A fast-crystallizing modified PET composition and its preparation method and application

Abstract

The invention discloses a fast-crystallizing modified PET composition and a preparation method and application thereof. The composition comprises the following components by mass: 42-74 parts of PET resin, 30-50 parts of glass fiber, 1-3 parts of a compatibilizer, 3-10 parts of a crystallization accelerator, 0.1-1 parts of an antioxidant, and 0.3-2 parts of a nucleating agent. The nucleating agent is a mixture of an organic ionic metal sodium salt nucleating agent and surface carbonyl modified magnesium hydroxide, and has a high crystallization temperature, a narrow crystallization half-peak width, and a high crystallization rate.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials, and in particular to a rapidly crystallized modified PET composition, a preparation method thereof, and an application thereof. Background Art

[0002] PET is widely used in films and fibers, but its application as an engineering plastic is still very limited. This is primarily due to PET's slow crystallization rate and long molding cycles. Furthermore, PET's crystallization temperature is very low, reaching injection mold temperatures of 120-140°C, making its production cycle excessively long and uneconomical. Therefore, nucleating agents and crystallization accelerators are generally added to increase the crystallization rate and reduce mold temperatures. Currently, the most commonly used nucleating agents for PET include clays such as talc, metal oxides such as zinc oxide, inorganic salts such as calcium carbonate, and organic acid salts. As the most versatile general-purpose resin, PET is also widely used in automotive, electronics, and other fields. Compared with PBT, PET has weaker molecular chain mobility, resulting in slower crystallization and cooling times, and a longer molding cycle. Compared with international manufacturers, the level of PET modification in China still lags significantly.

[0003] Although the current nucleation system can meet most application requirements, it still has shortcomings in some parts with high requirements on appearance, such as low crystallization temperature, slow crystallization rate, and large crystallization half-peak width, which lead to a narrow processing window. Therefore, the nucleation system needs to be optimized. Summary of the Invention

[0004] In view of this, the present application provides a rapidly crystallizing modified PET composition and its preparation method and application, which has the characteristics of high crystallization temperature, narrow half-peak width of crystallization, high crystallization rate and high weld mark strength.

[0005] In order to achieve the above technical objectives, this application adopts the following technical solutions:

[0006] In the first aspect, the present application provides a rapidly crystallized modified PET composition, comprising the following components in parts by mass: 42-74 parts of PET resin, 30-50 parts of glass fiber, 1-3 parts of a compatibilizer, 0.1-1 parts of an antioxidant, 3-10 parts of a crystallization promoter, and 0.3-2 parts of a nucleating agent, wherein the nucleating agent is a mixture of an organic ionic metal sodium salt nucleating agent and a surface carbonyl-modified magnesium hydroxide.

[0007] Preferably, the mass fraction of PET resin is 50-70 parts; more preferably, the mass fraction of PET resin is 55-65 parts;

[0008] Preferably, the mass fraction of glass fiber is 35-45 parts; more preferably, the mass fraction of glass fiber is 40-45 parts;

[0009] Preferably, the mass fraction of the crystallization accelerator is 5-8 parts; more preferably, the mass fraction of the crystallization accelerator is 6-8 parts.

[0010] Preferably, the mass fraction of the nucleating agent is 0.5-1 part; more preferably, the mass fraction of the nucleating agent is 0.8-1 part.

[0011] Preferably, the mass ratio of the organic ionic metal sodium salt nucleating agent to the surface-modified magnesium hydroxide is 2-4:1.

[0012] Preferably, the organic ionic metal sodium salt nucleating agent is metal sodium salt type surlyn resin.

[0013] Preferably, the preparation method of the surface carbonylation modified magnesium hydroxide is: mixing magnesium hydroxide with an organic surface modifier and then drying the mixture, wherein the organic surface modifier includes one or more of an unsaturated fatty acid, a titanate coupling agent and an aluminate coupling agent.

[0014] Preferably, the particle size of the surface carbonyl-modified magnesium hydroxide is 1-4 μm.

[0015] Preferably, the viscosity of the PET resin is 0.65-0.8 dl / g, and the test standard is ISO 1628-5.

[0016] Preferably, the compatibilizer is a terpolymer containing ethylene-butyl acrylate-glycidyl methacrylate or an ethylene-methyl acrylate copolymer. More preferably, the compatibilizer is a terpolymer containing ethylene-butyl acrylate-glycidyl methacrylate.

[0017] Preferably, the crystallization accelerator is polyethylene glycol with a molecular weight of 6000-8000.

