown in Table 2.

[0053] Table 2 Performance test results of comparative examples and embodiments

[0054]

[0055] As can be seen from Table 2, in Examples 1-3, TPEE and MDI saturated solutions were heated to 50℃-70℃ under nitrogen protection and reacted fully for 4-8 hours. After 5 repeated extrusions, the melt index of the material remained stable, which provides a reliable guarantee for the complete reuse of secondary materials generated during blow molding.

[0056] Compared with Example 2, Comparative Example 1 showed that the chain extender MDI in Comparative Example 1 had a lower absorption reaction temperature, resulting in fewer dimers and thus fewer sources of slow release. Compared with MDI monomers, the melt index of the blow-molded thermoplastic polyester elastomer after granulation was the lowest at the beginning of the reaction. However, the melt index of the material increased significantly as the number of repeated extrusion cycles increased.

[0057] Compared with Example 2, Comparative Example 2 has a higher absorption reaction temperature and longer reaction time due to the chain extender MDI. This results in a side reaction that produces a biuret structure, reducing the monomer content and the dimer content. Therefore, the melt index of the material after granulation is higher at the beginning of the reaction. Furthermore, the melt index increases significantly with the increase in the number of extrusions in the later stages.

[0058] Compared with Example 1, Comparative Example 3 directly added MDI, meaning that MDI was not dispersed in the solvent, and therefore did not form protection for the chain extension groups, resulting in greater losses. At the same time, relatively less MDI was absorbed into the TPEE, and fewer dimers were formed. Therefore, the melt index of the material was higher at the beginning of the reaction and granulation. In addition, the melt index increased significantly with the increase of repeated extrusions in the later stages, and it could not be guaranteed that all the secondary material could be stably blow-molded again.

[0059] In Comparative Example 4, because diglycidyl tetrahydrophthalate was not added, the carboxyl groups in TPEE could not be eliminated in time, resulting in significant degradation during later processing.

[0060] Comparative Example 5, due to the addition of only diglycidyl tetrahydrophthalate and the absence of absorption by the saturated MDI solution, showed a significantly reduced chain extension effect.

[0061] Therefore, this invention utilizes the stepwise absorption reaction of two chain extenders to form a dimer of MDI under appropriate process conditions, and partially embeds epoxy groups to form a source of chain extension and slow release. Ultimately, it exhibits stable melt strength in multiple processing steps, which provides a reliable guarantee for factories to reuse blow-molded thermoplastic polyester elastomers multiple times.

[0062] Example 4:

[0063] A method for preparing a reusable blow-molding grade thermoplastic polyester elastomer includes the following steps:

[0064] S1: Dissolve 3 parts of chain extender toluene diisocyanate (TDI) in acetone solvent until it no longer dissolves to obtain a saturated chain extender solution;

[0065] S2: Dry 92 parts of thermoplastic polyester elastomer in a dehumidifying oven at 90°C, ensuring that its moisture content is less than 0.05 wt%.

[0066] S3: Add the saturated chain extender solution to the dried thermoplastic polyester elastomer at room temperature, and shake well to allow the thermoplastic polyester elastomer to fully absorb the saturated chain extender solution.

[0067] S4: After absorbing the thermoplastic polyester elastomer, heat it in a protective atmosphere of nitrogen at 55°C for 7 hours to fully react, and then remove excess solvent from the saturated solution of the chain extender by vacuuming.

[0068] S5: Add 0.8 parts of bis((3,4-epoxycyclohexyl)methyl) adipate to step S4 and carry out the absorption reaction at 25°C for 7 hours;

[0069] S4: The thermoplastic polyester elastomer after absorption reaction is mixed with 0.8 parts of antioxidant 619 and then extruded and granulated in a twin-screw extruder to obtain the desired product.

[0070] The twin-screw extruder has a granulation temperature of 200℃, a vacuum degree of -0.08MPa, a screw speed of 100r / min, and a feeding speed of 80Kg / h.

[0071] The obtained blow-molding grade thermoplastic polyester elastomer was extruded five times using a twin-screw extruder. The melt index of the thermoplastic polyester elastomer changed very little, with a change of about 0.2 g / 10 min.

[0072] Example 5:

[0073] A method for preparing a reusable blow-molding grade thermoplastic polyester elastomer includes the following steps:

[0074] S1: Dissolve 1 part of chain extender cyclohexyl dimethylene diisocyanate (HXDI) in acetone solvent until it no longer dissolves to obtain a saturated chain extender solution;

[0075] S2: Dry 99 parts of thermoplastic polyester elastomer in a dehumidifying oven at 110℃, ensuring that its moisture content is less than 0.05wt%.

[0076] S3: Add the saturated chain extender solution to the dried thermoplastic polyester elastomer at room temperature, and shake well to allow the thermoplastic polyester elastomer to fully absorb the saturated chain extender solution.

[0077] S4: After absorbing the thermoplastic polyester elastomer, heat it in a protective atmosphere of nitrogen at 65°C for 5 hours to fully react, and then remove excess solvent from the saturated solution of the chain extender by vacuuming.

[0078] S5: Add 2.4 parts of diglycidyl tetrahydrophthalate to step S4 and carry out the absorption reaction at 35°C for 5 hours.

