Polybutylene terephthalate composite material for nonwoven fabric and method for manufacturing the same

Abstract

This invention relates to a polybutylene terephthalate (PET) composite material for nonwoven fabrics and its preparation method, belonging to the field of polymer composite materials technology. The composite material comprises: 4.5-6.2 wt% modified plasticizer, 0.08-0.1 wt% electret powder, 0.75-0.9 wt% lubricant, and 0.11-0.14 wt% antioxidant, with the balance being PBT resin. The modified plasticizer is prepared by substituting α-hydroxyacetic acid ester and divinyldichlorosilane to form an intermediate, which is then hydrosilylated with octamethyltetrasiloxane to form a double-comb-shaped polymer with a silicon chain as the main chain and short-branched ester structures in the side chains. The design of this double-comb-shaped plasticizing functional structure simultaneously overcomes the bottlenecks in the flowability and water resistance of PBT meltblown processing, improving the water resistance of the fiber while reducing fiber fineness, providing a new generation solution for high-end weather-resistant filter materials.

Description

Technical Field

[0001] This invention belongs to the field of polymer composite materials technology, specifically, it relates to a polybutylene terephthalate composite material for nonwoven fabrics and its preparation method. Background Technology

[0002] Meltblown nonwoven fabric is a core component of filter materials. It is formed by stretching polymer melt into ultrafine fibers through high-temperature, high-speed airflow, creating a three-dimensional network structure with high porosity, thereby achieving high-efficiency filtration. Traditional polypropylene (PP) meltblown fabric is widely used due to its high melt index and convenient processing, but its heat resistance and chemical resistance are insufficient, and it is prone to failure in high-temperature or corrosive environments.

[0003] Polybutylene terephthalate (PBT) has become an ideal alternative substrate for high-end filter materials due to its excellent heat resistance, solvent resistance, and mechanical strength. However, PBT has the following drawbacks in nonwoven applications: PBT has a low melt flow index, resulting in a relatively large fiber diameter during spinning, leading to large pore size and low filtration efficiency. In existing technologies, flow modifiers are added to improve melt flowability and improve fiber fineness. However, PBT has poor water resistance, and under high temperature and humidity environments, the molecular chains are prone to breakage, resulting in a significant decrease in strength. The reduction in fiber fineness further deteriorates fiber stability, thus greatly limiting the application of PBT in nonwoven materials. Summary of the Invention

[0004] In order to solve the technical problems mentioned in the background art, the purpose of this invention is to provide a polybutylene terephthalate composite material for nonwoven fabrics and a method for preparing the same.

[0005] The objective of this invention can be achieved through the following technical solutions:

[0006] A polybutylene terephthalate composite material for nonwoven fabrics, comprising: 4.5-6.2 wt% modified plasticizer, 0.08-0.1 wt% electret powder, 0.75-0.9 wt% lubricant and 0.11-0.14 wt% antioxidant, with the balance being PBT resin.

[0007] The modified plasticizer is prepared by the following method:

[0008] Step A1: Mix α-hydroxyacetic acid ester, triethylamine and anhydrous tetrahydrofuran, purge with dry nitrogen for protection, control the temperature in an ice-water bath at 0-10℃, slowly add divinyldichlorosilane and stir for 2.5-3h, then raise the temperature to 50-60℃ and continue the reaction for 1-1.3h. After the reaction is complete, filter to remove salts, and remove tetrahydrofuran by rotary evaporation to obtain the intermediate.

[0009] In step A1, the ratio of divinyldichlorosilane, α-hydroxyacetic acid ester, triethylamine, and anhydrous tetrahydrofuran is 0.1 mol: 0.2 mol: 28-35 mL: 220-300 mL. α-hydroxyacetic acid ester undergoes a substitution reaction with divinyldichlorosilane to graft a bibranched ester structure.

[0010] Preferably, the α-hydroxyacetic acid ester is ethyl glycolate or butyl glycolate. The introduced short branched ester chain can effectively extend into the PBT macromolecular chain, weaken the interaction force, and improve the melt viscosity of PBT.

[0011] Step A2: Mix the intermediate, octamethyltetrasiloxane and toluene, purge with nitrogen, heat to 75-85℃, slowly add Karstedt catalyst and stir for 3.5-4.2h, then add butyl acrylate and continue heating to 100℃ and stirring for 1.5-2h. After the reaction is complete, remove toluene by rotary evaporation under reduced pressure to obtain the modified plasticizer.

