Flowable adjuvants and methods for their preparation
By adding polyimide compounds to liquid crystal polyester, the problem of poor flowability of liquid crystal polyester was solved, enabling thermal processing at low temperatures and improving processing efficiency and material stability.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- TAIWAN TEXTILE RESEARCH INSTITUTE
- Filing Date
- 2025-08-29
- Publication Date
- 2026-06-16
AI Technical Summary
Liquid crystal polyester has poor flowability during processing, resulting in high processing viscosity, which requires high energy input, and existing improvement methods often sacrifice its mechanical properties or dimensional stability.
By adding polyimide compounds, especially polyimide compounds generated by the reaction of 2,2-bis[4-dicarboxylic acid phenoxyphenyl]propane dianhydride with m-phenylenediamine, a flow aid is formed to reduce processing viscosity and improve flowability, while maintaining heat resistance and structural stability.
Achieving thermal processing of liquid crystal polyester at lower temperatures improves production efficiency, reduces energy consumption, and maintains the material's mechanical properties and chemical stability.
Smart Images
Figure CN122213623A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a processing aid and a method for preparing the same, and more particularly to a flow aid and a method for preparing the same. Background Technology
[0002] Liquid crystal polyesters possess excellent mechanical properties, heat resistance, and dimensional stability due to their rigid molecular backbone and highly ordered molecular arrangement. However, these characteristics also present challenges during processing. For example, the rigid structure of liquid crystal polyesters often results in poor flowability and high processing viscosity in the molten state, requiring higher energy input to achieve plastic processing. Furthermore, the molecular chains of liquid crystal polyesters are prone to over-orientation in the molten state, affecting the structural uniformity and stability of the final product.
[0003] In existing technologies, improving the flowability of liquid crystal polyesters typically involves altering processing temperatures or selecting specific processing techniques. However, these methods often sacrifice the mechanical properties or dimensional stability of the liquid crystal polyester. For example, increasing the temperature may cause excessive orientation of molecular chains, affecting the crystallinity and uniformity of the material, thereby reducing the performance of the final product. These technical choices have become major bottlenecks limiting the widespread application of liquid crystal polyesters, necessitating the development of new improvement schemes to balance their structural properties and processing characteristics. Summary of the Invention
[0004] According to one or more embodiments of the present invention, the flow aid comprises a liquid crystal polyester and a polyimide compound. The polyimide compound has repeating units as shown in formula (1):
[0005]
[0006] The intrinsic viscosity of a 15% (by weight) solution of polyimide compound dissolved in N-methylpyrrolidone at temperatures between 20°C and 50°C is between 100 and 190 centipoise.
[0007] In one or more embodiments of the present invention, the liquid crystal polyester has monomer units as shown in formulas (2) and (3):
[0008]
[0009] In one or more embodiments of the present invention, the weight of the polyimide compound accounts for 1% to 5% of the total weight of the flow aid.
[0010] In one or more embodiments of the present invention, the glass transition temperature of the polyimide compound is between 141°C and 167°C.
[0011] In one or more embodiments of the present invention, the 10% thermal decomposition temperature of the polyimide compound is between 509°C and 527°C.
[0012] According to one or more embodiments of the present invention, a method for preparing a flow-type additive includes: reacting 2,2-bis[4-dicarboxylic acid phenoxyphenyl]propane dianhydride with m-phenylenediamine to form a polyimide compound, wherein the molar ratio of 2,2-bis[4-dicarboxylic acid phenoxyphenyl]propane dianhydride to m-phenylenediamine is 2:1 to 4:3; and mixing the polyimide compound with a liquid crystal polyester to form a flow-type additive.
[0013] In one or more embodiments of the present invention, the liquid crystal polyester has monomer units as shown in formulas (2) and (3):
[0014]
[0015] In one or more embodiments of the present invention, the content of the polyimide compound is from 1 part by weight to 5 parts by weight, and the content of the liquid crystal polyester is from 95 parts by weight to 99 parts by weight.
[0016] In one or more embodiments of the present invention, the glass transition temperature of the polyimide compound is between 141°C and 167°C.
[0017] In one or more embodiments of the present invention, the 10% thermal decomposition temperature of the polyimide compound is between 509°C and 527°C.
