Self-adaptive flexible TPE clamp material and preparation method thereof

Abstract

The invention discloses a self-adaptive flexible TPE clamp material which comprises TPE resin and a shape memory compound compounded with the TPE resin, and the TPE resin comprises the following components: 50-70 wt% of an SEBS matrix, 10-20 wt% of C9 petroleum resin, 10-20 wt% of a plasticizer and 5-15 wt% of a functional additive; the shape memory compound is prepared from the following raw material components in percentage by weight: 50 to 70 percent of polycaprolactone diol, 15 to 35 percent of 4, 4 '-diphenylmethane diisocyanate, 5 to 15 percent of chain extender and 2 to 6 percent of nano graphene oxide. According to the technical scheme, the TPE fixture material is mainly prepared by compounding the TPE resin and the shape memory compound with the shape memory function, so that the fixture can recover to the original shape more quickly to adapt to objects with different sizes.

Description

Technical Field

[0001] This application relates to the technical field of thermoplastic elastomer materials, and particularly to an adaptive flexible TPE fixture material and a preparation method thereof. Background Art

[0002] TPE (thermoplastic elastomer) is a polymer material that combines rubber elasticity and plastic processing performance. It exhibits rubber characteristics at room temperature and can be plastically formed at high temperatures. It can be processed by thermoplastic processes such as injection molding and extrusion without vulcanization. Its molecular structure consists of "hard segments" (resin phase) and "soft segments" (rubber phase). The hard segments form microdomains through physical cross-linking, and the soft segments provide elasticity.

[0003] In recent years, due to its unique "elasticity + plasticity" advantages, TPE materials have rapidly replaced traditional rubbers and some plastics in fields such as automotive, medical, and electronics. For example, in the automotive industry, TPE materials are mainly used in the preparation of soft-touch layers of instrument panels, seat support pads, etc.; in the medical field, TPE materials are mainly used in the preparation of infusion tubes, gaskets, etc.; in the wire and cable field, TPE materials are mainly used in insulation layers and sheaths; in the construction industry, TPE materials are mainly used in the preparation of waterproof coatings, sealing materials, etc.; in the consumer goods industry, TPE materials are mainly used in scenarios such as mobile phone cases, grips of sports equipment, toys, and fixtures.

[0004] With the progress of technology, the performance of TPE materials is also constantly improving, but there are still some deficiencies. For example, the rigid-flexible switching of traditional TPE fixture materials (such as SEBS-based materials) mainly relies on external heating / cooling to achieve, with a slow response speed; the rebound recovery force is single and cannot meet the clamping requirements of complex curved surfaces; or, plastic deformation is likely to occur after long-term use, resulting in insufficient clamping stability, thus affecting the use of consumers. Summary of the Invention

[0005]

Problems to be Solved

[0006] This application aims to solve at least one of the technical problems existing in the prior art. For this reason, an object of this application is to provide a flexible fixture material with shape adaptability and a preparation method thereof, which has better elasticity and rebound recovery force, can respond quickly, and is particularly suitable for scenarios such as robot gripping, precision instrument clamping, instrument clamping, instrument fixing or positioning, etc., and is more in line with the needs of users.

[0007]

Means for Solving the Problems

[0008] An adaptive flexible TPE fixture material, comprising a TPE resin and a shape memory composite compounded with the TPE resin. The TPE resin comprises the following components: 50-70 wt% SEBS matrix, 10-20 wt% C9 petroleum resin, 10-20 wt% plasticizer, and 5-15 wt% functional additive; the raw materials of the shape memory composite comprise the following components: 50-70 wt% polycaprolactone diol (PCL-diol), 15-35 wt% 4,4'-diphenylmethane diisocyanate (MDI), 5-15 wt% chain extender, and 2-6 wt% nano-graphene oxide.

[0009] This technical solution mainly prepares a TPE fixture material by compounding a TPE resin and a shape memory composite with shape memory function, enabling the fixture to restore its original shape more quickly to adapt to objects of different sizes.

[0010] Among them, the mass ratio of the TPE resin to the shape memory composite is 2-5:1.