[0012] In step A2, the ratio of octamethyltetrasiloxane, intermediate, butyl acrylate, Karstedt catalyst, and toluene is 0.1 mol: 90-95 mmol: 25-35 mmol: 10-15 mg: 370-450 mL. Octamethyltetrasiloxane and the intermediate undergo hydrosilylation to form a chain compound with a silicon main chain, which is then capped by butyl acrylate.

[0013] Preferably, the electret powder is an organic fluorine-based formulation, which has good compatibility with the PBT matrix and synergistically improves the filtration performance of the nonwoven fabric.

[0014] Preferably, the lubricant is a combination of stearate and polyester wax, which has good thermal stability and maintains a stable lubrication effect during meltblowing, thus helping to maintain the stability of the meltblown wire.

[0015] A method for preparing a polybutylene terephthalate composite material for nonwoven fabrics specifically involves: premixing a modified plasticizer, electret powder, lubricant, and antioxidant, then mixing them with PBT resin, followed by plasticizing and granulating the mixture using a twin-screw extruder to obtain the composite material.

[0016] Preferably, the temperature process during plasticizing and extrusion is as follows: feeding zone 170-180℃, melting zone 220-230℃, mixing zone 240-250℃, and die head 230-240℃. Under this temperature process, the components can be fully and uniformly mixed, which is beneficial to the stability of meltblown wire performance.

[0017] The beneficial effects of this invention are:

[0018] This invention introduces a self-developed modified plasticizer into PBT-based nonwoven fabric materials. The modified plasticizer is formed by the substitution reaction of α-hydroxyacetic acid ester and divinyldichlorosilane to form an intermediate. This intermediate then undergoes hydrosilylation with octamethyltetrasiloxane to form a bi-comb-shaped polymer with a silicon main chain and short-branched ester side chains. The short-branched ester structure of the molecular side chains has high compatibility with PBT molecules, effectively intercalating between the PBT macromolecular chains during melting and mixing, weakening the intermolecular forces and reducing PBT chain entanglement. Its main chain, being an organosilicon chain, provides strong lubrication, reducing intermolecular sliding resistance and significantly improving melt flowability. Furthermore, its bi-comb-shaped structure has a strong anchoring effect, preventing segregation in high-temperature melts and thus providing stable flowability gains. Thanks to the anchoring effect of the bi-comb, organosilicon chain composites are stably introduced between PBT molecular chains, effectively improving the water resistance of PBT. Detailed Implementation

[0019] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0020] Example 1: Preparation of polybutylene terephthalate composite material for nonwoven fabrics. The specific implementation process is as follows:

[0021] (1) Preparation of modified plasticizers

[0022] Step A1: Mix butyl glycolate, triethylamine, and anhydrous tetrahydrofuran, purge with dry nitrogen for protection, and control the temperature in an ice-water bath at 10°C. Slowly add divinyldichlorosilane and stir for 2.5 h. Then raise the temperature to 60°C and continue the reaction for 1 h. The ratio of divinyldichlorosilane, butyl glycolate, triethylamine, and anhydrous tetrahydrofuran is 0.1 mol: 0.2 mol: 35 mL: 300 mL. After the reaction is complete, filter to remove salts, and remove tetrahydrofuran by rotary evaporation to obtain the intermediate.

[0023] Step A2: Mix the intermediate, octamethyltetrasiloxane, and toluene, purge with nitrogen, heat to 85°C, slowly add Karstedt catalyst and stir for 3.5 h, then add butyl acrylate and continue heating to 100°C and stirring for 1.5 h. The ratio of octamethyltetrasiloxane, intermediate, butyl acrylate, Karstedt catalyst, and toluene is 0.1 mol: 95 mmol: 25 mmol: 15 mg: 450 mL. After the reaction is complete, remove toluene by rotary evaporation under reduced pressure to obtain the modified plasticizer.

