Surface modification method for treating polyarylate fiber or fabric by using coupling agent in cooperation with alkali

Abstract

The invention discloses a surface modification method for treating polyarylester fiber or fabric by using a coupling agent in cooperation with alkali. The surface modification method comprises the following steps: (1) carrying out dipping treatment on the polyarylester fiber or fabric in a pretreatment solution, and drying the polyarylester fiber or fabric; (2) dipping the polyarylate fiber or fabric in an alkali solution for alkali treatment, and washing and drying after the reaction is finished; (3) dipping the polyarylate fiber or fabric in a coupling agent solution for treatment, and washing and drying after the reaction is finished; and (4) uniformly coating the polyarylate fiber or fabric with epoxy resin and a curing agent according to a certain ratio, and curing to obtain the polyarylate fiber or fabric / epoxy resin composite material. The invention provides the surface modification method for the polyarylester fiber fabric, which is low in cost, does not need complex instruments and equipment, only acts on the surface of the fiber fabric without influencing the body structure, can maintain the effect for a long time, is convenient in process operation and simple in treatment process, and can improve the peel strength and bonding capacity between the polyarylester fiber or fabric and resin.

Description

Technical Field

[0001] The invention relates to the technical field of fiber or fabric surface modification, and in particular to a surface modification method of polyarylate fiber or fabric by using a coupling agent in coordination with an alkali. Background Art

[0002] Compared with the three traditional high-performance fibers, thermotropic liquid crystal polyarylate fiber (TLCP fiber) is the only high-performance fiber that can be prepared by melt spinning. The rigidity of the polyarylate molecular chain is high, and the molecular chain relaxation time is long. After cooling and solidification, its high orientation structure is almost completely retained. Therefore, in the melt spinning production process, when the polyarylate melt passes through the spinneret hole, even if the shear rate is low, a high degree of orientation can be obtained. Polyarylate fiber does not require post-stretching and other processes. Only heat treatment is required to further improve the modulus and strength, so that the mechanical properties of the fiber reach a high level. Due to its low preparation cost and low pollution to the environment, polyarylate fiber is widely used in aerospace, military, sports and other fields.

[0003] In practical application scenarios, thermotropic liquid crystal polyarylate fibers are often used as high-performance fiber reinforcement materials and organic polymer matrix materials to form resin-based composite materials. Resin-based composite materials combine the excellent properties of both resin and fiber materials, and have the characteristics of good fatigue resistance, chemical resistance, simple molding, and designable performance. When polyarylate fibers are used as reinforcements, no small molecules are released during the thermosetting resin thermal curing molding process, and there is almost no effect on the performance of the resin matrix, so the stability of the composite material is also excellent. However, the surface of polyarylate fibers is smooth, there are almost no active groups, and the surface energy is extremely low, resulting in poor bonding performance between the fiber surface and the resin matrix material, thereby limiting its further application in resin-based composite materials. Therefore, it is necessary to study a safe, feasible, low-cost, and effective surface modification method for polyarylate fibers to improve their interfacial bonding performance with the resin matrix material.

[0004] At present, the surface modification technologies of fibers and fabrics mainly include ultrasonic impregnation modification, γ-ray irradiation modification, plasma modification, surface coating technology and chemical reagent modification. The above technologies have the following characteristics:

[0005] (1) Ultrasonic impregnation modification: Ultrasonic waves are used to destroy the morphological structure of the fiber surface, opening the hydrogen bonds between the fiber molecular chains to improve the wetting performance of the resin on the fiber; however, the equipment cost is too high and it cannot be combined with other modification technologies at present, so the utilization rate is low;

[0006] (2) γ- Radiation modification: After high-energy radiation, chemical reactions are induced in the solid, liquid and gas phases at any temperature to activate the fiber surface and generate free radicals, thereby increasing the chemical bonding between the fiber and the resin, and achieving the purpose of improving the bonding properties of the composite material; however, special high-energy radiation devices are required, the modification mechanism is not clear, and the radiation can penetrate the substrate, it is not a single surface reaction, and further deep reactions will affect the structure of the fiber itself;

[0007] (3) Plasma modification: Active particles in plasma, such as oxygen or nitrogen, are activated and introduced into the fiber surface, causing physical or chemical effects on the fiber surface and increasing the number of polar groups on the fiber surface. After etching, obvious spots will appear on the surface due to bombardment by high-energy particles or free radicals, and the presence of pits provides a larger specific surface area. However, the treatment is time-sensitive. If it cannot be combined with the resin in time, the active groups on the fiber surface will quickly react with the medium in the air, thereby greatly reducing the modification effect.