[0018] In a second aspect, the present application provides a method for preparing a rapidly crystallized modified PET composition, comprising the following steps: mixing PET resin, glass fiber, compatibilizer, antioxidant, crystallization promoter, and nucleating agent in parts by mass, adding the mixture to a twin-screw extruder for melt mixing, and then traction granulation to obtain the result.

[0019] In a third aspect, the present application provides an application of a rapidly crystallized modified PET composition in automobile wiper arms and electronic appliance connectors.

[0020] The beneficial effects of the present application are as follows: the present application compounds an organic ionic metal sodium salt nucleating agent with a surface carbonyl modified magnesium hydroxide. The surface carbonyl modified magnesium hydroxide can provide nucleation sites in the first time, and the carbonyl group on the surface is more conducive to dispersion in the PET resin. During the cooling process, the organic ionic metal sodium salt nucleating agent has a certain molecular flexibility. As the melt viscosity increases, it can continuously provide nucleation sites and promote crystallization. The nucleating agent and the crystallization promoter work together to achieve a higher crystallization temperature and a narrow crystallization half-peak width, thereby achieving a higher crystallization rate and high weld mark strength. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0022] The raw materials in the embodiments and comparative examples of this scheme are shown in the following table:

[0023]

[0024] Ingredients Description:

[0025] Surface carbonylation organically modified magnesium hydroxide-1: obtained by mixing magnesium hydroxide and a monoalkoxy pyrophosphate type titanate coupling agent, drying the mixture, and grinding the mixture to an average particle size of 1 μm.

[0026] Surface organically modified magnesium hydroxide-2: obtained by mixing magnesium hydroxide and oleic acid, drying the mixture, and grinding the mixture to an average particle size of 4 μm.

[0027] The viscosity of PET was tested according to ISO 1628-5 standard, and the test solvent was phenol / tetrachloroethane = 50:50.

[0028] Surface carbonyl-modified talc powder: The modification method is basically the same as that of surface carbonyl-organically modified magnesium hydroxide-1, the difference being that talc powder is used instead of magnesium hydroxide.

[0029] Magnesium hydroxide surface treated with KH550: The modification method is basically the same as that of surface carbonylation organically modified magnesium hydroxide-1, except that KH550 is used instead of monoalkoxy pyrophosphate type titanate coupling agent for modification.

[0030] Surface carbonylation-modified attapulgite: The modification method is basically the same as that of surface carbonylation-organically modified magnesium hydroxide-1, except that attapulgite is used instead of magnesium hydroxide.

[0031] The present invention is further described below through specific examples.

[0032] Examples 1-11 and Comparative Examples 1-7

[0033] A rapidly crystallizing modified PET composition comprises the components shown in Table 1 (Examples 1-11 in Table 1-1, Comparative Examples 1-7 in Table 1-2), and is prepared by mixing the corresponding raw materials in parts by mass, adding the mixture to a twin-screw extruder for melt mixing, and then granulating the mixture by pulling.

[0034] Table 1-1 Composition formulation of Example 1-11

[0035]

[0036]

[0037] Table 1-2 Composition formulation of comparative examples 1-7

[0038]

[0039]

[0040] Evaluation Test

[0041] The DSC test was conducted according to ISO 11357 standard, with a heating and cooling rate of 10°C / min. The crystallization temperature and half-peak width of the crystallization were calculated from the DSC curve. The higher the crystallization temperature and the narrower the half-peak width of the crystallization are, the more conducive to nucleation and the better the crystallization effect.

[0042] Spiral length test: Under fixed injection molding process conditions, continuously inject 80 spirals, and test the spiral length of the last mold. The lower the spiral length, the lower the fluidity of the composition. Low fluidity is more conducive to welding at the weld line position, reducing the occurrence of defects and improving welding strength.

[0043] The results of testing the crystallization temperature, crystallization half-peak width, and helix length of the compositions in Examples 1-11 and Comparative Examples 1-7 are shown in Table 2;

[0044] Table 2 Composition performance test results

[0045]

[0046]

[0047] Compared with Example 3, Example 2 has a different mass ratio of the organic ionic metal sodium salt nucleating agent to the surface carbonylation organically modified magnesium hydroxide. The crystallization temperature of Example 3 is lowered, the half-peak width is widened, and the spiral length is lengthened, indicating that when the organic ionic metal sodium salt nucleating agent and the surface carbonylation organically modified magnesium hydroxide are in the limited range of 2-4:1, it is beneficial to improve the nucleation speed of the composition and reduce the fluidity, the crystallization effect is better, and the weld strength is improved; Compared with Example 1, Example 2 increases the content of the nucleation promoter, which is beneficial to improve the nucleation speed of the composition, reduce the fluidity, and improve the weld strength; Compared with Example 4, Example 1 changes the type of organic ionic nucleating agent, indicating that the nucleating effect of the organic ionic metal aluminum salt nucleating agent is not as significant as that of the organic ionic metal sodium salt nucleating agent, and its crystallization temperature is lower and the half-peak width is increased, but it has little effect on the fluidity and weld strength;

[0048] Compared with Example 1, Examples 5-6 have different viscosities of the PET resin, indicating that as the viscosity of the PET resin increases, the length of the spiral line decreases, which is beneficial to reducing fluidity and improving weld strength.