[0024] (2) Preparation of composite materials

[0025] The following components are used: 4.5 wt% modified plasticizer, prepared in-house in this embodiment; 0.1 wt% electret powder, specifically TF12 organic fluorine electret powder; 0.9 wt% lubricant, a combination of stearate and polyester wax, specifically industrial-grade calcium stearate and HPL-6901 polyester wax in a weight ratio of 2:1; 0.14 wt% antioxidant, a combination of antioxidant 1010 and antioxidant 168 in a weight ratio of 1:1; the balance is PBT resin, specifically 300FP type resin raw material.

[0026] The modified plasticizer, electret powder, lubricant and antioxidant are added to a high-speed mixer and premixed at high speed. The premixed material is then mixed with PBT resin and fed into a twin-screw extruder. The barrel temperature is controlled as follows: 180°C in the feeding section, 230°C in the melting zone, 250°C in the mixing zone, and 240°C in the die head. The mixture is then plasticized, extruded, cooled, stretched and pelletized to obtain the composite material.

[0027] Example 2: Preparation of polybutylene terephthalate composite material for nonwoven fabrics. The specific implementation process is as follows:

[0028] (1) Preparation of modified plasticizers

[0029] Step A1: Mix ethyl glycolate, triethylamine, and anhydrous tetrahydrofuran, purge with dry nitrogen for protection, maintain the temperature at 0°C in an ice-water bath, slowly add divinyldichlorosilane and stir for 3 hours, then raise the temperature to 50°C and continue the reaction for 1.3 hours. The ratio of divinyldichlorosilane, butyl glycolate, triethylamine, and anhydrous tetrahydrofuran is 0.1 mol: 0.2 mol: 28 mL: 220 mL. After the reaction is complete, filter to remove salts, and remove tetrahydrofuran by rotary evaporation to obtain the intermediate.

[0030] Step A2: Mix the intermediate, octamethyltetrasiloxane, and toluene, purge with nitrogen, heat to 75°C, slowly add Karstedt catalyst and stir for 4.2 h, then add butyl acrylate and continue heating to 100°C and stirring for 2 h. The ratio of octamethyltetrasiloxane, intermediate, butyl acrylate, Karstedt catalyst, and toluene is 0.1 mol: 90 mmol: 35 mmol: 10 mg: 370 mL. After the reaction is complete, remove toluene by rotary evaporation under reduced pressure to obtain the modified plasticizer.

[0031] (2) Preparation of composite materials

[0032] The following components are used: 6.2 wt% modified plasticizer, prepared in-house in this embodiment; 0.08 wt% electret powder, specifically TF12 organic fluorine electret powder; 0.75 wt% lubricant, a combination of stearate and polyester wax, specifically industrial-grade calcium stearate and HPL-6901 polyester wax in a weight ratio of 2:1; 0.11 wt% antioxidant, a combination of antioxidant 1010 and antioxidant 168 in a weight ratio of 1:1; and the remainder is PBT resin, specifically 300FP type resin raw material.

[0033] The modified plasticizer, electret powder, lubricant and antioxidant are added to a high-speed mixer and premixed at high speed. The premixed material is then mixed with PBT resin and fed into a twin-screw extruder. The barrel temperature is controlled as follows: 170°C in the feeding section, 220°C in the melting zone, 240°C in the mixing zone and 230°C in the die head. The mixture is then plasticized, extruded, cooled, stretched and pelletized to obtain the composite material.

[0034] Example 3: Preparation of polybutylene terephthalate composite material for nonwoven fabrics. The specific implementation process is as follows:

[0035] (1) Preparation of modified plasticizers

[0036] Step A1: Mix butyl glycolate, triethylamine, and anhydrous tetrahydrofuran, purge with dry nitrogen for protection, and control the temperature in an ice-water bath at 10°C. Slowly add divinyldichlorosilane and stir for 3 hours. Then raise the temperature to 55°C and continue the reaction for 1.1 hours. The ratio of divinyldichlorosilane, butyl glycolate, triethylamine, and anhydrous tetrahydrofuran is 0.1 mol: 0.2 mol: 30 mL: 280 mL. After the reaction is complete, filter to remove salts, and remove tetrahydrofuran by rotary evaporation to obtain the intermediate.

