Production process for simultaneously producing different varieties of PBT (Polybutylece Terephthalate) resins

Abstract

The invention discloses a production process for simultaneously producing different varieties of PBT resin, and relates to the technical field of polyester production, different varieties of PBT products are simultaneously produced by adopting a six-kettle process flow, a titanium chelating catalyst is added, and the device is stable in production process and strong in anti-interference capability. Meanwhile, the product diversity is increased, the two esterification kettles are connected in series, the temperature and pressure requirements of the esterification reaction are low, the reaction is milder, the hydrolysis of a titanium ester catalyst is reduced, and the stability of the esterification rate can be ensured by adjusting the temperature, pressure, liquid level and other process conditions of the other reaction kettle when the process fluctuation of a single reaction kettle occurs; customized services are better provided for downstream customers, and the problem that the rate of superior products is reduced due to frequent production change in the traditional PBT production process is solved.

Description

Technical Field

[0001] The invention is applicable to the technical field of polyester production, and specifically is a production process for simultaneously producing different varieties of PBT resins. Background Art

[0002] Driven by the current diversified market demand, polybutylene terephthalate (PBT) resin, as a type of high-performance engineering plastic, has an increasingly wide range of applications, covering a wide range of fields from electronics and electrical, automobile manufacturing, aerospace to household appliances. Different application fields have different performance requirements for PBT resins. The production of traditional PBT resins is mainly carried out by direct esterification, but it is often difficult to efficiently switch to produce different varieties of PBT on the same production line, which limits production flexibility and market response speed. Most of the existing PBT devices in China use a three-kettle process flow and phthalate catalysts. The device load is low and can only produce a single variety of PBT products. Different downstream customers have different demands for PBT varieties, which leads to frequent production changes of the device. The viscosity of the product in the production change stage is unstable, and it can only be sold as transitional materials or secondary brand materials in the later stage. When the device encounters abnormal emergencies, the process fluctuates greatly and the recovery time is long, which directly affects the product quality and greatly reduces the product quality rate. Summary of the invention

[0003] In order to solve the above problems, that is, to solve the problems raised by the above background technology, the present invention proposes a production process for simultaneously producing different types of PBT resins, including slurry preparation, esterification, pre-shrinkage, final polycondensation, viscosity increase, and pelletizing, and the steps are as follows: Step 1: 1,4-butanediol (BDO) and PTA (purified terephthalic acid) are added to the slurry preparation tank at a molar ratio of 1.1-2:1, heated to 40-80°C, and transported to the esterification kettle through a delivery pump; Step 2: The reaction temperature of the esterification reactor 1 is 200-250°C, the reaction pressure is 30-90KPa, a titanium chelate catalyst is added, the titanium content in the catalyst is 50-90ppm of the PBT output, the material residence time is 100-300min, the esterification rate reaches 90-96%, and the esterified material is transported to the esterification reactor 2 through a delivery pump; Step 3: The reaction temperature of the esterification reactor 2 is 230-250°C, the reaction pressure is 20-50KPa, the material residence time is 100-150min, the esterification rate reaches 98-99.5%, and the esterified material is transported to the pre-shrinkage reactor 1 through a delivery pump; Step 4: The reaction temperature of pre-shrinkage 1 is 230-250°C, the pressure is 1-10KPa, the material residence time is 30-150min, the viscosity of the pre-shrinkage 1 discharge material is 0.12-0.3dL / g, and the pre-shrinkage 1 material is transported to the pre-shrinkage 2 kettle via a delivery pump; Step 5: The reaction temperature of pre-shrinkage 2 is 230-250°C, the pressure is 1-3KPa, the material residence time is 30-150min, the viscosity of the pre-shrinkage 1 discharge material is 0.3-0.6dL / g, and the pre-shrinkage 2 material is transported to the final polycondensation reactor via a delivery pump; Step 6: The reaction temperature of the final polycondensation kettle is 230-260°C, the pressure is 100-300Pa, the material residence time is 100-300min, the viscosity of the final polycondensation kettle discharge is 0.75-1.0dL / g, and the final polycondensation material enters the melt filter through the delivery pump for filtration and then goes to the pelletizer and viscosity increasing kettle; Step 7: The reaction temperature of the viscosity increasing kettle is 230-260°C, the pressure is 100-300Pa, the material residence time is 60-200min, the viscosity of the material discharged from the viscosity increasing kettle is 1.00-1.30dL / g, and the material of the viscosity increasing kettle enters the screen changer through the delivery pump for filtration and then goes to the pelletizer.

