Thermoplastic elastomer material, process for its preparation and use

Abstract

The application provides a thermoplastic elastomer material and a preparation method and application thereof, and belongs to the technical field of thermoplastic elastomers. The application prepares zinc calcium phytate particles, regulates Zn / Ca equivalent, and controls the pH of a reaction solution, so that the structure is stable and the surface retains P-OH sites; washing and desalting reduce moisture absorption corrosion and extrusion defects, and then a small amount of zinc stearate is used for hydrophobization to improve dispersibility and does not completely shield active sites, the particle size is regulated to balance interface reaction, touch and processability; a plasticizing phase is compounded with epoxy soybean oil and hydroxyl-terminated polybutadiene, and partial ring opening or hydrogen bonding is used under a low hydroxyl equivalent to enlarge the migration unit and avoid hardening; P-OH induces ring opening of the epoxy soybean oil to form a P-O-C bonding layer on the surface of the particles during extrusion, and the remaining epoxy and the hydroxyl-terminated polybutadiene are added to chain extension, so that the synergistic effect of interface covalent anchoring and molecular weight growth reduces the migration and oil seepage tendency of the plasticizer, and vacuum devolatilization and underwater cutting are used to obtain a thermoplastic elastomer material suitable for toothbrushes.

Description

Technical Field

[0001] This invention belongs to the field of thermoplastic elastomer technology, and relates to a thermoplastic elastomer material, its preparation method and application. Background Technology

[0002] Thermoplastic elastomers (TPEs), especially composites based on styrene-ethylene-butene-styrene block copolymers (SEBS), are widely used in daily necessities, particularly as covering materials (soft rubber) for toothbrush handles, due to their unique rubber elasticity, good processability, and soft touch. To achieve a comfortable grip on toothbrush handles, current technologies typically require filling the SEBS matrix with a large amount of non-polar mineral oil (such as white oil) as a plasticizer. However, existing technologies face significant technical bottlenecks in preparing high-performance TPE materials for toothbrushes.

[0003] Existing technologies mostly rely on physical mixing of white oil for plasticizing. Because the white oil lacks a strong binding mechanism with the matrix, small molecules are prone to migration under high temperature and humidity or mechanical extrusion, which can cause the handle surface to become sticky and hard, or even cause the soft rubber to peel off from the hard handle, seriously affecting the user experience and product life.

[0004] Secondly, the oral environment is moist and prone to bacterial growth. However, traditionally added antibacterial agents (such as nano-silver) have poor compatibility in hydrophobic matrices and are prone to aggregation and precipitation, posing a risk of swallowing. Over-coating treatment can also mask active sites, resulting in short antibacterial duration and difficulty in maintaining a stable antibacterial effect throughout the toothbrush's entire lifespan. Summary of the Invention

[0005] To address the aforementioned problems, the present invention aims to provide a thermoplastic elastomer material, its preparation method, and its applications. This application prepares zinc calcium phytate particles, adjusting the Zn / Ca equivalent and controlling the pH of the reaction solution to ensure structural stability and retain P-OH sites on the surface. Washing and desalting reduce hygroscopic corrosion and extrusion defects. Subsequently, a small amount of zinc stearate is used for hydrophobication to improve dispersibility and partially mask active sites. Particle size is adjusted to balance interfacial reaction, tactile feel, and processability. The plasticizing phase is a blend of epoxidized soybean oil and hydroxyl-terminated polybutadiene. At a low hydroxyl equivalent, partial ring-opening or hydrogen bonding amplifies migration units and prevents hardening. During extrusion, P-OH induces ring-opening of the epoxidized soybean oil, forming a POC bonded layer on the particle surface. The remaining epoxy and hydroxyl-terminated polybutadiene undergo addition chain extension. Through interfacial covalent anchoring and synergistic molecular weight growth, plasticizer migration and oil seepage tendencies are reduced. Combined with vacuum devolatilization and underwater pelletizing, a thermoplastic elastomer material suitable for toothbrushes is obtained.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides a method for preparing a thermoplastic elastomer material, the method comprising:

[0008] S1: Prepare sodium phytate solution; Disperse zinc chloride and calcium chloride in deionized water to obtain a metal salt solution, add sodium phytate solution dropwise to the metal salt solution to obtain reaction solution A, react, filter under pressure to obtain filter cake, wash and disperse the filter cake in a mixed solvent, add zinc stearate dispersion to obtain reaction solution B, dry under reduced pressure to remove solvent, then vacuum dry to obtain the first powder, classify by air jet milling to obtain the second powder, and vacuum dry a second time to obtain modified zinc calcium phytate;

[0009] S2: Epoxidized soybean oil and hydroxyl-terminated polybutadiene are mixed to obtain mixture C, which is mechanically stirred and then degassed and dehydrated under vacuum to obtain a reactive plasticized compound solution.

[0010] S3: Styrene-ethylene-butene-styrene block copolymer, random copolymer polypropylene, modified zinc calcium phytate and SEBS-g-MAH (maleic anhydride-grafted styrene-ethylene-butene-styrene block copolymer) are premixed in a mixer to obtain a solid mixture component; the solid mixture component is added to a twin-screw extruder, white oil and reactive plasticizer compound are added and mixed and sheared, and vacuum is maintained during mixing and shearing, and underwater pelleting is performed to obtain thermoplastic elastomer material.

