Sodium polyacrylate / polydopamine micro powder modified thermoplastic elastomer TPE as well as preparation method and application thereof

Abstract

The invention particularly relates to a sodium polyacrylate / polydopamine micro powder modified thermoplastic elastomer (TPE) and a preparation method and application thereof, the preparation method comprises the following steps: dissolving dopamine hydrochloride in deionized water, then uniformly mixing with a sodium polyacrylate aqueous solution, then adjusting the pH value to be alkaline, and reacting to obtain a mixed solution containing sodium polyacrylate / polydopamine; the mixed solution containing sodium polyacrylate / polydopamine is dried, smashed and ball-milled into sodium polyacrylate / polydopamine powder; the preparation method comprises the following steps: uniformly mixing sodium polyacrylate / polydopamine powder and a thermoplastic elastomer TPE, and carrying out melt extrusion granulation to obtain the sodium polyacrylate / polydopamine gel micro-powder modified thermoplastic elastomer TPE. Dopamine hydrochloride contains a large amount of hydroxyl, imino and other groups, and has good affinity with sodium polyacrylate molecules; the polydopamine plays a role of a compatilizer between the sodium polyacrylate and the TPE, so that the compatibility of the sodium polyacrylate and the TPE is improved, the hydrophilicity of the modified composite material is improved, the improvement of the wet friction property is facilitated due to the improvement of the hydrophilicity, and a very good anti-skid effect is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer synthesis, and specifically to a modified thermoplastic elastomer TPE and a preparation method and application thereof. Background Art

[0002] Thermoplastic elastomer (TPE) is a polymer phase that is soft at high temperature but becomes fluid after high temperature melting, while other discontinuous phases are polymer phases that are soft and elastic at room temperature. TPE combines the elasticity of vulcanized rubber at room temperature with the excellent processability and recyclability of plastics at high temperature, and can replace some traditional vulcanized rubbers and resins. Therefore, replacing traditional vulcanized rubber with TPE can not only improve production efficiency, but also better save energy and utilize resources. In recent years, TPE has developed rapidly, and now there are many types of TPE applications in many fields. Products made of TPE anti-slip pads have good resilience, wear resistance, tear resistance, good tensile strength, excellent anti-slip performance, comfortable feel, good environmental resistance, and can adapt to various harsh weather environments in my country. Whether it is in low temperature weather of minus 40℃ or in outdoor environments up to 80℃, it can be used normally.

[0003] Conventional TPE floor mats do not have good anti-slip performance. Once the ground is wet, users are prone to slipping and falling. This is because when water falls on the road, it does not simply cover the ground, but forms a thin layer of water film. This layer of water film will change the contact state between the ground and the floor mat, reducing the friction between the floor mat and the ground, which makes it easy to slip. In order to increase the dry friction between the floor mat and the ground, the hygroscopicity of the floor mat can be used to absorb the water film on the surface of the ground, so that the floor mat can form direct contact with the ground surface, so as to achieve the purpose of increasing dry friction and reducing wet friction, thereby playing an anti-slip role. Now there is an urgent need for a TPE floor mat material with good hydrophilicity to solve the above problems.

[0004] The hydrophilic water absorption of TPE can be improved by adding hydrophilic water-absorbing polymers. However, due to the large differences in structure and physical and chemical properties between the water-absorbing resin and the thermoplastic elastomer matrix, the compatibility between the two is poor, which makes it difficult to evenly disperse the water-absorbing resin in the TPE matrix, making processing difficult and the various properties of the material poor. Summary of the invention

[0005] In view of the problems existing in the prior art, the present invention proposes a sodium polyacrylate / polydopamine powder modified thermoplastic elastomer TPE and a preparation method and application thereof. The defects and shortcomings of the thermoplastic elastomer TPE, such as poor water absorption and insufficient anti-skid performance, are overcome. The sodium polyacrylate / polydopamine powder modified thermoplastic elastomer TPE of the present invention is applied to floor mats, which effectively improves the friction coefficient of the floor mats, thereby improving the anti-skid performance of the floor mats.

