Fiber reinforced composite stationary ring and preparation method thereof

Abstract

The invention relates to the field of composite materials, in particular to a fiber reinforced composite material static ring and a preparation method thereof. The preparation method provided by the invention comprises the following steps: firstly, compounding and twisting aramid fibers and nylon fibers to prepare a core wire, and then coating cotton and linen fibers on the surface of the core wire to obtain coated yarns; secondly, weaving the wrap yarn into a strip through a tatting process; secondly, the strip obtained in the second step is subjected to gum dipping through a specific glue solution and then dried, and prepreg is obtained; then, the obtained prepreg is subjected to winding forming on an annular mold, and an annular sample is formed; and then, the annular sample is put into a mold to be subjected to mold pressing curing forming, and the fiber reinforced composite material static ring is obtained. The obtained static ring has excellent impact strength, compression strength, water absorption, wear resistance and the like, and the performance requirements of a ship stern shaft sealing friction pair are met.

Description

Technical Field

[0001] This invention relates to the field of composite materials, and in particular to a fiber-reinforced composite static ring and its preparation method. Background Technology

[0002] The function of a mechanical seal relies on a set of friction pairs, with the stationary ring as the core component, together with the rotating ring, forming an end-face friction pair (such as...). Figure 1 As shown, where 1 is the moving ring and 2 is the stationary ring, it undertakes multiple key functions such as sealing and buffering. The stationary ring material of a mechanical seal needs to have properties such as wear resistance, corrosion resistance, self-lubrication, good thermal conductivity, and low coefficient of linear expansion. Common types include: graphite materials (pure graphite, resin-impregnated graphite, metal-impregnated graphite), engineering ceramic materials (silicon carbide SiC, alumina ceramic Al2O3, silicon nitride Si3N4), hard alloy materials, and polymer materials (polytetrafluoroethylene PTFE, nylon PA), etc.

[0003] Stern shaft seals play an indispensable role in marine propulsion systems, crucial for ensuring the stable operation of the ship's power transmission system and preventing seawater intrusion and lubricating oil leakage. There are various types of stern shaft seals, with mechanical seals being one of the most widely used. In mechanical seals, the stationary ring, through an elastic compensation mechanism, maintains a tight seal with the rotating ring, forming a liquid film barrier between them. This effectively prevents seawater intrusion and lubricating oil leakage. This liquid film acts as a robust defense, ensuring the stern shaft seal's tightness and thus maintaining the normal operation of the ship's propulsion system.

[0004] However, the stationary ring of the stern shaft seal faces extremely complex and harsh operating conditions. From a mechanical load perspective, shaft vibration, propeller thrust fluctuations, and ship collisions all exert varying degrees of force on the stationary ring. During ship navigation, the periodic thrust of the propeller and shaft vibration generate high-frequency impacts, which continuously act on the stationary ring, testing its structural strength. Under extreme conditions, such as sudden stops, reversing, or being hit by waves, the stern shaft may experience instantaneous load changes, and this sudden, enormous impact force has a more severe effect on the stationary ring. In terms of thermal loads, the frictional heat generated by the friction between the dynamic and stationary rings, as well as the temperature difference between seawater and lubricating oil, all have a thermal impact on the stationary ring. Continuous frictional heat will cause the stationary ring temperature to rise, while the temperature difference between seawater and lubricating oil may lead to thermal stress, further affecting the performance of the stationary ring. Chemical corrosion is also a major challenge for the stationary ring. Due to long-term contact with corrosive components in seawater and lubricating oil, the stationary ring material is easily corroded, thus affecting its performance and service life.

[0005] Traditional inorganic stationary ring materials such as graphite, ceramics, and metals have poor toughness and impact resistance. Under vibration and impact conditions on ship stern shafts, the stationary ring is prone to collision with the rotating ring material, causing damage. Brittle failure is a common problem. Traditional brittle stationary ring materials are easily susceptible to the propagation of microcracks upon impact, which can even lead to complete fragmentation, rendering the sealing device ineffective. While single polymer stationary rings have strong lubrication performance and impact resistance, they are less adaptable to extreme operating conditions; high-temperature failure is particularly prominent. On the one hand, the different coefficients of thermal expansion of different materials can lead to thermal deformation mismatch, reducing the fit of the stationary ring end face and causing warping, resulting in leakage from the friction pair. On the other hand, when the temperature exceeds 100°C, the lubricating film may vaporize, disrupting the stability of the sealing interface and affecting the sealing effect. In addition, polymer materials may soften or oxidize at high temperatures, leading to decreased hardness and accelerated wear, and gradual degradation of material properties. Summary of the Invention

[0006] In view of this, the present invention provides a fiber-reinforced composite stationary ring and its preparation method. The fiber-reinforced composite stationary ring prepared by the present invention can solve the problem of maintaining high reliability of stationary ring materials under complex working conditions such as high speed, boundary lubrication, and impact vibration, and avoid the problem of malfunctioning and causing seal leakage.