[0008] (4) Surface coating technology: A flexible coating is applied on the fiber surface. This layer can absorb more fracture energy through modified composite materials, passivate the crack tip, and promote local plastic deformation at the crack tip. It can also serve as a stress release medium to reduce the stress concentration around the fiber caused by matrix shrinkage during the curing process. In addition, the coating protects the surface of the fiber, avoiding the reduction of the effect. Specific polar groups can also be introduced into the coating to increase the bonding ability between the fiber and the resin, thereby increasing the interfacial shear strength. However, there are many restrictions, such as the selected coating must have the same structural unit as the matrix resin, or have good bonding with the fiber and resin, it is difficult to control the coating thickness, the process operability is poor, and the coating is easy to peel off.

[0009] (5) Chemical reagent modification: Chemical reagents are used to etch or graft the fiber surface, causing the fiber molecular chain to break or graft new molecular chains, thereby increasing the surface polarity of the fiber. Compared with the aforementioned methods, the chemical reagent modification method has a simple process and easy-to-control reaction conditions, and is suitable for large-scale production. However, this method generally requires the use of a large amount of degreasing agent and acidic reagent, which not only fails to effectively reduce the concentration of alkali, but also further increases the pressure of chemical reagent recovery, and does not involve the impact on the bonding properties of fiber fabrics. Summary of the invention

[0010] The technical problem to be solved by the present invention is to overcome the technical defects of the background technology and provide a surface modification method of polyarylate fiber or fabric by using a coupling agent in combination with an alkali. The purpose of the present invention is to provide a surface modification method of polyarylate fiber fabric which has low cost, does not require complicated instruments and equipment, acts only on the surface of the fiber fabric without affecting the main structure, can maintain the effect for a long time, is convenient to operate, and has a simple treatment process, and can improve the peel strength and bonding ability between the polyarylate fiber or fabric and the resin.

[0011] The technical solution adopted by the present invention to solve the above technical problems is as follows:

[0012] A surface modification method for polyarylate fiber or fabric by using a coupling agent and alkali to treat the surface of the polyarylate fiber or fabric comprises the following steps:

[0013] (1) Pretreatment: The polyarylate fiber or fabric is immersed in a pretreatment solution and then dried for standby use;

[0014] (2) Alkali treatment: immersing the treated polyarylate fiber or fabric obtained in step (1) in an alkaline solution for alkaline treatment, and after the reaction is completed, washing and drying;

[0015] (3) Coupling agent treatment: the treated polyarylate fiber or fabric obtained in step (2) is immersed in a coupling agent solution for treatment, and after the reaction is completed, it is washed with water and dried;

[0016] (4) Preparation of polyarylate fiber or fabric / epoxy resin composite material: epoxy resin and curing agent are uniformly coated on the treated polyarylate fiber or fabric obtained in step (3) in a certain ratio, and the polyarylate fiber or fabric / epoxy resin composite material is obtained after curing.

[0017] Preferably, in step (1), the pretreatment liquid is any one or more of ethanol, acetone, and a degreasing agent.

[0018] Preferably, in step (1), the concentration of the pretreatment solution is 10%.

[0019] Preferably, in step (1), the immersion temperature is 20 to 90° C. and the immersion time is 30 to 120 min.

[0020] Preferably, in step (1), the bath ratio during the immersion is 1:20 to 1:100.

[0021] Preferably, in step (1), the drying temperature is 50 to 150° C. and the drying time is 10 to 60 minutes.

[0022] Preferably, in step (2), the immersion temperature is 40 to 90° C. and the immersion time is 10 to 90 min.

[0023] Preferably, in step (2), the bath ratio during the immersion is 1:30 to 1:110.

[0024] Preferably, in step (2), the alkali in the alkaline solution is any one or more of sodium hydroxide, potassium hydroxide, sodium carbonate, and sodium bicarbonate, and the solvent is deionized water.

[0025] Preferably, in step (2), the concentration of the alkaline solution is 5 wt% to 15 wt%.

