Low-chroma isosorbide polycarbonate and preparation method thereof

Abstract

The invention discloses a low-chroma isosorbide polycarbonate and a preparation method thereof.The preparation method comprises the steps that diphenyl carbonate, isosorbide and 1, 4-cyclohexanedimethanol are mixed and stirred at a certain temperature, a catalyst aqueous solution is added after uniform stirring, and after water in a reaction system is removed, the low-chroma isosorbide polycarbonate is obtained; raising the temperature of the reaction system to 160-170 DEG C for transesterification, and reducing the vacuum degree of the reaction system to 26-28 KPa to remove a byproduct phenol; then continuously raising the reaction temperature to 210-230 DEG C, carrying out polycondensation reaction, reducing the vacuum degree of a reaction system to 80-500 Pa, removing phenol and light components, and after the polycondensation reaction is finished, carrying out cold-lacking pelletizing, so as to obtain the isosorbide polycarbonate with the ground chroma. According to the preparation method disclosed by the invention, the reaction temperature is reduced by compounding related catalysts and antioxidants, so that the oxidation reaction of the isosorbide is inhibited, the chromaticity of the product is reduced, the market demand is better met, and the application range of the isosorbide polycarbonate is expanded.

Description

Technical Field

[0001] This invention relates to the field of isosorbide-based polycarbonate technology, specifically to a low-color isosorbide-based polycarbonate and its preparation method. Background Technology

[0002] Isosorbide-based polycarbonate is an important type of polycarbonate with excellent thermal properties, optical properties and biocompatibility, and is widely used in medical, food, engineering plastics and other fields.

[0003] High optical transparency bio-based polycarbonates are commonly used in optical lenses, medical devices, and food containers. These fields place extremely high demands on the intrinsic purity and light transmittance of the materials; even trace amounts of coloration or haze can directly impair the optical performance of the final product, affecting its aesthetics and market acceptance. Meanwhile, the superior transparency exhibited by isosorbide-based polycarbonates provides excellent modifiability, facilitating customized processing through dyeing or surface coating to meet the diverse design needs of downstream companies.

[0004] The reason affecting the color of isosorbide-based polycarbonate is that during the transesterification process, the secondary hydroxyl groups in the isosorbide molecule are easily oxidized at high temperatures to generate carbonyl groups (such as isosorbide ketone). These carbonyl compounds have color-developing properties, which causes isosorbide-based polycarbonate to turn yellow.

[0005] In view of this, the present invention is hereby proposed. Summary of the Invention

[0006] The purpose of this invention is to provide a low-color isosorbide-based polycarbonate and its preparation method. The preparation method of this invention reduces the color of the product by selecting a suitable catalyst and antioxidant and lowering the reaction temperature to inhibit the oxidation reaction of isosorbide.

[0007] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted:

[0008] The first aspect of this invention provides a method for preparing low-color isosorbide-based polycarbonate, the method comprising the following steps:

[0009] (a) Diphenyl carbonate, isosorbide and 1,4-cyclohexanediethanol are mixed and heated to 110-130°C. After the diphenyl carbonate and isosorbide melt, a mixed aqueous solution of catalyst and antioxidant is added. The mixture is thoroughly mixed and the water is removed under vacuum of 29-32 kPa and stirring at 100-150 rpm.

[0010] (b) Under the condition of constant stirring speed, the reactor is heated to 160-170°C to carry out transesterification reaction, and the vacuum is adjusted to 26-28 kPa to remove the byproduct phenol;

[0011] (c) Continue the reaction for a period of time under a vacuum of 12–18 kPa while maintaining the stirring speed and reaction temperature.

[0012] (d) The esterification reaction was carried out at 160–170 °C, 50–100 rpm, and 4–6 kPa under vacuum conditions.

[0013] (e) While maintaining a constant stirring speed, raise the temperature of the reactor to a reaction temperature of 210–230°C and adjust the vacuum to 70–90 Pa to carry out the polycondensation reaction;

[0014] (f) After the polycondensation reaction is completed, the reaction product is condensed and pelletized to obtain the low-color isosorbide polycarbonate.

