A high-transmittance polyester material for injection molding and its preparation method and application

Abstract

The present invention belongs to the technical field of polyester material synthesis and production, and discloses a highly transparent polyester material for injection molding, its preparation method, and application. The preparation method of the polyester material of the present invention comprises: taking terephthalic acid, isophthalic acid, adipic acid, and ethylene glycol in a weight ratio of (20-21):(3-4):(1-2):(11-12) to carry out an esterification reaction, followed by mixing with a composite catalyst to carry out a preliminary polycondensation reaction and a final polycondensation reaction to obtain a polyester material, wherein the composite catalyst is composed of antimony acetate and germanium dioxide in an input mass ratio of (20-32):(20-26). The polyester material obtained by the present invention has good injection molding performance, a highly transparent color, and is recyclable, and has good practical application prospects.

Description

Technical Field

[0001] The present invention belongs to the technical field of polyester material synthesis and production, and in particular relates to a high-transmittance polyester material for injection molding, a preparation method and an application thereof. Background Art

[0002] At present, the high-transparency polyester used for injection molding is mainly polyethylene terephthalate (PETG), which is a product made by esterification and polycondensation of three monomers: terephthalic acid (PTA), ethylene glycol (EG) and 1,4-cyclohexanedimethanol (CHDM) or neopentyl glycol (NPG). It has the advantages of good mechanical properties, high transparency and good biosafety. It is widely used in the production of high-gloss plastic products such as lip gloss tubes, cream bottles, lotion bottles, eyebrow pencils and medical blood collection tubes.

[0003] However, PETG has a low glass transition temperature and melting point. During the recycling process, the low-melting-point amorphous PETG will cause the recycled materials to aggregate and agglomerate, causing the recycling process to be interrupted. PETG is regarded as a pollutant by recyclers. Summary of the Invention

[0004] The purpose of the present invention is to obtain a plastic material with high transparency, high injection molding performance and recyclability, and to provide a high-transparency polyester material for injection molding, a preparation method and an application thereof.

[0005] In a first aspect, the present invention provides a method for preparing a polyester material using the following technical solutions:

[0006] A method for preparing a polyester material comprises: S1, mixing terephthalic acid, isophthalic acid, adipic acid and ethylene glycol in a weight ratio of (20-21):(3-4):(1-2):(11-12), and performing an esterification reaction to obtain a first reactant;

[0007] S2. Taking the first reaction product and adding a composite catalyst to perform a pre-polycondensation reaction to obtain a second reactant, wherein the composite catalyst is composed of antimony acetate and germanium dioxide, and the input mass ratio of the antimony acetate and germanium dioxide is (20-32): (20-26);

[0008] S3. Taking the second reactant and carrying out a final polycondensation reaction under stirring to obtain the polyester material.

[0009] In some specific embodiments, the added weight of the terephthalic acid is 100-105 parts, the added weight of the isophthalic acid is 16-20 parts, the added weight of the adipic acid is 5-7 parts, and the added weight of the ethylene glycol is 55-60 parts.

[0010] In some specific embodiments, the esterification reaction is carried out at a temperature of 240 to 249° C., a pressure of 180 to 185 kPa, and a time of 2.7 to 3.0 h.

[0011] In some specific embodiments, the pre-polycondensation reaction is carried out at a temperature of 270-277° C., a pressure of 2.0-2.3 kPa, and a time of 1.0-1.1 h.

[0012] In some specific embodiments, the temperature of the final polycondensation reaction is 275-278° C., the pressure is 0.080-0.15 kPa, and the time is 1.2-1.3 h.

[0013] In some specific embodiments, the amount of antimony acetate added is 140-220 ppm.

[0014] In some specific embodiments, the amount of germanium dioxide added is 120-180 ppm.

[0015] In a second aspect, the polyester material provided by the present invention adopts the following technical solutions:

[0016] A polyester material is prepared by the above polyester material preparation method and is made of the following raw materials in parts by weight:

[0017]

[0018] In a third aspect, the present invention provides a recyclable plastic product comprising the above-mentioned polyester material.