[0026] More preferably, in step (2), the concentration of the alkaline solution is 5 wt% to 10 wt%.

[0027] Preferably, in step (2), the drying temperature is 80 to 180° C. and the drying time is 10 to 60 min.

[0028] Preferably, in step (3), the immersion temperature is 20 to 50° C. and the immersion time is 10 to 60 minutes.

[0029] Preferably, in step (3), the bath ratio during the immersion is 1:25 to 1:105.

[0030] Preferably, in step (3), the solvent in the coupling agent solution is any one or more of deionized water, methanol, and ethanol, and the coupling agent is any one or more of KH560, KH561, KH781, KH1770, KH1771, and KH78, wherein the chemical structural formulas of the coupling agents are:

[0031]

[0032] Preferably, in step (3), the concentration of the coupling agent solution is 0.05wt% to 15wt%.

[0033] More preferably, in step (3), the concentration of the coupling agent solution is 5 wt % to 10 wt %.

[0034] Preferably, in step (3), the drying temperature is 30 to 130° C. and the drying time is 10 to 60 min.

[0035] Preferably, in step (4), the mass ratio of the epoxy resin to the curing agent is 1:1.1.

[0036] Preferably, in step (4), the curing time is 24 hours.

[0037] A polyarylate fiber or fabric / epoxy resin composite material is prepared by using the surface modification method of polyarylate fiber or fabric treated with a coupling agent in coordination with alkali as described above.

[0038] Basic principles of the present invention:

[0039] The present invention hydrolyzes the polyarylate fiber or fabric through alkali treatment, breaks the ester bond in the polyarylate molecular chain, promotes the formation of depressions and reduces the single fiber fineness to increase the surface roughness of the polyarylate fiber or fabric, and at the same time increases the reaction sites for coupling agent treatment; the silane coupling agent has a double functional group structure and can react with the reinforcing fiber and the resin matrix at the same time, that is, the carbon functional group at one end reacts with the reinforcing fiber, and the silicon functional group at the other end reacts with the resin matrix, which is equivalent to building a "bridge" between the fiber and the resin, thereby improving the interface bonding force between the fiber and the resin and enabling stress to be transferred between the two phases; the polyarylate fiber or fabric grafted with the silane coupling agent forms an entanglement at the interface with the epoxy resin matrix, obtains a better interface transition zone, thereby improving the interface structure, eliminating stress strain, and improving the peel strength between the polyarylate fiber or fabric and the epoxy resin, thereby enhancing the bonding ability of the polyarylate fiber or fabric.

[0040] Compared with the prior art, the present invention has the following beneficial effects:

[0041] (1) The method of the present invention has low cost, simple equipment, good treatment effect, convenient operation and fast processing speed;

[0042] (2) The polyarylate fiber or fabric treated by the present invention has increased surface roughness and the number of active functional groups, greatly improving the peel strength between the polyarylate fiber or fabric and the epoxy resin, thereby enhancing the bonding ability of the polyarylate fiber or fabric;

[0043] (3) The present invention uses a coupling agent while reducing the concentration of alkali, thereby reducing the pollution of waste liquid to the environment to a certain extent. DETAILED DESCRIPTION

[0044] In order to better understand the content of the present invention, further description is given below in conjunction with specific embodiments. It should be understood that these embodiments are only used to further illustrate the present invention, and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content described in the present invention, those skilled in the art make some non-essential changes or adjustments to the present invention, which still belong to the protection scope of the present invention.

[0045] The specific parameters of the polyarylate fabrics selected in Examples 1 to 8 of the present invention are as follows:

[0046] Sample parameters: Sample size 15cm× 15cm, sample weight 2.04 grams.

[0047] Example 1

[0048] (1) Pretreatment: The polyarylate fabric was immersed in an aqueous solution containing 10% brightening and degreasing agent at a temperature of 50°C for 2 hours, with a bath ratio of 1:40, and then dried at 100°C for 30 minutes for use;

[0049] (2) Alkali treatment: The pretreated polyarylate fabric was immersed in a 5 wt % NaOH / water solution at 80° C. for 1 h, with a bath ratio of 1:40, then washed with deionized water, and dried at 100° C. for 30 min;

[0050] (3) Preparation of polyarylate fabric / epoxy resin composite material: First, epoxy resin and curing agent are mixed in a mass ratio of 1:1.1 and stirred for 2 minutes; after the epoxy resin mixture is stirred evenly, it is evenly applied to the surface of the polyarylate fabric obtained in step (2) with a brush; then the coated polyarylate fabric is placed at room temperature for curing for 24 hours;

[0051] (4) The bonding properties of the prepared polyarylate fabric / epoxy resin composite material are shown in Table 1.