[0004] The patent of the present invention is further configured as follows: the water and by-product THF generated by the reaction in the esterification reactor 1 enter the process tower for separation and are transported to the THF recovery device for purification.

[0005] The patent of the present invention is further configured as follows: the water and by-product THF generated by the reaction in the esterification reactor 2 enter the process tower for separation and are transported to the THF recovery device for purification.

[0006] The patent of the present invention is further configured as follows: the preparation method of the titanium-based chelate catalyst is to add a polyol into a preparation tank, heat it to 100-110°C, remove the water content of the polyol, add a titanate compound and heat it to 110-160°C, add a complex and react at a constant temperature to remove small molecules, add a phosphate compound and heat it to 150-180°C and keep it at a constant temperature for 3 hours to remove small molecules to obtain a hydrolysis-resistant catalyst.

[0007] The patent of the present invention is further configured as follows: the molar ratio of the polyol to the titanate compound is 5-20:1, and the polyol is ethylene glycol, 1,3-propylene glycol, 1,2-butanediol, 1,3-butanediol and 1,4-butanediol, preferably 1,4-butanediol.

[0008] The patent of the present invention is further configured as follows: the molar ratio of the complex to the titanate compound is 0.1-1:1, and the complex is one or more of lactic acid, malic acid, citric acid, and tartaric acid.

[0009] The patent of the present invention is further configured as follows: the molar ratio of the phosphate compound to the titanate compound is 0.1-0.3:1, and the phosphate compound is one or more of trimethyl phosphate, triethyl phosphate, tripropyl phosphate, and triphenyl phosphate.

[0010] The beneficial technical effects of the patent of the present invention are as follows: the patent adopts a 6-reactor process to simultaneously produce different varieties of PBT products, adds a titanium-based chelated catalyst, the device has a stable production process, strong anti-interference ability, and adopts a series design of two esterification kettles. The temperature and pressure requirements of the esterification reaction are low, the reaction is more gentle, and the hydrolysis of the titanium ester catalyst is reduced. When encountering process fluctuations in a single reactor, the temperature, pressure, liquid level and other process conditions of another reactor can be adjusted to ensure the stability of the esterification rate, which will not affect the post-system process control and product indicators. At the same time, it increases product diversity, better provides customized services for downstream customers, and reduces the problem of a decrease in the rate of superior products caused by frequent production changes in the traditional PBT production process. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a flow chart of the present invention. DETAILED DESCRIPTION

[0012] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the protection scope of the present invention.