[0019] In some specific embodiments, the highly transparent plastic product is one or more of a lip gloss tube, a cream bottle, a lotion bottle, an eyebrow pencil, and a medical blood collection tube.

[0020] Beneficial effects:

[0021] In the present invention, terephthalic acid, isophthalic acid, adipic acid and ethylene glycol in a specific weight ratio are used as raw materials, and antimony acetate and germanium dioxide are used as a composite catalyst. The specific raw materials and feed ratios form an organic whole. Through the synergistic effect of various elements, the polyester material finally prepared has good injection molding ability and appropriate crystallization performance. The plastic products produced using the polyester material as raw material have high transparency, good mechanical properties and weather resistance. Moreover, when the plastic products are recycled together with ordinary polyester, they will not cause aggregation and agglomeration of the material flow, thereby realizing the recycling and reuse of the polyester material. DETAILED DESCRIPTION

[0022] PETG is the most commonly used high-transparency polyester for injection molding. Essentially a glycol-modified PET, it possesses excellent mechanical and optical properties. However, PETG has a significantly lower melting point than PET. During recycling, PETG adheres to the PET material used in conventional bottles, causing the entire material flow to aggregate and agglomerate, interrupting the process and preventing the production of high-quality recycled products. Consequently, PETG is considered a contaminant by recyclers. Based on the existing problems with PETG materials, the inventors of the present invention conducted extensive and in-depth research to arrive at the technical solution of the present invention.

[0023] In the technical solution provided by the present invention, phthalic acid, isophthalic acid, adipic acid and ethylene glycol in a specific weight ratio are used as raw materials, and a composite catalyst system composed of antimony acetate and germanium dioxide is used. Through esterification reaction, pre-polycondensation reaction and final polycondensation reaction under specific reaction conditions, the polyester material is obtained. The polyester material has high transparency and injection molding ability and can be recycled and processed together with the PET material used in conventional bottles. The method specifically includes:

[0024] S1. Mix terephthalic acid, isophthalic acid, adipic acid, and ethylene glycol in a weight ratio of (20-21):(3-4):(1-2):(11-12), and perform an esterification reaction to obtain a first reactant;

[0025] S2. Taking the first reaction product and adding a composite catalyst to perform a pre-polycondensation reaction to obtain a second reactant, wherein the composite catalyst is composed of antimony acetate and germanium dioxide, and the input mass ratio of the antimony acetate and germanium dioxide is (20-32): (20-26);

[0026] S3. Taking the second reactant and carrying out a final polycondensation reaction under stirring to obtain the polyester material.

[0027] In the present invention, terephthalic acid, isophthalic acid, adipic acid and ethylene glycol need to be added in a specific weight ratio, and the polycondensation reaction process parameters need to be regulated.

[0028] In some specific embodiments, the added weight of terephthalic acid is 100-105 parts, specifically 100 parts, 101 parts, 102 parts, 103 parts, 104 parts, 105 parts or any value therebetween; the added weight of isophthalic acid is 16-20 parts, specifically 16 parts, 19 parts, 20 parts or any value therebetween; the added weight of adipic acid is 5-7 parts, specifically 5 parts, 6 parts, 7 parts or any value therebetween; the added weight of ethylene glycol is 55-60 parts, specifically 55 parts, 56 parts, 57 parts, 58 parts, 59 parts, 60 parts or any value therebetween.

[0029] The conditions for the esterification reaction are not particularly limited in the present invention. In some specific embodiments, the temperature of the esterification reaction may be, but is not limited to, 240-249° C., the pressure may be, but is not limited to, 180-185 kPa, and the time may be, but is not limited to, 2.7-3.0 h.

