CN120735200A - Continuous fiber reinforced prepreg tape and preparation method thereof - Google Patents
Continuous fiber reinforced prepreg tape and preparation method thereofInfo
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- CN120735200A CN120735200A CN202511205217.0A CN202511205217A CN120735200A CN 120735200 A CN120735200 A CN 120735200A CN 202511205217 A CN202511205217 A CN 202511205217A CN 120735200 A CN120735200 A CN 120735200A
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Abstract
本发明属于预浸带生产技术领域，尤其涉及一种连续纤维增强预浸带及其制备方法。所述方法包括：1）对基体纤维进行预处理，得到预处理纤维；2）以气流展纱法对预处理纤维进行展纱处理，得到连续纤维薄层带；3）对连续纤维薄层带进行分段浸渍增强处理，随后冷却定型得到连续纤维增强预浸带。本发明通过气流展纱和浸镀技术的有机结合，从微观层面增强了预浸带的Y轴结合强度并改良了纤维分布形式，使得预浸带的整体力学性能得到显著的提升优化，并通过浸料的处理改进使得预浸带的耐候性也得到了显著的提升。The present invention belongs to the technical field of prepreg production, and in particular relates to a continuous fiber-reinforced prepreg and a method for preparing the same. The method comprises: 1) pre-treating matrix fibers to obtain pre-treated fibers; 2) performing an air-flow yarn spreading process on the pre-treated fibers to obtain a continuous fiber thin layer tape; 3) performing a segmented impregnation reinforcement process on the continuous fiber thin layer tape, followed by cooling and shaping to obtain a continuous fiber-reinforced prepreg. The present invention organically combines air-flow yarn spreading and impregnation techniques to enhance the Y-axis bonding strength of the prepreg at a microscopic level and improve the fiber distribution pattern, thereby significantly improving and optimizing the overall mechanical properties of the prepreg. Furthermore, through improved impregnation treatment, the weather resistance of the prepreg is also significantly improved.
Description
Technical Field
The invention belongs to the technical field of prepreg tape production, and particularly relates to a continuous fiber reinforced prepreg tape and a preparation method thereof.
Background
Fiber reinforced resin-based composites can be classified into two types, thermosetting resin-based composites and thermoplastic resin-based composites, according to the nature of the resin matrix. Thermosetting resin-based composite materials have some inherent disadvantages such as low fracture toughness and damage tolerance, poor moisture absorption and environmental suitability, long processing period, difficult recovery and the like, so that the development and application of the thermosetting resin-based composite materials are limited to a certain extent. The thermoplastic resin matrix composite material has the advantages of good toughness, high fatigue strength, high impact damage tolerance, unlimited storage period of fiber prepreg and sheet molding compound, good thermoforming process, short forming period and high production efficiency, and is environment-friendly, and 4, leftover materials or waste materials can be remelted for forming or recycling. Thermoplastic composites are therefore becoming increasingly interesting and a focus of research and development in the composite field.
In the production process of the traditional prepreg tape, a series of technical bottleneck problems to be solved are faced, namely, firstly, uneven fiber unfolding is a prominent problem. In the fiber tow spreading stage, partial accumulation or loosening is extremely easy to occur due to the difficulty in precisely controlling tension distribution. This phenomenon directly negatively affects the subsequent impregnation uniformity, which threatens the quality of the final product. Second, the inefficiency of resin impregnation is also a great challenge. The existing impregnation die runner structure is single, so that molten resin is faced with a plurality of obstacles when penetrating fiber bundles, and uniform penetration is difficult to fully realize. As a result, dry spots appear on the prepreg tape or fluctuation occurs in the gel content, which seriously affects the performance and quality stability of the product. Furthermore, the coupling relationship between the process parameters is very complex. The traction speed, the resin viscosity, the temperature and other key parameters are related and mutually influenced, and if the parameters are not regulated and controlled accurately, the performance stability of the prepreg tape is poor, so that the requirement of high-quality production is difficult to meet.
In this regard, there are studies on improving the uniformity of the fiber development of prepreg tapes by combining the air-laid yarn technique. However, in such researches, it has been found that the method can effectively improve the main properties of the product, namely the tensile strength of the X axis (axial direction of the long fibers), and can improve the impregnation uniformity and the impregnation efficiency obviously, but the method has limited or even worse performances in the Y axis (axial direction perpendicular to the long fibers) strength of the prepreg tape product. And the weatherability of prepreg tapes is still relatively limited.
Disclosure of Invention
Aiming at the problems of uneven fiber unfolding, low fat impregnation efficiency, complex technological parameter coupling and the like in the traditional fiber reinforcement scheme, and the defects of poor partial performance of the novel yarn unfolding dip plating technology and the like, the technical scheme of the invention provides a continuous fiber reinforcement prepreg tape and a preparation method thereof.
The invention mainly aims to realize efficient and uniform spreading of fiber filaments in a prepreg tape.
2. Improving the impregnation efficiency and uniformity of the molten resin.
3. The resin content and the dimensional stability of the prepreg tape are precisely controlled.
4. The comprehensive mechanical property and weather resistance of the prepreg tape are effectively improved.
In order to achieve the above purpose, the present invention adopts the following technical scheme.
A method for preparing a continuous fiber reinforced prepreg tape comprises 1) pretreating a base fiber to obtain a pretreated fiber.
2) And performing yarn spreading treatment on the pretreated fibers by using an air flow yarn spreading method to obtain the continuous fiber lamellar belt.
