A high-toughness SMMA composite material and its preparation method

Abstract

The present invention discloses a high-toughness SMMA composite material and a preparation method thereof. Preparation method: Mix SMMA, TPU and SMA by kneading at 225 - 235 °C. The obtained blend is crushed and dried, and then placed in a flat vulcanizing machine. The temperature of the flat vulcanizing machine is set at 225 - 235 °C, and the pressure is set at 9 - 11 MPa. After hot pressing for 9 - 11 minutes, it is cold pressed at room temperature for 4 - 6 minutes under a pressure of 9 - 11 MPa for shaping, so as to obtain the high-toughness SMMA composite material; based on the total mass of SMMA and TPU being 100%, the mass percentage content of SMMA is 60% - 70%, the mass percentage content of TPU is 30% - 40%, and the mass percentage content of SMA is 1% - 5%. The notched impact toughness of the high-toughness SMMA composite material of the present invention is greater than 3 kJ / m<supgt;2< / supgt>, and the unnotched impact toughness is greater than 10 kJ / m<supgt;2< / supgt>.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials, and particularly relates to a high-toughness SMMA composite material and a preparation method thereof. Background Art

[0002] Polymer materials have been widely used in all aspects of human production and life in the past more than one hundred years. Polymer materials have excellent properties, low density, easy processing and other advantages. However, for most polymer materials, poor toughness often becomes the key factor restricting their application.

[0003] Styrene dimethyl methacrylate copolymer (SMMA), as a vitreous plastic, has a series of advantages such as high strength, easy processing, and high surface gloss. However, due to the presence of a large number of rigid groups in the molecular chain, its toughness is extremely poor. For this reason, the further wide application of SMMA is restricted. From the perspective of energy dissipation, when SMMA is impacted, energy dissipation mainly occurs in the form of crazes. Moreover, the compatibility between SMMA and commonly used elastomers such as POE and TPU (thermoplastic polyurethane elastomer) is very poor. Therefore, it is very difficult to induce a shear yield band in the SMMA matrix by simply adding an elastomer, thereby dissipating a large amount of energy and improving its impact performance.

[0004] The patent specification with the publication number CN 116120679 A discloses a high-toughness SMMA microcellular foaming material and a preparation method thereof. The notched impact strength of the high-toughness SMMA microcellular foaming material is above 2 KJ / m 2 2, the elongation at break is greater than 2.5%, the weight loss rate is above 25%, the average cell size is less than 40 microns, and the cell density is greater than 10 7 cells / cm 3 3. The preparation method includes: blending and extruding 60wt%-90wt% of SMMA, 10wt%-40wt% of elastomer SBS, and 0-5wt% of nucleating agent through a twin-screw extruder. After the obtained composite material is dried, it is added to a foaming injection molding machine. The foaming gas pressure is 4-10 MPa, and pre-plasticization is carried out to obtain a uniform melt of the composite material and a melt of gas. Then it is injected into the mold cavity, pressure is maintained, and then the mold is opened for foaming and cooling to obtain the high-toughness SMMA microcellular foaming material.

[0005] Jiang Zhongying et al. dissolved polystyrene-methyl methacrylate copolymer (SMMA, containing 40 wt% polystyrene) and polystyrene-maleic anhydride copolymer (SMA, containing 7 wt% maleic anhydride MA) in tetrahydrofuran solvent, and then obtained the SMMA / SMA mixture by casting and drying, and further studied the thermal dynamic characteristics of the free volume of the mixture and the PALS study on phase separation behavior (Acta Physica Sinica, Vol. 55, No. 6, June 2006). Summary of the Invention

[0006] The present invention provides a preparation method of a high-toughness SMMA composite material. Aiming at the problem of poor compatibility between SMMA and TPU (especially TPU without benzene ring structure), SMA is used for compatibilization. The benzene ring and maleic anhydride groups on SMA are used for bridging, shortening the reaction distance with the polar groups of SMMA and TPU, and improving the compatibility between the elastomeric groups of SMMA and TPU, so as to achieve the effect of improving impact toughness.

[0007] The specific technical solution is as follows:

[0008] A preparation method of a high-toughness SMMA composite material, wherein SMMA, TPU and SMA are melt-blended by internal mixer at 225-235°C. The obtained blend is crushed and dried and then placed in a flat vulcanizing machine. The temperature of the flat vulcanizing machine is set at 225-235°C, the pressure is set at 9-11 MPa, after hot pressing for 9-11 minutes, cold pressing is carried out at room temperature under a pressure of 9-11 MPa for 4-6 minutes for shaping, so as to obtain the high-toughness SMMA composite material;

[0009] Calculated based on the total mass of SMMA and TPU being 100%, the mass percentage content of SMMA is 60%-70%, the mass percentage content of TPU is 30%-40%, and the mass percentage content of SMA is 1%-5%.