[0037] Step A2: Mix the intermediate, octamethyltetrasiloxane, and toluene, purge with nitrogen, heat to 80°C, slowly add Karstedt catalyst and stir for 4 hours, then add butyl acrylate and continue heating to 100°C and stirring for 2 hours. The ratio of octamethyltetrasiloxane, intermediate, butyl acrylate, Karstedt catalyst, and toluene is 0.1 mol: 90 mmol: 30 mmol: 12 mg: 400 mL. After the reaction is complete, remove toluene by rotary evaporation under reduced pressure to obtain the modified plasticizer.

[0038] (2) Preparation of composite materials

[0039] The following components are used: 5.2 wt% modified plasticizer, prepared in-house according to this embodiment; 0.09 wt% electret powder, specifically TF12 organic fluorine electret powder; 0.85 wt% lubricant, a combination of stearate and polyester wax, specifically industrial-grade calcium stearate and HPL-6901 polyester wax in a weight ratio of 2:1; 0.12 wt% antioxidant, a combination of antioxidant 1010 and antioxidant 168 in a weight ratio of 1:1; the balance is PBT resin, specifically 300FP type resin raw material.

[0040] The modified plasticizer, electret powder, lubricant and antioxidant are added to a high-speed mixer and premixed at high speed. The premixed material is then mixed with PBT resin and fed into a twin-screw extruder. The barrel temperature is controlled as follows: 175°C in the feeding section, 220°C in the melting zone, 250°C in the mixing zone, and 240°C in the die head. The mixture is then plasticized, extruded, cooled, stretched and pelletized to obtain the composite material.

[0041] Example 4: Preparation of polybutylene terephthalate composite material for nonwoven fabrics. The specific implementation process is as follows:

[0042] (1) Preparation of modified plasticizers

[0043] Step A1: Mix ethyl glycolate, triethylamine, and anhydrous tetrahydrofuran, purge with dry nitrogen for protection, maintain the temperature at 5°C in an ice-water bath, slowly add divinyldichlorosilane and stir for 3 hours, then raise the temperature to 50°C and continue the reaction for 1.2 hours. The ratio of divinyldichlorosilane, butyl glycolate, triethylamine, and anhydrous tetrahydrofuran is 0.1 mol: 0.2 mol: 32 mL: 250 mL. After the reaction is complete, filter to remove salts, and remove tetrahydrofuran by rotary evaporation to obtain the intermediate.

[0044] Step A2: Mix the intermediate, octamethyltetrasiloxane, and toluene, purge with nitrogen, heat to 80°C, slowly add Karstedt catalyst and stir for 3.5 h, then add butyl acrylate and continue heating to 100°C and stirring for 12 h. The ratio of octamethyltetrasiloxane, intermediate, butyl acrylate, Karstedt catalyst, and toluene is 0.1 mol: 92 mmol: 35 mmol: 10 mg: 420 mL. After the reaction is complete, remove toluene by rotary evaporation under reduced pressure to obtain the modified plasticizer.

[0045] (2) Preparation of composite materials

[0046] The following components are used: 5.7 wt% modified plasticizer, prepared in-house in this embodiment; 0.1 wt% electret powder, specifically TF12 organic fluorine electret powder; 0.8 wt% lubricant, a combination of stearate and polyester wax, specifically industrial-grade calcium stearate and HPL-6901 polyester wax in a weight ratio of 2:1; 0.13 wt% antioxidant, a combination of antioxidant 1010 and antioxidant 168 in a weight ratio of 1:1; the balance is PBT resin, specifically 300FP type resin raw material.

[0047] The modified plasticizer, electret powder, lubricant and antioxidant are added to a high-speed mixer and premixed at high speed. The premixed material is then mixed with PBT resin and fed into a twin-screw extruder. The barrel temperature is controlled as follows: 180°C in the feeding section, 220°C in the melting zone, 240°C in the mixing zone and 230°C in the die head. The mixture is then plasticized, extruded, cooled, stretched and pelletized to obtain the composite material.

[0048] Comparative Example 1: This comparative example is a blank control. The implementation process is the same as in Example 4, but without the addition of a modified plasticizer.

[0049] Comparative Example 2, referring to the existing technical solution, uses organosilicon water-resistant agent and flow modifier to modify PBT to prepare composite material and use it for non-woven fabric. Specifically, 1.7% of L-200 type flow modifier and 4wt% of KF-869 type silicone oil are used to replace the modified plasticizer in Example 4 in equal amounts, and the rest of the implementation process is exactly the same.