[0015] Preferably, in step (a), the mass ratio of diphenyl carbonate, isosorbide, 1,4-cyclohexanediol and catalyst is (8-12):(3-8):(1.5-4):(0.01-0.15).

[0016] Preferably, in step (a), the aqueous solution of catalyst and antioxidant is an aqueous solution of cesium carbonate and sodium borohydride, wherein the concentration of cesium carbonate is 0.2‰ to 0.4‰ and the concentration of sodium borohydride is 0.05‰ to 0.10‰.

[0017] Preferably, in step (b), the transesterification reaction time is 1.2 to 1.8 hours.

[0018] Preferably, in step (c), the reaction continues for a period of 0.5 to 1 hour.

[0019] Preferably, in step (d), the esterification reaction time is 0.8 to 1.2 h.

[0020] Preferably, in step (e), the polycondensation reaction time is 0.5 to 1 hour.

[0021] A second aspect of the present invention provides a low-color isosorbide-type polycarbonate prepared by the above-described preparation method.

[0022] Compared with the prior art, the beneficial effects of the present invention include at least the following:

[0023] The preparation method of this invention, by selecting appropriate catalysts and antioxidants, lowers the reaction temperature, inhibits the oxidation reaction of isosorbide, and thus reduces the color of the product, which can better meet market demand and expand the application range of isosorbide-based polycarbonate. Detailed Implementation

[0024] The embodiments of the technical solution of the present invention will be described in detail below with reference to the examples. The following embodiments are only used to illustrate the technical solution of the present invention more clearly, and are therefore only examples, and should not be used to limit the scope of protection of the present invention.

[0025] It should be noted that, unless otherwise stated, the technical or scientific terms used in this application should have the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains.

[0026] This invention provides a method for preparing low-color isosorbide-based polycarbonate, the method comprising the following steps:

[0027] (a) Mix diphenyl carbonate, isosorbide and 1,4-cyclohexanediethanol and heat to 110-130°C. After the diphenyl carbonate and isosorbide melt, add the aqueous solution of catalyst and antioxidant. Mix thoroughly under vacuum of 29-32 kPa and stirring at 100-150 rpm and remove water.

[0028] (b) Under the condition of constant stirring speed, the reactor is heated to 160-170°C to carry out transesterification reaction, and the vacuum is adjusted to 26-28 kPa to remove the byproduct phenol;

[0029] (c) Continue the reaction for a period of time under a vacuum of 12–18 kPa while maintaining the stirring speed and reaction temperature.

[0030] (d) The esterification reaction was carried out at 160–170 °C, 50–100 rpm, and 4–6 kPa under vacuum conditions.

[0031] (e) While maintaining a constant stirring speed, raise the temperature of the reactor to a reaction temperature of 210–230°C and adjust the vacuum to 70–90 Pa to carry out the polycondensation reaction;

[0032] (f) After the polycondensation reaction is completed, the reaction product is condensed and pelletized to obtain the low-color isosorbide polycarbonate.

[0033] The preparation method of this invention, by selecting a suitable catalyst and lowering the reaction temperature, inhibits the oxidation reaction of isosorbide, thereby reducing the color of the product, which can better meet market demand and expand the application range of isosorbide-based polycarbonate.

[0034] In one embodiment, in step (a), the mass ratio of diphenyl carbonate, isosorbide, 1,4-cyclohexanediol and catalyst is (8-12):(3-8):(1.5-4):(0.01-0.15).

[0035] In one embodiment, in step (a), the aqueous solution of catalyst and antioxidant is a mixed aqueous solution of cesium carbonate and sodium borohydride, wherein the concentration of the catalyst cesium carbonate is 0.2‰ to 0.4‰ and the concentration of the antioxidant sodium borohydride is 0.05‰ to 0.10‰.

[0036] In one embodiment, in step (b), the transesterification reaction time is 1.2 to 1.8 hours.

[0037] In one embodiment, in step (c), the reaction continues for a period of 0.5 to 1 hour.

[0038] In one embodiment, the esterification reaction time in step (d) is 0.8 to 1.2 hours.

[0039] In one embodiment, in step (e), the polycondensation reaction time is 0.5 to 1 hour.