[0013] The present invention proposes a production process for simultaneously producing different types of PBT resins, including slurry preparation, esterification, pre-shrinkage, final polycondensation, viscosity enhancement, and pelletizing. The steps are as follows: Step 1: 1,4-butanediol (BDO) and PTA (purified terephthalic acid) are added to the slurry preparation tank at a molar ratio of 1.1-2:1, heated to 40-80°C, and transported to the esterification kettle through a delivery pump; Step 2: The reaction temperature of the esterification kettle 1 is 200-250°C, the reaction pressure is 30-90KPa, a titanium chelate catalyst is added, the titanium content in the catalyst is 50-90ppm of the PBT output, the material residence time is 100-300min, the esterification rate reaches 90-96%, the water and by-product THF generated by the reaction enter the process tower for separation, and are transported to the THF recovery device for purification. The esterified material is transported to the esterification 2 reactor through a delivery pump; Preparation method of titanium chelate catalyst: add polyol to the preparation tank, heat it to 100-110°C, remove the water content of the polyol, add titanate compound and heat it to 110-160°C, add complex to react at a constant temperature to remove small molecules, add phosphate compound and heat it to 150-180°C and keep it at a constant temperature for 3 hours to remove small molecules to obtain a hydrolysis-resistant catalyst. The catalyst will not be affected by environmental changes and can be stored for a long time. It can reduce impurities in the esterification water during the PBT production process and reduce the burden on the THF recovery station. It can avoid scaling of the inner wall of the esterification reactor caused by hydrolysis of the catalyst under high temperature conditions, reduce the switching frequency of the melt filter, and extend the maintenance cycle of the device. The molar ratio of the polyol to the titanate compound is 5-20:1 (the polyol is ethylene glycol, 1,3-propylene glycol, 1,2-butanediol, 1,3-butanediol and 1,4-butanediol, preferably 1,4-butanediol); The molar ratio of the complex to the titanate compound is 0.1-1:1 (the complex is one or more of lactic acid, malic acid, citric acid, and tartaric acid); The molar ratio of the phosphate compound to the titanate compound is 0.1-0.3:1 (the phosphate compound is one or more of trimethyl phosphate, triethyl phosphate, tripropyl phosphate, and triphenyl phosphate); Step 3: The reaction temperature of the esterification reactor 2 is 230-250°C, the reaction pressure is 20-50KPa, the material residence time is 100-150min, the esterification rate reaches 98-99.5%, the water and by-product THF generated by the reaction enter the process tower for separation, and are transported to the THF recovery device for purification. The esterified material is transported to the pre-shrinkage reactor 1 through a delivery pump; Step 4: The reaction temperature of pre-shrinkage 1 is 230-250°C, the pressure is 1-10KPa, the material residence time is 30-150min, the viscosity of the pre-shrinkage 1 discharge material is 0.12-0.3dL / g, and the pre-shrinkage 1 material is transported to the pre-shrinkage 2 kettle via a delivery pump; Step 5: The reaction temperature of pre-shrinkage 2 is 230-250°C, the pressure is 1-3KPa, the material residence time is 30-150min, the viscosity of the pre-shrinkage 1 discharge material is 0.3-0.6dL / g, and the pre-shrinkage 2 material is transported to the final polycondensation reactor via a delivery pump; Step 6: The reaction temperature of the final polycondensation kettle is 230-260°C, the pressure is 100-300Pa, the material residence time is 100-300min, the viscosity of the final polycondensation kettle discharge is 0.75-1.0dL / g, and the final polycondensation material enters the melt filter through the delivery pump for filtration and then goes to the pelletizer and viscosity increasing kettle; Step 7: The reaction temperature of the viscosity increasing kettle is 230-260°C, the pressure is 100-300Pa, the material residence time is 60-200min, the viscosity of the material discharged from the viscosity increasing kettle is 1.00-1.30dL / g, and the material of the viscosity increasing kettle enters the screen changer through the delivery pump for filtration and then goes to the pelletizer.

[0014] This patent adopts a series design of two esterification kettles. The temperature and pressure requirements of esterification 1 and esterification 2 are low, the reaction is more gentle, and the hydrolysis of the titanium ester catalyst is reduced. When encountering process fluctuations in a single reactor, the temperature, pressure, liquid level and other process conditions of another reactor can be adjusted to ensure the stability of the esterification rate, which will not affect the process control and product indicators of the subsequent system; The viscosity of the final polymerization kettle of this patent is 0.75-1.0dL / g, and the viscosity of the viscosity-increasing kettle is 1.00-1.30 dL / g. Two reactors are used to control products of different viscosities. The reaction is relatively gentle, the side reaction is small, and the amount of oligomers produced is small (specifically: the filter switching cycle of the BDO spray system corresponding to the final polymerization kettle is extended from the original 2h to more than 4h), and two different varieties of products can be produced at the same time.

[0015] Although the present invention has been described with reference to the preferred embodiments, various modifications may be made thereto and parts thereof may be replaced with equivalents without departing from the scope of the present invention. In particular, the various technical features mentioned in the various embodiments may be combined in any manner as long as there is no structural conflict. The present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

[0016] In the description of the present invention, the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicating directions or positional relationships are based on the directions or positional relationships shown in the drawings, which are only for the convenience of description, and do not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0017] In addition, it should be noted that in the description of the present invention, unless otherwise clearly specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two components. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances.

[0018] The term "comprise" or any other similar term is intended to cover a non-exclusive inclusion, such that a process, article, or apparatus / device that includes a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, article, or apparatus / device.