[0011] Preferably, the nano-graphene oxide is loaded on a thermosensitive material, and the preparation method of the loading comprises the following steps:

[0012] (1) Mix the thermosensitive material and nano-graphene oxide for preliminary adsorption; among them, the thermosensitive material and nano-graphene oxide can be preliminarily adsorbed through π-π conjugation or hydrogen bond interaction;

[0013] (2) Add a crosslinking agent or initiator and carry out in-situ polymerization at 50-70 °C to form a chemical bonding network;

[0014] (3) Remove unreacted monomers or impurities by centrifugation or dialysis.

[0015] The compounding of nano-graphene oxide and the thermosensitive material can form an intelligent responsive composite material, especially thermosensitive responsiveness, thereby enhancing the mechanical strength, response speed, and functional diversity of the shape memory composite.

[0016] Preferably, the thermosensitive material is poly(N-isopropylacrylamide) (PNIPAM) or PBI-PNIPAM, purchased from Shenzhen Regent Chemical Co., Ltd.

[0017] Preferably, the shape memory composite is prepared through the following steps:

[0018] A. Preparation of prepolymer: React polycaprolactone diol with 4,4'-diphenylmethane diisocyanate to obtain a prepolymer;

[0019] B. Chain extension and functionalization: Add a chain extender and a catalyst to the prepolymer for chain extension; then add the dispersed nano-graphene oxide and mix and disperse to obtain.

[0020] Preferably, the specific steps of step A are as follows: After the polycaprolactone diol is vacuum dehydrated in an environment of 100-120°C in advance, it is then reacted with 4,4'-diphenylmethane diisocyanate in a nitrogen environment of 70-90°C to obtain a prepolymer.

[0021] Preferably, in step B, the temperature condition for chain extension is 65-85°C; the chain extender is an aliphatic diol; the mass ratio of the catalyst is 0.5-1.5 wt%.

[0022] Furthermore, the chain extender is preferably 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol or 1,6-hexanediol; the catalyst is dibutyltin dilaurate; the nano-graphene oxide is dispersed by ultrasonic treatment in dimethylformamide (DMF) added in advance.

[0023] In this technical solution, the SEBS matrix, as the basic elastomer, has the effects of high elasticity and aging resistance. Adding a plasticizer is beneficial to improving the temperature-sensitive characteristics of the TPE resin, producing the effects of low-temperature plasticization and high-temperature softening, so that the fixture can fit the object more easily.

[0024] In the TPE resin of this technical solution, C9 petroleum resin is added. The C9 petroleum resin has good compatibility with the SEBS matrix and forms physical crosslinking points through molecular chain entanglement, significantly improving the cohesive strength, wear resistance and flexibility; in addition, the C9 petroleum resin forms a uniform dispersion system with the TPE molecular chain in the molten state, which can reduce the melt viscosity, shorten the injection molding cycle and reduce energy consumption.

[0025] Preferably, the plasticizer is paraffin oil or naphthenic oil. Further preferably, the paraffin oil is paraffin oil 150N or 500N oil; the naphthenic oil is KN4006 or KN4010.

[0026] Preferably, the functional additive includes one or more of nano-silica, antioxidant, photoinitiator, UV stabilizer and conductive filler.

[0027] Specifically, nano-silica can enhance rigidity and improve the wear resistance and dispersibility of the TPE fixture; antioxidants, photoinitiators, UV stabilizers, etc. are beneficial to avoiding the thermal oxidative degradation of the TPE fixture, thereby improving the outdoor durability of the TPE fixture. The addition of the conductive filler is beneficial to activating the shape memory of the TPE fixture through electrothermal response to achieve dynamic adjustment.

[0028] Preferably, the conductive filler includes one or more of conductive carbon black, graphene and carbon nanotubes.

[0029] Furthermore, the functional additive includes 0.5-5 wt% nano-silica, 0.5-1.5 wt% antioxidant, 1-2 wt% photoinitiator, 0.5-2 wt% UV stabilizer, and 0.5-5 wt% conductive filler.

[0030] A preparation method of the TPE fixture material as described above, the TPE fixture material is obtained through the following steps:

[0031] S1: Premixing: Premix the SEBS matrix, C9 petroleum resin, and plasticizer, and then add them to the main feeding port of the extruder to obtain a premix.

[0032] S2: Blending: Add the shape memory composite and the functional additive to the side feeding port of the extruder, and then perform melt blending and extrusion with the premix.

[0033] S3: Molding: Adopt an injection molding process, inject into the mold, and cool and demold.