[0040] Another embodiment of the present invention provides a low-color isosorbide-type polycarbonate prepared by the above preparation method.

[0041] The technical solution of the present invention will be further described in detail below through specific embodiments.

[0042] Example 1

[0043] This embodiment provides a method for preparing low-color isosorbide-based polycarbonate, the method comprising the following steps:

[0044] (a) Diphenyl carbonate, isosorbide, and 1,4-cyclohexanediethanol are mixed and heated to 120°C. After the diphenyl carbonate and isosorbide melt, a mixed aqueous solution of catalyst and antioxidant is added. The mixture is thoroughly mixed and the water is removed under stirring at 130°C, 30 kPa vacuum, and 150 rpm. The mass ratio of diphenyl carbonate, isosorbide, 1,4-cyclohexanediethanol, and catalyst is 10.8:7:3:0.024. The mixed aqueous solution of catalyst and antioxidant is a mixed aqueous solution of cesium carbonate and sodium borohydride, wherein the concentration of cesium carbonate is 0.4‰ and the concentration of sodium borohydride is 0.05‰.

[0045] (b) Under constant stirring speed, the temperature was raised to 160°C for 1.5 h for transesterification, and the vacuum was adjusted to 27 kPa to remove the byproduct phenol.

[0046] (c) Continue the reaction for 1 hour under a vacuum of 15 kPa while maintaining the stirring speed and reaction temperature.

[0047] (d) The esterification reaction was carried out at 160℃, 100rpm stirring speed and 5KPa vacuum for 1h;

[0048] (e) While maintaining a constant stirring speed, raise the temperature of the reactor to a reaction temperature of 220°C and adjust the vacuum to 80 Pa to carry out the polycondensation reaction for 40 min.

[0049] (f) After the polycondensation reaction is completed, the reaction product is condensed and pelletized to obtain the low-color isosorbide polycarbonate.

[0050] Example 2

[0051] This embodiment provides a method for preparing low-color isosorbide-based polycarbonate, the method comprising the following steps:

[0052] (a) Diphenyl carbonate, isosorbide, and 1,4-cyclohexanediethanol are mixed and heated to 120°C. After the diphenyl carbonate and isosorbide melt, a mixed aqueous solution of catalyst and antioxidant is added. The mixture is thoroughly mixed and the water is removed under stirring at 130°C, 30 kPa vacuum, and 150 rpm. The mass ratio of diphenyl carbonate, isosorbide, 1,4-cyclohexanediethanol, and catalyst is 10.8:7:3:0.024. The mixed aqueous solution of catalyst and antioxidant is a mixed aqueous solution of cesium carbonate and sodium borohydride. The concentration of cesium carbonate catalyst is 0.32‰, and the concentration of sodium borohydride is 0.08‰.

[0053] (b) Under constant stirring speed, the temperature was raised to 160°C for 1.5 h for transesterification, and the vacuum was adjusted to 27 kPa to remove the byproduct phenol.

[0054] (c) Continue the reaction for 1 hour under a vacuum of 15 kPa while maintaining the stirring speed and reaction temperature.

[0055] (d) The esterification reaction was carried out at 160℃, 100rpm stirring speed and 5KPa vacuum for 1h;

[0056] (e) While maintaining a constant stirring speed, raise the temperature of the reactor to a reaction temperature of 220°C and adjust the vacuum to 80 Pa to carry out the polycondensation reaction for 40 min.

[0057] (f) After the polycondensation reaction is completed, the reaction product is condensed and pelletized to obtain the low-color isosorbide polycarbonate.

[0058] Example 3

[0059] This embodiment provides a method for preparing low-color isosorbide-based polycarbonate, the method comprising the following steps:

[0060] (a) Diphenyl carbonate, isosorbide, and 1,4-cyclohexanediethanol are mixed and heated to 120°C. After the diphenyl carbonate and isosorbide melt, a mixed aqueous solution of catalyst and antioxidant is added. The mixture is thoroughly mixed and the water is removed under stirring at 130°C, 30 kPa vacuum, and 150 rpm. The mass ratio of diphenyl carbonate, isosorbide, 1,4-cyclohexanediethanol, and catalyst is 10.8:7:3:0.024. The mixed aqueous solution of catalyst and antioxidant is a mixed aqueous solution of cesium carbonate and sodium borohydride, wherein the concentration of cesium carbonate is 0.32‰ and the concentration of sodium borohydride is 0.05‰.