[0006] In order to achieve the above object, the technical solution of the present invention is achieved as follows:

[0007] A method for preparing a sodium polyacrylate / polydopamine powder-modified thermoplastic elastomer TPE comprises the following steps:

[0008] (1) dissolving dopamine hydrochloride in deionized water and then mixing the mixture evenly with a sodium polyacrylate aqueous solution, and then adjusting the pH to alkaline using a tris(hydroxymethyl)aminomethane-hydrochloric acid buffer solution to obtain a mixed solution containing sodium polyacrylate / polydopamine;

[0009] (2) drying and grinding the mixed solution containing sodium polyacrylate / polydopamine in step (1) into sodium polyacrylate / polydopamine powder by ball milling;

[0010] (3) The sodium polyacrylate / polydopamine powder of step (2) and the thermoplastic elastomer TPE are uniformly mixed, melt-extruded and granulated to obtain the sodium polyacrylate / polydopamine gel micropowder modified thermoplastic elastomer TPE.

[0011] Preferably, in step (1), the mass ratio of dopamine hydrochloride, deionized water and sodium polyacrylate aqueous solution is 0.5-4:100:30-50, and the concentration of the sodium polyacrylate aqueous solution is 20-50wt%.

[0012] Preferably, the pH in step (1) is 8.5.

[0013] Preferably, the reaction temperature in step (1) is 30-50°C and the reaction time is 6-12h.

[0014] Preferably, the drying temperature in step (2) is 60-100° C. and the drying time is 4-10 h.

[0015] Preferably, the particle size of the powder in step (2) is 1-3 μm.

[0016] Preferably, in step (3), the mass ratio of sodium polyacrylate / polydopamine powder to thermoplastic elastomer TPE is 5-20:80-95.

[0017] Preferably, the mixing temperature in step (2) is 30-60°C, the mixing time is 30-120 min, and the melt extrusion temperature is 165-175°C.

[0018] Preferably, the sodium polyacrylate / polydopamine powder prepared by the method is a thermoplastic elastomer TPE modified with polyacrylate / polydopamine powder.

[0019] Preferably, the sodium polyacrylate / polydopamine powder modified thermoplastic elastomer TPE is used in floor mats.

[0020] Beneficial effects of the present invention:

[0021] 1. The present invention introduces the highly absorbent resin sodium polyacrylate into the thermoplastic elastomer matrix, and the water absorption rate of TPE can be greatly increased. Thermoplastic elastomer modified with sodium polyacrylate / polydopamine micropowder can quickly absorb moisture and keep the ground dry in a slippery environment. It will have broad application prospects when applied to the field of floor mat materials. However, the highly absorbent resin itself has a large cohesive force and is difficult to disperse evenly in the matrix material. It is incompatible with the TPE matrix. In order to solve the compatibility of the two-phase polymer, this patent first uses dopamine hydrochloride to modify sodium polyacrylate. Dopamine hydrochloride contains a large number of hydroxyl groups, imino groups and other groups. Dopamine hydrochloride and sodium polyacrylate undergo oxidative self-polymerization in a Tris-HCl buffer solution. Polydopamine plays the role of a compatibilizer between sodium polyacrylate and the thermoplastic elastomer TPE, increasing the compatibility of sodium polyacrylate and the thermoplastic elastomer TPE.

[0022] 2. Polydopamine can adhere to almost all types of material surfaces, including inert substrates, so it is vividly called "universal glue". In the present invention, by introducing polydopamine, the composite material is given stronger adhesion and the dry and wet friction coefficient of the floor mat product is increased.