3) And carrying out sectional impregnation reinforcing treatment on the continuous fiber lamellar band, and then cooling and shaping to obtain the continuous fiber reinforced prepreg band.
Preferably, in the step 1), the matrix fiber is carbon fiber, the carbon fiber is mixed fiber of continuous long fiber and chopped fiber, the continuous long fiber is more than or equal to 200 m, and the length of the chopped fiber is 5-15 mm.
Preferably, the chopped fibers in the matrix fibers account for 12-18 wt%.
The pretreatment process of the step 1) is preferably carried out by dissolving modified leaching material in concentrated sulfuric acid solution to prepare pretreatment liquid, uniformly atomizing and spraying the pretreatment liquid on base fibers, standing for 5-10 min, washing with deionized water, and drying, wherein the concentrated sulfuric acid is industrial concentrated sulfuric acid with the sulfuric acid degree of more than or equal to 70wt%, the concentration of the modified leaching material in the pretreatment liquid is 5-8wt%, and the use amount of the pretreatment liquid is 8-10wt% of the base fibers.
Preferably, in the step 2), the temperature of the air flow is controlled to be 350-380 ℃ and the flow speed of the air flow is controlled to be 3-5 m/s in the yarn spreading treatment process.
The method comprises the steps of, preferably, step 3), placing a continuous fiber thin layer belt in a protective atmosphere and carrying out impregnation treatment under a fusion modified impregnating condition, wherein the step 3) comprises primary movement impregnation and final infiltration impregnation, the primary movement impregnation controls the traction rate of the continuous fiber thin layer belt in the fusion modified impregnating material to be 3-5 m/min, the intermediate prepreg belt is obtained after impregnation, the mass content of matrix fibers in the intermediate prepreg belt is 92-95 wt%, the final infiltration impregnation controls the traction rate of the intermediate prepreg belt in the fusion modified impregnating material to be 1.5-2.5 m/min, the semi-finished prepreg belt is obtained after impregnation, and the mass content of matrix fibers in the semi-finished prepreg belt is 68-72 wt%.
The modified leaching material is prepared by mixing modified polyether-ether-ketone, maleic anhydride grafting compatilizer, antioxidant B215 and N, N-hexamethylene bis-stearamide according to the mass ratio of 50:1.5:1.5:0.1, heating the modified polyether-ether-ketone to be just molten, adding other components, and uniformly mixing, wherein the modified polyether-ether-ketone is prepared by uniformly mixing the polyether-ether-ketone and 95-98 wt% of concentrated sulfuric acid according to the mass ratio of 1 (0.8-1.2), reacting for 1.75-2.25 h under the environmental condition that the temperature is 55-65 ℃, dialyzing to pH of 6.8-7.2 by using ionized water, vacuum drying, preparing sulfonated polyether-ether-ketone, uniformly mixing the sulfonated polyether-ether-ketone and the modifier according to the mass ratio of 1 (0.4-0.6), and performing melt blending in a twin screw extruder under the environmental condition that the temperature is 340-360 ℃ and the screw speed is 80-90 rpm.
The modifier is furan and N, N '- (4, 4' -methylenediphenyl) bismaleimide which are uniformly mixed according to the mass ratio of 1 (1.75-1.95).
Preferably, in the cooling and shaping process in the step 3), the relative humidity of the environment is controlled to be less than or equal to 30 percent.
A continuous fiber reinforced prepreg tape.
For the technical scheme of the invention, the core is the organic combination of the air-laid yarn technology and the dip plating technology.
In the airflow yarn spreading link, the invention abandons the traditional mechanical rolling or tension control mode, and instead adopts high-pressure airflow to perform non-contact spreading on the fiber tows, thereby effectively avoiding the problems of fiber damage, local stress concentration and the like possibly caused by the traditional method and providing better fiber foundation conditions for the subsequent process flow.
However, in the early development process, it was also found that simply adopting the combination of the air-laid yarn technology and the dip plating technology will cause a great distribution difference in the mechanical properties of the prepreg tape, which is excellent in the X-axis and worse in the Y-axis, mainly because the air-laid yarn can actually greatly improve the distribution uniformity of the fibers, but the distribution axis is too single, and after the prepreg tape is prepared by combining the dip plating technology, the Y-axis properties are mainly provided after the dip material is cured, resulting in a more remarkable uneven distribution of the mechanical properties.
Therefore, the invention adopts a special treatment method, so that the air-laid yarn technology and the dip plating technology in the preparation process can be combined more effectively. In this process, it is of particular importance first to pretreat the matrix fibers, i.e. the carbon fibers used in the present invention. In general, the air-laid prepreg tape is usually only made of continuous long fibers, because short fibers are easily gathered together in the air flow, and are difficult to be uniformly dispersed like the long fibers, so that the yarn-laying effect is poor, a uniform fiber thin layer cannot be formed, and meanwhile, the short fibers are easily entangled and knotted with each other in the air flow to form a lump, so that the uniformity and the continuity of the yarn-laying are affected. On the other hand, because the short fiber length is shorter, the short fiber is more easily impacted and rubbed by the air flow in the air flow, fiber breakage and filament increase are easily caused, the strength and quality of the fiber are reduced, the fiber can be repeatedly folded and bent, the damage of the fiber is further aggravated, and the mechanical property is influenced.