[0010] The preparation method of the present invention adopts the process of internal mixer melt-blending - hot pressing reaction - cold pressing shaping. Among them: the temperature of internal mixer melt-blending and the temperature of the flat vulcanizing machine are set at 225-235°C. If the temperature is too high, SMMA, TPU and SMA are prone to decomposition. If the temperature is too low, it is difficult or even impossible to process; the pressure of the flat vulcanizing machine is set at 9-11 MPa. If the pressure is too low, the product will have depressions and the surface will be uneven; the hot pressing time of the flat vulcanizing machine is 9-11 minutes. If the time is too short, the melt-blended mixture of SMMA, TPU and SMA is not thoroughly melted. If the time is too long, SMMA, TPU and SMA are prone to degradation; the room temperature cold pressing process is used for product shaping, and sufficient pressure and time are required. If the pressure is too small or the time is too short, it is difficult or even impossible to shape.

[0011] The present invention also defines the composition ratios of SMMA, TPU, and SMA in the high-toughness SMMA composite material. Based on the total mass of SMMA and TPU being 100%, the mass percentage content of SMMA is 60% - 70%, the mass percentage content of TPU is 30% - 40%, and the mass percentage content of SMA is 1% - 5%. Excessive SMMA will result in poor toughness of the composite material, while excessive TPU will lead to poor rigidity of the composite material. Under the above-mentioned preparation process of internal mixer blending - hot pressing reaction - cold pressing shaping in the present invention, only 1% - 5% of SMA (based on the total mass of SMMA and TPU being 100%) can exhibit excellent compatibility effect. Further increasing the dosage, the improvement effect of the toughness of the composite material is not obvious. Too low dosage of SMA will lead to insufficient compatibility and poor toughness of the composite material.

[0012] In a preferred example, for the preparation method of the high-toughness SMMA composite material, the content of styrene in the SMMA is 45wt% - 55wt%. In this range, the SMMA can have better rigidity.

[0013] In order to obtain better toughening effect, in a preferred example, for the preparation method of the high-toughness SMMA composite material, the Shore hardness of the TPU is 65A - 95A. Too soft or too hard TPU has poor toughening effect on SMMA.

[0014] In a preferred example, for the preparation method of the high-toughness SMMA composite material, the content of maleic anhydride in the SMA is 15wt% - 40wt%. This can not only provide sufficient compatibility but also prevent the SMA from being easily decomposed during the preparation process.

[0015] In a preferred example, for the preparation method of the high-toughness SMMA composite material, the internal mixing time is 10 - 20 min, which is beneficial to ensuring good dispersion of SMMA, TPU, and SMA and forming a uniformly mixed blend.

[0016] In a preferred example, for the preparation method of the high-toughness SMMA composite material, the internal mixing is carried out in an internal mixer, and the rotation speed of the internal mixer is 40 - 80 rpm, which is beneficial to ensuring good dispersion of SMMA, TPU, and SMA and forming a uniformly mixed blend.

[0017] In a preferred example, for the preparation method of the high-toughness SMMA composite material, the drying temperature is 60 - 80 °C and the time is 6 - 8 h.

[0018] As a general inventive concept, the present invention also provides the high-toughness SMMA composite material prepared by the described preparation method.

[0019] The notched impact toughness of the high-toughness SMMA composite material described in the present invention is greater than 3 kJ / m 2 , and the unnotched impact toughness is greater than 10 kJ / m 2 . Test standard: GB / T 1834-1996.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] Aiming at the problem of poor compatibility between SMMA and TPU (especially TPU without benzene ring structure), the present invention uses SMA for compatibilization. On the basis of limiting the dosage ratio of SMMA and TPU to ensure that the composite material can take into account toughness and rigidity, through a specific internal mixer blending - hot pressing reaction - cold pressing shaping process, SMA can play a significant compatibilizing role at a lower dosage.

[0022] The present invention utilizes the bridging effect of the benzene ring and maleic anhydride groups on SMA to shorten the reaction distance with the polar groups of SMMA and TPU, improve the compatibility between the elastomer groups of SMMA and TPU, and thus achieve the effect of improving impact toughness. Description of the Drawings

[0023] Figure 1 It is a scanning electron microscope (SEM) photograph of the high-toughness SMMA composite material prepared in Example 2.

[0024] Figure 2 It is a scanning electron microscope photograph of the high-toughness SMMA composite material prepared in Example 3.

[0025] Figure 3 It is a scanning electron microscope photograph of the high-toughness SMMA composite material prepared in Example 4.

[0026] Figure 4 It is a scanning electron microscope photograph of the SMMA composite material prepared in Comparative Example 2. Detailed Embodiments

[0027] The present invention will be further described below in conjunction with the drawings and specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention.