[0007] This invention provides a method for preparing a stationary ring of a fiber-reinforced composite material, comprising the following steps:

[0008] (A) Preparation of the covered yarn:

[0009] Aramid fibers and nylon fibers are combined and twisted to form a core yarn. Then, cotton and linen fibers are wrapped around the surface of the core yarn to obtain a covered yarn.

[0010] (B) Braided strip material:

[0011] The covered yarn is woven into a strip using a weaving process;

[0012] (C) Preparation of prepreg:

[0013] The strip obtained in step (B) is impregnated with adhesive solution and then dried to obtain prepreg:

[0014] The adhesive solution comprises the following components in the indicated mass ratios:

[0015] Phenolic resin 50%~60%;

[0016] Thermally conductive filler 10%~15%;

[0017] Self-lubricating component: 1.0%~2.0%;

[0018] Reinforcing filler 1%~3%;

[0019] Interfacial coupling agent 0.3%~1.5%;

[0020] Solvent balance;

[0021] (D) Molding:

[0022] The prepreg obtained in step (C) is wound onto a ring mold to form a ring-shaped sample; then, the ring-shaped sample is placed into the mold for compression molding to obtain a fiber-reinforced composite static ring.

[0023] Preferably, in step (A):

[0024] The linear density of the aramid fiber is 200~800D;

[0025] The linear density of the nylon fiber is 800~1400D;

[0026] The linear density of the core wire is 1000~2200D;

[0027] The mass ratio of aramid fiber to nylon fiber is (0.3~1):1.

[0028] Preferably, in step (A):

[0029] The composite twisting process preferably includes: applying Z-axis twist to aramid fibers, applying Z-axis twist to nylon fibers, then combining the twisted aramid and nylon fibers and applying S-axis twist to obtain the core wire;

[0030] The twist of the Z-direction twist on aramid fibers is 100~300Z, the twist of the Z-direction twist on nylon fibers is 50~300Z, and the twist of the S-direction twist is 100~250S.

[0031] Preferably, in step (A):

[0032] The cotton and linen fiber is a cotton sliver made up of natural cotton and linen short fibers, with an average length of 25-33 mm for a single fiber and an average diameter of 4-8 mm for the sliver after aggregation.

[0033] The mass ratio of cotton and linen fibers to core yarn is (3.5~6):1.

[0034] Preferably, in step (B):

[0035] The width of the strip is 50~200mm;

[0036] The weaving process uses the covered yarn as the warp and nylon yarn as the weft; wherein the linear density is 800D; the warp density is 8~15 threads / cm, and the weft density is 1~2 threads / cm.

[0037] Preferably, in step (C):

[0038] The thermally conductive filler is at least one of alumina, zinc oxide and dolomite;

[0039] The self-lubricating component is at least one of graphite and polytetrafluoroethylene;

[0040] The reinforcing filler is at least one of carbon nanotubes and aramid chopped fibers;

[0041] The interface coupling agent is KH-550;

[0042] The solvent is at least one of ethanol, methanol, acetone, and ethylene glycol.

[0043] Preferably, in step (C), a continuous prepreg production equipment is used for impregnation;

[0044] The prepreg production equipment includes an unwinding device, a tension control device, a glue tank, a drying tunnel, and a winding device;

[0045] The impregnation process includes: the strip obtained in step (B) is discharged from the unwinding device, the tension control device applies tension to the narrow strip, the narrow strip enters one end of the glue tank at a set speed, and is impregnated with glue in the glue tank;

[0046] The tension control device applies a tension of 80~150N to the narrow strip; the set speed is 2~5m / min.

[0047] The drying temperature is 120~140℃ and the time is 15~20min.

[0048] Preferably, in step (D), the winding tension of the winding process is 150~300N.