However, in the invention, the pretreatment method is adopted to dissolve part of the material soaked in the invention by using commercially available 70 wt% industrial concentrated sulfuric acid before air-stream yarn spreading, so that a pretreatment liquid with better fluidity is formed and uniformly moistened on the surface of the matrix fiber for pretreatment by using an atomization spraying method, and the process can generate 'distributed point treatment' on the fiber. Because the concentrated acid in the pretreatment liquid can actually change the surface properties of the matrix carbon fibers to some extent, especially in terms of polarity performance, in addition to the leaching treatment.
The carbon fiber is used as one of the first-choice fibers of the air-jet yarn spreading technology, and because nonpolar or weak-polarity fibers are more suitable for the air-jet yarn spreading technology, agglomeration and agglomeration are not easy, after the carbon fiber is pretreated by the method, the polarity of the surface of the carbon fiber can be changed to a certain extent, under the proper concentration of concentrated sulfuric acid and proper treatment conditions, polar functional groups such as carbonyl groups and carboxyl groups are introduced into the surface of the carbon fiber, so that the surface energy and wettability of the carbon fiber are improved, the bonding strength of the carbon fiber and modified soaks can be further improved, uniform polar points can be formed as linking points to realize the linking of long and short fibers, the distribution form of the base fibers is changed by taking the linking points as the movement characteristics of 'axle centers' and short fibers in the air-jet yarn spreading process, the short fibers can be uniformly distributed among the long fibers in an oblique and vertical mode, the Y-axis linking effect is enhanced, the pretreatment time is properly controlled, the fiber is prevented from being subjected to remarkable oxidation damage, the performance of the carbon fiber is reduced, the polar points can be simultaneously realized, and the preliminary oxidation point position is fixed on the surface of the carbon fiber is coated with the primary-coated carbon fiber, and the primary oxidation point is realized.
Of course, the process also needs to be matched and improved, and in the air-spreading process, the operation method of hot air pre-spreading fibers is used as the air-spreading air flow, so that the axial property of the long fiber spreading yarn is better, the stress concentration caused by local fiber enrichment is reduced, short fibers are effectively and naturally distributed, and the yield and average performance of products are improved.
The invention also makes adjustments to the impregnation process. The sectional type dipping treatment is adopted, different traction rates (the traction direction is along the axial direction of the long fibers) are respectively adopted in the sectional type dipping treatment process, and also because the pretreatment process and the front-end air flow spreading are matched, the short fibers in the continuous fiber lamellar belt can be obliquely distributed to a certain extent, the Y-axis distribution trend of the short fibers can be further enhanced in the primary motion dipping process, meanwhile, the primary coating and fixation of the dipping material on the long and short fibers are realized, and then the effective and complete coating and fixation of the dipping material are realized by adopting the final-stage penetration dipping similar to the conventional dipping, so that the finished prepreg belt is obtained.
The invention is not limited to this, but has another core point that the leaching material is improved and optimized. Namely, the thermoplastic resin is subjected to organic treatment, a reversible network and a guiding function are constructed by introducing polar functional groups through sulfonation modification and a dynamic cross-linking agent, so that the resin material can be effectively subjected to good performance enhancement, and the organic functional groups and the polar groups on the surface of the fiber form a cross-linked network, thereby effectively strengthening the mechanical properties of the resin material. The organized treatment of polyether-ether-ketone realizes strong constraint and uniform distribution of fibers at a molecular level. The synergistic effect (hydrogen bond, covalent bond and dynamic bond) of the chemical bond obviously improves the interfacial strength, wet heat resistance and functional characteristics of the prepreg tape, and ensures the high performance of the prepreg tape in extreme environments.
The polyether-ether-ketone is a semi-crystalline high-performance thermoplastic polymer, and the main chain of the polyether-ether-ketone is alternately composed of benzene rings, ether bonds and ketone groups, so that the polyether-ether-ketone is endowed with excellent high temperature resistance, chemical stability and mechanical strength. However, unmodified polyetheretherketone is less polar and has weak interfacial bonds with non-polar or weakly polar fibers (e.g., carbon fibers), resulting in insufficient interlaminar shear strength of the composite. The invention introduces specific functional groups and chemical bonds through the organic treatment, which can remarkably enhance interface combination and optimize fiber distribution.
In the invention, polyether-ether-ketone is dissolved in concentrated sulfuric acid, and sulfonic acid groups are introduced on benzene rings through electrophilic substitution reaction, so that the wettability of resin and fiber surfaces is remarkably improved by means of the strong polarity of the sulfonic acid groups. The sulfonic acid matrix in the resin substrate can form hydrogen bond with hydroxyl groups on the surface of the fiber after sulfonation, and can bond the connection strength between the substrate and the fiber through electrostatic action in an alkaline environment. And the polar groups reduce the adsorption of moisture at the interface through chemical bonding, so that the material still has higher strength retention after wet heat aging.
The modified polyether-ether-ketone matrix and the fiber interface have the effects of load transmission, effective connection groups and reinforcement. In the invention, conjugated diene and dienophile can be used for constructing a cycloolefin skeleton in a lower temperature environment between maleimide and furan, the connection strength of the modified polyether-ether-ketone substrate to continuous fibers is enhanced, in a high-temperature use environment, the resin viscosity in the prepreg tape is reduced, the fibers generate larger displacement, the cycloolefin skeleton can be opened to form an effective carbon chain, the fibers are allowed to be stretched and arranged by shearing force, the chemical linkage of the substrate to the fibers is ensured, the tensile strength of the prepreg tape in an extreme environment is improved, and the cycloolefin skeleton is recovered after cooling to form a crosslinked network for fixing the positions of the fibers.