[0028] For the operation methods without specific conditions noted in the following embodiments, they are usually carried out under conventional conditions or according to the conditions recommended by the manufacturer.

[0029] Unless otherwise specified, "parts" in the following embodiments and comparative examples all refer to parts by mass.

[0030] The notched impact toughness and unnotched impact toughness in the following embodiments and comparative examples are tested according to the GB / T1834-1996 standard.

[0031] Example 1

[0032] Preparation of a 70SMMA / 30TPU / 3SMA blend by blending 70 parts of SMMA (styrene content 50 wt%) with 30 parts of TPU (Shore hardness 95A) and 3 parts of SMA (maleic anhydride content 15 wt%).

[0033] Blend 70 parts of SMMA, 30 parts of TPU and 3 parts of SMA in a Banbury mixer at a mixing speed of 60 rpm, a temperature of 230 °C and a mixing time of 10 min.

[0034] Crush the blend obtained from the Banbury mixer and dry it in an oven at 80 °C for 8 hours.

[0035] Place the dried material in a flat vulcanizing machine and hot press it at 230 °C and a pressure of 10 MPa for 10 min, then cold press it at room temperature under a pressure of 10 MPa for 5 min in another flat vulcanizing machine to obtain a high toughness SMMA composite material.

[0036] Analyze and characterize the properties of the high toughness SMMA composite material prepared in this example. Its notched impact strength is 3.62 kJ / m 2 , and its unnotched impact strength is 13.5 kJ / m 2 . It can be found by SEM characterization that introducing SMA according to the preparation process of the present invention plays a good compatibilizing role, and there is no obvious phase interface between the SMMA matrix and TPU.

[0037] Example 2

[0038] Preparation of a 60SMMA / 40TPU / 1SMA blend by blending 60 parts of SMMA (styrene content 50 wt%) with 40 parts of TPU (Shore hardness 95A) and 1 part of SMA (maleic anhydride content 15 wt%).

[0039] Blend 60 parts of SMMA, 40 parts of TPU and 1 part of SMA in a Banbury mixer at a mixing speed of 60 rpm, a temperature of 230 °C and a mixing time of 10 min.

[0040] Crush the blend obtained from the Banbury mixer and dry it in an oven at 80 °C for 8 hours.

[0041] Place the dried material in a flat vulcanizing machine and hot press it at 230 °C and a pressure of 10 MPa for 10 min, then cold press it at room temperature under a pressure of 10 MPa for 5 min in another flat vulcanizing machine to obtain a high toughness SMMA composite material.

[0042] The properties of the high-toughness SMMA composite material prepared in this example were analyzed and characterized. Its notched impact strength was 3.24 kJ / m 2 , and its unnotched impact strength was 26.9 kJ / m 2 . It can be found through SEM characterization that introducing SMA according to the preparation process of the present invention played a good compatibilizing role, and there was no obvious phase interface between the SMMA matrix and TPU, as Figure 1 shown.

[0043] Example 3

[0044] Preparation of a 60SMMA / 40TPU / 3SMA blend by blending 60 parts of SMMA (styrene content 50 wt%), 40 parts of TPU (Shore hardness 95A), and 3 parts of SMA (maleic anhydride content 15 wt%).

[0045] 60 parts of SMMA, 40 parts of TPU, and 3 parts of SMA were blended by a kneader at a kneading speed of 60 rpm, a temperature of 230 °C, and a kneading time of 10 min.

[0046] The blend obtained by kneading was pulverized by a pulverizer and then dried in an oven at 80 °C for 8 hours.

[0047] The dried material was hot-pressed in a flat vulcanizer at 230 °C and a pressure of 10 MPa for 10 min, and then cold-pressed at room temperature under a pressure of 10 MPa for 5 min in another flat vulcanizer to obtain a high-toughness SMMA composite material.

[0048] The properties of the high-toughness SMMA composite material prepared in this example were analyzed and characterized. Its notched impact strength was 3.48 kJ / m 2 , and its unnotched impact strength was 35.9 kJ / m 2 . It can be found through SEM characterization that introducing SMA according to the preparation process of the present invention played a good compatibilizing role, and there was no obvious phase interface between the SMMA matrix and TPU. Compared with Example 2, the compatibility between the phase interfaces was further improved, as Figure 2 shown.

[0049] Example 4

[0050] Preparation of a 60SMMA / 40TPU / 5SMA blend by blending 60 parts of SMMA (styrene content 50 wt%), 40 parts of TPU (Shore hardness 95A), and 5 parts of SMA (maleic anhydride content 15 wt%).

[0051] 60 parts of SMMA, 40 parts of TPU, and 5 parts of SMA were blended by a kneader at a kneading speed of 60 rpm, a temperature of 230 °C, and a kneading time of 10 min.

[0052] The blend obtained by melt blending was crushed by a crusher and then dried in an oven at 80 °C for 8 hours.

