A modified polyester for improving plastic toughness, heat resistance and oil resistance and preparation method thereof

Abstract

The present invention provides a modified polyester for improving the toughness, heat resistance and oil resistance of plastics and a preparation method thereof. The modified polyester comprises the following components in parts by weight: 100 parts of polyester resin, 1-10 parts of a composite modifier and 0-5 parts of an auxiliary agent, wherein the composite modifier comprises at least one of a coupling agent and modified titanium dioxide. The present invention uses a coupling agent and modified titanium dioxide to modify the polyester resin to functionalize the polyester surface. The formed modified polyester contains groups such as ester groups, hydroxyl groups, and silicon oxygen bonds, has good compatibility with PVC, and the polyester molecules can effectively entangle with the PVC molecular chains. It has the advantages of good thermal stability, good oil resistance, etc., and can play a good plasticizing effect in PVC sheets.

Description

Technical Field

[0001] The invention relates to the technical field of polymer materials, and in particular to a modified polyester for improving the toughness, heat resistance and oil resistance of plastics and a preparation method thereof. Background Art

[0002] Polyester is a polymer obtained by the condensation of polyols and polyacids. It has the characteristics of high molecular weight, low volatility, low migration, oil resistance and resistance to soap and water extraction. It has been widely used in oil-resistant cables, gas pipes, waterproof membranes, artificial leather, shoe materials, high-temperature resistant wire coatings, water tank sealing strips, gaskets and moldings of various equipment (including refrigeration equipment and motor vehicles), high-end interior decorations, and special products that are resistant to oil and gasoline.

[0003] However, existing polyesters are mainly composed of carbon and hydrogen elements, have a low limiting oxygen index (LOI), are very easy to burn, have poor flame retardancy and heat resistance, produce a lot of harmful smoke when burned, and the resin's own charring ability is very poor. In addition, this type of polyester resin has poor degradability and mechanical properties. Summary of the invention

[0004] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a modified polyester for improving the toughness, temperature resistance and oil resistance of plastics and a preparation method thereof.

[0005] In the first aspect, the present invention provides a modified polyester for improving the toughness, heat resistance and oil resistance of plastics. A modified polyester for improving the toughness, heat resistance and oil resistance of plastics is characterized in that it includes the following components in parts by weight: 100 parts of polyester resin, 1-10 parts of composite modifier and 0-5 parts of auxiliary agent, wherein the composite modifier includes a coupling agent and modified titanium dioxide.

[0006] As a preferred embodiment of the present invention, the coupling agent is a silane coupling agent, preferably 3-aminopropyltriethoxysilane.

[0007] As a preferred embodiment of the present invention, the modified titanium dioxide is formed by coating the surface of unsaturated oil alcoholysis product with titanium dioxide.

[0008] As a preferred embodiment of the present invention, the preparation method of the modified titanium dioxide is: adding n-butyl titanate to anhydrous ethanol, mixing and preparing dispersion A; adding unsaturated oil alcoholysis product to anhydrous ethanol, mixing and preparing dispersion B; adding dispersion B dropwise to dispersion A at 70-85°C, and after the dropwise addition is completed, reflux reaction is carried out at 70-85°C for 8-12 hours; and the modified titanium dioxide is obtained after drying.

[0009] Furthermore, the mass ratio of the unsaturated oil alcoholysate in the dispersion B to the n-butyl titanate in the dispersion A is (0.2-2):1.

[0010] Furthermore, the preparation method of the unsaturated oil alcoholysate is: at 240-255° C., glycerol and unsaturated oil are reacted under the catalysis of a catalyst for 4-6 hours to obtain the unsaturated oil alcoholysate, wherein the mass ratio of the glycerol to the unsaturated oil is (2-4):1, and the mass of the catalyst accounts for 0.1-0.5% of the total mass of the glycerol and the unsaturated oil; the catalyst includes lithium hydroxide.

[0011] During the research, the inventor unexpectedly discovered that glycerol and unsaturated oils undergo alcoholysis reaction under catalysis at high temperature. After the surface of the unsaturated oil alcoholysis product obtained by the reaction is coated with modified titanium dioxide, the temperature resistance and mechanical properties of polyester can be effectively improved.

[0012] As a preferred embodiment of the present invention, the composite modifier includes a coupling agent and modified titanium dioxide, and the mass ratio of the coupling agent to the modified titanium dioxide is (0.1-0.5):1.