[0049] Preferably, in step (D), the heating temperature for curing is 150~180℃, the pressure is 5~10MPa, and the time is 10~20h.

[0050] The present invention also provides a fiber-reinforced composite static ring prepared by the preparation method described in the above technical solution.

[0051] To address the problem that traditional static ring materials are prone to failure under complex operating conditions and cannot meet the high reliability requirements of ship stern shaft sealing devices, this invention makes several improvements. The preparation method provided by this invention first starts with basic fiber raw materials, preparing multi-strand twisted core yarns through composite twisting. Then, cotton and linen fibers are wrapped around the outer layer of the core yarns using a ring spinning process, resulting in a multi-level structural skeleton fiber with an inner layer of organic blended long fibers and an outer layer of short fibers wrapped with cotton and linen fibers. Next, a glue solution containing a matrix resin, various functional fillers, and interfacial coupling agents is prepared, allowing the skeleton fibers to be fully impregnated, enabling the components to bind tightly and exert a synergistic effect. The impregnated skeleton fibers are dried to become prepreg fibers, preparing them for subsequent weaving. The prepreg fibers are woven into narrow strips using a shuttle weaving process. By flexibly adjusting the weaving structure and density, precise design and control of the skeleton fiber structure are achieved, meeting the specific performance requirements of the static ring material under different operating conditions. The woven prepreg narrow strips are wound into ring-shaped samples on a ring mold, and finally cured under high temperature and high pressure to form the final product. During the winding and molding process, the density of the stationary ring material can be precisely controlled within the range of 1.5-1.7 g / cm³. This not only ensures that the material has sufficient strength and toughness to cope with complex mechanical loads, but also gives the material a certain porosity, which can quickly guide and drain water during the friction sealing process, effectively solving the sealing problems and material performance degradation caused by water accumulation.

[0052] Test results show that the product obtained by this invention has an impact strength of over 75 MPa, a compressive strength of over 120 MPa, a water absorption rate of over 2.7%, and a linear expansion coefficient of over 11 × 10⁻⁶. -5 Below this, the coefficient of friction is below 0.21, exhibiting excellent mechanical properties, high water absorption, and friction resistance, ensuring the performance requirements of the ship's stern shaft sealing friction pair. Attached Figure Description

[0053] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0054] Figure 1 This is a schematic diagram of the seal structure composed of a stationary ring and a rotating ring;

[0055] Figure 2 This is a schematic diagram of the multi-level structure skeleton fiber of the coated yarn obtained in step (A) of the preparation method of the present invention. Detailed Implementation

[0056] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0057] In this article, the technical features described in an open-ended manner include both closed technical solutions composed of the listed features and open technical solutions that include the listed features.

[0058] The term “and / or” as used herein includes any and all combinations of one or more of the related listed items.

[0059] In this document, numerical ranges are referred to as continuous unless otherwise specified, and include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when a range refers to an integer, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.

[0060] In this article, when referring to units for data ranges, if the unit is only followed by the right endpoint, it indicates that the units for the left and right endpoints are the same. For example, 50~200mm means that the units for the left endpoint "50" and the right endpoint "200" are both mm.

[0061] In a first aspect, the present invention provides a method for preparing a stationary ring of a fiber-reinforced composite material, comprising the following steps:

[0062] (A) Preparation of the covered yarn:

[0063] Aramid fibers and nylon fibers are combined and twisted to form a core yarn. Then, cotton and linen fibers are wrapped around the surface of the core yarn to obtain a covered yarn.

[0064] (B) Braided strip material:

[0065] The covered yarn is woven into a strip using a weaving process;

[0066] (C) Preparation of prepreg:

[0067] The strip obtained in step (B) is impregnated with adhesive solution and then dried to obtain prepreg:

[0068] The adhesive solution comprises the following components in the indicated mass ratios:

[0069] Phenolic resin 50%~60%;

[0070] Thermally conductive filler 10%~15%;

[0071] Self-lubricating component: 1.0%~2.0%;

[0072] Reinforcing filler 1%~3%;

[0073] Interfacial coupling agent 0.3%~1.5%;

[0074] Solvent balance;

[0075] (D) Molding:

[0076] The prepreg obtained in step (C) is wound onto a ring mold to form a ring-shaped sample; then, the ring-shaped sample is placed into the mold for compression molding to obtain a fiber-reinforced composite static ring.