[0011] As a preferred embodiment of the present invention, in S1, the mass fraction of the sodium phytate solution is 5-10 wt.%, for example, it can be 5.0 wt.%, 5.5 wt.%, 6.0 wt.%, 6.5 wt.%, 7.0 wt.%, 7.5 wt.%, 8.0 wt.%, 8.5 wt.%, 9.0 wt.%, 9.5 wt.% or 10.0 wt.%, but it is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0012] In some optional embodiments, the molar ratio of zinc chloride to calcium chloride is (1-2):(2-1), for example, it can be (1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9 or 2.0):(2.0, 1.9, 1.8, 1.7, 1.6, 1.5, 1.4, 1.3, 1.2, 1.1 or 1.0), but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0013] In some alternative embodiments, the total concentration of the metal salt solution is 0.1-0.5M, for example, it can be 0.10M, 0.14M, 0.18M, ​​0.22M, 0.26M, 0.30M, 0.34M, 0.38M, 0.42M, 0.46M or 0.50M, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0014] In some optional embodiments, the total molar amount of zinc chloride and calcium chloride to sodium phytate is in a molar ratio of (5-6):1, for example, it can be 5.0:1, 5.1:1, 5.2:1, 5.3:1, 5.4:1, 5.5:1, 5.6:1, 5.7:1, 5.8:1, 5.9:1 or 6.0:1, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0015] In some alternative embodiments, the pH of the reaction solution A is 5-5.8, for example, it can be 5.00, 5.08, 5.16, 5.24, 5.32, 5.40, 5.48, 5.56, 5.64, 5.72 or 5.80, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0016] In some optional embodiments, the reaction temperature of the reaction solution A is 40-60°C, for example, it can be 40°C, 42°C, 44°C, 46°C, 48°C, 50°C, 52°C, 54°C, 56°C, 58°C or 60°C, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0017] In some optional embodiments, the reaction time of the reaction solution A is 1-2 hours, for example, it can be 1.0 hours, 1.1 hours, 1.2 hours, 1.3 hours, 1.4 hours, 1.5 hours, 1.6 hours, 1.7 hours, 1.8 hours, 1.9 hours or 2.0 hours, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0018] Preferably, the conductivity of the filtrate after washing is <200 μS / cm.

[0019] In some optional embodiments, the zinc stearate dispersion has a mass fraction of 5-15 wt.%, for example, it may be 5 wt.%, 6 wt.%, 7 wt.%, 8 wt.%, 9 wt.%, 10 wt.%, 11 wt.%, 12 wt.%, 13 wt.%, 14 wt.%, or 15 wt.%, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0020] In some optional embodiments, the volume ratio of ethanol to deionized water in the mixed solvent is (1-3):1, for example, it can be 1.0:1, 1.2:1, 1.4:1, 1.6:1, 1.8:1, 2.0:1, 2.2:1, 2.4:1, 2.6:1, 2.8:1 or 3.0:1, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0021] In some optional embodiments, the mass ratio of zinc stearate to sodium phytate is (0.5-3.5):100, for example, it can be 0.5:100, 0.8:100, 1.1:100, 1.4:100, 1.7:100, 2.0:100, 2.3:100, 2.6:100, 2.9:100, 3.2:100 or 3.5:100, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0022] In some optional embodiments, the vacuum drying temperature of the reaction solution B is 40-60°C, for example, it can be 40°C, 42°C, 44°C, 46°C, 48°C, 50°C, 52°C, 54°C, 56°C, 58°C or 60°C, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0023] In some optional embodiments, the vacuum drying temperature is 60-80°C, for example, it can be 60°C, 62°C, 64°C, 66°C, 68°C, 70°C, 72°C, 74°C, 76°C, 78°C or 80°C, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0024] In some optional embodiments, the particle size D50 of the second powder is 0.5-1.5 μm, for example, it can be 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1.0 μm, 1.1 μm, 1.2 μm, 1.3 μm, 1.4 μm or 1.5 μm, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0025] As a preferred technical solution of the present invention, in S2, the epoxy value of the epoxidized soybean oil is 6.0-7.0%, for example, it can be 6.0%, 6.1%, 6.2%, 6.3%, 6.4%, 6.5%, 6.6%, 6.7%, 6.8%, 6.9% or 7.0%, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0026] In some optional embodiments, the molar ratio of epoxy groups to hydroxyl groups in the mixture C is 1:(0.05-0.25), for example, it can be 1:0.05, 1:0.07, 1:0.09, 1:0.11, 1:0.13, 1:0.15, 1:0.17, 1:0.19, 1:0.21, 1:0.23 or 1:0.25, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0027] In some optional embodiments, the temperature of mechanical stirring of the mixture C is 50-60°C, for example, it can be 50°C, 51°C, 52°C, 53°C, 54°C, 55°C, 56°C, 57°C, 58°C, 59°C or 60°C, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0028] In some optional embodiments, the mechanical stirring time of the mixture C is 20-30 min, for example, it can be 20 min, 21 min, 22 min, 23 min, 24 min, 25 min, 26 min, 27 min, 28 min, 29 min or 30 min, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0029] In some optional embodiments, the vacuum degassing and dehydration time of the mixture C after mechanical stirring is 10-30 min, for example, it can be 10 min, 12 min, 14 min, 16 min, 18 min, 20 min, 22 min, 24 min, 26 min, 28 min or 30 min, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0030] As a preferred technical solution of the present invention, in S3, the premixing time is 1-3 min, for example, it can be 1.0 min, 1.2 min, 1.4 min, 1.6 min, 1.8 min, 2.0 min, 2.2 min, 2.4 min, 2.6 min, 2.8 min or 3.0 min, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0031] In some alternative embodiments, the mass ratio of the styrene-ethylene-butene-styrene block copolymer to the random copolymer polypropylene is 100:(30-45), for example, it can be 100:30.0, 100:31.5, 100:33.0, 100:34.5, 100:36.0, 100:37.5, 100:39.0, 100:40.5, 100:42.0, 100:43.5 or 100:45.0, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0032] In some optional embodiments, the mass ratio of the styrene-ethylene-butene-styrene block copolymer to the modified zinc calcium phytate is 100:(3-8), for example, it can be 100:3.0, 100:3.5, 100:4.0, 100:4.5, 100:5.0, 100:5.5, 100:6.0, 100:6.5, 100:7.0, 100:7.5 or 100:8.0, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0033] In some optional embodiments, the mass ratio of the styrene-ethylene-butene-styrene block copolymer to SEBS-g-MAH is 100:(2-4), for example, it can be 100:2.0, 100:2.2, 100:2.4, 100:2.6, 100:2.8, 100:3.0, 100:3.2, 100:3.4, 100:3.6, 100:3.8 or 100:4.0, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0034] In some optional embodiments, the mass ratio of the styrene-ethylene-butene-styrene block copolymer to the white oil is 100:(40-70), for example, it can be 100:40, 100:43, 100:46, 100:49, 100:52, 100:55, 100:58, 100:61, 100:64, 100:67 or 100:70, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0035] In some optional embodiments, the mass ratio of the styrene-ethylene-butene-styrene block copolymer to the reactive plasticizer compound is 100:(10-25), for example, it can be 100:10.0, 100:11.5, 100:13.0, 100:14.5, 100:16.0, 100:17.5, 100:19.0, 100:20.5, 100:22.0, 100:23.5 or 100:25.0, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0036] In some alternative embodiments, the extruder screw speed is 300-500 rpm, for example, 300 rpm, 320 rpm, 340 rpm, 360 rpm, 380 rpm, 400 rpm, 420 rpm, 440 rpm, 460 rpm, 480 rpm or 500 rpm, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0037] In some alternative embodiments, the temperature of the mixed shearing is 190-210°C, for example, it can be 190°C, 192°C, 194°C, 196°C, 198°C, 200°C, 202°C, 204°C, 206°C, 208°C or 210°C, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0038] In some optional embodiments, the mixed shearing time is 30-60s, for example, it can be 30s, 33s, 36s, 39s, 42s, 45s, 48s, 51s, 54s, 57s or 60s, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0039] In some optional embodiments, the vacuum degree of the mixed shearing is -0.08 to -0.09 MPa, for example, it can be -0.090 MPa, -0.089 MPa, -0.088 MPa, -0.087 MPa, -0.086 MPa, -0.085 MPa, -0.084 MPa, -0.083 MPa, -0.082 MPa, -0.081 MPa or -0.080 MPa, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0040] Secondly, the present invention provides a thermoplastic elastomer material prepared by the preparation method described above.