[0018] According to the above embodiments of the present invention, the present invention provides a method for improving the processability of liquid crystal polyester, specifically by mixing the liquid crystal polyester with a suitable polyimide compound to form a flow-type additive with good processability. The polyimide compound can reduce the processing viscosity of the liquid crystal polymer, improve its flowability, and at the same time maintain its physical properties (e.g., heat resistance and structural stability) to a certain extent. In this way, the flow-type additive can have a wide range of processing applications. On the other hand, since the processing viscosity is significantly reduced, the flow-type additive can be molded at lower processing temperatures (e.g., injection molding, extrusion molding, compression molding, etc.), thereby improving production efficiency and reducing energy consumption. Attached Figure Description
[0019] To make the above and other objects, features, advantages and embodiments of the present invention more apparent and understandable, the accompanying drawings are described below:
[0020] Figure 1 This is a schematic flowchart of a method for preparing a flow-type additive according to some embodiments of the present invention.
[0021] In the attached figures, the following labels are used:
[0022] S10~S20: Steps Detailed Implementation
[0023] The following describes several embodiments of the present invention with reference to the accompanying drawings. For clarity, many practical details will be described in the following description. However, it should be understood that these practical details are not intended to limit the invention. That is, in some embodiments of the invention, these practical details are not essential and therefore should not be used to limit the invention. Furthermore, for the sake of simplicity, some conventional structures and components will be shown in the drawings in a simplified schematic manner. In addition, for the reader's convenience, the dimensions of the components in the drawings are not drawn to scale.
[0024] In this article, the structure of polymers or groups is sometimes represented by a skeleton formula. This representation may omit carbon atoms, hydrogen atoms, and carbon-hydrogen bonds. Of course, if the structural formula explicitly shows atoms or atomic groups, the representation shown by the artist shall prevail.
[0025] This invention provides a flow aid comprising a liquid crystal polyester and a modifier for improving the processability of the liquid crystal polyester. By adding a suitable modifier to the liquid crystal polyester, the problem of poor processability of the liquid crystal polyester can be effectively overcome. This results in the modified liquid crystal polyester not only possessing better flow properties and being suitable for thermal processing (e.g., injection molding, extrusion molding, or compression molding), but also effectively reducing the processing temperature. The modifier enables the liquid crystal polyester to reach a good melting state at a lower temperature, thereby reducing energy consumption and lowering the heat load on equipment, while maintaining its mechanical properties and chemical stability at high temperatures, further enhancing its practicality and processing flexibility in thermal processing applications. Furthermore, this invention also provides a method for preparing the above-mentioned flow aid. For clarity, the preparation method of the flow aid will be described first herein.
[0026] Please see Figure 1 This is a schematic flow diagram of a method for preparing a flow-type additive according to some embodiments of the present invention. The method for preparing the flow-type additive includes steps S10 to S20. In step S10, a dianhydride is reacted with a diamine to form a modifier. In step S20, the modifier is mixed with a liquid crystal polymer (liquid crystal polyester) to form a flow-type additive.
[0027] First, in step S10, 2,2-bis[4-dicarboxylic acid phenoxyphenyl]propane dianhydride is reacted with m-phenylenediamine to form a modifier. In other words, the modifier is a polyimide compound, and the polyimide compound has repeating units as shown in formula (1):
[0028]
[0029] In some embodiments, m-phenylenediamine can be placed in N-methylpyrrolidone and stirred for about 25 to 35 minutes (e.g., 30 minutes) until completely dissolved. Then, 2,2-bis[4-dicarboxylic acid phenoxyphenyl]propane dianhydride is added in portions to control the total solid content at 25 wt% to 35 wt% (e.g., 30 wt%), and a condensation polymerization reaction is carried out to generate polyamic acid. After the polymerization reaction is completed, an appropriate amount of catalyst (pyridine) and acetic anhydride are added, and the temperature is raised to 115 to 125 degrees Celsius (e.g., 120 degrees Celsius) and reacted for 2.5 to 3.5 hours (e.g., 3 hours) to allow the polyamic acid to cyclize into a polyimide compound.
[0030] Polyimide compounds, through their chemical structure design, can effectively reduce the processing viscosity of liquid crystal polyesters, improve flowability, and thus enhance the stability and efficiency of thermal processing. Specifically, 2,2-bis[4-dicarboxylic acid phenoxyphenyl]propane dianhydride contains ether bonds and alkyl structures. Introducing these flexible groups into the polyimide backbone reduces the rigidity of the polyimide molecular chain, increases the rotational freedom of the molecular chain, and makes the material more prone to intermolecular slip at high temperatures, thereby improving flowability. Furthermore, the meta-structure of m-phenylenediamine can disrupt the linearity of the polyimide backbone, reduce π-π stacking between molecular chains, and weaken intermolecular forces, making it easier for liquid crystal polyesters to melt and flow during thermal processing. Additionally, the propane group in 2,2-bis[4-dicarboxylic acid phenoxyphenyl]propane dianhydride can further prevent regular stacking of molecular chains, reduce the crystallinity of the material, and thus contribute to improving intermolecular flowability.