[0077] Under the complex and harsh operating conditions of ship stern shaft sealing devices, traditional inorganic and polymer stationary ring materials exhibit numerous problems. They struggle to maintain high reliability under conditions such as high speed, boundary lubrication, and impact vibration, easily leading to severe damage, seal leakage, and seriously affecting the normal operation of the ship's propulsion system. This invention provides a novel composite structure stationary ring material design and molding process, achieving excellent wear resistance, impact resistance, and high-temperature resistance to solve the aforementioned problems, providing a superior and more stable stationary ring solution for ship stern shaft sealing devices.

[0078] Regarding step (A) :

[0079] (A) Preparation of covered yarn: Aramid fibers and nylon fibers are combined and twisted to form a core yarn, and then cotton and linen fibers are covered on the surface of the core yarn to obtain covered yarn.

[0080] According to the present invention, two different fibers are first combined and twisted to form a core wire.

[0081] In this invention, the linear density of the aramid fiber (i.e., aramid filament) is preferably 200~800D, specifically 200D, 250D, 300D, 350D, 400D, 450D, 500D, 550D, 600D, 650D, 700D, 750D, or 800D.

[0082] In this invention, the linear density of the nylon fiber (i.e., nylon filament) is preferably 800~1400D, specifically 800D, 840D, 900D, 950D, 1000D, 1050D, 1100D, 1150D, 1200D, 1260D, 1300D, 1350D, and 1400D.

[0083] In this invention, the preferred linear density ratio of nylon fiber to aramid fiber is (1~8):1, specifically 1.05:1, 2:1, 3:1, 3.15:1, 4:1, 5:1, 6:1, 7:1, or 8:1. In some embodiments of this invention, the combination of nylon fiber and aramid fiber is as follows: nylon fiber 1260D / aramid 400D, or nylon fiber 840D / aramid 800D, or nylon fiber 1400D / aramid 200D, etc.

[0084] In this invention, the linear density of the obtained core wire is preferably 1000~2200D, specifically 1000D, 1100D, 1200D, 1300D, 1400D, 1500D, 1600D, and more preferably 1600D.

[0085] In this invention, the composite twisting (also known as twisted composite) refers to the process of winding and combining two different fibers (aramid fiber and nylon fiber in this invention) together using a twisting device to form a yarn. Preferably, the composite twisting process includes: applying Z-axis twist to the aramid fiber, applying Z-axis twist to the nylon fiber, then combining the twisted aramid and nylon fibers and applying S-axis twist to obtain the core yarn; the above twisting process combines the two fibers into a composite fiber structure. In this invention, when adding Z-direction twist to aramid fibers, the twist is preferably 100~300Z, specifically 100Z, 110Z, 120Z, 130Z, 140Z, 150Z, 160Z, 170Z, 180Z, 190Z, 200Z, 210Z, 220Z, 230Z, 240Z, 250Z, 260Z, 270Z, 280Z, 290Z, 300Z, and more preferably 200Z. In this invention, when adding Z-direction twist to the nylon fibers, the twist is preferably 50~300Z, specifically 50Z, 60Z, 70Z, 80Z, 90Z, 100Z, 110Z, 120Z, 130Z, 140Z, 150Z, 160Z, 170Z, 180Z, 190Z, 200Z, 210Z, 220Z, 230Z, 240Z, 250Z, 260Z, 270Z, 280Z, 290Z, 300Z, and more preferably 200Z. In this invention, the S-direction twist is preferably 100~250S, specifically 100S, 110S, 120S, 130S, 140S, 150S, 160S, 170S, 180S, 190S, 200S, 210S, 220S, 230S, 240S, 250S, and more preferably 150S. The twist refers to the number of twists per unit length of yarn, i.e., the number of loops per unit length of yarn. In this invention, the unit length is 1m; taking 200Z as an example, it means 200Z / m. Z and S represent twist direction. Twist direction refers to the inclined spiral line formed by the rotation of the unit of the yarn around the yarn axis when the yarn is in a vertical position (i.e., the spiral direction of the fiber / yarn). It is generally divided into Z direction and S direction. Taking 200Z as an example, it means that the number of twists along the Z direction of a unit length of 1m yarn is 200.