[0041] This application constructs a modified zinc calcium phytate with controllable surface activity, enabling it to achieve stable dispersion in nonpolar thermoplastic elastomer systems while retaining sufficient residual acidic sites for subsequent interfacial reactions. Sodium phytate and Zn 2+ / Ca 2 + In the aqueous phase, multidentate complexation occurs, forming a sparingly soluble precipitate. The Zn / Ca ratio and the coordination equivalent of the total metal ions relative to the sodium phytate molecule jointly determine the composition and coordination saturation of the precipitate. Controlling the pH of reaction solution A at 5.0-5.8 can prevent agglomeration and coarsening caused by excessive acidity, while promoting the stability of the precipitate structure and allowing some phosphate hydroxyl groups to remain on the particle surface in an incompletely neutralized / incompletely coordinated form, providing reactive P-OH sites for subsequent epoxy ring-opening. Subsequent pressure filtration and washing are used to remove free Cl. - / Na + The presence of impurities reduces the risk of moisture absorption and corrosion in the finished product, and also reduces defects such as bubbles and silver streaks during the extrusion process.

[0042] In reaction stage B, zinc stearate, in dispersed form, hydrophobically treats the inorganic precipitate in an ethanol / water mixture. Long-chain fatty acid salts undergo physical deposition and weak coordination adsorption on the particle surface, forming an outer hydrophobic shell. This reduces particle surface energy and hygroscopicity, improving wetting and dispersion stability in a non-polar matrix. Simultaneously, because the amount of zinc stearate is limited to a low range, the particle surface is not completely coated, maintaining a certain amount of residual acidic sites. Subsequent staged drying, air jet milling, and classification control moisture and residual solvent levels to a low level, keeping D50 within 0.5-1.5 μm. This balances specific surface area (facilitating interfacial anchoring reactions) and tactile / processing flow (avoiding surface roughness and stress concentration caused by coarse particles).

[0043] This application introduces a reactive plasticizing compound. It reduces the effective diffusion capacity of plasticizer migration units through a reactive and chain-extending mechanism. Epoxidized soybean oil, as a low-molecular-weight, multifunctional epoxy carrier, provides subsequent ring-opening reaction sites and imparts a soft feel. Hydroxyl-terminated polybutadiene, as a high-molecular-weight flexible synergistic component, undergoes partial ring-opening addition or forms strong hydrogen bonds during melt shearing under low hydroxyl equivalent conditions. This amplifies the migration units of epoxidized soybean oil to a larger hydrodynamic volume, reducing the diffusion rate and preventing over-reaction and material hardening caused by excessive hydroxyl content. Vacuum degassing and dehydration aim to reduce water consumption in the epoxy by side reactions and the risk of extrusion bubbles, while maintaining the compound in a relatively stable and metered injection state before extrusion.