The invention has the beneficial effects that through the organic combination of the air-laid yarn and the dip plating technology, the Y-axis bonding strength of the prepreg tape is enhanced from a microscopic level, the fiber distribution form is improved, the integral mechanical property of the prepreg tape is obviously improved and optimized, and the weather resistance of the prepreg tape is also obviously improved through the treatment improvement of the dipping material.
Detailed Description
The present invention will be described in further detail with reference to specific examples. Those of ordinary skill in the art will be able to implement the invention based on these descriptions. In addition, the embodiments of the present invention referred to in the following description are typically only some, but not all, embodiments of the present invention. Therefore, all other embodiments, which can be made by one of ordinary skill in the art without undue burden, are intended to be within the scope of the present invention, based on the embodiments of the present invention.
The raw materials used in the examples of the present invention are all commercially available or available to those skilled in the art unless otherwise specified, and the methods used in the examples of the present invention are all known to those skilled in the art.
The carbon fiber continuous long fiber length used in the embodiment of the invention is 220-250 m, the carbon fiber chopped fiber length is 5-15 mm, and the carbon fiber continuous long fiber length is high-quality carbon fibers with the tensile strength of 3600-3800 MPa.
The embodiment 1 of the preparation method of the continuous fiber reinforced prepreg tape comprises the steps of 1) preparing a modified leaching material, wherein the modified leaching material is formed by mixing modified polyether ether ketone, a maleic anhydride grafting compatilizer, an antioxidant B215 and N, N-hexamethylene bisstearamide according to the mass ratio of 50:1.5:1.5:0.1, heating the modified polyether ether ketone to be just melted, and then adding other components to be uniformly mixed to obtain the modified leaching material.
The modified polyether-ether-ketone is prepared by uniformly mixing polyether-ether-ketone and 96 wt% concentrated sulfuric acid according to a mass ratio of 1:1, reacting at 62 ℃ under the environment condition of 2 h, dialyzing to pH 7 by using ionized water, and vacuum drying to prepare sulfonated polyether-ether-ketone.
Uniformly mixing sulfonated polyether-ether-ketone and a modifier according to the mass ratio of 1:0.5, and carrying out melt blending in a double-screw extruder under the environmental conditions of the temperature of 350 ℃ and the screw rotating speed of 85 rpm to prepare the modified polyether-ether-ketone.
The modifier is furan and N, N '- (4, 4' -methylenediphenyl) bismaleimide which are uniformly mixed according to the mass ratio of 1:1.8.
2) Carbon fiber continuous long fibers and carbon fiber chopped fibers with the mass ratio of 85:15 are used as matrix fibers, the continuous long fibers are unfolded, the chopped fibers are uniformly spread on the surfaces of the continuous long fibers and then are pretreated, during the pretreatment process, modified polyether-ether-ketone is dissolved in 70wt% concentrated sulfuric acid solution to prepare pretreatment liquid with the concentration of 6.5 wt%, the pretreatment liquid is uniformly atomized and sprayed on the matrix fibers, the usage amount of the pretreatment liquid is 8 wt% of the matrix fibers, and the pretreated fibers are obtained after standing for 10min and washing with deionized water and drying.
3) And (3) carrying out yarn spreading treatment on the pretreated fibers by using an air flow yarn spreading method, wherein the air flow temperature is controlled to be 355 ℃ and the air flow speed is controlled to be 4 m/s in the air flow yarn spreading treatment process, so as to obtain the continuous fiber lamellar belt.
4) The method comprises the steps of carrying out segmented impregnation and reinforcement treatment on a continuous fiber thin layer belt, wherein the segmented impregnation is divided into primary motion impregnation and final infiltration impregnation, the traction rate of the continuous fiber thin layer belt in 355-360 ℃ melt modified impregnation is controlled to be 4. 4.5 m/min in the primary motion impregnation process, an intermediate prepreg belt is obtained after impregnation, the mass content of matrix fibers in the intermediate prepreg belt is 93.1-wt%, the traction rate of the intermediate prepreg belt in the 355-360 ℃ melt modified impregnation is controlled to be 2 m/min in the final infiltration impregnation process, a semi-finished prepreg belt is obtained after impregnation, the mass content of matrix fibers in the semi-finished prepreg belt is 69.6-wt%, and then the continuous fiber reinforced prepreg belt is obtained after natural cooling and shaping in an environment with the relative humidity less than or equal to 30%.
The fiber reinforced prepreg tape prepared in this example was subjected to performance detection, and specific characterization results are as follows.
Performing air flow spreading uniformity detection, namely performing cross section slicing on the fiber layer subjected to the spreading in the step (1), observing monofilament distribution by using a Scanning Electron Microscope (SEM), randomly selecting 10 points along the axial direction of the continuous long fiber, measuring the standard deviation (sigma) of the spreading width and the average value (z) of the spreading width of the continuous long fiber, and calculating the variation coefficient (c.v percent) of the continuous long fiber by combining the standard deviation of the spreading width and the average value of the spreading width, wherein the specific calculation formula is as follows:。
Resin impregnation efficiency three-dimensional imaging is carried out on the prepreg tape, the permeability of resin in the fiber bundles is analyzed, 1m prepreg tape is randomly intercepted, and the dry spot area ratio (without resin coverage area) is counted.
And (3) mechanical property detection, namely respectively carrying out characterization detection on the tensile strength of the X axis and the tensile strength of the Y axis of the prepreg tape.
And (3) detecting the durability of a wet heat environment, namely aging the fiber reinforced prepreg tape prepared in the example by 500 h under the environment condition that the temperature is 85 ℃ and the environment humidity is 85%, and testing the retention rate of mechanical properties.