[0052] Example 2

[0053] (1) Pretreatment: The polyarylate fabric was immersed in an aqueous solution containing 10% brightening and degreasing agent at a temperature of 50°C for 2 hours, with a bath ratio of 1:40, and then dried at 100°C for 30 minutes for use;

[0054] (2) Alkali treatment: The pretreated polyarylate fabric was immersed in a 10 wt % NaOH / water solution at 80°C for 1 h, with a bath ratio of 1:40, then washed with deionized water, and dried at 100°C for 30 min;

[0055] (3) Preparation of polyarylate fabric / epoxy resin composite material: First, epoxy resin and curing agent are mixed in a mass ratio of 1:1.1 and stirred for 2 minutes; after the epoxy resin mixture is stirred evenly, it is evenly applied to the surface of the polyarylate fabric obtained in step (2) with a brush; then the coated polyarylate fabric is placed at room temperature for curing for 24 hours;

[0056] (4) The bonding properties of the prepared polyarylate fabric / epoxy resin composite material are shown in Table 1.

[0057] Example 3

[0058] (1) Pretreatment: The polyarylate fabric was immersed in an aqueous solution containing 10% brightening and degreasing agent at a temperature of 50°C for 2 hours, with a bath ratio of 1:40, and then dried at 100°C for 30 minutes for use;

[0059] (2) Coupling agent treatment: The pretreated polyarylate fabric was immersed in a 5 wt % coupling agent KH560 / ethanol solution at 25°C for 30 min, with a bath ratio of 1:40, then washed with deionized water and dried at 100°C for 30 min;

[0060] (3) Preparation of polyarylate fabric / epoxy resin composite material: First, epoxy resin and curing agent are mixed in a mass ratio of 1:1.1 and stirred for 2 minutes; after the epoxy resin mixture is stirred evenly, it is evenly applied to the surface of the polyarylate fabric obtained in step (2) with a brush; then the coated polyarylate fabric is placed at room temperature for curing for 24 hours;

[0061] (4) The bonding properties of the prepared polyarylate fabric / epoxy resin composite material are shown in Table 1.

[0062] Example 4

[0063] (1) Pretreatment: The polyarylate fabric was immersed in an aqueous solution containing 10% brightening and degreasing agent at a temperature of 50°C for 2 hours, with a bath ratio of 1:40, and then dried at 100°C for 30 minutes for use;

[0064] (2) Coupling agent treatment: The pretreated polyarylate fabric was immersed in a 10 wt % coupling agent KH560 / ethanol solution at 25°C for 30 min, with a bath ratio of 1:40, then washed with deionized water and dried at 100°C for 30 min;

[0065] (3) Preparation of polyarylate fabric / epoxy resin composite material: First, epoxy resin and curing agent are mixed in a mass ratio of 1:1.1 and stirred for 2 minutes; after the epoxy resin mixture is stirred evenly, it is evenly applied to the surface of the polyarylate fabric obtained in step (2) with a brush; then the coated polyarylate fabric is placed at room temperature for curing for 24 hours;

[0066] (4) The bonding properties of the prepared polyarylate fabric / epoxy resin composite material are shown in Table 1.

[0067] Example 5

[0068] (1) Pretreatment: The polyarylate fabric was immersed in an aqueous solution containing 10% brightening and degreasing agent at a temperature of 50°C for 2 hours, with a bath ratio of 1:40, and then dried at 100°C for 30 minutes for use;

[0069] (2) Alkali treatment: The pretreated polyarylate fabric was immersed in a 5 wt % NaOH / water solution at 80° C. for 1 h, with a bath ratio of 1:40, then washed with deionized water, and dried at 100° C. for 30 min;

[0070] (3) Coupling agent treatment: The polyarylate fabric obtained in step (2) was immersed in a 5 wt % coupling agent KH560 / ethanol solution at a temperature of 25° C. for 30 min, with a bath ratio of 1:40, and then washed with deionized water and dried at 100° C. for 30 min;

[0071] (4) Preparation of polyarylate fabric / epoxy resin composite material: First, epoxy resin and curing agent are mixed in a mass ratio of 1:1.1 and stirred for 2 minutes; after the epoxy resin mixture is stirred evenly, it is evenly applied to the surface of the polyarylate fabric obtained in step (3) with a brush; then the coated polyarylate fabric is placed at room temperature for curing for 24 hours;

[0072] (5) The bonding properties of the prepared polyarylate fabric / epoxy resin composite material are shown in Table 1.