[0044] Solid premixing enables modified zinc calcium phytate to achieve initial uniform dispersion in a styrene-ethylene-butene-styrene block copolymer / random copolymer polypropylene system. With the assistance of SEBS-g-MAH, it improves the interfacial wetting and adhesion between polar inorganic particles and the polyolefin phase, providing a foundation for subsequent overcoating or bonding with rigid materials. After entering the twin-screw extruder, in the high-shear melting environment of 190-210℃, the residual P-OH sites on the surface of the modified zinc calcium phytate induce interfacially confined ring-opening reactions of the epoxy groups in epoxidized soybean oil, forming bonded structures such as POCs on the surface of the inorganic particles. This fixes the originally easily migrating small-molecule plasticizer around the inorganic framework in the form of a bonded plasticizing layer. Simultaneously, the epoxy groups not consumed by the inorganic surface can undergo partial ring-opening addition with the terminal hydroxyl groups of hydroxyl-terminated polybutadiene, further extending the chain length of the plasticizing phase. Under the conditions described in this application, where the equivalence ratio of epoxy groups to hydroxyl groups is as described and no external curing agent is added, the ring-opening addition reaction is mainly characterized by end-group reaction / oligomerization. The degree of reaction is limited by residence time and diffusion, and it usually does not form a continuous cross-linked network, but rather forms branched oligomers or linear chain-extended products. Therefore, although the epoxidized soybean oil participating in the reaction has an increased molecular weight and reduced migration ability, it still retains the characteristics of flexible chain segments rather than a rigid cross-linked structure, and the material as a whole still exhibits the soft characteristics of a thermoplastic elastomer. It should be noted that, due to the participation of some epoxidized soybean oil in interfacial anchoring and limited chain extension reactions, its effective content as a free plasticizer is reduced, and the initial hardness of the material is slightly higher than that of a system in which the same amount of plasticizer exists entirely in the form of free white oil; however, it is precisely this plasticizer-limited effect that allows the material to maintain more stable hardness and mechanical properties during long-term use, exchanging a moderately increased initial hardness for significantly optimized durability. This synergistic effect of interfacial covalent anchoring and in-situ molecular weight growth helps reduce the migration and diffusion of plasticizers, thus achieving a drier feel and better resistance to aging and oil seepage without introducing a continuous irreversible chemical cross-linking network. The material retains the reprocessable properties of thermoplastic elastomers. Under melt shear conditions, the anhydride groups of SEBS-g-MAH may also undergo partial esterification with the terminal hydroxyl groups, thus contributing to the binding of the plasticizing phase along with the epoxy ring-opening process. Vacuum devolatilization removes residual moisture, low-boiling-point volatiles, and entrained air, reducing the risk of bubbles and odors; underwater pelletizing ensures stable pelleting and consistency in subsequent injection molding and overmolding processes.

[0045] This application avoids reliance on traditional migratory antibacterial agents or simply on compatibilizers. Instead, it uses zinc calcium phytate inorganic particles as an interfacial reaction platform. Dispersibility in thermoplastic elastomers is achieved through surface hydrophobicity, and in-situ interfacial anchoring of epoxy plasticizers is achieved through residual acidic sites. Furthermore, hydroxyl-terminated polybutadiene is used to perform limited chain extension of the plasticizing phase, forming a ternary stable structure of "inorganic skeleton fixation - plasticizing layer confinement - matrix elasticity retention." This transforms the requirements for a soft touch and low migration and oil resistance into synergistically optimizable interfacial engineering. Simultaneously, in the context of moist oral environments, the phytate system and Zn... 2+ It exhibits certain antibacterial and antifouling tendencies under the influence of moisture in the microenvironment, providing a material route for toothbrush products that balances safety and durability.

[0046] Thirdly, the present invention provides an application of a thermoplastic elastomer material in the preparation of toothbrushes.

[0047] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0048] This application yields zinc calcium phytate particles. The structure is stabilized and some surface P-OH active sites are retained by adjusting the Zn / Ca equivalent and pH (5.0-5.8). Washing and desalination reduce hygroscopic corrosion and extrusion defects. A small amount of zinc stearate is then used to hydrophobize and form an outer shell, improving dispersibility in non-polar thermoplastic elastomer systems without completely obscuring active sites. Drying, pulverizing, and classification control the D50 to 0.5-1.5 μm, balancing interfacial reaction, tactile feel, and processability.

[0049] This application uses epoxidized soybean oil and hydroxyl-terminated polybutadiene to form a reactive plasticizing compound: epoxidized soybean oil provides ring-opening reaction sites and a soft feel, while hydroxyl-terminated polybutadiene partially ring-opens or associates with it under low hydroxyl equivalent, increasing the molecular volume of the plasticizing phase, reducing diffusion migration, and avoiding excessive reaction and hardening; the compound is degassed and dehydrated under vacuum to reduce epoxy side reactions and bubbles, while ensuring stable and meterable addition before extrusion.

[0050] Solid premixing promotes uniform dispersion of modified zinc calcium phytate in SEBS / PP, and SEBS-g-MAH improves the interfacial wetting and adhesion between inorganic particles and the matrix. Under high shear extrusion, P-OH on the particle surface induces ring opening of epoxidized soybean oil and forms a POC bonded layer on the surface. At the same time, the remaining epoxy and hydroxyl-terminated polybutadiene partially add to achieve chain extension of the plasticizing phase. The synergistic effect of interfacial covalent anchoring and molecular weight increase reduces plasticizer migration and oil seepage, maintaining thermoplasticity and reprocessability. Vacuum devolatilization removes moisture / volatiles / air to reduce foaming and deodorize, and underwater pelleting ensures consistency between granulation and subsequent coating.