[0019] So far, the technical solution of the present invention has been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present invention.

Claims

1. A production process for producing different varieties of PBT resins simultaneously, including slurry preparation, esterification, pre-shrinkage, final polycondensation, tackification, and pelletization. The steps are as follows: Step 1:

1. The molar ratio of 4 butanediol (BDO) and PTA (substantial terephthalic acid) is 1.1-2:

1. Add slurry to prepare a tank, heat up to 40-80℃, and transport to the esterification kettle through a conveying pump; Step 2: The reaction temperature of the esterification reactor 1 is 200-250°C, the reaction pressure is 30-90KPa, a titanium chelate catalyst is added, the titanium content in the catalyst is 50-90ppm of the PBT output, the material residence time is 100-300min, the esterification rate reaches 90-96%, and the esterified material is transported to the esterification reactor 2 through a delivery pump; Step 3: The reaction temperature of the esterification kettle 2 is 230-250℃, the reaction pressure is 20-50KPa, the material residence time is 100-150min, and the esterification rate reaches 98-99.5%. The esterification 2 material is transported to the pre-shrinkage 1 reactor through a conveying pump; Step 4: The reaction temperature of pre-shrinkage 1 is 230-250℃, the pressure is 1-10KPa, the material residence time is 30-150min, the output viscosity of pre-shrinkage 1 is 0.12-0.3dL / g, and the pre-shrinkage 1 material is transported to the pre-shrinkage 2 kettle through the conveying pump; Step 5: The reaction temperature of pre-condensation 2 is 230-250℃, the pressure is 1-3KPa, the material residence time is 30-150min, the viscosity of pre-condensation 2 discharge is 0.3-0.6dL / g, and the pre-condensation 2 material is transported to the final polycondensation kettle through the conveying pump; Step 6: The reaction temperature of the final polycondensation kettle is 230-260°C, the pressure is 100-300Pa, the material residence time is 100-300min, the viscosity of the final polycondensation kettle discharge is 0.75-1.0dL / g, and the final polycondensation material enters the melt filter through the delivery pump and then goes to the pelletizer and viscosity increasing kettle; Step 7: The reaction temperature of the viscosity increasing kettle is 230-260°C, the pressure is 100-300Pa, the material residence time is 60-200min, the viscosity of the material discharged from the viscosity increasing kettle is 1.00-1.30dL / g, and the material of the viscosity increasing kettle enters the screen changer through the delivery pump for filtration and then goes to the pelletizer.

2. A production process for simultaneously producing different varieties of PBT resins according to claim 1, characterized in that: The water generated by the reaction of the esterification kettle 1 and the by-product THF are separated into the process tower and transported to the THF recovery device for purification.

3. A production process for simultaneously producing different varieties of PBT resins according to claim 1, characterized in that: The water generated by the reaction of the esterification kettle 2 and the by-product THF are separated into the process tower and transported to the THF recovery device for purification.

4. A production process for simultaneously producing different varieties of PBT resins according to claim 1, characterized in that: The preparation method of the titanium chelate catalyst is as follows: adding polyol to a preparation tank, heating to 100-110°C, removing water from the polyol, adding a titanate compound and heating to 110-160°C, adding a complex and reacting at a constant temperature to remove small molecules, adding a phosphate compound and heating to 150-180°C and keeping the temperature constant for 3 hours to remove small molecules and obtain a hydrolysis-resistant catalyst.

5. A production process for simultaneously producing different varieties of PBT resins according to claim 4, characterized in that: The molar ratio of the polyol to the titanate compound is 5-20:1, and the polyols are ethylene glycol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol and 1,4-butanediol, preferably 1,4-butanediol.

6. A production process for simultaneously producing different varieties of PBT resins according to claim 4, characterized in that: The molar ratio of the complex to the titanate compound is 0.1-1:1, and the complex is one or more of lactic acid, malic acid, citric acid, and tartaric acid.

7. A production process for simultaneously producing different varieties of PBT resins according to claim 4, characterized in that: The molar ratio of the phosphate compound and the titanate compound is 0.1-0.3:1, and the phosphate compound is one or more of trimethyl phosphate, triethyl phosphate, tripropyl phosphate, and triphenyl phosphate.

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