The results of the performance tests are shown in table 1 below.
Table 1 results of example 1 sample performance test:
From the characterization results in table 1, it is obvious that the prepreg tape of the present invention has very significant performance advantages. In terms of the coefficient of variation, the fiber shows extremely small coefficient of variation, which indicates that the continuous long fibers are extremely uniform in distribution and extremely smooth in spreading, the connection points formed by pretreatment can keep extremely good axial spreading and transverse arrangement under the cooperation of the hot air flow spreading process, mainly because a small amount of the dipping material of the connection points softens and even melts to form molten drops under the temperature condition of the hot air flow spreading yarn, the long fiber link point can slide along the axial direction of the long fiber link point to realize flattening under the coordination of tension of molten drops, polar connection among fibers and the like, so that bending and other conditions are reduced, and meanwhile, the condition that the short fibers which are uniformly linked originally are influenced to generate enrichment is avoided, but too high hot air temperature is not adopted, and the too high hot air temperature can cause agglomeration and agglomeration of the short fibers, and on the contrary, the variation coefficient is increased and the mechanical property is reduced. And the extremely low dry spot rate also shows good dip coating effect. On the other hand, the mechanical properties are very excellent. Generally, a resin matrix in the prepreg tape forms a certain structure after curing, the performance of the resin matrix has an important influence on the strength of the composite material, and the resin can enhance the mechanical property of the fiber, improve the toughness, the impact resistance, the environmental stress cracking resistance and the like of the composite material, but compared with the high strength of the carbon fiber, the strength of the resin matrix is relatively low, and the overall axial tensile strength is reduced to a certain extent. For example, the tensile strength of fiber used in UD unidirectional tape prepreg tape prepared from IMS65 carbon fiber sold in the market is about 5800 MPa, the tensile strength of X axis of the product is about 2900 MPa, the tensile strength of Y axis is only about 90-102 MPa, the tensile strength of X axis is only about 50% of that of original carbon fiber, and the modified leaching material used in the invention is as high as 73.4-77.5%, which shows that the modified leaching material used in the invention is far superior to the commercially available leaching material, the combination effect is better, the load transferring effect can be better formed, and thus, the higher performance retention rate is shown, and the theoretical use of better quality carbon fiber can show extremely superior tensile strength performance. The Y-axis tensile strength is more obviously optimized, the Y-axis tensile strength of the existing carbon fiber prepreg tape is generally only 90-110 MPa, and the performance of the invention is more than ten times, so that the special distribution of the short fibers is realized through the three-party cooperative coordination of pretreatment, hot air spreading and segmented dip plating, the Y-axis tensile strength is obviously enhanced, the tensile strength can reach about 28.7-30.3% of the tensile strength of the fibril, and is far higher than the tensile strength of the modified polyether-ether-ketone, so that the short fibers are proved to have the tensile enhancement effect in the Y-axis direction, and the effectiveness of the scheme is shown. Besides optimizing the mechanical properties of the material, the modified polyether-ether-ketone also has extremely excellent weather resistance, and the overall strength retention rate can reach more than 95% even after an aging experiment.
Embodiment 2. A preparation method of a continuous fiber reinforced prepreg tape comprises 1) preparing a modified leaching material, wherein the modified leaching material is formed by mixing modified polyether ether ketone, a maleic anhydride grafting compatilizer, an antioxidant B215 and N, N-hexamethylene bisstearamide according to the mass ratio of 50:1.5:1.5:0.1, heating the modified polyether ether ketone to be just melted, and then adding other components to be uniformly mixed, thus obtaining the modified leaching material.
The modified polyether-ether-ketone is prepared by uniformly mixing polyether-ether-ketone and 98 wt% concentrated sulfuric acid according to the mass ratio of 1:0.8, reacting at the temperature of 55 ℃ for 2.25: 2.25 h, dialyzing with ionized water until the pH value is 6.8, and vacuum drying to prepare sulfonated polyether-ether-ketone.
The sulfonated polyether-ether-ketone and the modifier are uniformly mixed according to the mass ratio of 1:0.4, and are melt-blended in a double-screw extruder under the environmental conditions of 340 ℃ and 80 rpm of screw speed to prepare the modified polyether-ether-ketone.
The modifier is furan and N, N '- (4, 4' -methylenediphenyl) bismaleimide which are uniformly mixed according to the mass ratio of 1:1.75.
2) The preparation method comprises the steps of taking carbon fiber continuous long fibers and carbon fiber chopped fibers with the mass ratio of 82:18 as matrix fibers, spreading the continuous long fibers, uniformly spreading the chopped fibers on the surfaces of the continuous long fibers, carrying out pretreatment, dissolving modified polyether-ether-ketone in 70 wt% concentrated sulfuric acid solution to prepare pretreatment liquid with the concentration of 8.0 wt% of the modified polyether-ether-ketone in the pretreatment process, uniformly atomizing and spraying the pretreatment liquid on the matrix fibers, keeping the usage amount of the pretreatment liquid to be 10.0 wt% of the matrix fibers, standing for 5 min, and washing and drying with deionized water to obtain the pretreated fibers.
3) The pretreated fiber is subjected to yarn spreading treatment by an air flow yarn spreading method, and the air flow temperature is controlled to be 350 ℃ and the air flow speed is controlled to be 3 m/s in the air flow yarn spreading treatment process, so that the continuous fiber lamellar band is obtained.