[0013] As a preferred embodiment of the present invention, the modified polyester comprises the following components in parts by weight: 100 parts of polyester resin, 3-6 parts of composite modifier and 0.5-1 part of auxiliary agent.

[0014] As a preferred embodiment of the present invention, the auxiliary agent includes at least one of zinc stearate, an antioxidant, a lubricant, and a compatibilizer.

[0015] In a second aspect, the present invention provides a method for preparing the modified polyester as described in the first aspect, comprising the following steps:

[0016] After the components are mixed, they are melt-extruded, drawn, cooled, pelletized and dried in a twin-screw extruder to obtain the modified polyester.

[0017] As a preferred embodiment of the present invention, the temperature of the melt extrusion is 200-260° C. and the rotation speed is 200-500 rpm.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] The present invention adopts coupling agent and modified titanium dioxide to modify polyester resin, so that the polyester surface is functionalized. The formed modified polyester contains ester group, hydroxyl group, silicon oxygen bond and other groups, has good compatibility with PVC, polyester molecules can effectively entangle with PVC molecular chains, has the advantages of good thermal stability, good oil resistance and the like, and can play a good plasticizing effect in PVC sheets. DETAILED DESCRIPTION

[0020] In order to better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments and comparative examples, the purpose of which is to understand the content of the present invention in detail, rather than to limit the present invention. All other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0021] Unless otherwise specified, the experimental reagents and instruments involved in the implementation of the present invention are all commonly used ordinary reagents and instruments.

[0022] Example 1

[0023] The embodiment of the modified polyester of the present invention, the preparation method of the modified polyester is:

[0024] S1, stirring glycerol, dehydrated castor oil and lithium hydroxide at a mass ratio of glycerol: dehydrated castor oil: lithium hydroxide = 3:1:0.006 at 100 rpm and 245°C for 5 hours, and naturally cooling to obtain an unsaturated oil alcoholysis product;

[0025] S2. Add n-butyl titanate to anhydrous ethanol, mix evenly, and prepare dispersion A; add the unsaturated oil alcoholysis product obtained in step S1 to anhydrous ethanol, mix evenly, and prepare dispersion B; at 80° C., uniformly drop dispersion B into dispersion A for 30 minutes, and continue to reflux at 80° C. for 10 hours after the dropwise addition; then use a rotary evaporator to evaporate the ethanol to obtain modified titanium dioxide particles; the mass ratio of dispersion B to dispersion A is 1:1, and the mass ratio of the unsaturated oil alcoholysis product in dispersion B to n-butyl titanate in dispersion A is 1:1.

[0026] S3, mixing 3-aminopropyltriethoxysilane, anhydrous ethanol and deionized water in a mass ratio of 3-aminopropyltriethoxysilane: anhydrous ethanol: deionized water = 1:20:2, and stirring at 60° C. and 100 rpm for 30 min to obtain a coupling mixture;

[0027] S4, adding the modified titanium dioxide particles obtained in step S2 to the coupling mixture obtained in step S3, wherein the mass ratio of 3-aminopropyltriethoxysilane to the modified titanium dioxide particles obtained in step S2 in the coupling mixture obtained in step S3 is 0.2:1, stirring at 80°C at a speed of 100 rpm for 3 hours, filtering and taking the filter residue, drying the filter residue at 80°C for 12 hours, and crushing it to a particle size of no more than 0.5 μm to obtain a composite modifier;

[0028] S5, drying the polyester resin at 130°C for 4h to obtain a dried polyester resin; adding the following components in parts by weight into a high-speed mixer for mixing: 100 parts of the dried polyester resin, 3 parts of the composite modifier obtained in step S4, and 0.5 parts of zinc stearate, the mixing speed is 300rpm, and the mixing time is 20min; then transferring to a twin-screw extruder for melt extrusion, stranding, cooling, pelletizing, and drying to obtain a modified polyester, the speed of the twin-screw extruder is 300rpm, and the temperatures of the screws in each section are: 200°C in zone 1, 220°C in zone 2, 240°C in zone 3, 260°C in zone 4, 260°C in zone 5, 240°C in zone 6, 240°C in zone 7, 220°C in zone 8, and 220°C in zone 9.