[0034] Preferably, in step S1, the SEBS matrix, C9 petroleum resin, and plasticizer are premixed by a high-speed mixer at a rotational speed of 8000-12000 rpm for 3-5 minutes; in step S2, after the shape memory composite and the functional additive are mixed, the temperature for melt blending with the premix is 180-220 °C; in step S3, the mold temperature in the injection molding process is 40-60 °C, and the injection pressure is 80-100 MPa.

[0035] Preferably, in step S3, after the mixture is injected into the mold, it is irradiated with ultraviolet light at an intensity of 50-100 mW / cm 2 , for a time of 0.5-1.5 min to initiate a cross-linking reaction to form a three-dimensional network.

[0036] A fixture, comprising the above-mentioned TPE fixture material.

[0037]

Invention Effect

[0038] In the TPE fixture material of this application, a shape memory composite is mainly added. The shape memory composite forms a strong interfacial bond with the TPE resin through hydrogen bonds / van der Waals forces, etc., effectively transmits external stress during the deformation process, improves the reliability and response speed of the shape memory effect, and improves the mechanical properties and anti-permanent deformation ability of the TPE fixture material.

[0039] The shape memory composite of this application can, by introducing nano-graphene oxide, quickly trigger a phase change under specific electrothermal stimulation to achieve shape recovery, breaking through the spatial limitations of traditional thermal responses, thereby endowing the TPE fixture with fast, precise, and controllable recovery capabilities. Detailed Embodiments

[0040] To further elaborate on the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the following is a detailed description of the specific implementation manner, structure, characteristics and their effects of the present invention in combination with embodiments:

[0041] Example 1

[0042] An adaptive flexible TPE fixture material, comprising a TPE resin and a shape memory composite compounded with the TPE resin. Among them, the mass ratio of the TPE resin to the shape memory composite is 4:1. Among them, 100 parts by weight of the TPE resin includes the following components and parts by weight: 64 parts of SEBS matrix, 15 parts of C9 petroleum resin, 15 parts of paraffin oil 150N, 3 parts of nano-silica, and 3 parts of conductive carbon black.

[0043] Specifically, the raw materials of 100 parts by weight of the shape memory composite include the following components and parts by weight: 60 parts of polycaprolactone diol, 25 parts of 4,4'-diphenylmethane diisocyanate, 10 parts of 1,4-butanediol, 4 parts of nano-graphene oxide, and 1 part of catalyst. The shape memory composite is obtained by the following steps:

[0044] A. Preparation of prepolymer: Dehydrate polycaprolactone diol under vacuum at 110°C for 2 hours, and then react with 4,4'-diphenylmethane diisocyanate under nitrogen protection at 80°C for 3 hours (NCO / OH molar ratio = 2:1) to obtain a prepolymer;

[0045] B. Chain extension and functionalization: After adding 1,4-butanediol and the catalyst dibutyltin dilaurate to the prepolymer, carry out chain extension at 75°C for 1 hour; then add the dispersed nano-graphene oxide and mix, and stir and disperse for 2 hours to obtain.

[0046] Among them, the nano-graphene oxide is loaded on the thermosensitive material, including the following steps:

[0047] (1) Mix the thermosensitive material poly(N-isopropylacrylamide) with nano-graphene oxide, and preliminarily adsorb through π-π conjugation or hydrogen bonding;

[0048] (2) Add the crosslinking agent glutaraldehyde, and carry out in-situ polymerization at 60°C to form a chemical bonding network;

[0049] (3) After removing unreacted monomers or impurities by centrifugation or dialysis, collect the composite.

[0050] Among them, the specific steps for dispersing the nano-graphene oxide are: Add the nano-graphene oxide to dimethylformamide and ultrasonically treat for 30 minutes.

[0051] The TPE fixture material is obtained by the following steps:

[0052] S1: Premixing: Premix the SEBS matrix, C9 petroleum resin, and paraffin oil 150N using a high-speed mixer. The rotation speed of the high-speed mixer is 10,000 rpm, and the premixing time is 3 - 5 minutes. Subsequently, add it to the main feeding port of a twin-screw extruder to obtain a premixed material.

[0053] S2: Blending: Add the shape memory composite prepared above to the side feeding port of a twin-screw extruder, then add nano-silica and conductive carbon black. After mixing, melt-blend it with the premixed material at the main feeding port at 180 °C and then extrude.