[0030] In the present invention, the inventors comprehensively considered the conditions adopted in conventional polycondensation reactions and, through creative efforts, controlled the temperature of the pre-polycondensation reaction to 270-277°C, the pressure to 2.0-2.3 kPa, and the time to 1.0-1.1 h, and controlled the temperature of the final polycondensation reaction to 275-278°C, the pressure to 0.080-0.15 kPa, and the time to 1.2-1.3 h.

[0031] In some specific embodiments, the temperature of the pre-condensation reaction is specifically 270°C, 271°C, 272°C, 273°C, 274°C, 275°C, 276°C, 277°C or any value therebetween, the pressure is specifically 2.0kPa, 2.05kPa, 2.10kPa, 2.15kPa, 2.20kPa, 2.25kPa, 2.30kPa or any value therebetween, and the time is specifically 1.0h, 1.02h, 1.03h, 1.05h, 1.06h, 1.08h, 1.10h or any value therebetween.

[0032] In some specific embodiments, the temperature of the final polycondensation reaction is specifically 275°C, 276°C, 277°C, 278°C or any value therebetween, the pressure is specifically 0.080kPa, 0.09kPa, 0.10kPa, 0.11kPa, 0.12kPa, 0.130kPa, 0.140kPa, 0.150kPa or any value therebetween, and the time is specifically 1.20h, 1.21h, 1.23h, 1.25h, 1.26h, 1.28h, 1.30h or any value therebetween.

[0033] In the present invention, a composite catalyst system of antimony acetate and germanium dioxide with an input mass ratio of (20-32):(20-26) is used to catalyze the reaction, and multiple factors such as the raw material input ratio and reaction conditions work synergistically. The obtained polyester material has high transparency, excellent injection molding performance and good recyclability, and has great application prospects.

[0034] In some specific embodiments, the amount of antimony acetate added is 140-180 ppm, specifically 140 ppm, 150 ppm, 160 ppm, 170 ppm, 180 ppm or any value therebetween; the amount of germanium dioxide added is 120-180 ppm, specifically 120 ppm, 130 ppm, 140 ppm, 150 ppm, 160 ppm, 170 ppm, 180 ppm or any value therebetween.

[0035] In the present invention, the addition amounts of antimony acetate and germanium dioxide can also be limited in parts by weight. The addition amount of antimony acetate is 0.020 to 0.032 parts by weight, and the addition amount of germanium dioxide is 0.020 to 0.026 parts by weight.

[0036] The technical solution provided by the present invention also includes a polyester material prepared by the above polyester material preparation method.

[0037] More specifically, the polyester material is made from the following raw materials in parts by weight:

[0038]

[0039] The technical solution provided by the present invention also includes a recyclable high-gloss plastic product, which includes the above-mentioned polyester material.

[0040] In some specific embodiments, the recyclable high-gloss plastic product may be, but is not limited to, one or more of a lip gloss tube, a cream bottle, a lotion bottle, an eyebrow pencil, and a medical blood collection tube.

[0041] The embodiments of the present invention are described in detail below. The examples of the embodiments are intended to explain the present invention and are not to be construed as limiting the present invention. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this area or according to the product specifications. Reagents or instruments used that do not specify the manufacturer are all conventional products that can be obtained commercially.

[0042] Example 1.

[0043] This example is used to illustrate a polyester material with high transparency, good mechanical properties and recycling performance. The polyester material is produced from the following materials in parts by weight as raw materials:

[0044]

[0045] And the polyester material is produced by the following method:

[0046] S1. Add terephthalic acid, isophthalic acid, adipic acid and ethylene glycol according to the above weight parts into a slurry preparation tank for slurry preparation, and mix them evenly to obtain a slurry;

[0047] S2. The slurry is pumped into an esterification kettle and subjected to esterification reaction at 245° C. and 181 kPa for 2.9 h to obtain a first reactant;

[0048] S3, taking the first reactant, mixing it with 0.028 parts of antimony acetate and 0.021 parts of germanium dioxide, and introducing it into a pre-polycondensation reactor, and performing a pre-polycondensation reaction at 275° C. and 2.3 kPa for 1.05 hours to obtain a second reactant;

[0049] S4. Introducing the second reactant into a horizontal squirrel cage stirred reactor, carrying out a final polycondensation reaction under stirring at 276° C. and 0.100 kPa for 1.3 hours to obtain a polyester material.