[0051] This application uses hydrophobic zinc calcium phytate as an interfacial reaction platform, utilizing its residual acidic sites to in-situ anchor epoxy plasticizers and combine it with hydroxyl-terminated polybutadiene for limited chain extension, constructing a stable structure of "inorganic skeleton fixation - plasticized layer confinement - matrix elasticity retention," achieving a synergistic effect of soft touch and low migration and oil impermeability. Because some epoxidized soybean oil participates in the interfacial anchoring and chain extension reaction and no longer exists as a free plasticizer, the initial hardness of the material is moderately increased compared to pure white oil plasticized systems, while significantly improving long-term stability and aging resistance, achieving a balanced optimization between initial feel and long-term durability. It also possesses certain antibacterial and anti-fouling potential in the moist environment of the oral cavity, making it suitable for thermoplastic elastomer materials for toothbrushes. Detailed Implementation

[0052] The technical solution of the present invention will be described in detail below with reference to specific embodiments. The embodiments described herein are specific implementations of the present invention and are used to illustrate the concept of the present invention; these descriptions are explanatory and exemplary and should not be construed as limiting the implementation of the present invention or the scope of protection of the present invention. In addition to the embodiments described herein, those skilled in the art can also adopt other obvious technical solutions based on the content disclosed in the claims and the specification of this application. These technical solutions include technical solutions that employ any obvious substitutions and modifications made to the embodiments described herein.

[0053] The chemical reagents used in the embodiments and comparative examples of this invention are all commercially available products and have not undergone further purification or processing.

[0054] Example 1

[0055] This embodiment provides a thermoplastic elastomer material and its preparation method. The preparation method of the thermoplastic elastomer material specifically includes the following steps:

[0056] S1: Prepare an 8 wt.% sodium phytate solution; disperse zinc chloride and calcium chloride in deionized water to obtain a metal salt solution, wherein the molar ratio of zinc chloride to calcium chloride is 1.5:1.5, and the total concentration of the metal salt solution is 0.4M. Add the sodium phytate solution dropwise to the metal salt solution to obtain reaction solution A, wherein the molar ratio of the total molar amount of zinc chloride and calcium chloride to sodium phytate is 5.8:1, and the pH of reaction solution A is 5.6. Otherwise, adjust with sodium hydroxide or hydrochloric acid. React at 55℃ for 1.8 h, filter under pressure, and obtain... The filter cake was washed until the conductivity of the filtrate was <200 μS / cm. The filter cake was dispersed in a mixed solvent, and a zinc stearate dispersion with a mass fraction of 12 wt.% was added to obtain reaction solution B. The volume ratio of ethanol to deionized water in the mixed solvent was 2.5:1, and the mass ratio of zinc stearate to sodium phytate was 2.5:100. The solvent was removed by vacuum drying at 52℃, and then vacuum dried at 75℃ to obtain the first powder. The second powder with a particle size D50 of 1.2 μm was obtained by air jet milling and classification. The modified zinc calcium phytate was obtained by secondary vacuum drying.

[0057] S2: Epoxidized soybean oil with an epoxy value of 6.8% is mixed with hydroxyl-terminated polybutadiene to obtain mixture C, wherein the molar ratio of epoxy groups to hydroxyl groups in mixture C is 1:0.2. The mixture is mechanically stirred at 58°C for 28 min and then vacuum degassed and dehydrated for 25 min to obtain a reactive plasticizing compound solution.

[0058] S3: Styrene-ethylene-butene-styrene block copolymer, random copolymer polypropylene, modified zinc calcium phytate, and SEBS-g-MAH are premixed in a mixer for 2.5 min to obtain a solid mixture; wherein the mass ratio of styrene-ethylene-butene-styrene block copolymer, random copolymer polypropylene, modified zinc calcium phytate, and SEBS-g-MAH is 100:40:7:3.5. The solid mixture is added to a twin-screw extruder, along with white oil and reactive plasticizer compound, and mixed and sheared at 205℃, -0.085MPa, and 450rpm for 50s. The mass ratio of styrene-ethylene-butene-styrene block copolymer, white oil, and reactive plasticizer compound is 100:60:20. The mixture is then pelletized underwater to obtain a thermoplastic elastomer material.

[0059] Example 2

[0060] This embodiment provides a thermoplastic elastomer material and its preparation method. The preparation method of the thermoplastic elastomer material specifically includes the following steps:

[0061] S1: Prepare a 5 wt.% sodium phytate solution; disperse zinc chloride and calcium chloride in deionized water to obtain a metal salt solution, wherein the molar ratio of zinc chloride to calcium chloride is 1:2, and the total concentration of the metal salt solution is 0.1M. Add the sodium phytate solution dropwise to the metal salt solution to obtain reaction solution A, wherein the total molar ratio of zinc chloride and calcium chloride to sodium phytate is 5:1, and the pH of reaction solution A is 5. Otherwise, adjust with sodium hydroxide or hydrochloric acid. React at 40℃ for 1 hour, filter by pressure, and obtain a filter cake. Wash until the conductivity of the filtrate is <200 μS / cm, disperse the filter cake in a mixed solvent, add 5 wt.% zinc stearate dispersion to obtain reaction solution B, wherein the volume ratio of ethanol to deionized water in the mixed solvent is 1:1, and the mass ratio of zinc stearate to sodium phytate is 0.5:100. Dry under reduced pressure at 60℃ to remove the solvent, and then vacuum dry at 60℃ to obtain the first powder. After air jet milling and classification, the second powder with a particle size D50 of 0.5 μm is obtained. After a second vacuum drying, modified zinc phytate calcium is obtained.