4) The method comprises the steps of carrying out segmented impregnation and reinforcement treatment on a continuous fiber thin layer belt, wherein the segmented impregnation is divided into primary motion impregnation and final infiltration impregnation, the traction rate of the continuous fiber thin layer belt in 355-360 ℃ melt modified impregnation is controlled to be 3 m/min in the primary motion impregnation process, an intermediate prepreg belt is obtained after impregnation, the mass content of matrix fibers in the intermediate prepreg belt is 92.6 wt%, the traction rate of the intermediate prepreg belt in 355-360 ℃ melt modified impregnation is controlled to be 1.5m/min in the final infiltration impregnation process, a semi-finished prepreg belt is obtained after impregnation, the mass content of matrix fibers in the semi-finished prepreg belt is 70.2 wt%, and then the continuous fiber reinforced prepreg belt is obtained after natural cooling and shaping in an environment with the relative humidity less than or equal to 30%.
The fiber reinforced prepreg tape prepared in this example was subjected to performance detection, and specific characterization results are as follows.
Performing air flow spreading uniformity detection, namely performing cross section slicing on the fiber layer subjected to the spreading in the step (1), observing monofilament distribution by using a Scanning Electron Microscope (SEM), randomly selecting 10 points along the axial direction of the continuous long fiber, measuring the standard deviation (sigma) of the spreading width and the average value (z) of the spreading width of the continuous long fiber, and calculating the variation coefficient (c.v percent) of the continuous long fiber by combining the standard deviation of the spreading width and the average value of the spreading width, wherein the specific calculation formula is as follows:。
resin impregnation efficiency three-dimensional imaging is carried out on the prepreg tape, the permeability of resin in the fiber bundles is analyzed, 1m prepreg tape is randomly intercepted, and the dry spot area ratio (without resin coverage area) is counted.
And (3) mechanical property detection, namely respectively carrying out characterization detection on the tensile strength of the X axis and the tensile strength of the Y axis of the prepreg tape.
And (3) detecting the durability of a wet heat environment, namely aging the fiber reinforced prepreg tape prepared in the example by 500 h under the environment condition that the temperature is 85 ℃ and the environment humidity is 85%, and testing the retention rate of mechanical properties.
The results of the performance tests are shown in table 2 below.
Table 2 sample performance test results for example 2:
From the characterization results in table 2, the invention uses more modified leaching materials in the pretreatment process, further enhances the preliminary linking effect, leads the tensile strength of the Y axis to be further optimized and improved, but leads the strength of the X axis to be obviously reduced, and simultaneously increases the variation coefficient and the dry spot rate, thus the pretreatment process has obvious influence on the straight and smooth distribution uniformity and the mechanical property of continuous long fibers of the product.
Embodiment 3 relates to a preparation method of a continuous fiber reinforced prepreg tape, which comprises 1) preparing a modified leaching material, wherein the modified leaching material is formed by mixing modified polyether ether ketone, a maleic anhydride grafting compatilizer, an antioxidant B215 and N, N-hexamethylene bisstearamide according to the mass ratio of 50:1.5:1.5:0.1, heating the modified polyether ether ketone to be just melted, and then adding other components to be uniformly mixed to obtain the modified leaching material.
The modified polyether-ether-ketone is prepared by uniformly mixing polyether-ether-ketone and 95 wt% concentrated sulfuric acid according to a mass ratio of 1:1.2, reacting at 65 ℃ under the environment condition of 1.75: 1.75 h, dialyzing to pH value of 7.2 by using ionized water, and vacuum drying to prepare sulfonated polyether-ether-ketone.
The sulfonated polyether-ether-ketone and the modifier are uniformly mixed according to the mass ratio of 1:0.6, and are melt-blended in a double-screw extruder under the environmental conditions of the temperature of 360 ℃ and the screw rotating speed of 90 rpm to prepare the modified polyether-ether-ketone.
The modifier is furan and N, N '- (4, 4' -methylenediphenyl) bismaleimide which are uniformly mixed according to the mass ratio of 1:1.95.
2) The preparation method comprises the steps of taking carbon fiber continuous long fibers and carbon fiber chopped fibers with a mass ratio of 88:12 as matrix fibers, spreading the continuous long fibers, uniformly spreading the chopped fibers on the surfaces of the continuous long fibers, carrying out pretreatment, dissolving modified polyether-ether-ketone in 70 wt% concentrated sulfuric acid solution to prepare pretreatment liquid with the concentration of 5.0 wt% of the modified polyether-ether-ketone in the pretreatment process, uniformly atomizing and spraying the pretreatment liquid on the matrix fibers, wherein the use amount of the pretreatment liquid is 8 wt% of the matrix fibers, standing for 10min, and then washing and drying with deionized water to obtain the pretreated fibers.
3) And (3) carrying out yarn spreading treatment on the pretreated fibers by an air flow yarn spreading method, wherein the air flow temperature is controlled to be 360 ℃ and the air flow speed is controlled to be 5 m/s in the air flow yarn spreading treatment process, so as to obtain the continuous fiber lamellar band.