[0023] 3. The sodium polyacrylate, thermoplastic elastomer, dopamine hydrochloride, etc. used in the present invention are all environmentally friendly additives, and the anti-slip modified thermoplastic elastomer can be recycled and reused. Therefore, the present invention complies with the national environmental protection concept and meets the requirements of sustainable development. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0025] Figure 1 It is a cross-sectional scanning electron microscope image, wherein picture A is comparative example 2, and picture B is example 1.

[0026] Figure 2 Graphs showing contact angles, wherein Picture A is Comparative Example (pure TPE) 1, Picture B is Comparative Example 2, and Picture C is Example 1.

[0027] Figure 3 Figure A is a sample photo of Comparative Example 1, Figure B is a sample photo of Comparative Example 2, and Figure C is a sample photo of Example 1. DETAILED DESCRIPTION

[0028] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] Raw materials: thermoplastic elastomer (TPE), Dongguan Shanyi Plastics Co., Ltd.; sodium polyacrylate, Shanghai MacLean Biochemical Technology Co., Ltd.; dopamine hydrochloride, Shanghai MacLean Biochemical Technology Co., Ltd. In the following examples and comparative examples, 1 part = 1 g.

[0030] Example 1

[0031] This embodiment provides a method for preparing a sodium polyacrylate / polydopamine powder-modified thermoplastic elastomer TPE, the steps of which are as follows:

[0032] (1) 4 parts of dopamine hydrochloride are added to 100 parts of deionized water, and stirred to dissolve the dopamine hydrochloride to obtain an aqueous solution of dopamine hydrochloride. 50 parts of a 20% by mass sodium polyacrylate aqueous solution are added to the dopamine hydrochloride aqueous solution, and after mixing evenly, a tris-hydroxymethylaminomethane-hydrochloric acid buffer solution (Tris-HCl buffer solution) is added to adjust the pH value to 8.5, and then the solution is allowed to stand at 50° C. for 6 hours. During this process, due to the alkaline environment provided by the buffer solution, the dopamine hydrochloride is polymerized in situ to generate polydopamine, thereby obtaining a mixed solution containing sodium polyacrylate / polydopamine.

[0033] (2) drying the mixed solution of sodium polyacrylate / polydopamine at 100° C. for 4 hours; and crushing and ball milling to obtain water-absorbent sodium polyacrylate / polydopamine powder with a diameter of 1 to 3 μm.

[0034] (3) 20 parts of sodium polyacrylate / polydopamine powder and 80 parts of thermoplastic elastomer are put into a high-speed mixer at a temperature of 60° C. for 30 min; the mixture is uniformly mixed and melt-blended and granulated at 165° C. using a twin-screw extruder to obtain a sodium polyacrylate / polydopamine gel powder modified thermoplastic elastomer.

[0035] The obtained pellets were placed in a mold, and hot pressed in a flat vulcanized bed for 15 minutes at a molding temperature of 170°C and a pressure of 20MPa to obtain a sample for performance testing. The obtained product was tested for dry friction coefficient and wet friction coefficient according to GB / T 3903.37-2008, and for tensile strength and elongation at break according to GB / T 1040-2006. The dry friction coefficient was 0.73, the wet friction coefficient was 0.96, the tensile strength was 2.7MPa, and the elongation at break was 590%.

[0036] Comparative Example 1

[0037] This comparative example provides a thermoplastic elastomer material TPE, which is the pure TPE in Example 1; the pure TPE is placed in a mold, and hot pressed in a flat vulcanized bed for 15 minutes under the conditions of a molding temperature of 170°C and a pressure of 20MPa to obtain a sample for performance testing. The obtained product is tested for dry friction coefficient and wet friction coefficient according to GB / T 3903.37-2008 standard, and for tensile strength and elongation at break according to GB / T1040-2006 standard, and the dry friction coefficient is measured to be 0.35, the wet friction coefficient is 0.24, the tensile strength is 3.1MPa, and the elongation at break is 650%.