[0062] S2: Epoxidized soybean oil with an epoxy value of 6.0% is mixed with hydroxyl-terminated polybutadiene to obtain mixture C, wherein the molar ratio of epoxy groups to hydroxyl groups in mixture C is 1:0.05. The mixture is mechanically stirred at 50°C for 20 min and then vacuum degassed and dehydrated for 10 min to obtain a reactive plasticizing compound.

[0063] S3: Styrene-ethylene-butene-styrene block copolymer, random copolymer polypropylene, modified zinc calcium phytate, and SEBS-g-MAH are premixed in a mixer for 1 min to obtain a solid mixture; wherein the mass ratio of styrene-ethylene-butene-styrene block copolymer, random copolymer polypropylene, modified zinc calcium phytate, and SEBS-g-MAH is 100:30:3:2. The solid mixture is added to a twin-screw extruder, along with white oil and reactive plasticizer compound, and mixed and sheared at 190℃, -0.09MPa, and 450rpm for 30s. The mass ratio of styrene-ethylene-butene-styrene block copolymer, white oil, and reactive plasticizer compound is 100:40:10. The mixture is then pelletized underwater to obtain a thermoplastic elastomer material.

[0064] Example 3

[0065] This embodiment provides a thermoplastic elastomer material and its preparation method. The preparation method of the thermoplastic elastomer material specifically includes the following steps:

[0066] S1: Prepare a 10 wt.% sodium phytate solution; disperse zinc chloride and calcium chloride in deionized water to obtain a metal salt solution, wherein the molar ratio of zinc chloride to calcium chloride is 1.2:1.8, and the total concentration of the metal salt solution is 0.2M. Add the sodium phytate solution dropwise to the metal salt solution to obtain reaction solution A, wherein the molar ratio of the total molar amount of zinc chloride and calcium chloride to sodium phytate is 5.2:1, and the pH of reaction solution A is 5.2. Otherwise, adjust with sodium hydroxide or hydrochloric acid. React at 45℃ for 1.2 h, filter under pressure, and obtain... The filter cake was washed until the conductivity of the filtrate was <200 μS / cm. The filter cake was dispersed in a mixed solvent, and 8 wt.% zinc stearate dispersion was added to obtain reaction solution B. The volume ratio of ethanol to deionized water in the mixed solvent was 1.5:1, and the mass ratio of zinc stearate to sodium phytate was 1.5:100. The solvent was removed by vacuum drying at 58℃, and then vacuum dried at 65℃ to obtain the first powder. The second powder with a particle size D50 of 0.8 μm was obtained by air jet milling and classification. The modified zinc calcium phytate was obtained by secondary vacuum drying.

[0067] S2: Epoxidized soybean oil with an epoxy value of 6.2% is mixed with hydroxyl-terminated polybutadiene to obtain mixture C, wherein the molar ratio of epoxy groups to hydroxyl groups in mixture C is 1:0.1. The mixture is mechanically stirred at 52℃ for 22 min and then vacuum degassed and dehydrated for 15 min to obtain a reactive plasticizing compound solution.

[0068] S3: Styrene-ethylene-butene-styrene block copolymer, random copolymer polypropylene, modified zinc calcium phytate, and SEBS-g-MAH are premixed in a mixer for 1.5 min to obtain a solid mixture; wherein the mass ratio of styrene-ethylene-butene-styrene block copolymer, random copolymer polypropylene, modified zinc calcium phytate, and SEBS-g-MAH is 100:35:5:2.5. The solid mixture is added to a twin-screw extruder, along with white oil and reactive plasticizer compound, and mixed and sheared at 195℃, -0.088MPa, and 350rpm for 40s. The mass ratio of styrene-ethylene-butene-styrene block copolymer, white oil, and reactive plasticizer compound is 100:50:15. The mixture is then pelletized underwater to obtain a thermoplastic elastomer material.

[0069] Example 4

[0070] This embodiment provides a thermoplastic elastomer material and its preparation method. The preparation method of the thermoplastic elastomer material specifically includes the following steps:

[0071] S1: Prepare a 7 wt.% sodium phytate solution; disperse zinc chloride and calcium chloride in deionized water to obtain a metal salt solution, wherein the molar ratio of zinc chloride to calcium chloride is 2:1, and the total concentration of the metal salt solution is 0.5M. Add the sodium phytate solution dropwise to the metal salt solution to obtain reaction solution A, wherein the molar ratio of the total molar amount of zinc chloride and calcium chloride to sodium phytate is 6:1, and the pH of reaction solution A is 5.8. Otherwise, adjust with sodium hydroxide or hydrochloric acid. React at 60℃ for 2 hours, filter by pressure, and obtain a filter cake. Wash until the conductivity of the filtrate is <200 μS / cm, disperse the filter cake in a mixed solvent, add 15 wt.% zinc stearate dispersion to obtain reaction solution B, wherein the volume ratio of ethanol to deionized water in the mixed solvent is 3:1, and the mass ratio of zinc stearate to sodium phytate is 3.5:100. Dry under reduced pressure at 40℃ to remove the solvent, and then vacuum dry at 80℃ to obtain the first powder. After air jet milling and classification, the second powder with a particle size D50 of 1.5 μm is obtained. After a second vacuum drying, modified zinc calcium phytate is obtained.