[0049] Compared with Example 1, the molecular weight of the crystallization promoter in Examples 8-10 is different. When the molecular weight is lower than 6000 or higher than 8000, the crystallization temperature decreases and the helix length becomes higher, indicating that within the range of 6000-8000, it is beneficial to improve weld strength, reduce fluidity and promote nucleation. Compared with Example 1, Comparative Example 1 uses surface carbonyl-modified talc to replace the surface carbonyl-modified organically modified magnesium hydroxide as a composite component of the nucleation promoter. The crystallization temperature of Comparative Example 1 is greatly reduced, the half-peak width is increased and the helix length is greatly lengthened, indicating that the surface carbonyl-modified organically modified magnesium hydroxide is better in nucleation than the surface carbonyl-modified talc, and the weld strength is higher when compounded with an organic ionic metal sodium salt nucleating agent.

[0050] Compared with Example 1, Comparative Examples 2 and 4 both used a single-ingredient nucleation promoter, and the crystallization temperature decreased, the crystallization half-peak width increased, and the spiral length increased, indicating that the combination of the nucleation promoter and the crystallization promoter of this solution is more effective than the combination of a single-ingredient nucleation promoter and a crystallization promoter, which is beneficial to nucleation, improving weld strength, and reducing fluidity. Compared with Example 1, Comparative Examples 3 and 5 only used a crystallization promoter or a nucleation promoter. Under the condition of using the same total amount, the crystallization temperature decreased, the crystallization half-peak width increased, and the spiral length increased significantly, indicating that the crystallization promoter and the composite nucleating agent of the present application have a synergistic effect, which can synergistically increase the crystallization temperature, the crystallization half-peak width, and reduce the spiral length, which is beneficial to synergistically improve the crystallization speed, improve the weld strength, and reduce fluidity.

[0051] The above are only preferred specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or replacements that can be easily thought of by any technician familiar with this technical field within the technical scope disclosed by the present invention should be covered by the scope of protection of the present invention.

Claims

1. A fast crystallized modified PET composition, characterized in that: The invention comprises the following components in parts by mass: 42-74 parts of PET resin, 30-50 parts of glass fiber, 1-3 parts of compatibilizer, 0.1-1 parts of antioxidant, 0.3-2 parts of nucleating agent, and 3-10 parts of crystallization accelerator, wherein the nucleating agent is a mixture of an organic ionic metal salt nucleating agent and surface carbonylation-modified magnesium hydroxide; the organic ionic metal salt nucleating agent is a metal sodium salt type surlyn resin; and the preparation method of the surface carbonylation-modified magnesium hydroxide is: magnesium hydroxide is mixed with an organic surface modifier and then dried to obtain the mixture, wherein the organic surface modifier comprises one or more of an unsaturated fatty acid, a titanate coupling agent, and an aluminate coupling agent.

2. The fast crystallized modified PET composition according to claim 1, characterized in that The mass ratio of the organic ionic metal sodium salt nucleating agent to the surface carbonylation modified magnesium hydroxide is 2-4:

1.

3. The fast crystallized modified PET composition according to claim 1, characterized in that The particle size of the surface carbonylation modified magnesium hydroxide is 1-4 μm.

4. The fast crystallized modified PET composition according to claim 1, characterized in that The viscosity of the PET resin is 0.65-0.8 dl / g, and the testing standard is ISO 1628-5.

5. The fast crystallized modified PET composition according to claim 1, characterized in that: The compatibilizer is a terpolymer of ethylene-butyl acrylate-glycidyl methacrylate.

6. The fast crystallized modified PET composition according to claim 1, characterized in that: The crystallization accelerator is polyethylene glycol with a molecular weight of 6000-8000.

7. A method for preparing a fast crystallized modified PET composition according to any one of claims 1 to 6, characterized in that: The method comprises the following steps: PET resin, glass fiber, compatibilizer, antioxidant, nucleating agent and crystallization accelerator are mixed according to mass fractions, added into a twin-screw extruder for melting and mixing, and then granulated by pulling.

8. Use of the fast-crystallizing modified PET composition according to any one of claims 1 to 6 in automobiles and electronic and electrical parts.

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