[0029] Example 2

[0030] The embodiment of the modified polyester of the present invention, the preparation method of the modified polyester is:

[0031] S1, stirring glycerol, dehydrated castor oil and lithium hydroxide at a mass ratio of glycerol: dehydrated castor oil: lithium hydroxide = 2:1:0.004 at 240°C for 6 hours, and naturally cooling to obtain an unsaturated oil alcoholysis product;

[0032] S2. Add n-butyl titanate to anhydrous ethanol, mix evenly, and prepare dispersion A; add the unsaturated oil alcoholysis product obtained in step S1 to anhydrous ethanol, mix evenly, and prepare dispersion B; at 75° C., uniformly add dispersion B to dispersion A dropwise for 45 minutes, and continue to reflux at 75° C. for 12 hours after the dropwise addition; then use a rotary evaporator to evaporate the ethanol to obtain modified titanium dioxide particles; the mass ratio of the dispersion B to the dispersion A is 1:1, and the mass ratio of the unsaturated oil alcoholysis product in the dispersion B to the n-butyl titanate in the dispersion A is 1:1.

[0033] S3, mixing 3-aminopropyltriethoxysilane, anhydrous ethanol and deionized water in a mass ratio of 3-aminopropyltriethoxysilane: anhydrous ethanol: deionized water = 1:20:2, and stirring at 60° C. and 100 rpm for 30 min to obtain a coupling mixture;

[0034] S4, adding the modified titanium dioxide particles obtained in step S2 to the coupling mixture obtained in step S3, wherein the mass ratio of 3-aminopropyltriethoxysilane to the modified titanium dioxide particles obtained in step S2 in the coupling mixture obtained in step S3 is 0.2:1, stirring at 80°C at a speed of 100 rpm for 3 hours, filtering and taking the filter residue, drying the filter residue at 80°C for 12 hours, and crushing it to a particle size of no more than 0.5 μm to obtain a composite modifier;

[0035] S5, drying the polyester resin at 130°C for 4h to obtain a dried polyester resin; adding the following components in parts by weight into a high-speed mixer for mixing: 100 parts of the dried polyester resin, 10 parts of the composite modifier obtained in step S4, and 1 part of zinc stearate, the mixing speed is 300rpm, and the mixing time is 20min; then transferring to a twin-screw extruder for melt extrusion, stranding, cooling, pelletizing, and drying to obtain a modified polyester, the speed of the twin-screw extruder is 300rpm, and the temperatures of each screw section are: 200°C in zone 1, 220°C in zone 2, 240°C in zone 3, 260°C in zone 4, 260°C in zone 5, 240°C in zone 6, 240°C in zone 7, 220°C in zone 8, and 220°C in zone 9.

[0036] Example 3

[0037] The embodiment of the modified polyester of the present invention, the preparation method of the modified polyester is:

[0038] S1, stirring glycerol, dehydrated castor oil and lithium hydroxide at a mass ratio of glycerol: dehydrated castor oil: lithium hydroxide = 4:1:0.005 at 255°C for 4 hours, and naturally cooling to obtain an unsaturated oil alcoholysis product;

[0039] S2. Add n-butyl titanate to anhydrous ethanol, mix evenly, and prepare dispersion A; add the unsaturated oil alcoholysis product obtained in step S1 to anhydrous ethanol, mix evenly, and prepare dispersion B; at 80° C., uniformly drop dispersion B into dispersion A for 30 minutes, and continue to reflux at 80° C. for 10 hours after the dropwise addition; then use a rotary evaporator to evaporate the ethanol to obtain modified titanium dioxide particles; the mass ratio of dispersion B to dispersion A is 1:1, and the mass ratio of the unsaturated oil alcoholysis product in dispersion B to n-butyl titanate in dispersion A is 1:1.

[0040] S3, mixing 3-aminopropyltriethoxysilane, anhydrous ethanol and deionized water in a mass ratio of 3-aminopropyltriethoxysilane: anhydrous ethanol: deionized water = 1:20:2, and stirring at 60° C. and 100 rpm for 30 min to obtain a coupling mixture;

[0041] S4, adding the modified titanium dioxide particles obtained in step S2 to the coupling mixture obtained in step S3, wherein the mass ratio of 3-aminopropyltriethoxysilane to the modified titanium dioxide particles obtained in step S2 in the coupling mixture obtained in step S3 is 0.2:1, stirring at 80°C at a speed of 100 rpm for 3 hours, filtering and taking the filter residue, drying the filter residue at 80°C for 12 hours, and crushing it to a particle size of no more than 0.5 μm to obtain a composite modifier;

[0042] S5, drying the polyester resin at 130°C for 4h to obtain a dried polyester resin; adding the following components in parts by weight into a high-speed mixer for mixing: 100 parts of the dried polyester resin, 1 part of the composite modifier obtained in step S4, and 0.5 parts of zinc stearate, the mixing speed is 300rpm, and the mixing time is 20min; then transferring to a twin-screw extruder for melt extrusion, stranding, cooling, pelletizing, and drying to obtain a modified polyester, the speed of the twin-screw extruder is 300rpm, and the temperatures of each screw section are: 200°C in zone 1, 220°C in zone 2, 240°C in zone 3, 260°C in zone 4, 260°C in zone 5, 240°C in zone 6, 240°C in zone 7, 220°C in zone 8, and 220°C in zone 9.