4) The method comprises the steps of carrying out segmented impregnation and reinforcement treatment on a continuous fiber thin layer belt, wherein the segmented impregnation is divided into primary motion impregnation and final infiltration impregnation, the traction rate of the continuous fiber thin layer belt in 355-360 ℃ melt modified impregnation is controlled to be 4. 4.5 m/min in the primary motion impregnation process, an intermediate prepreg belt is obtained after impregnation, the mass content of matrix fibers in the intermediate prepreg belt is 92.9 wt%, the traction rate of the intermediate prepreg belt in 355-360 ℃ melt modified impregnation is controlled to be 2 m/min in the final infiltration impregnation process, a semi-finished prepreg belt is obtained after impregnation, the mass content of matrix fibers in the semi-finished prepreg belt is 69.9 wt%, and then the continuous fiber reinforced prepreg belt is obtained after natural cooling and shaping in an environment with the relative humidity less than or equal to 30%.
The fiber reinforced prepreg tape prepared in this example was subjected to performance detection, and specific characterization results are as follows.
Performing air flow spreading uniformity detection, namely performing cross section slicing on the fiber layer subjected to the spreading in the step (1), observing monofilament distribution by using a Scanning Electron Microscope (SEM), randomly selecting 10 points along the axial direction of the continuous long fiber, measuring the standard deviation (sigma) of the spreading width and the average value (z) of the spreading width of the continuous long fiber, and calculating the variation coefficient (c.v percent) of the continuous long fiber by combining the standard deviation of the spreading width and the average value of the spreading width, wherein the specific calculation formula is as follows:。
resin impregnation efficiency three-dimensional imaging is carried out on the prepreg tape, the permeability of resin in the fiber bundles is analyzed, 1m prepreg tape is randomly intercepted, and the dry spot area ratio (without resin coverage area) is counted.
And (3) mechanical property detection, namely respectively carrying out characterization detection on the tensile strength of the X axis and the tensile strength of the Y axis of the prepreg tape.
And (3) detecting the durability of a wet heat environment, namely aging the fiber reinforced prepreg tape prepared in the example by 500 h under the environment condition that the temperature is 85 ℃ and the environment humidity is 85%, and testing the retention rate of mechanical properties.
The results of the performance tests are shown in table 3 below.
Table 3 sample performance test results for example 3:
From the characterization results in table 3, the modified leaching used in the pretreatment process is relatively reduced, which has no significant effect on the product variation coefficient, dry spot rate and X-axis tensile strength, but has a significant effect on Y-axis tensile strength. It can be seen that the pretreatment process is extremely critical to build good Y-axis tensile properties of the product.
Comparative example 1 based on example 1, this example was not subjected to the pretreatment described in step 2), and was compared laterally with example 1, the following comparative group was specifically set.
Table 4 transverse comparison of the preparation process of comparative example 1 and example 1:
The same experimental characterization is carried out on each group of products, and the experimental characterization specifically comprises the steps of carrying out air flow spreading uniformity detection, namely carrying out cross section slicing on a fiber layer subjected to spreading in the step (1), observing monofilament distribution by using a Scanning Electron Microscope (SEM), randomly selecting 10 points along the axial direction of continuous long fibers, measuring a standard deviation (sigma) of the spreading width and an average value (z) of the spreading width of the continuous long fibers, and calculating a variation coefficient (c.v percent) of the continuous long fibers by combining the standard deviation of the spreading width and the average value of the spreading width, wherein the specific calculation formula is as follows: 。
resin impregnation efficiency three-dimensional imaging is carried out on the prepreg tape, the permeability of resin in the fiber bundles is analyzed, 1m prepreg tape is randomly intercepted, and the dry spot area ratio (without resin coverage area) is counted.
And (3) mechanical property detection, namely respectively carrying out characterization detection on the tensile strength of the X axis and the tensile strength of the Y axis of the prepreg tape.
And (3) detecting the durability of a wet heat environment, namely aging the fiber reinforced prepreg tape prepared in the example by 500 h under the environment condition that the temperature is 85 ℃ and the environment humidity is 85%, and testing the retention rate of mechanical properties.
The results of the performance tests are shown in table 5 below.
Table 5 results of comparative example 1 sample performance test:
As is apparent from the above characterization results of table 5, the pretreatment process of the present invention has a very significant effect on the primary distribution fixation of the long and short fibers, and if no effective pretreatment is performed, the subsequent steps are the same as in example 1, and extremely large performance differences are generated, but the difference in the Y-axis performance is several times as high although the difference in the X-axis is relatively small.
Comparative example 2 based on example 1, which controls the air-laid process of step 3), a transverse comparison was made, the following comparative group being specifically set.
Table 6 transverse comparison of the preparation process of comparative example 2 and example 1:
The same experimental characterization is carried out on each group of products, and the experimental characterization specifically comprises the steps of carrying out air flow spreading uniformity detection, namely carrying out cross section slicing on a fiber layer subjected to spreading in the step (1), observing monofilament distribution by using a Scanning Electron Microscope (SEM), randomly selecting 10 points along the axial direction of continuous long fibers, measuring a standard deviation (sigma) of the spreading width and an average value (z) of the spreading width of the continuous long fibers, and calculating a variation coefficient (c.v percent) of the continuous long fibers by combining the standard deviation of the spreading width and the average value of the spreading width, wherein the specific calculation formula is as follows: 。
resin impregnation efficiency three-dimensional imaging is carried out on the prepreg tape, the permeability of resin in the fiber bundles is analyzed, 1m prepreg tape is randomly intercepted, and the dry spot area ratio (without resin coverage area) is counted.
And (3) mechanical property detection, namely respectively carrying out characterization detection on the tensile strength of the X axis and the tensile strength of the Y axis of the prepreg tape.
And (3) detecting the durability of a wet heat environment, namely aging the fiber reinforced prepreg tape prepared in the example by 500 h under the environment condition that the temperature is 85 ℃ and the environment humidity is 85%, and testing the retention rate of mechanical properties.