[0031] On the other hand, this invention ensures that the resulting polyimide compound has a small molecular structure by designing the molar ratio between 2,2-bis[4-dicarboxylic acid phenoxyphenyl]propane dianhydride and m-phenylenediamine. The small molecular structure of the polyimide compound results in a lower molecular weight and relatively lower melt viscosity, making it easier to flow under external force during processing, thereby reducing energy consumption during processing. Furthermore, the small molecular structure of the polyimide compound exhibits lower entanglement of molecular chains in the molten state, significantly reducing intermolecular sliding resistance and resulting in better processing performance. Additionally, the small molecular structure of the polyimide compound can suppress the rigidity and stacking regularity of molecular chains, thereby increasing its molecular freedom in the molten state, enabling it to form a more uniform mixed phase with the liquid crystal polyester, reducing phase separation, and further promoting its overall flowability. Moreover, the small molecular structure of the polyimide compound has a lower molecular weight and higher molecular mobility, making it easier to enter the molecular chains of the liquid crystal polyester, thus forming a more uniform mixture and further improving the overall flowability of the liquid crystal polyester.
[0032] Specifically, to form polyimide compounds with small molecular structures, the present invention controls the molar ratio of 2,2-bis[4-dicarboxylic acid phenoxyphenyl]propane dianhydride to m-phenylenediamine to be between 2:1 and 4:3 (e.g., 3:2). More specifically, when the molar ratio is less than 2:1 (e.g., 1:1), the proportion of dianhydride is insufficient, which may cause the resulting polyimide compound to tend to form a high molecular weight linear polymer. Furthermore, due to the excess of amino groups in m-phenylenediamine, unreacted amino group ends may remain in the structure, leading to enhanced interchain forces and making the molecular chains prone to entanglement. This results in a material exhibiting high viscosity, which is detrimental to flowability during thermal processing. Conversely, when the molar ratio is greater than 4:3 (e.g., 5:4), the proportion of dianhydride is too high. The excess anhydride functional groups tend to participate in cross-linking reactions, generating network or highly cross-linked and high molecular weight polymer structures. This increases the entanglement and stacking of molecular chains, making intermolecular sliding difficult and also detrimental to flowability during thermal processing.
[0033] The small-molecule polyimide compounds obtained by this invention can be characterized by their viscosity. More specifically, at temperatures between 20°C and 50°C, the intrinsic viscosity of a 15% (w / w) solution of the polyimide compound dissolved in N-methylpyrrolidone is between 100 and 190 centipoise (e.g., 110, 120, 130, 140, 150, 160, 170, and 180 centipoise). When the intrinsic viscosity of the polyimide compound falls within this range, it indicates that the polyimide compound has a suitable molecular weight and low intermolecular forces, thereby ensuring its good flowability in the molten state. Furthermore, this characteristic viscosity range also indirectly reflects the balanced characteristics of the polyimide compound in its structural design. That is, by adjusting the molar ratio of 2,2-bis[4-dicarboxylic acid phenoxyphenyl]propane dianhydride to m-phenylenediamine, it is neither too linearized, resulting in high viscosity, nor too cross-linked, leading to processing difficulties.
[0034] In some embodiments, the glass transition temperature of the polyimide compound is between 141°C and 167°C (e.g., 143°C, 145°C, 147°C, 149°C, 151°C, 153°C, 155°C, 159°C, 161°C, 163°C, and 165°C). When the glass transition temperature of the polyimide compound falls within this range, the polyimide compound can maintain appropriate molecular mobility at high temperatures, promoting the fluidity of the molecular chains, thereby effectively reducing the processing viscosity of the liquid crystal polyester. In other words, the liquid crystal polyester can be processed at lower processing temperatures, improving the stability and efficiency of thermal processing. If the glass transition temperature of a polyimide compound is too high, the molecular chains of the polyimide compound may be too rigid, thus limiting the mobility of the molecular chains; if the glass transition temperature of a polyimide compound is too low, the molecular chains of the polyimide compound may be too flexible, easily causing unstable melting behavior, and may lead to insufficient control during the thermal processing, thereby reducing the stability and efficiency of thermal processing.