[0043] Example 4

[0044] The embodiment of the modified polyester of the present invention is different from the embodiment 1 in that, in the embodiment, the mass ratio of 3-aminopropyltriethoxysilane in the coupling mixture obtained in step S3 to the modified titanium dioxide particles obtained in step S2 is 0.1:1.

[0045] Example 5

[0046] The embodiment of the modified polyester of the present invention is different from the embodiment 1 in that, in the embodiment, the mass ratio of 3-aminopropyltriethoxysilane in the coupling mixture obtained in step S3 to the modified titanium dioxide particles obtained in step S2 is 0.4:1.

[0047] Example 6

[0048] The embodiment of the modified polyester of the present invention is different from the embodiment 1 in that, in the embodiment, the mass ratio of 3-aminopropyltriethoxysilane in the coupling mixture obtained in step S3 to the modified titanium dioxide particles obtained in step S2 is 0.5:1.

[0049] Example 7

[0050] The embodiment of the modified polyester of the present invention is different from the embodiment 1 in that, in the embodiment, the mass ratio between the unsaturated oil alcoholysate in the dispersion B and the n-butyl titanate in the dispersion A is 0.2:1.

[0051] Example 8

[0052] The embodiment of the modified polyester of the present invention is different from the embodiment 1 in that, in the embodiment, the mass ratio between the unsaturated oil alcoholysate in the dispersion B and the n-butyl titanate in the dispersion A is 0.5:1.

[0053] Example 9

[0054] The embodiment of the modified polyester of the present invention is different from the embodiment 1 in that, in the embodiment, the mass ratio between the unsaturated oil alcoholysate in the dispersion B and the n-butyl titanate in the dispersion A is 2:1.

[0055] Example 10

[0056] The embodiment of the modified polyester of the present invention is different from the embodiment 1 in that the following components in parts by weight are added into a high-speed mixer for mixing: 100 parts of dried polyester resin, 6 parts of the composite modifier obtained in step S4, and 1 part of zinc stearate.

[0057] Comparative Example 1

[0058] The comparative example of the modified polyester of the present invention, the preparation method of the modified polyester is:

[0059] S1, stirring glycerol, dehydrated castor oil and lithium hydroxide at a mass ratio of glycerol: dehydrated castor oil: lithium hydroxide = 3:1:0.006 at 100 rpm and 245°C for 5 hours, and naturally cooling to obtain an unsaturated oil alcoholysis product;

[0060] S2. Add n-butyl titanate to anhydrous ethanol, mix evenly, and prepare dispersion A; add the unsaturated oil alcoholysis product obtained in step S1 to anhydrous ethanol, mix evenly, and prepare dispersion B; at 80° C., uniformly drop dispersion B into dispersion A for 30 minutes, and continue to reflux at 80° C. for 10 hours after the dropwise addition; then use a rotary evaporator to evaporate the ethanol to obtain modified titanium dioxide particles; the mass ratio of dispersion B to dispersion A is 1:1, and the mass ratio of the unsaturated oil alcoholysis product in dispersion B to n-butyl titanate in dispersion A is 1:1.

[0061] S3, drying the polyester resin at 130°C for 4 hours to obtain a dried polyester resin; adding the following components in parts by weight into a high-speed mixer for mixing: 100 parts of the dried polyester resin, 3 parts of the modified titanium dioxide obtained in step S2, and 0.5 parts of zinc stearate, the mixing speed is 300 rpm, and the mixing time is 20 minutes; then transferring to a twin-screw extruder for melt extrusion, stranding, cooling, pelletizing, and drying to obtain a modified polyester, the speed of the twin-screw extruder is 300 rpm, and the temperatures of each screw section are: 200°C in zone 1, 220°C in zone 2, 240°C in zone 3, 260°C in zone 4, 260°C in zone 5, 240°C in zone 6, 240°C in zone 7, 220°C in zone 8, and 220°C in zone 9.