[0086] In this invention, the preferred mass ratio of aramid fiber to nylon fiber is (0.3~1):1, specifically 0.3:1, 0.32:1, 0.4:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, or 1.0:1. The nylon / aramid composite structure employed in this invention ensures that the core wire possesses sufficient strength and flexibility to meet the requirements of subsequent processes and practical applications.

[0087] According to the present invention, after the core wire is prepared, cotton and linen fibers are coated on its surface.

[0088] In this invention, the cotton and linen fiber is a cotton sliver formed by aggregating natural cotton and linen short fibers. The average length of a single fiber is preferably 25-33 mm, specifically 25 mm, 26 mm, 27 mm, 28 mm, 29 mm, 30 mm, 31 mm, 32 mm, or 33 mm. The average diameter of the aggregated cotton sliver is preferably 4-8 mm, specifically 4 mm, 5 mm, 6 mm, 7 mm, or 8 mm.

[0089] In this invention, a ring spinning machine is used to coat the surface of the core yarn with cotton and linen fibers. The invention precisely controls the coating ratio; specifically, the preferred mass ratio of the cotton and linen fibers to the core yarn is (3.5~6):1, and can be 3.5:1, 4.0:1, 4.5:1, 5.0:1, 5.5:1, or 6.0:1.

[0090] This invention involves coating a twisted core yarn with cotton and linen fibers to form a covered yarn with an inner layer of organic blended long fibers and an outer layer of short fibers coated with cotton and linen fibers. This yarn has a multi-level structural skeleton fiber, which serves as the basis for subsequent preparations. The resulting multi-level structural skeleton fiber is shown below. Figure 2 As shown.

[0091] In terms of material design, this invention employs a fiber-reinforced composite material structure. The skeleton fibers utilize a multi-level composite structure, combining multiple excellent properties such as high strength, high toughness, wear resistance, and self-lubrication. This composite fiber structure, through the design of its composition and proportions, allows fibers with different properties to work synergistically. For example, the specific composite fiber structure of this invention integrates the advantages of aramid fiber's high strength and high temperature resistance, nylon fiber's high toughness and self-lubrication, and natural cotton and linen fibers' moisture-wicking properties and strong resin bonding. This fusion enables the skeleton fiber to perform exceptionally well in terms of high-temperature resistance, impact resistance, and maintaining self-lubrication, providing a solid foundation for static ring materials.

[0092] Regarding step (B) :

[0093] (B) Braided strip: The covered yarn is braided into a strip by a shuttle weaving process.

[0094] In this invention, the strip material is preferably a narrow strip with a width of 50-200mm, specifically 50mm, 60mm, 70mm, 80mm, 90mm, 100mm, 110mm, 120mm, 130mm, 140mm, 150mm, 160mm, 170mm, 180mm, 190mm, or 200mm. The width of the narrow strip is determined by the axial width of the final product and is controlled to be 1.2-1.3 times the axial length of the stationary ring; for example, after impregnation and molding processes, the axial length of the final stationary ring product prepared from a 120-130mm wide skeleton fiber narrow strip can be around 100mm.

[0095] In this invention, preferably, the covered yarn is used as the warp and the nylon yarn as the weft, and the yarn is woven into a strip using a shuttle weaving process. The linear density of the nylon yarn is preferably 800D; the weft yarn serves to fix the warp yarn in place.

[0096] In this invention, the main control during the weaving process is the warp and weft yarn density. The preferred warp yarn density is 8-15 yarns / cm, specifically 8, 9, 10, 11, 12, 13, 14, or 15 yarns / cm. The preferred weft yarn density is 1-2 yarns / cm, specifically 1 or 2 yarns / cm.

[0097] Regarding step (C) :

[0098] (C) Preparation of prepreg: The strip obtained in step (B) is impregnated with adhesive solution and then dried to obtain prepreg.

[0099] In this invention, the adhesive comprises the following components in the indicated mass ratios:

[0100] Phenolic resin 50%~60%;

[0101] Thermally conductive filler 10%~15%;

[0102] Self-lubricating component: 1.0%~2.0%;

[0103] Reinforcing filler 1%~3%;

[0104] Interfacial coupling agent 0.3%~1.5%;

[0105] Solvent balance.

[0106] in:

[0107] The source of the phenolic resin is not particularly limited; it can be a commercially available product or prepared according to methods known in the art. The content of the phenolic resin is 50% to 60%, specifically 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, or 60%.