[0072] S2: Epoxidized soybean oil with an epoxy value of 7.0% is mixed with hydroxyl-terminated polybutadiene to obtain mixture C, wherein the molar ratio of epoxy groups to hydroxyl groups in mixture C is 1:0.25. The mixture is mechanically stirred at 60°C for 30 min and then vacuum degassed and dehydrated for 30 min to obtain a reactive plasticizing compound.

[0073] S3: Styrene-ethylene-butene-styrene block copolymer, random copolymer polypropylene, modified zinc calcium phytate, and SEBS-g-MAH are premixed in a mixer for 3 min to obtain a solid mixture; wherein the mass ratio of styrene-ethylene-butene-styrene block copolymer, random copolymer polypropylene, modified zinc calcium phytate, and SEBS-g-MAH is 100:45:8:4. The solid mixture is added to a twin-screw extruder, along with white oil and reactive plasticizer compound, and mixed and sheared at 210℃, -0.08MPa, and 500rpm for 60s. The mass ratio of styrene-ethylene-butene-styrene block copolymer, white oil, and reactive plasticizer compound is 100:70:25. The mixture is then pelletized underwater to obtain a thermoplastic elastomer material.

[0074] Comparative Example 1

[0075] This comparative example provides a thermoplastic elastomer material. The difference from Example 1 is that the reactive plasticizing compound liquid in S2 and S3 is omitted and replaced with white oil in equal amounts. Other operating steps and process parameters are exactly the same as in Example 1.

[0076] Comparative Example 2

[0077] This comparative example provides a thermoplastic elastomer material. The difference from Example 1 is that S2 is omitted and epoxidized soybean oil is used to replace the reactive plasticizing compound in S3. Other operating steps and process parameters are exactly the same as in Example 1.

[0078] Comparative Example 3

[0079] This comparative example provides a thermoplastic elastomer material. The difference from Example 1 is that the zinc stearate dispersion treatment step is omitted in S1, and the untreated zinc calcium phytate is directly obtained for use. Other operation steps and process parameters are exactly the same as in Example 1.

[0080] Comparative Example 4

[0081] This comparative example provides a thermoplastic elastomer material. The difference from Example 1 is that in S1, the mass ratio of zinc stearate to sodium phytate is 1:10, while other operating steps and process parameters are exactly the same as in Example 1.

[0082] The performance of the thermoplastic elastomer materials of Examples 1-4 and Comparative Examples 1-4 was tested, and the specific process is as follows:

[0083] The hardness of the samples and the hardness after aging treatment were tested according to GB / T 531.1-2008.

[0084] The tensile strength of the samples and the tensile strength after aging treatment were tested according to GB / T 528-2009.

[0085] The samples were subjected to accelerated aging treatment (70℃, 168h) according to GB / T 3512-2014 before the hardness and tensile strength were tested.

[0086] The antibacterial properties (Escherichia coli) and antibacterial properties after aging treatment were tested according to GB / T 31402-2023.

[0087] The liquid resistance of the samples was tested according to GB / T 1690-2010;

[0088] The test results are shown in Table 1.

[0089] Table 1. Performance test results of thermoplastic elastomer materials in Examples 1-4 and Comparative Examples 1-4

[0090]

[0091] As shown in Table 1, the test results of Example 1 and Comparative Example 1 show that, omitting steps S2 and S3, the reactive plasticizing compound was replaced with an equal amount of white oil. In Comparative Example 1, all plasticizing phases were free white oil. Due to the lack of epoxidized soybean oil participating in the interfacial anchoring reaction and the consumption of hydroxyl-terminated polybutadiene chain extension, the content of free plasticizer was higher, resulting in a lower initial hardness than in Example 1. However, the plasticization in the system mainly relied on the weak van der Waals interaction between white oil and SEBS segments, lacking the binding mechanism of P-OH-induced epoxy ring-opening anchoring on the inorganic particle surface and the limited chain extension amplification migration unit of epoxidized soybean oil and hydroxyl-terminated polybutadiene. Under thermal aging and service stress, small molecule white oil was more likely to migrate from the matrix to the surface and be extracted and lost, resulting in a greater increase in hardness and a lower tensile strength retention rate after aging, while the weight loss from hexane extraction increased. On the other hand, white oil migration and surface enrichment led to a more obvious surface oiliness / fouling tendency, making the surface state related to contact antibacterial and antifouling more unstable, thus reducing the antibacterial retention rate after aging.

[0092] From the test results of Example 1 and Comparative Example 2 in Table 1, it can be seen that by omitting step S2 and replacing the reactive plasticizer compound with epoxidized soybean oil in S3, although epoxidized soybean oil can still undergo interfacial ring-opening reaction with the residual P-OH on the surface of modified zinc calcium phytate to a certain extent, due to the lack of synergistic chain extension and hydrogen bonding of terminal hydroxyl polybutadiene, the epoxidized soybean oil that is not consumed by the inorganic surface is more likely to exist in the form of small molecule migration units; the content of free plasticizer is higher than that in Example 1, so the initial hardness is slightly lower than that in Example 1; however, due to the lack of the binding mechanism of chain extension and amplification of migration units, under aging and solvent extraction conditions, its extraction weight loss and performance degradation are both increased, which is manifested as a higher hardness recovery after aging, a decrease in tensile strength and antibacterial performance retention rate, and an increase in hexane extraction weight loss.