[0038] Comparative Example 2

[0039] This embodiment prepares a sodium polyacrylate modified thermoplastic elastomer TPE, which differs from the embodiment 1 in that steps (1) and (2) are omitted, and the preparation steps are as follows:

[0040] 20 parts of sodium polyacrylate are directly dried and ground into micro powder with a diameter of 1 to 3 μm, and 80 parts of thermoplastic elastomer are put into a high-speed mixer at a temperature of 60° C. and a mixing time of 30 minutes; the mixture is evenly mixed, and a twin-screw extruder is used to melt-blend and granulate at 165° C. to obtain a sodium polyacrylate modified thermoplastic elastomer.

[0041] The obtained pellets were placed in a mold, and hot pressed in a flat vulcanized bed for 15 minutes at a molding temperature of 170°C and a pressure of 20MPa to obtain a sample for performance testing. The obtained product was tested for dry friction coefficient and wet friction coefficient according to GB / T 3903.37-2008, and for tensile strength and elongation at break according to GB / T 1040-2006. The dry friction coefficient was 0.29, the wet friction coefficient was 0.56, the tensile strength was 1.8MPa, and the elongation at break was 350%.

[0042] Figure 1 The cross-sectional SEM images are shown in Figure A, where Figure A is Comparative Example 2 and Figure B is Example 1. As shown in Figure A, a large amount of sodium polyacrylate was found to be agglomerated in Comparative Example 2, and its compatibility with the matrix TPE was poor; Figure B is Example 1, where after polydopamine was introduced during the preparation process, sodium polyacrylate\polydopamine was evenly dispersed in TPE, which greatly improved the compatibility of sodium polyacrylate and TPE, which were originally completely incompatible.

[0043] Figure 2The contact angle diagram is shown in Figure 1, where Picture A is Comparative Example 1 (pure TPE), Picture B is Comparative Example 2, and Picture C is Example 1. It can be seen from the figure that the contact angle of the sample prepared by pure TPE is 99.3°, and the hydrophilicity is poor. Comparative Example 2 is only modified by blending with sodium polyacrylate, and the contact angle of the sample is 64.4°. This is because sodium polyacrylate has water absorption and hydrophilicity, so the hydrophilicity of the sample modified by physical blending (Comparative Example 2) is increased; after the introduction of dopamine (Example 1), the compatibility of sodium polyacrylate and TPE is better, and polydopamine contains more hydrophilic groups, and the contact angle of the sample is 44.6°, and the hydrophilicity is further increased.

[0044] Figure 3 The following are sample photos, where Figure A is Comparative Example 1, Figure B is Comparative Example 2, and Figure C is a sample photo of Example 1. It can be seen from the figure that the pure TPE sample of Comparative Example 1 is white; Comparative Example 2 is only modified by blending with sodium polyacrylate, and the color is basically unchanged; Example 1 introduces polydopamine, and the color becomes darker.

[0045] Example 2

[0046] This embodiment provides a method for preparing a sodium polyacrylate / polydopamine powder-modified thermoplastic elastomer TPE, the steps of which are as follows:

[0047] (1) 0.5 parts of dopamine hydrochloride are added to 100 parts of deionized water, and the dopamine hydrochloride is dissolved by stirring to obtain an aqueous solution of dopamine hydrochloride. 30 parts of a 50% sodium polyacrylate aqueous solution are added to the aqueous solution of dopamine hydrochloride, and after mixing evenly, a Tris-HCl buffer solution is added to adjust the pH value to 8.5, and then the solution is allowed to stand at 30° C. for 12 hours. During this process, due to the alkaline environment provided by the buffer solution, the dopamine hydrochloride is polymerized in situ to generate polydopamine, thereby obtaining a mixed solution containing sodium polyacrylate / polydopamine.

[0048] (2) drying the mixed solution of sodium polyacrylate / polydopamine at 60° C. for 10 h; and crushing and ball milling to obtain water-absorbent sodium polyacrylate / polydopamine powder with a diameter of 1 to 3 μm.