[0108] The thermally conductive filler is preferably at least one selected from alumina, zinc oxide, and dolomite. The content of the thermally conductive filler is 10% to 15%, specifically 10%, 11%, 12%, 13%, 14%, and 15%.

[0109] The self-lubricating component is preferably at least one of graphite and polytetrafluoroethylene. The content of the self-lubricating component is 1.0% to 2.0%, specifically 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, or 2.0%.

[0110] The reinforcing filler is preferably at least one of carbon nanotubes and chopped aramid fibers. The content of the reinforcing filler is 1% to 3%, specifically 1%, 2%, or 3%.

[0111] The preferred interfacial coupling agent is KH-550, which enhances the bonding force between the matrix resin, the skeletal fibers, and the functional fillers. The content of the interfacial coupling agent is 0.3% to 1.5%, specifically 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, and 1.5%.

[0112] The solvent is preferably at least one selected from ethanol, methanol, acetone, and ethylene glycol. The amount of solvent used is the balance, i.e., to make up to 100%.

[0113] In this invention, the adhesive solution is preferably prepared by the following method: mixing phenolic resin, thermally conductive filler, self-lubricating component, reinforcing filler, interfacial coupling agent, and solvent to obtain the adhesive solution. The mixing method is not particularly limited; any conventional mixing method in the art that can mix the materials evenly is acceptable, such as stirring. The stirring speed is preferably 300~500 r / min, specifically 300 r / min, 310 r / min, 320 r / min, 330 r / min, 340 r / min, 350 r / min, 360 r / min, 370 r / min, 380 r / min, 390 r / min, 400 r / min, 410 r / min, 420 r / min, 430 r / min, 440 r / min, 450 r / min, 460 r / min, 470 r / min, 480 r / min, 490 r / min, and 500 r / min. The preferred mixing time is 15-30 min, specifically 15 min, 16 min, 17 min, 18 min, 19 min, 20 min, 21 min, 22 min, 23 min, 24 min, 25 min, 26 min, 27 min, 28 min, 29 min, and 30 min.

[0114] In this invention, when impregnating the strip obtained in step (B) with adhesive, a continuous prepreg production equipment is preferably used. The prepreg production equipment includes an unwinding device, a tension control device, an adhesive tank, a drying tunnel, and a winding device. The composite fiber narrow strip is located at the unwinding device, first being pulled sequentially through the impregnation device by a lead wire, and then wound onto the winding device. The traction force provided by the winding device drags the narrow strip through the impregnation production line. The impregnation process is as follows: the composite fiber woven narrow strip is discharged from the unwinding device, the tension control device applies tension to the narrow strip, and the narrow strip enters one end of the adhesive tank at a set speed, where it is impregnated with adhesive. During this process, the narrow strip is squeezed by rollers in the adhesive tank to ensure uniform impregnation. After impregnation is complete, the narrow strip is discharged from the other end of the adhesive tank and dried through the drying tunnel to remove excess solvent and moisture, producing a prepreg narrow strip. The tension control device preferably applies a tension of 80-150N to the narrow strip, specifically 80N, 90N, 100N, 110N, 120N, 130N, 140N, or 150N, more preferably 100N. The set speed is preferably 2-5 m / min, specifically 2 m / min, 3 m / min, 4 m / min, or 5 m / min. The drying temperature is preferably 120-140℃, specifically 120℃, 125℃, 130℃, 135℃, or 140℃. The drying time is adjusted according to the solvent content of the fiber and the performance of the drying equipment, generally 15-20 minutes, to allow all the solvent in the prepreg fiber to evaporate, achieving a suitable resin content and degree of dryness to meet the requirements of subsequent weaving processes. The dried prepreg narrow strip is then wound up and sealed for storage. In this invention, the amount of adhesive on the prepreg obtained after drying is preferably 40% to 60%, specifically 40%, 45%, 50%, 55%, or 60%.