[0050] Examples 2 to 4.

[0051] Examples 2 to 4 use the method provided in Example 1 to prepare polyester materials, except that the weight parts of the raw materials used are different, as shown in Table 1, and other conditions are the same.

[0052] Table 1.

[0053]

[0054] Examples 5 and 6.

[0055] Examples 5 and 6 use the method provided in Example 1 to prepare polyester materials, except that the conditions for the esterification reaction, the pre-polycondensation reaction, and the final polycondensation reaction are different, as shown in Table 2. Other conditions are the same.

[0056] Table 2.

[0057]

[0058] Comparative Example 1.

[0059] The polyester material was prepared by the method provided in Example 1, except that 0.010 parts of antimony acetate was used instead of 0.010 parts of germanium dioxide, and other conditions were the same.

[0060] Comparative Examples 2 to 4.

[0061] Comparative Examples 2 to 4 use the method provided in Example 1 to prepare polyester materials, except that the raw material input weight parts used are different, and the raw material input weight parts used are outside the scope of the present invention, as shown in Table 3, and other conditions are the same.

[0062] Table 3.

[0063]

[0064] Test example.

[0065] The polyester materials provided in Examples 1 to 6 and Comparative Examples 1 to 4 were tested for melting point and color value, and the crystallinity after crystallization under the same conditions was tested. The results are shown in Table 4.

[0066] Table 4.

[0067]

[0068] The test results are shown in Table 4. Compared with the polyester material provided in Comparative Example 1, the B value is higher and the L value is lower. The polyester materials provided in Comparative Examples 2 and 3 have low melting points, clumping together during crystallization, making them difficult to crystallize and unrecyclable. The polyester material provided in Comparative Example 4 has a high melting point, poor injection molding fluidity, and requires a higher processing temperature. The polyester materials provided in Examples 1 to 6 of the present invention have excellent injection molding performance, good color, and a certain degree of crystallinity.

[0069] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention without departing from the principles and purpose of the present invention.

Claims

1. A method for preparing a polyester material, characterized in that: The method includes: S1, mixing terephthalic acid, isophthalic acid, adipic acid and ethylene glycol, and performing an esterification reaction to obtain a first reactant; S2. Taking the first reaction product and adding a composite catalyst to perform a pre-polycondensation reaction to obtain a second reactant, wherein the composite catalyst is composed of antimony acetate and germanium dioxide, and the input mass ratio of the antimony acetate and germanium dioxide is (20-32): (20-26); S3, taking the second reactant and carrying out a final polycondensation reaction under stirring to obtain the polyester material; Among them, the added weight parts of terephthalic acid are 100-105 parts, the added weight parts of isophthalic acid are 16-20 parts, the added weight parts of adipic acid are 5-7 parts, and the added weight parts of ethylene glycol are 55-60 parts; the temperature of the esterification reaction is 240-249°C, the pressure is 180-185kPa, and the time is 2.7-3.0h; the temperature of the preliminary polycondensation reaction is 270-277°C, the pressure is 2.0-2.3kPa, and the time is 1.0-1.1h; the temperature of the final polycondensation reaction is 275-278°C, the pressure is 0.080-0.15kPa, and the time is 1.2-1.3h.

2. The method for preparing a polyester material according to claim 1, wherein: The added amount of the antimony acetate is 140 to 220 ppm.

3. The method for preparing the polyester material according to claim 1, wherein: The added amount of the germanium dioxide is 120-180 ppm.

4. A polyester material prepared by the method for preparing a polyester material according to any one of claims 1 to 3, characterized in that: The polyester material is made of the following raw materials in parts by weight:

5. A recyclable high-gloss plastic product, characterized in that: The polyester material according to claim 4 is included.

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