[0079] S4: The thermoplastic polyester elastomer after absorption reaction is mixed with 0.1 parts of antioxidant 1098 and then added to a twin-screw extruder for extrusion granulation to obtain blow molding grade thermoplastic polyester elastomer.

[0080] The twin-screw extruder has a granulation temperature of 230℃, a vacuum degree of -0.08MPa, a screw speed of 200r / min, and a feeding speed of 100Kg / h.

[0081] The obtained blow-molding grade thermoplastic polyester elastomer underwent five twin-screw extrusions, and the melt index of the thermoplastic polyester elastomer changed very little.

[0082] Although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

[0083] Therefore, the above description is only a preferred embodiment of this application and is not intended to limit the scope of this application; that is, all equivalent modifications made in accordance with the scope of the claims of this application shall be within the protection scope of the claims of this application.

Claims

1. A recyclable blow molding grade thermoplastic polyester elastomer characterized in that, It is prepared from the following components by weight parts: thermoplastic polyester elastomer 92-99 parts, isocyanate chain extender 1-3 parts, dual functional epoxy resin 0.8-2.4 parts, antioxidant 0.1-0.8 parts; The preparation method comprises the following steps: S1: at room temperature, the chain extender saturated solution is added to the dried thermoplastic polyester elastomer, and the thermoplastic polyester elastomer is shaken to fully absorb the chain extender saturated solution; S2: after the absorption of the thermoplastic polyester elastomer, the excess solvent in the chain extender saturated solution is removed by heating and reacting under a protective atmosphere, and then vacuumizing; wherein the heating and reacting is fully reacted at 50-70℃ for 4-8 hours; S3: the dual functional epoxy resin is added to step S2 for absorption reaction; the absorption reaction temperature is 20-40℃, and the time is 4-8 hours; S4: the thermoplastic polyester elastomer after the absorption reaction is mixed with the antioxidant and then added to the double screw extruder for extruding and granulating to obtain the blow molding grade thermoplastic polyester elastomer; The isocyanate chain extender includes one of diphenylmethane diisocyanate, toluene diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, hexamethylene diisocyanate, cyclohexyl dimethylene diisocyanate, lysine diisocyanate, and tris (hexamethylene isocyanate) isocyanurate. The dual functional epoxy resin is one of 3,4-epoxycyclohexylmethyl-3',4'-epoxycyclohexylmethyl carboxylate, bis ((3,4-epoxycyclohexyl) methyl) adipate, dicyclopentadiene diepoxy, tetrahydroindenyl diepoxy, ethylene dioxy cyclohexene, (3,4,3',4'-dioxo) bicyclohexane, tetrahydrophthalic acid diglycidyl ester, cyclohexane-1,2-dicarboxylic acid diglycidyl ester, 3,4-epoxycyclohexylmethyl-3',4'-epoxycyclohexylmethyl carboxylate and caprolactone synthesized into a polymer product with a molar ratio of 1:1, 3,4-epoxycyclohexylmethyl-3',4'-epoxycyclohexylmethyl carboxylate and caprolactone synthesized into a polymer product with a molar ratio of 1:

3.

2. A recyclable blow moulding grade thermoplastic polyester elastomer according to claim 1, characterised in that, The thermoplastic polyester elastomer has a specific viscosity of 1.1-1.5 dl / g.

3. The reusable blow molding grade thermoplastic polyester elastomer according to claim 1, wherein the antioxidant is at least one of pentaerythritol dodecylthiopropylate, 4,4-bis (α, α-dimethylbenzyl) diphenylamine, bis (2,4-di-tert-butylphenyl) pentaerythritol diphosphite, tetra (Β-(3,5-di-tert-butyl 4-hydroxyphenyl) propionic acid) pentaerythritol ester, tris [2,4-di-tert-butylphenyl] phosphite, N, N'-bis- (3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyl) hexanediamine, pentaerythritol distearyl phosphite, (3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid n-octadecyl ester, tetramethylene (3,5-di-tert-butyl-4-hydroxyphenyl propionic acid) methyl ester, bis [ethyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) ] 2,2 oxamide, and dioctadecyl tetraol diphosphite.

4. A recyclable blow molding grade thermoplastic polyester elastomer according to claim 1, wherein, The saturated solution of the chain extender refers to dissolving the chain extender in a solvent until no more is dissolved; the solvent is an aprotic polar solvent.

5. A recyclable blow moulding grade thermoplastic polyester elastomer according to claim 4, characterised in that, The aprotic polar solvent is dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide or acetone.

6. A recyclable blow molding grade thermoplastic polyester elastomer according to claim 1, wherein, The dried thermoplastic polyester elastomer refers to drying the thermoplastic polyester elastomer in a 90-110℃ dehumidifying oven, and ensuring that the moisture is less than 0.05wt%.

7. A recyclable blow molding grade thermoplastic polyester elastomer according to claim 1, wherein, The granulation temperature of the double screw extruder in step S4 is 180-230℃, the vacuum degree is -0.08MPa, the screw rotation speed is 50-200r / min, and the feeding speed is 50-100Kg / h.

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