[0049] (3) 5 parts of sodium polyacrylate / polydopamine powder and 95 parts of thermoplastic elastomer are put into a high-speed mixer at a temperature of 30° C. for a mixing time of 120 min; the mixture is uniformly mixed, and melt-blended and granulated at 175° C. using a twin-screw extruder to obtain a sodium polyacrylate / polydopamine gel powder modified thermoplastic elastomer.

[0050] The obtained pellets were placed in a mold, and hot pressed in a flat vulcanized bed for 15 minutes at a molding temperature of 170°C and a pressure of 20MPa to obtain a sample for performance testing. The obtained product was tested for dry friction coefficient and wet friction coefficient according to GB / T 3903.37-2008, and for tensile strength and elongation at break according to GB / T 1040-2006. The dry friction coefficient was 0.54, the wet friction coefficient was 0.69, the tensile strength was 3.2MPa, and the elongation at break was 572%.

[0051] Example 3

[0052] This embodiment provides a method for preparing a sodium polyacrylate / polydopamine powder-modified thermoplastic elastomer TPE, the steps of which are as follows:

[0053] (1) 2 parts of dopamine hydrochloride are added to 100 parts of deionized water, and the dopamine hydrochloride is dissolved by stirring to obtain an aqueous solution of dopamine hydrochloride. 40 parts of a 30% by mass sodium polyacrylate aqueous solution are added to the aqueous solution of dopamine hydrochloride, and after mixing evenly, a tris-hydroxymethylaminomethane-hydrochloric acid buffer solution (Tris-HCl buffer solution) is added to adjust the pH value to 8.5, and then the solution is allowed to stand at 40° C. for 10 hours. During this process, due to the alkaline environment provided by the buffer solution, dopamine hydrochloride is polymerized in situ to generate polydopamine, thereby obtaining a mixed solution containing sodium polyacrylate / polydopamine.

[0054] (2) drying the mixed solution of sodium polyacrylate / polydopamine at 80° C. for 7 hours; and crushing and ball milling to obtain water-absorbent sodium polyacrylate / polydopamine powder with a diameter of 1 to 3 μm.

[0055] (3) 10 parts of sodium polyacrylate / polydopamine powder and 90 parts of thermoplastic elastomer are put into a high-speed mixer at a temperature of 50° C. for 90 min; the mixture is evenly mixed, and melt-blended and granulated at 170° C. using a twin-screw extruder to obtain a sodium polyacrylate / polydopamine gel powder modified thermoplastic elastomer.

[0056] The obtained pellets were placed in a mold, and hot pressed in a flat vulcanized bed for 15 minutes at a molding temperature of 170°C and a pressure of 20MPa to obtain a sample for performance testing. The obtained product was tested for dry friction coefficient and wet friction coefficient according to GB / T 3903.37-2008, and for tensile strength and elongation at break according to GB / T 1040-2006. The dry friction coefficient was 0.58, the wet friction coefficient was 0.77, the tensile strength was 3.0MPa, and the elongation at break was 630%.

[0057] Example 4

[0058] This embodiment provides a method for preparing a sodium polyacrylate / polydopamine powder-modified thermoplastic elastomer TPE, the steps of which are as follows:

[0059] (1) 3 parts of dopamine hydrochloride are added to 100 parts of deionized water, and the dopamine hydrochloride is dissolved by stirring to obtain an aqueous solution of dopamine hydrochloride. 45 parts of a 40% sodium polyacrylate aqueous solution are added to the aqueous solution of dopamine hydrochloride, and after mixing evenly, a Tris-HCl buffer solution is added to adjust the pH value to 8.5, and then the solution is allowed to stand at 45° C. for 9 hours. During this process, due to the alkaline environment provided by the buffer solution, the dopamine hydrochloride is polymerized in situ to generate polydopamine, thereby obtaining a mixed solution containing sodium polyacrylate / polydopamine.