[0062] Comparative Example 2

[0063] The comparative example of the modified polyester of the present invention, the preparation method of the modified polyester is:

[0064] S1. Mix 3-aminopropyltriethoxysilane, anhydrous ethanol and deionized water in a mass ratio of 3-aminopropyltriethoxysilane: anhydrous ethanol: deionized water = 1:20:2, and stir at 60° C. and 100 rpm for 30 min to obtain a coupling mixture;

[0065] S2, adding titanium dioxide to the coupling mixture obtained in step S1, wherein the mass ratio of 3-aminopropyltriethoxysilane to titanium dioxide in the coupling mixture obtained in step S1 is 0.2:1, stirring at 80°C at a speed of 100 rpm for 3 hours, filtering and taking the filter residue, drying the filter residue at 80°C for 12 hours, and crushing it to a particle size of no more than 0.5 μm to obtain a composite modifier;

[0066] S5, drying the polyester resin at 130°C for 4h to obtain a dried polyester resin; adding the following components in parts by weight into a high-speed mixer for mixing: 100 parts of the dried polyester resin, 3 parts of the composite modifier obtained in step S4, and 0.5 parts of zinc stearate, the mixing speed is 300rpm, and the mixing time is 20min; then transferring to a twin-screw extruder for melt extrusion, stranding, cooling, pelletizing, and drying to obtain a modified polyester, the speed of the twin-screw extruder is 300rpm, and the temperatures of the screws in each section are: 200°C in zone 1, 220°C in zone 2, 240°C in zone 3, 260°C in zone 4, 260°C in zone 5, 240°C in zone 6, 240°C in zone 7, 220°C in zone 8, and 220°C in zone 9.

[0067] In order to further verify the performance of the modified polyester obtained in the above embodiments and comparative examples, the present invention uses the modified polyester obtained in the above embodiments and comparative examples to prepare a PVC test piece. The preparation method of the PVC test piece is as follows: prepare the following components in parts by weight: 100 parts of PVC resin and 30 parts of modified polyester, add the components into a high-speed universal grinder for mixed grinding, and then transfer them into a micro screw machine, mix them at a speed of 30 rpm and 170° C. for 5 minutes, and after extrusion, use a micro injection molding machine to form the mold, the temperature of the molding mold is 70° C., the pressure is 1 MPa, and the holding time is 20 s to obtain the PVC test piece.

[0068] The PVC test piece was subjected to a tensile test and an oil resistance test. The test results are shown in Table 1.

[0069] Table 1

[0070]

[0071] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A modified polyester for improving the toughness, heat resistance and oil resistance of plastics, characterized in that: The invention comprises the following components in parts by weight: 100 parts of polyester resin, 1-10 parts of composite modifier and 0-5 parts of auxiliary agent, wherein the composite modifier comprises a coupling agent and modified titanium dioxide, and the mass ratio of the coupling agent to the modified titanium dioxide is (0.1-0.5):1; the modified titanium dioxide is formed by coating the surface of unsaturated oil alcoholysis product with titanium dioxide, and the preparation method of the modified titanium dioxide is as follows: n-butyl titanate is added to anhydrous ethanol, and the mixture is mixed to prepare dispersion A; unsaturated oil alcoholysis product is added to anhydrous ethanol, and the mixture is mixed to prepare dispersion B; dispersion B is added dropwise to dispersion A at 70-85°C, and after the addition is completed, the mixture is refluxed at 70-85°C for 8-12h; and the modified titanium dioxide is obtained after drying; the coupling agent is a silane coupling agent.

2. The modified polyester according to claim 1, characterized in that The silane coupling agent is 3-aminopropyltriethoxysilane.

3. The modified polyester according to claim 1, characterized in that The mass ratio of the unsaturated oil alcoholysate in the dispersion B to the n-butyl titanate in the dispersion A is (0.2-2):

1.

4. The modified polyester according to claim 1, characterized in that The invention comprises the following components in parts by weight: 100 parts of polyester resin, 3-6 parts of composite modifier and 0.5-1 part of auxiliary agent.

5. The modified polyester according to claim 1, characterized in that The auxiliary agent includes at least one of an antioxidant, a lubricant, and a compatibilizer.

6. A method for preparing the modified polyester according to any one of claims 1 to 5, characterized in that: The steps include: After the components are mixed, they are melt-extruded, drawn, cooled, pelletized and dried in a twin-screw extruder to obtain the modified polyester.

7. The method for preparing the modified polyester according to claim 6, characterized in that: The temperature of the melt extrusion is 200-260°C.

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