[0073] Example 6

[0074] (1) Pretreatment: The polyarylate fabric was immersed in an aqueous solution containing 10% brightening and degreasing agent at a temperature of 50°C for 2 hours, with a bath ratio of 1:40, and then dried at 100°C for 30 minutes for use;

[0075] (2) Alkali treatment: The pretreated polyarylate fabric was immersed in a 10 wt % NaOH / water solution at 80° C. for 1 h, with a bath ratio of 1:40, then washed with deionized water, and dried at 100° C. for 30 min;

[0076] (3) Coupling agent treatment: The polyarylate fabric obtained in step (2) was immersed in a 10 wt % coupling agent KH560 / ethanol solution at a temperature of 25° C. for 30 min, with a bath ratio of 1:40, and then washed with deionized water and dried at 100° C. for 30 min;

[0077] (4) Preparation of polyarylate fabric / epoxy resin composite material: First, epoxy resin and curing agent are mixed in a mass ratio of 1:1.1 and stirred for 2 minutes; after the epoxy resin mixture is stirred evenly, it is evenly applied to the surface of the polyarylate fabric obtained in step (3) with a brush; then the coated polyarylate fabric is placed at room temperature for curing for 24 hours;

[0078] (5) The bonding properties of the prepared polyarylate fabric / epoxy resin composite material are shown in Table 1.

[0079] Example 7

[0080] (1) Pretreatment: The polyarylate fabric was immersed in an aqueous solution containing 10% brightening and degreasing agent at a temperature of 50°C for 2 hours, with a bath ratio of 1:40, and then dried at 100°C for 30 minutes for use;

[0081] (2) Preparation of polyarylate fabric / epoxy resin composite material: First, epoxy resin and curing agent are mixed in a mass ratio of 1:1.1 and stirred for 2 minutes; after the epoxy resin mixture is stirred evenly, it is evenly applied to the surface of the polyarylate fabric obtained in step (1) with a brush; and then the coated polyarylate fabric is placed at room temperature for curing for 24 hours;

[0082] (3) The bonding properties of the prepared polyarylate fabric / epoxy resin composite material are shown in Table 1.

[0083] Example 8

[0084] (1) Preparation of polyarylate fabric / epoxy resin composite material: First, epoxy resin and curing agent were mixed in a mass ratio of 1:1.1 and stirred for 2 min; after the epoxy resin mixture was stirred evenly, it was evenly applied to the surface of the polyarylate fabric that had not been pretreated using a brush; then the coated polyarylate fabric was placed at room temperature for curing for 24 h;

[0085] (2) The bonding properties of the prepared polyarylate fabric / epoxy resin composite material are shown in Table 1.

[0086] In the above embodiments, embodiments 5 and 6 are specific implementation cases within the protection scope of the claims of the present invention, and the remaining embodiments are comparative implementation cases.

[0087] The peel strength test method of the polyarylate fabric / epoxy resin composite materials prepared in Examples 1 to 8 is as follows: according to the 180° peeling method, a YG028 universal material testing machine is used to test the sample, the sample width is 25 mm, the clamping length is 100 mm, and the tensile speed is 100 mm / min.

[0088] The main process parameters involved in Examples 1 to 8 of the present invention and the performance test results of the polyarylate fabric / epoxy resin composite materials prepared in Examples 1 to 8 are shown in Table 1.