[0054] S3: Molding: Adopt an injection molding process, inject it into a mold, with the mold temperature at 50 °C and the injection pressure at 100 MPa, then cool and demold.

[0055] Example 2

[0056] The difference between this example and Example 1 is that 100 parts by weight of the shape memory composite includes the following components and parts by weight: 50 parts of polycaprolactone diol, 35 parts of 4,4'-diphenylmethane diisocyanate, 10 parts of 1,4-butanediol, 3.5 parts of nano-graphene oxide, and 1.5 parts of catalyst.

[0057] Example 3

[0058] The difference between this example and Example 1 is that 100 parts by weight of the shape memory composite includes the following components and parts by weight: 70 parts of polycaprolactone diol, 15 parts of 4,4'-diphenylmethane diisocyanate, 12.5 parts of 1,4-butanediol, 2.5 parts of nano-graphene oxide, and 0.5 parts of catalyst.

[0059] Example 4

[0060] The difference between this example and Example 1 is that 100 parts by weight of the TPE resin includes the following components and parts by weight: 53 parts of SEBS matrix, 20 parts of C9 petroleum resin, 20 parts of naphthenic oil KN4006, 3 parts of nano-silica, and 4 parts of graphene.

[0061] Example 5

[0062] The difference between this example and Example 1 is that 100 parts by weight of the TPE resin includes the following components and parts by weight: 70 parts of SEBS matrix, 10 parts of C9 petroleum resin, 10 parts of paraffin oil 500N, 3 parts of nano-silica, 3 parts of antioxidant (1010), 2 parts of photoinitiator benzophenone, and 2 parts of graphene.

[0063] Example 6

[0064] The difference between this embodiment and Embodiment 1 lies in that in step S2 of the preparation process of the TPE fixture material, no shape memory composite is added. Instead, after step S3, a shape memory composite is coated on the surface of the obtained TPE fixture material with a coating thickness of 200 - 220 μm. Then, the TPE composite is placed in an oven at 80 °C for curing for 6 hours to obtain the required TPE fixture material.

[0065] Comparative Example 1

[0066] The difference between this comparative example and Embodiment 1 is that the TPE fixture material only contains TPE resin and no shape memory composite.

[0067] Comparative Example 2

[0068] The difference between this comparative example and Embodiment 1 is that in the preparation of the shape memory composite of the TPE fixture material, graphene oxide nanosheets are replaced by graphene.

[0069] Comparative Example 3

[0070] The difference between this comparative example and Embodiment 1 is that the graphene oxide nanosheets added to the shape memory composite of the TPE fixture material are not pre - loaded on the thermosensitive material.

[0071] Comparative Example 4

[0072] The difference between this comparative example and Embodiment 1 is that in the preparation of the TPE fixture material, C9 petroleum resin is replaced by white mineral oil.

[0073] The fixtures obtained above are numbered. Among them, the fixtures of Embodiments 1 - 6 are numbered 1 - 6, and the fixtures of Comparative Examples 1 - 4 are numbered 7 - 10.

[0074] Shape recovery performance test

[0075] Test method: The fixtures of the embodiments and comparative examples are heated by electricity to 60 °C, and an external force is applied to bend them to 90 ° and fixed; then, after power - off and cooling to 25 °C, the external force is removed, and the initial deformation angle is recorded; then, it is heated to 60 °C again, and the recovered angle is measured to calculate the shape recovery rate. The shape recovery rate = recovered angle / initial deformation angle × 100%.

[0076]

Evaluation

[0077] 1. Mechanical strength

[0078] Test method: 1. Referring to the ASTM D412 standard, measure the tensile strength and elongation at break of the fixtures of the embodiments and comparative examples. Among them, the tensile strength is the stress (MPa) when the fixture breaks, and the elongation at break is the elongation rate (%) when the fixture breaks. Among them, the elongation at break = (L t-(L0) / L0×100%, where L0 is the length measured before the fixture is stretched, and L t is the length measured when the fixture breaks.

[0079] 2. Anti-deformation property

[0080] Referring to the ASTM D395 standard, after measuring the original height of the fixtures in the examples and comparative examples, place the fixtures in the examples and comparative examples in a compression device. Under the condition of a constant temperature of 70°C, compress the fixture by 25% deformation for 24 hours, and measure the height in the compressed state. After removing the load, let it stand for 30 minutes and measure the height after recovery, and calculate the compression permanent deformation rate (%).