[0115] This invention uses phenolic resin as the matrix resin and modifies it by introducing other materials, giving it high-temperature resistance and wear resistance. It maintains stable performance even under high temperatures generated by friction between the moving and stationary rings, and is less prone to softening or deformation due to high temperatures, thus effectively extending the service life of the stationary ring and ensuring reliable sealing performance. Multiple functional composite fillers are introduced to further enhance the stationary ring material's superior properties. Alumina, zinc oxide, and dolomite thermally conductive fillers provide excellent thermal conductivity, rapidly dissipating the heat generated by stationary ring friction and preventing thermal deformation caused by localized high temperatures. Graphite and polytetrafluoroethylene (PTFE) provide self-lubrication under harsh working conditions, reducing friction between the moving and stationary rings and minimizing wear. The addition of carbon nanotubes and aramid chopped fibers endows the material with high strength and resistance to fatigue crack propagation, allowing it to maintain structural integrity under impact and long-term fatigue loads, improving impact resistance and fatigue resistance. Through precise proportioning of resin, fillers, and fibers, and optimized design of the overall material structure, the directional functional design of the stationary ring material is achieved, meeting the diverse performance requirements of stationary ring materials under complex working conditions.

[0116] Regarding step (D) :

[0117] (D) Molding: The prepreg obtained in step (C) is wound on a ring mold to form a ring-shaped sample; then, the ring-shaped sample is placed in the mold for compression molding to obtain a fiber-reinforced composite static ring.

[0118] In this invention, the molding process includes two processes: winding and curing.

[0119] The winding process includes: winding the prepreg obtained in step (C) onto a ring mold to form a ring-shaped sample. In this invention, the winding tension is preferably 150~300N, specifically 150N, 160N, 170N, 180N, 190N, 200N, 210N, 220N, 230N, 240N, 250N, 260N, 270N, 280N, 290N, or 300N. Maintaining the tension at these levels helps ensure product integrity and performance. Excessive tension may lead to fiber breakage or prepreg damage, while insufficient tension may affect product density and strength. In this invention, the number of winding layers is calculated from the inner and outer diameters of the final static ring product: number of winding layers = (outer diameter of product - inner diameter of product) / prepreg tape thickness.

[0120] After the above winding process, curing and molding are performed: the annular sample is placed in a mold for compression molding and curing. Specifically, the wound annular sample is placed in the mold, the inner and outer diameters of the annular sample are constrained by the mold, and the axial direction can be compressed by the mold slider; the mold is placed in a high-temperature flat vulcanizing machine, and the sample is cured and molded under high temperature and high pressure. In this invention, the heating temperature for curing and molding is preferably 150~180℃, specifically 150℃, 160℃, 170℃, or 180℃. During the curing process, the curing pressure (i.e., the axial pressure of the equipment on the sample) is preferably controlled at 5~10MPa, specifically 5MPa, 6MPa, 7MPa, 8MPa, 9MPa, or 10MPa; the above pressure control ensures that the density of the stationary ring material is 1.5~1.7g / cm³. 3 This process achieves an optimal balance between material strength, toughness, and porosity, meeting the water-guiding and hydrophobic requirements of the stern shaft sealing device during the friction sealing process. The curing time is preferably 10-20 hours, specifically 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 hours. After curing and molding, a fiber-reinforced composite stationary ring product is obtained.

[0121] Secondly, the present invention also provides a fiber-reinforced composite stationary ring prepared by the preparation method described in the above-mentioned technical solution. The fiber-reinforced composite stationary ring provided by the present invention is a fiber-reinforced composite stationary ring for a ship's stern shaft sealing device.

[0122] To address the problem that traditional static ring materials are prone to failure under complex operating conditions and cannot meet the high reliability requirements of ship stern shaft sealing devices, this invention makes several improvements. The preparation method provided by this invention first starts with basic fiber raw materials, preparing multi-strand twisted core yarns through composite twisting. Then, cotton and linen fibers are wrapped around the outer layer of the core yarns using a ring spinning process, resulting in a multi-level structural skeleton fiber with an inner layer of organic blended long fibers and an outer layer of short fibers wrapped with cotton and linen fibers. Next, a glue solution containing a matrix resin, various functional fillers, and interfacial coupling agents is prepared, allowing the skeleton fibers to be fully impregnated, enabling the components to bind tightly and exert a synergistic effect. The impregnated skeleton fibers are dried to become prepreg fibers, preparing them for subsequent weaving. The prepreg fibers are woven into narrow strips using a shuttle weaving process. By flexibly adjusting the weaving structure and density, precise design and control of the skeleton fiber structure are achieved, meeting the specific performance requirements of the static ring material under different operating conditions. The woven prepreg narrow strips are wound into ring-shaped samples on a ring mold, and finally cured under high temperature and high pressure to form the final product. During the winding and molding process, the density of the stationary ring material can be precisely controlled within the range of 1.5-1.7 g / cm³. This not only ensures that the material has sufficient strength and toughness to cope with complex mechanical loads, but also gives the material a certain porosity, which can quickly guide and drain water during the friction sealing process, effectively solving the sealing problems and material performance degradation caused by water accumulation.