[0050] Samples were taken from the composite material prepared above, and the melt flow index (230℃, 2.16kg) of the composite material was tested according to ASTM D1238-23 standard. The non-Newtonian index was tested using a rotational rheometer.

[0051] The composite material prepared above was melt-blown to prepare nonwoven fabric. The spinning temperature was 255℃, the hot air speed was 0.8Mach, and the receiving distance was 15cm. Samples were taken from the prepared nonwoven fabric, the surface was sprayed with gold, and the fiber diameter was detected by scanning electron microscopy. The tensile strength of the nonwoven fabric was tested according to GB / T 24218.3-2010 standard. The sample was immersed in a 60℃ water bath for 168h, and the tensile strength retention rate after hot water immersion was detected.

[0052] The specific test results are shown in Table 1 above.

[0053]

[0054] As can be seen from the test data in Table 1, the composite material prepared in the example has a higher melt index, a higher melt non-Newtonian index, higher melt fluidity, and a lower fiber diameter formed by spinning, which makes it easier to form fine pores and has higher filtration performance. At the same time, after hot water immersion test, the tensile strength retention rate is higher, which shows excellent hot water resistance and the nonwoven fabric made from it has higher stability.

[0055] In the description of this specification, the references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0056] The above description is merely an example and illustration of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described, or use similar methods to replace them, as long as they do not deviate from the invention or exceed the scope defined in the claims, all of which should fall within the protection scope of the present invention.

Claims

1. A polybutylene terephthalate composite material for nonwoven fabrics, characterized by, The specific components are: 4.5-6.2 wt% modified plasticizer, 0.08-0.1 wt% electret powder, 0.75-0.9 wt% lubricant and 0.11-0.14 wt% antioxidant, with the balance being PBT resin; The modified plasticizer is prepared by the following method: Step A1: Mix α-hydroxyacetic acid ester, triethylamine and anhydrous tetrahydrofuran, purge with dry nitrogen gas, control the temperature in an ice-water bath at 0-10℃, slowly add divinyldichlorosilane and stir for 2.5-3 hours, then raise the temperature to 50-60℃ and continue the reaction for 1-1.3 hours to prepare an intermediate; Step A2: Mix the intermediate, octamethyltetrasiloxane and toluene, purge with nitrogen for protection, heat to 75-85℃, slowly add Karstedt catalyst and stir for 3.5-4.2h, then add butyl acrylate and continue heating to 100℃ and stirring for 1.5-2h to prepare the modified plasticizer.

2. The polybutylene terephthalate composite material for a nonwoven fabric according to claim 1, characterized by The ratio of divinyldichlorosilane, α-hydroxyacetic acid, triethylamine, and anhydrous tetrahydrofuran is 0.1 mol: 0.2 mol: 28-35 mL: 220-300 mL.

3. The polybutylene terephthalate composite material for nonwoven fabrics according to claim 2, characterized in that, The α-hydroxyacetic acid ester is ethyl glycolate or butyl glycolate.

4. The polybutylene terephthalate composite material for a nonwoven fabric according to claim 3, characterized by The ratio of octamethyltetrasiloxane, intermediate, butyl acrylate, Karstedt catalyst, and toluene is 0.1 mol: 90-95 mmol: 25-35 mmol: 10-15 mg: 370-450 mL.

5. The polybutylene terephthalate composite material for nonwoven fabrics according to claim 1, characterized in that, Electret powder is an organic fluorine compound.

6. The polybutylene terephthalate composite material for nonwoven fabrics according to claim 1, characterized in that, The lubricant is a combination of stearate and polyester wax.

7. A method for preparing a polybutylene terephthalate composite material for nonwoven fabrics according to any one of claims 1-6, characterized in that, Specifically, the modified plasticizer, electret powder, lubricant and antioxidant are premixed, then mixed with PBT resin, and the mixture is then plasticized, extruded and granulated using a twin-screw extruder to obtain the composite material.

8. The method for preparing a polybutylene terephthalate composite material for nonwoven fabrics according to claim 7, characterized in that, The temperature process during plasticizing extrusion is as follows: feeding section 170-180℃, melting zone 220-230℃, mixing zone 240-250℃, and die head 230-240℃.

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