[0060] (2) drying the mixed solution of sodium polyacrylate / polydopamine at 73° C. for 8 h; and crushing and ball milling to obtain water-absorbent sodium polyacrylate / polydopamine powder with a diameter of 1 to 3 μm.

[0061] (3) 12 parts of sodium polyacrylate / polydopamine powder and 88 parts of thermoplastic elastomer are put into a high-speed mixer at a temperature of 55° C. for 80 min; the mixture is uniformly mixed and melt-blended and granulated at 168° C. using a twin-screw extruder to obtain a sodium polyacrylate / polydopamine gel powder modified thermoplastic elastomer.

[0062] The obtained pellets were placed in a mold, and hot pressed in a flat vulcanized bed for 15 minutes at a molding temperature of 170°C and a pressure of 20MPa to obtain a sample for performance testing. The obtained product was tested for dry friction coefficient and wet friction coefficient according to GB / T 3903.37-2008, and for tensile strength and elongation at break according to GB / T 1040-2006. The dry friction coefficient was 0.55, the wet friction coefficient was 0.73, the tensile strength was 2.85MPa, and the elongation at break was 615%.

[0063] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a sodium polyacrylate / polydopamine powder modified thermoplastic elastomer TPE, characterized in that: The following steps are involved: (1) dissolving dopamine hydrochloride in deionized water and then mixing the mixture evenly with a sodium polyacrylate aqueous solution, and then adjusting the pH to alkaline using a tris(hydroxymethyl)aminomethane-hydrochloric acid buffer solution to obtain a mixed solution containing sodium polyacrylate / polydopamine; (2) drying and grinding the mixed solution containing sodium polyacrylate / polydopamine in step (1) into sodium polyacrylate / polydopamine powder by ball milling; (3) The sodium polyacrylate / polydopamine powder of step (2) and the thermoplastic elastomer TPE are uniformly mixed, melt-extruded and granulated to obtain the sodium polyacrylate / polydopamine gel micropowder modified thermoplastic elastomer TPE.

2. The method for preparing the sodium polyacrylate / polydopamine powder modified thermoplastic elastomer TPE according to claim 1, characterized in that: In the step (1), the mass ratio of dopamine hydrochloride, deionized water and sodium polyacrylate aqueous solution is 0.5-4:100:30-50, and the concentration of the sodium polyacrylate aqueous solution is 20-50wt%.

3. The method for preparing the sodium polyacrylate / polydopamine powder modified thermoplastic elastomer TPE according to claim 1 or 2, characterized in that: The pH in the step (1) is 8.

5.

4. The method for preparing the sodium polyacrylate / polydopamine powder modified thermoplastic elastomer TPE according to claim 1, characterized in that: The reaction temperature in step (1) is 30-50°C and the reaction time is 6-12h.

5. The method for preparing the sodium polyacrylate / polydopamine powder modified thermoplastic elastomer TPE according to claim 1, characterized in that: The drying temperature in step (2) is 60-100° C. and the drying time is 4-10 hours.

6. The method for preparing the sodium polyacrylate / polydopamine powder modified thermoplastic elastomer TPE according to claim 1, characterized in that: The particle size of the powder in step (2) is 1-3 μm.

7. The method for preparing the sodium polyacrylate / polydopamine powder modified thermoplastic elastomer TPE according to claim 1, characterized in that: In the step (3), the mass ratio of sodium polyacrylate / polydopamine powder to thermoplastic elastomer TPE is 5-20:80-95.

8. The method for preparing the sodium polyacrylate / polydopamine powder modified thermoplastic elastomer TPE according to claim 1, characterized in that: The mixing temperature in step (2) is 30-60°C, the mixing time is 30-120 min, and the melt extrusion temperature is 165-175°C.

9. Sodium polyacrylate / polydopamine powder modified thermoplastic elastomer TPE prepared by the method according to any one of claims 1 to 8.

10. Use of the sodium polyacrylate / polydopamine powder modified thermoplastic elastomer TPE according to claim 9 in floor mats.

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