[0053] The dried material was hot-pressed in a flat vulcanizer at 230 °C under a pressure of 10 MPa for 10 min, and then cold-pressed at room temperature under a pressure of 10 MPa for 5 min in another flat vulcanizer to shape, obtaining a high-toughness SMMA composite material.

[0054] The properties of the high-toughness SMMA composite material prepared in this example were analyzed and characterized. Its notched impact strength was 3.61 kJ / m 2 , and the unnotched impact strength was 40.8 kJ / m 2 . It can be found through SEM characterization that introducing SMA according to the preparation process of the present invention played a good compatibilizing role, and there was no obvious phase interface between the SMMA matrix and TPU. Compared with Example 3, the compatibility between the phase interfaces was further improved, as Figure 3 shown.

[0055] Comparative Example 1

[0056] Preparation of a 70SMMA / 30TPU blend by blending 70 parts of SMMA (styrene content 50 wt%) with 30 parts of TPU (Shore hardness 95A).

[0057] 70 parts of SMMA and 30 parts of TPU were melt blended by a mixer at a mixing speed of 60 rpm, a temperature of 230 °C, and a mixing time of 10 min.

[0058] The blend obtained by melt blending was crushed by a crusher and then dried in an oven at 80 °C for 8 hours.

[0059] The dried material was hot-pressed in a flat vulcanizer at 230 °C under a pressure of 10 MPa for 10 min, and then cold-pressed at room temperature under a pressure of 10 MPa for 5 min in another flat vulcanizer to shape, obtaining a SMMA composite material with high toughness.

[0060] The properties of the SMMA composite material prepared in this comparative example were analyzed and characterized. Its notched impact strength was 1.55 kJ / m 2 , and the unnotched impact strength was 3.7 kJ / m 2 . It can be found through SEM characterization that the phase interface between the SMMA matrix and TPU was obvious, and the compatibility was significantly poor.

[0061] Comparative Example 2

[0062] Preparation of a 60SMMA / 40TPU blend by blending 60 parts of SMMA (styrene content 50 wt%) with 40 parts of TPU (Shore hardness 95A).

[0063] 60 parts of SMMA and 40 parts of TPU were blended by a Banbury mixer at a mixing speed of 60 rpm, a temperature of 230 °C, and a mixing time of 10 min.

[0064] The blend obtained from the Banbury mixing was crushed by a crusher and then dried in an oven at 80 °C for 8 hours.

[0065] The dried material was hot-pressed in a flat vulcanizer at 230 °C and a pressure of 10 MPa for 10 min, and then cold-pressed at room temperature under a pressure of 10 MPa for 5 min in another flat vulcanizer for shaping, to obtain a high-toughness SMMA composite material.

[0066] The properties of the SMMA composite material prepared in this comparative example were analyzed and characterized. Its notched impact strength was 2.38 kJ / m 2 , and its unnotched impact strength was 4.7 kJ / m 2 . It can be found through SEM characterization that the phase interface between the SMMA matrix and TPU is obvious, and the compatibility is significantly poor, as Figure 4 shown.

[0067] In addition, it should be understood that after reading the above description of the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of this application.

Claims

1. A preparation method of a high-toughness SMMA composite material, characterized in that, SMMA, TPU and SMA are melt-blended in a mixer at 225 - 235 °C. The resulting blend is crushed and dried, and then placed in a flat vulcanizing machine. The temperature of the flat vulcanizing machine is set at 225 - 235 °C, and the pressure is set at 9 - 11 MPa. After hot pressing for 9 - 11 minutes, it is cold pressed at room temperature under a pressure of 9 - 11 MPa for 4 - 6 minutes for shaping, thus obtaining the high-toughness SMMA composite material; Based on the total mass of SMMA and TPU being 100%, the mass percentage of SMMA is 60% - 70%, the mass percentage of TPU is 30% - 40%, and the mass percentage of SMA is 1% - 5%; The content of styrene in the SMMA is 45 wt% - 55 wt%; The Shore hardness of the TPU is 65A - 95A; The content of maleic anhydride in the SMA is 15 wt% - 40 wt%; The notched impact toughness of the described high-toughness SMMA composite material is greater than 3 kJ / m 2 , and the unnotched impact toughness is greater than 10 kJ / m 2 .

2. The preparation method of the high-toughness SMMA composite material according to claim 1, wherein, The time of melt-blending is 10 - 20 min.

3. The preparation method of the high-toughness SMMA composite material according to claim 1, characterized in that, The melt-blending is carried out in a mixer, and the rotation speed of the mixer is 40 - 80 rpm.

4. The preparation method of the high-toughness SMMA composite material according to claim 1, wherein, The temperature of drying is 60 - 80 °C, and the time is 6 - 8 h.

5. A high-toughness SMMA composite material prepared by the preparation method according to any one of claims 1 - 4.

Images