[0035] In some embodiments, the 10% thermal decomposition temperature of the polyimide compound can be, for example, between 509°C and 527°C (e.g., 511°C, 513°C, 515°C, 517°C, 519°C, 521°C, 523°C, and 525°C). When the 10% thermal decomposition temperature of the polyimide compound falls within this range, the polyimide compound can maintain its structural stability under high-temperature conditions and effectively resist thermal degradation. Therefore, the polyimide compound is less prone to thermal decomposition during thermal processing and can maintain stable physical properties for extended periods at higher processing temperatures, avoiding performance degradation due to thermal degradation. If the 10% thermal decomposition temperature of a polyimide compound is too high, although the polyimide compound can maintain structural stability under high temperature conditions, its excessive heat resistance may lead to insufficient fluidity within the normal processing temperature range, thereby affecting processing efficiency; if the 10% thermal decomposition temperature of a polyimide compound is too low, the polyimide compound may begin to thermally decompose at a lower temperature, thereby affecting the structural stability during processing.
[0036] It should be noted that the intrinsic viscosity described in this article was obtained by capillary viscometer, the glass transition temperature was obtained by differential scanning calorimetry, and the thermal decomposition temperature was obtained by thermogravimetric analysis.
[0037] Subsequently, in step S20, the polyimide compound is mixed with the liquid crystal polyester to form a flow-forming aid. In some embodiments, the content of the polyimide compound may be from 1 part by weight to 5 parts by weight (e.g., 2 parts by weight, 3 parts by weight, 4 parts by weight), and the content of the liquid crystal polyester may be from 95 parts by weight to 99 parts by weight (e.g., 96 parts by weight, 97 parts by weight, 98 parts by weight), that is, the weight of the polyimide compound accounts for 1% to 5% (e.g., 2%, 3%, 4%) of the total weight of the flow-forming aid. If the content of the polyimide compound is too low (e.g., below 1%), it may not be able to effectively reduce the processing viscosity of the liquid crystal polyester, thus requiring a higher heat treatment temperature; while if the content of the polyimide compound is too high (e.g., above 5%), it may interfere with the original properties of the liquid crystal polyester, leading to a decrease in the stability of the liquid crystal phase in the mixture, and phase separation may occur, thereby reducing the uniformity of the processing and the stability of the material.
[0038] In some embodiments, the liquid crystal polyester is a polyarylate. Polyarylates possess a highly ordered liquid crystal arrangement and a rigid backbone, giving them advantages in mechanical properties, heat resistance, dimensional stability, and chemical resistance. The rigid structure of polyarylates not only endows the material with good tensile strength and modulus but also maintains stable physical properties in high-temperature environments. When polyarylates are mixed with polyimide compounds, they form a complementary effect. Polyarylates provide high structural strength and thermal stability, while polyimide compounds improve flowability by reducing processing viscosity, thereby enhancing processing efficiency. This combination effectively alleviates the problem of poor processability of polyarylates, enabling the material to maintain good mechanical properties and achieve stable processing operations during high-temperature processing.
[0039] Furthermore, polyarylates and polyimide compounds exhibit excellent chemical compatibility. For instance, the intermolecular forces between the two can reduce phase separation, thereby promoting uniform mixing and ensuring the overall stability of the material properties. This good compatibility helps to form a consistent dispersed phase structure during processing, allowing the polyimide compound to penetrate more effectively into the molecular chain gaps of the polyarylate, further reducing viscosity and improving processability. Simultaneously, good compatibility also helps to improve the homogeneity of the final molded material, ensuring that excellent structural and functional properties are maintained even under high temperature or stress. In some embodiments, the weight-average molecular weight of the liquid crystal polyester can be from 40,000 Daltons to 200,000 Daltons, and the liquid crystal polyester can have monomer units as shown in formulas (2) and (3):
[0040]
[0041]
[0042] In the following description, several comparative examples and embodiments will be provided to demonstrate the effectiveness of the present invention. It should be understood that the present invention should not be interpreted as limiting by the embodiments described below.
[0043] Table 1 lists the physical properties of polyimide compounds obtained by reacting 2,2-bis[4-dicarboxylic acid phenoxyphenyl]propane dianhydride with m-phenylenediamine at different molar ratios.