[0061] (b) Under constant stirring speed, the temperature was raised to 160°C for 1.5 h for transesterification reaction, and the vacuum was adjusted to 27 kPa to remove the byproduct phenol;

[0062] (c) Continue the reaction for 1 hour under a vacuum of 15 kPa while maintaining the stirring speed and reaction temperature.

[0063] (d) The esterification reaction was carried out at 160℃, 100rpm stirring speed and 5KPa vacuum for 1h;

[0064] (e) While maintaining a constant stirring speed, the temperature of the reactor was raised to a reaction temperature of 220°C and the vacuum was adjusted to 80 Pa to carry out the polycondensation reaction for 1 hour;

[0065] (f) After the polycondensation reaction is completed, the reaction product is condensed and pelletized to obtain the low-color isosorbide polycarbonate.

[0066] Experimental Example

[0067] The low-color isosorbide-type polycarbonates prepared in Examples 1-3 were obtained respectively;

[0068] The colorimetry of the different low-color isosorbide polycarbonates mentioned above was measured using a colorimeter. The results are shown in Table 1.

[0069] Table 1

[0070]

[0071]

[0072] As shown in Table 1:

[0073] The isosorbide-based polycarbonate prepared in the embodiments of this application has a lower color intensity. Compared with different embodiments, the isosorbide-based polycarbonate prepared in Example 2 has an even lower color intensity.

[0074] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the claims and specification of the present invention.

Claims

1. A method for preparing a low-color isosorbide-based polycarbonate, characterized in that, The preparation method includes the following steps: (a) Diphenyl carbonate, isosorbide and 1,4-cyclohexanediethanol are mixed and heated to 110-130°C. After the diphenyl carbonate and isosorbide melt, a mixed aqueous solution of catalyst and antioxidant is added. The mixture is thoroughly mixed and the water is removed under vacuum of 29-32 kPa and stirring at 100-150 rpm. (b) Under the condition of constant stirring speed, the reactor is heated to 160-170°C to carry out transesterification reaction, and the vacuum is adjusted to 26-28 kPa to remove the byproduct phenol; (c) Continue the reaction for a period of time under a vacuum of 12–18 kPa while maintaining the stirring speed and reaction temperature constant; (d) The esterification reaction was carried out at 160–170 °C, a stirring speed of 50–100 rpm, and a vacuum environment of 4–6 kPa. (e) While maintaining a constant stirring speed, raise the temperature of the reactor to a reaction temperature of 210–230°C and adjust the vacuum to 70–90 Pa to carry out the polycondensation reaction; (f) After the polycondensation reaction is completed, the reaction product is condensed and pelletized to obtain the low-color isosorbide polycarbonate.

2. The preparation method according to claim 1, characterized in that, In step (a), the mass ratio of diphenyl carbonate, isosorbide, 1,4-cyclohexanediol and catalyst is (8-12):(3-8):(1.5-4):(0.01-0.15).

3. The preparation method according to claim 1, characterized in that, In step (a), the aqueous solution of catalyst and antioxidant is an aqueous solution of cesium carbonate and sodium borohydride, wherein the concentration of cesium carbonate catalyst is 0.2‰ to 0.4‰ and the concentration of sodium borohydride antioxidant is 0.05‰ to 0.10‰.

4. The preparation method according to claim 1, characterized in that, In step (b), the transesterification reaction time is 1.2 to 1.8 hours.

5. The preparation method according to claim 1, characterized in that, In step (c), the reaction continues for a period of 0.5 to 1 hour.

6. The preparation method according to claim 1, characterized in that, In step (d), the esterification reaction time is 0.8 to 1.2 hours.

7. The preparation method according to claim 1, characterized in that, In step (e), the polycondensation reaction time is 0.5 to 1 hour.

8. Low-color isosorbide-based polycarbonate prepared by any of the preparation methods described in claims 1 to 7.

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