[0089] Table 1 Main process parameters involved in Examples 1 to 8 of the present invention and performance test results of polyarylate fabric / epoxy resin composite materials prepared in Examples 1 to 8

[0090]

[0091] Compared with the prior art, the present invention has the following beneficial effects:

[0092] (1) The present invention simplifies the experimental device and avoids the use of complex equipment with difficult-to-control reaction conditions and high energy consumption, thereby reducing costs;

[0093] (2) The present invention simplifies the process flow and improves process operability, thus facilitating large-scale production;

[0094] (3) The present invention improves the treatment effect and greatly increases the bonding strength between the polyarylate fabric and the epoxy resin;

[0095] (4) The present invention reduces environmental pollution and lowers the concentration of alkali treatment.

[0096] The above description is not intended to limit the present invention, and the present invention is not limited to the above examples. Any changes, modifications, additions or substitutions made by a person skilled in the art within the spirit and scope of the present invention shall also fall within the protection scope of the present invention.

Claims

1. A method for surface modification of polyarylate fiber or fabric by using a coupling agent and alkali to treat the fiber or fabric. It is characterized in that The steps include: (1) Pretreatment: The polyarylate fiber or fabric is immersed in a pretreatment solution and then dried for standby use; (2) Alkali treatment: immersing the treated polyarylate fiber or fabric obtained in step (1) in an alkaline solution for alkaline treatment, and after the reaction is completed, washing and drying; (3) Coupling agent treatment: the treated polyarylate fiber or fabric obtained in step (2) is immersed in a coupling agent solution for treatment, and after the reaction is completed, it is washed with water and dried; (4) Preparation of polyarylate fiber or fabric / epoxy resin composite material: epoxy resin and curing agent are uniformly coated on the treated polyarylate fiber or fabric obtained in step (3) in a certain ratio, and the polyarylate fiber or fabric / epoxy resin composite material is obtained after curing.

2. The surface modification method of polyarylate fiber or fabric by using a coupling agent and alkali treatment as claimed in claim 1, It is characterized in that In step (1), the pretreatment liquid is any one or more of ethanol, acetone, and degreasing agent; the immersion temperature is 20 to 90° C., and the time is 30 to 120 minutes; and the bath ratio during the immersion is 1:20 to 1:

100.

3. The surface modification method of polyarylate fiber or fabric by using a coupling agent in combination with alkali treatment as claimed in claim 1, It is characterized in that The drying temperature is 50-150° C. and the drying time is 10-60 min.

4. The surface modification method of polyarylate fiber or fabric by using a coupling agent in combination with alkali treatment as claimed in claim 1, It is characterized in that In step (2), the immersion temperature is 40 to 90° C., and the immersion time is 10 to 90 min; and the bath ratio during the immersion is 1:30 to 1:

110.

5. The surface modification method of polyarylate fiber or fabric by using a coupling agent in combination with alkali treatment as claimed in claim 1, It is characterized in that In step (2), the alkali in the alkaline solution is any one or more of sodium hydroxide, potassium hydroxide, sodium carbonate, and sodium bicarbonate, and the solvent is deionized water; the concentration of the alkaline solution is 5wt% to 15wt%.

6. The surface modification method of polyarylate fiber or fabric by using a coupling agent in combination with alkali treatment as claimed in claim 1, It is characterized in that In step (2), the drying temperature is 80 to 180° C. and the drying time is 10 to 60 minutes.

7. The surface modification method of polyarylate fiber or fabric by using a coupling agent in combination with alkali treatment as claimed in claim 1, It is characterized in that In step (3), the immersion temperature is 20 to 50° C., and the immersion time is 10 to 60 min; and the bath ratio during the immersion is 1:25 to 1:

105.

8. The surface modification method of polyarylate fiber or fabric by using a coupling agent in combination with alkali treatment as claimed in claim 1, It is characterized in that In step (3), the solvent in the coupling agent solution is any one or more of deionized water, methanol, and ethanol, and the coupling agent is any one or more of KH560, KH561, KH781, KH1770, KH1771, and KH78; the concentration of the coupling agent solution is 0.05wt% to 15wt%.

9. The surface modification method of polyarylate fiber or fabric by using a coupling agent in combination with alkali treatment as claimed in claim 1, It is characterized in that In step (3), the drying temperature is 30 to 130° C. and the drying time is 10 to 60 minutes.

10. The surface modification method of polyarylate fiber or fabric by using a coupling agent and alkali treatment as claimed in claim 1, It is characterized in that In step (4), the mass ratio of the epoxy resin to the curing agent is 1:1.1, and the curing time is 24 hours.

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