The results of the performance tests are shown in table 7 below.
Table 7 comparative example 2 sample performance test results:
As is apparent from the above characterization results of table 7, the use of room temperature air flow for air-laid yarns resulted in a significant increase in the uniformity of distribution of the product, an increase in the dry spot rate, and a drastic decrease in the X-axis tensile strength, while the Y-axis supporting tensile effect was produced due to the possible winding twist of more obliquely distributed fibers or continuous filaments, but the overall performance was clearly not in accordance with the expected performance of the present invention. While hot air stretch using slightly lower temperatures also presents similar problems, but to a lesser extent. The hot air spreading yarn is performed at an excessively high temperature, the distribution of short fibers is obviously influenced, less agglomeration and caking are possibly generated, the variation coefficient is slightly increased, the X-axis tensile strength is at a better level although the reduction amplitude is smaller, the reduction amplitude of the Y-axis tensile strength is extremely huge, and the influence of the temperature on the short fibers in the air spreading yarn treatment process is obvious.
Comparative example 3 based on example 1, the control of the dipping treatment process of step 4) was performed for transverse comparison, and the following comparative group was specifically set.
Table 8 transverse comparison of the preparation process of comparative example 3 and example 1:
The same experimental characterization is carried out on each group of products, and the experimental characterization specifically comprises the steps of carrying out air flow spreading uniformity detection, namely carrying out cross section slicing on a fiber layer subjected to spreading in the step (1), observing monofilament distribution by using a Scanning Electron Microscope (SEM), randomly selecting 10 points along the axial direction of continuous long fibers, measuring a standard deviation (sigma) of the spreading width and an average value (z) of the spreading width of the continuous long fibers, and calculating a variation coefficient (c.v percent) of the continuous long fibers by combining the standard deviation of the spreading width and the average value of the spreading width, wherein the specific calculation formula is as follows: 。
resin impregnation efficiency three-dimensional imaging is carried out on the prepreg tape, the permeability of resin in the fiber bundles is analyzed, 1m prepreg tape is randomly intercepted, and the dry spot area ratio (without resin coverage area) is counted.
And (3) mechanical property detection, namely respectively carrying out characterization detection on the tensile strength of the X axis and the tensile strength of the Y axis of the prepreg tape.
And (3) detecting the durability of a wet heat environment, namely aging the fiber reinforced prepreg tape prepared in the example by 500 h under the environment condition that the temperature is 85 ℃ and the environment humidity is 85%, and testing the retention rate of mechanical properties.
The results of the performance tests are shown in table 9 below.
Table 9 results of comparative example 3 sample performance test:
as is apparent from the above characterization results in table 9, the dip plating process is a core process of the technical scheme of the present invention, and has a significant influence on the performance of the product. The sectional dip plating is a key process for controlling the distribution of long and short fibers, and an excessively small initial traction rate is adopted, so that the distribution form and the axial direction of the short fibers are deviated from an expected target after the initial coating and fixing of the short fibers, but the excessively large traction rate can possibly cause curling or even stages of continuous long fibers, the influence of the excessively large traction rate is not obvious for a conventional continuous fiber lamellar band, but the excessively large traction rate can possibly cause approaching nodes due to the fact that a linkage point is generated in the pretreatment process, fiber bending among the nodes and the like occur, and the performance is obviously reduced.
Comparative example 4 based on example 1, this example only adjusts the leaching.
Table 10 transverse comparison of the preparation process of comparative example 4 and example 1:
The same experimental characterization is carried out on each group of products, and the experimental characterization specifically comprises the steps of carrying out air flow spreading uniformity detection, namely carrying out cross section slicing on a fiber layer subjected to spreading in the step (1), observing monofilament distribution by using a Scanning Electron Microscope (SEM), randomly selecting 10 points along the axial direction of continuous long fibers, measuring a standard deviation (sigma) of the spreading width and an average value (z) of the spreading width of the continuous long fibers, and calculating a variation coefficient (c.v percent) of the continuous long fibers by combining the standard deviation of the spreading width and the average value of the spreading width, wherein the specific calculation formula is as follows: 。
resin impregnation efficiency three-dimensional imaging is carried out on the prepreg tape, the permeability of resin in the fiber bundles is analyzed, 1m prepreg tape is randomly intercepted, and the dry spot area ratio (without resin coverage area) is counted.
And (3) mechanical property detection, namely respectively carrying out characterization detection on the tensile strength of the X axis and the tensile strength of the Y axis of the prepreg tape.
And (3) detecting the durability of a wet heat environment, namely aging the fiber reinforced prepreg tape prepared in the example by 500 h under the environment condition that the temperature is 85 ℃ and the environment humidity is 85%, and testing the retention rate of mechanical properties.
The results of the performance tests are shown in table 11 below.
Table 11 results of the test for the properties of the samples of comparative example 4:
From the characterization results in table 11, it is obvious that the modified polyether ether ketone of the invention has a significant effect on the product performance. Because the bonding strength of the polyether-ether-ketone and the carbon fiber is limited, the polyether-ether-ketone is difficult to achieve good load transfer and reinforcement effects, and the weather resistance is far weaker than that of the modified polyether-ether-ketone constructed by the invention, so that the strength retention rate is also drastically reduced after the wet heat aging.
It is obvious from the above that for the technical scheme of the invention, the high-quality product is prepared and is effectively optimized by the pretreatment, hot air spreading and sectional dip plating through the cooperative matching.
Claims (9)
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