[0093] As shown in Table 1, the test results of Example 1 and Comparative Example 3 reveal that omitting the zinc stearate dispersion treatment step in S1 directly yields untreated zinc calcium phytate. This results in stronger surface polarity of the zinc calcium phytate particles, leading to poorer wetting and dispersibility in non-polar systems and a tendency to form aggregates. The increased rigidity of these aggregates results in a slightly higher initial hardness than in Example 1. Aggregation reduces the effective specific surface area and the utilization rate of active sites that can participate in interfacial reactions, decreasing the interfacial anchoring efficiency of the epoxy plasticizer and weakening its migration inhibition effect. This leads to a rebound in hardness after aging and increased weight loss from hexane extraction. Furthermore, aggregation causes localized stress concentration and an increase in interfacial defects, reducing tensile strength and its aging retention rate. In addition, higher exposure of polar sites increases the adsorption / retention of moisture, resulting in greater mass changes in water and further amplifying performance fluctuations under humid and hot conditions, thus reducing overall durability.

[0094] From the test results of Example 1 and Comparative Example 4 in Table 1, it can be seen that in S1, the mass ratio of zinc stearate to sodium phytate was 1:10. When the amount of zinc stearate was significantly increased, although the enhanced hydrophobicity of inorganic particles was beneficial to initial dispersion, the excessive fatty acid salt coating would more significantly mask the residual P-OH acidic sites on the particle surface, weakening its interfacial induced ring-opening and covalent anchoring effect on the epoxy plasticizer. As a result, the plasticizer existed more in a physically miscible / weakly interacting state, with a higher content of free plasticizer than in Example 1 and a lower initial hardness. However, due to insufficient anchoring, it was more prone to migration and loss under aging and extraction conditions, manifested as increased hardness recovery after aging, decreased tensile strength retention, and increased weight loss during hexane extraction. At the same time, the masking of active sites also weakened the Zn at the interface. 2+ The contribution of the phytate microenvironment to contact antibacterial and antifouling surfaces leads to a decrease in antibacterial retention rate after aging.

[0095] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for preparing a thermoplastic elastomer material, characterized in that, The preparation method includes: S1: Prepare sodium phytate solution; Disperse zinc chloride and calcium chloride in deionized water to obtain a metal salt solution, add sodium phytate solution dropwise to the metal salt solution to obtain reaction solution A, react, filter under pressure to obtain filter cake, wash and disperse the filter cake in a mixed solvent, add zinc stearate dispersion to obtain reaction solution B, dry under reduced pressure to remove solvent, then vacuum dry to obtain the first powder, classify by air jet milling to obtain the second powder, and vacuum dry a second time to obtain modified zinc calcium phytate; S2: Epoxidized soybean oil and hydroxyl-terminated polybutadiene are mixed to obtain mixture C, which is mechanically stirred and then degassed and dehydrated under vacuum to obtain a reactive plasticized compound solution. S3: Styrene-ethylene-butene-styrene block copolymer, random copolymer polypropylene, modified zinc calcium phytate and SEBS-g-MAH are premixed in a mixer to obtain a solid mixture component; the solid mixture component is added to a twin-screw extruder, white oil and reactive plasticizer compound are added and mixed and sheared, and vacuum is maintained during mixing and shearing, and underwater pelleting is performed to obtain thermoplastic elastomer material.

2. The method for preparing a thermoplastic elastomer material according to claim 1, characterized in that, In S1: The molar ratio of zinc chloride to calcium chloride is (1-2):(2-1); The total concentration of the metal salt solution is 0.1-0.5 M; The total molar amount of zinc chloride and calcium chloride is in a molar ratio of (5-6):1 with that of sodium phytate.

3. The method for preparing a thermoplastic elastomer material according to claim 1, characterized in that, In S1: The zinc stearate dispersion has a mass fraction of 5-15 wt.%; The volume ratio of ethanol to deionized water in the mixed solvent is (1-3):1; The mass ratio of zinc stearate to sodium phytate is (0.5-3.5):

100.

4. The method for preparing a thermoplastic elastomer material according to claim 1, characterized in that, In S2: The epoxy value of the epoxidized soybean oil is 6.0-7.0%; The molar ratio of epoxy groups to hydroxyl groups in the mixture C is 1:(0.05-0.25).

5. The method for preparing a thermoplastic elastomer material according to claim 1, characterized in that, In S3: The mass ratio of the styrene-ethylene-butene-styrene block copolymer to the random copolymer polypropylene is 100:(30-45).

6. The method for preparing a thermoplastic elastomer material according to claim 1, characterized in that, In S3: The mass ratio of the styrene-ethylene-butene-styrene block copolymer to the modified zinc calcium phytate is 100:(3-8); The mass ratio of the styrene-ethylene-butene-styrene block copolymer to SEBS-g-MAH is 100:(2-4).

7. The method for preparing a thermoplastic elastomer material according to claim 1, characterized in that, In S3: The mass ratio of the styrene-ethylene-butene-styrene block copolymer to white oil is 100:(40-70); The mass ratio of the styrene-ethylene-butene-styrene block copolymer to the reactive plasticizer compound is 100:(10-25).

8. The method for preparing a thermoplastic elastomer material according to claim 1, characterized in that, In S3: The temperature of the mixed shearing is 190-210℃; The vacuum degree of the hybrid shearing is -0.08 to -0.09 MPa.

9. A thermoplastic elastomer material, characterized in that, It is prepared according to any one of claims 1-8.

10. The application of the thermoplastic elastomer material as described in claim 9 in the manufacture of toothbrushes.

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