[0044] Table 1
[0045]
[0046] As shown in Table 1, when the molar ratio of 2,2-bis[4-dicarboxylic acid phenoxyphenyl]propane dianhydride to m-phenylenediamine falls within the range of 2:1 to 4:3, the glass transition temperature of the polyimide compound falls within the range of 141°C to 167°C, and the 10% thermal decomposition temperature falls within the range of 509°C to 527°C, both of which are superior to the case with a molar ratio of 1:1. Furthermore, a suitable molar ratio range also allows the polyimide compound to possess both hot-melt and solvent-processable properties, thereby enhancing its application flexibility in different processing techniques.
[0047] Table 2 lists the physical properties of the flow aids in each embodiment and comparative example. Among them, the modifier used in each embodiment is a polyimide compound as shown in formula (1). The polyimide compound is prepared by using 2,2-bis[4-dicarboxylic acid phenoxyphenyl]propane dianhydride and m-phenylenediamine in a molar ratio of 2:1.
[0048] Table 2
[0049]
[0050]
[0051] As can be seen from the comparative examples and embodiments in Table 2, the flow additives of the present invention have melting points that are very similar to those of the original liquid crystal polyester, indicating that the addition of the modifier does not significantly affect the melting point of the modified liquid crystal polyester. Furthermore, the 5% thermal decomposition temperature of the flow additives in each embodiment shows a small change compared to the original liquid crystal polyester, still exhibiting excellent thermal properties. Most notably, in each group, the melt index of each embodiment is significantly greater than that of the comparative examples, demonstrating that the addition of the modifier effectively improves the flowability of the liquid crystal polyester and significantly reduces processing viscosity. Overall, the addition of the modifier improves flowability without adversely affecting the melting point and thermal stability of the liquid crystal polyester.
[0052] According to the above embodiments of the present invention, the present invention provides a method for improving the processability of liquid crystal polyester, specifically by mixing the liquid crystal polyester with a suitable polyimide compound to form a flow-type additive with good processability. The polyimide compound can reduce the processing viscosity of the liquid crystal polymer, improve its flowability, and at the same time maintain its physical properties (e.g., heat resistance and structural stability) to a certain extent. In this way, the flow-type additive can have a wide range of processing applications. On the other hand, since the processing viscosity is significantly reduced, the flow-type additive can be molded at lower processing temperatures (e.g., injection molding, extrusion molding, compression molding, etc.), thereby improving production efficiency and reducing energy consumption.
[0053] Although the present invention has been disclosed above by way of embodiments, it is not intended to limit the present invention. Any person skilled in the art can make various modifications and refinements without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the scope defined in the appended claims.
Claims
1. A flow aid, characterized in that, include: One liquid crystal polyester; as well as A polyimide compound having repeating units as shown in formula (1): Formula (1), wherein at a temperature of 20°C to 50°C, the polyimide compound dissolved in N-methylpyrrolidone forms a solution with a weight percentage concentration of 15% and an intrinsic viscosity of 100 centipoise to 190 centipoise.
2. The flow aid according to claim 1, characterized in that, The liquid crystal polyester has monomer units as shown in formulas (2) and (3):
3. The flow aid according to claim 1, characterized in that, The polyimide compound accounts for 1% to 5% of the total weight of the flow aid.
4. The flow aid according to claim 1, characterized in that, The glass transition temperature of this polyimide compound is between 141°C and 167°C.
5. The flow aid according to claim 1, characterized in that, The 10% thermal decomposition temperature of this polyimide compound is between 509°C and 527°C.
6. A method for preparing a flow aid, characterized in that, include: 2,2-bis[4-dicarboxylate phenoxyphenyl]propane dianhydride is reacted with m-phenylenediamine to form a polyimide compound, wherein the molar ratio of the 2,2-bis[4-dicarboxylate phenoxyphenyl]propane dianhydride to the m-phenylenediamine is 2:1 to 4:3; and The polyimide compound is mixed with a liquid crystal polyester to form the flowable additive.
7. The method for preparing the flow aid according to claim 6, characterized in that, The liquid crystal polyester has monomer units as shown in formulas (2) and (3):
8. The method for preparing the flow aid according to claim 6, characterized in that, The content of the polyimide compound is from 1 part by weight to 5 parts by weight, and the content of the liquid crystal polyester is from 95 parts by weight to 99 parts by weight.
9. The method for preparing the flow aid according to claim 6, characterized in that, The glass transition temperature of this polyimide compound is between 141°C and 167°C.
10. The method for preparing the flow aid according to claim 6, characterized in that, The 10% thermal decomposition temperature of this polyimide compound is between 509°C and 527°C.