[0081] Compression permanent deformation rate = (H0 - H1) / (H0 - H s )×100%, where H0 is the original height, H1 is the height after recovery, and H s is the height in the compressed state.

[0082] The test results are shown in the following table

[0083]

[0084] From the above test results, it can be seen that the TPE fixtures prepared in this application have good test results in terms of shape recovery rate, tensile strength, elongation at break, and compression permanent deformation rate, and have better performance than the TPE fixtures in the comparative examples.

[0085] The above embodiments are only used to illustrate the technical solutions of this application, rather than to limit it; although this application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of this application, and they should all be covered within the scope of the claims and the description of this application. In particular, as long as there is no structural conflict, the technical features mentioned in each embodiment can be combined in any way. This application is not limited to the specific embodiments disclosed in the text, but includes all technical solutions that fall within the scope of the claims.

Claims

1. An adaptive flexible TPE fixture material, characterized in that It includes a TPE resin and a shape memory composite compounded with the TPE resin; wherein, the TPE resin includes the following components: 50-70wt% SEBS matrix, 10-20wt% C9 petroleum resin, 10-20wt% plasticizer, and 5-15wt% functional additive; the raw materials of the shape memory composite include the following components: 50-70wt% polycaprolactone diol, 15-35wt% 4,4'-diphenylmethane diisocyanate, 5-15wt% chain extender, and 2-6wt% nano-graphene oxide.

2. The TPE fixture material according to claim 1, characterized in that, The nano-graphene oxide is loaded on a thermosensitive material, and the preparation method of the loading includes the following steps: (1) Mix the thermosensitive material and nano-graphene oxide for preliminary adsorption; (2) Add a crosslinking agent or initiator and carry out in-situ polymerization at 50-70 °C to form a chemical bonding network; (3) Remove unreacted monomers or impurities by centrifugation or dialysis.

3. The TPE fixture material according to claim 1, characterized in that, The shape memory composite is obtained through the following steps: A. Preparation of prepolymer: React polycaprolactone diol with 4,4'-diphenylmethane diisocyanate to obtain a prepolymer; B. Chain extension and functionalization: Add a chain extender and a catalyst to the prepolymer for chain extension; then add the dispersed nano-graphene oxide and mix and disperse to obtain.

4. The TPE fixture material according to claim 3, wherein The specific steps of step A are: Polycaprolactone diol is pre-vacuum dehydrated in an environment of 100-120 °C, and then reacts with 4,4'-diphenylmethane diisocyanate in a nitrogen environment of 70-90 °C to obtain a prepolymer; in step B, the temperature condition for chain extension is 65-85 °C; the chain extender is an aliphatic diol, and the mass ratio of the catalyst is 0.5-1.5wt%;.

5. The TPE fixture material according to claim 4, wherein The chain extender is 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol or 1,6-hexanediol; the catalyst is dibutyltin dilaurate; the nano-graphene oxide is dispersed by pre-adding it to dimethylformamide (DMF) and ultrasonic treatment.

6. The TPE fixture material according to claim 1, wherein The plasticizer is paraffin oil or naphthenic oil.

7. The TPE fixture material according to claim 1, wherein The functional additive includes one or more of nano-silica, antioxidant, photoinitiator, UV stabilizer, and conductive filler.

8. A method for preparing the TPE fixture material according to any one of claims 1-7, characterized in that, The TPE fixture material is obtained through the following steps: S1: Premixing: Premix the SEBS matrix, C9 petroleum resin, and plasticizer and add them to the main feeding port of an extruder to obtain a premix; S2: Blending: Add the shape memory composite and the functional additive to the side feeding port of the extruder, and then carry out melt blending and extrusion with the premix; S3: Molding: Adopt an injection molding process, inject into a mold, cool and demold.

9. The preparation method according to claim 8, characterized in that, In step S1, the SEBS matrix, C9 petroleum resin, and plasticizer are premixed by a high-speed mixer at a rotation speed of 8000-12000 rpm for 3-5 minutes; in step S2, after the shape memory composite and the functional additive are mixed, the temperature for melt blending with the premix is 180-220 °C; in step S3, the mold temperature in the injection molding process is 40-60 °C, and the injection pressure is 80-100 MPa.

10. A fixture, characterized in that, It includes the TPE fixture material according to any one of claims 1 to 7.

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