[0123] Test results show that the product obtained by this invention has an impact strength of over 75 MPa, a compressive strength of over 120 MPa, a water absorption rate of over 2.7%, and a linear expansion coefficient of over 11 × 10⁻⁶. -5 Below this, the coefficient of friction is below 0.21, exhibiting excellent mechanical properties, high water absorption, and friction resistance, ensuring the performance requirements of the ship's stern shaft sealing friction pair.

[0124] To further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, and not for limiting the scope of the claims of the present invention.

[0125] Example 1

[0126] (A) Preparation of the covered yarn fiber skeleton:

[0127] Aramid fibers are twisted in the Z direction, nylon fibers are twisted in the Z direction, and then the twisted aramid and nylon fibers are combined and twisted in the S direction to form a core yarn. Then, cotton and linen fibers are wrapped around the surface of the core yarn to obtain a covered yarn.

[0128] in:

[0129] Aramid fiber: linear density 400D;

[0130] Nylon fiber: linear density 1260D;

[0131] The mass ratio of aramid fiber to nylon fiber is 0.32:1; the linear density of the core wire is 1600D;

[0132] During the composite twisting process, the twist of the aramid fiber is 200Z, the twist of the nylon fiber is 200Z, and the twist of the composite twisting is 150S.

[0133] Cotton and linen fiber: cotton slivers are made of natural cotton and linen short fibers. The average length of a single fiber is 30mm, and the average diameter of the cotton slivers after aggregation is 4mm.

[0134] The mass ratio of cotton and linen fibers to core yarn is 6:1.

[0135] (B) Braided strip material:

[0136] Using the covered yarn obtained in step (A) as the warp and 800D nylon yarn as the weft, a narrow strip with a width of 120mm is woven by a shuttle weaving process. The warp density is 8 threads / cm and the weft density is 1 thread / cm.

[0137] (C) Preparation of prepreg:

[0138] The narrow strip obtained in step (B) is impregnated in the adhesive solution (the impregnation process is as described above), and then dried (temperature 140℃, time 20min) to obtain a prepreg (adhesive content 50%).

[0139] The composition of the adhesive is as follows:

[0140] 55% phenolic resin;

[0141] Thermally conductive filler (dolomite) 15%;

[0142] Self-lubricating component (graphite) 2.0%;

[0143] Reinforcing filler (carbon nanotubes) 1%;

[0144] Interfacial coupling agent (KH-550 1%);

[0145] Solvent (ethanol) Balance.

[0146] (D) Molding:

[0147] The prepreg narrow strip obtained in step (C) is wound onto a ring mold and wound under a tension of 250N to form a ring sample with an inner diameter of 280mm and an outer diameter of 430mm. The above ring sample is then molded and cured at 140℃ and 5MPa (as described above) for 12 hours to obtain a stationary ring product. The axial length of the molded sample is approximately 90mm.

[0148] Example 2

[0149] (A) Preparation of the covered yarn fiber skeleton:

[0150] Aramid fibers are twisted in the Z direction, nylon fibers are twisted in the Z direction, and then the twisted aramid and nylon fibers are combined and twisted in the S direction to form a core yarn. Then, cotton and linen fibers are wrapped around the surface of the core yarn to obtain a covered yarn.

[0151] in:

[0152] Aramid fiber: linear density 800D;

[0153] Nylon fiber: linear density 840D;

[0154] The mass ratio of aramid fiber to nylon fiber is 1:1; the linear density of the core wire is 1600D;

[0155] During the composite twisting process, the twist of the aramid fiber is 200Z, the twist of the nylon fiber is 200Z, and the twist of the composite twisting is 150S.

[0156] Cotton and linen fiber: cotton slivers are made of natural cotton and linen short fibers. The average length of a single fiber is 30mm, and the average diameter of the cotton slivers after aggregation is 4mm.

[0157] The mass ratio of cotton and linen fibers to core yarn is 6:1.

[0158] (B) Braided strip material:

[0159] Using the covered yarn obtained in step (A) as the warp and 800D nylon yarn as the weft, a narrow strip with a width of 120mm is woven by a shuttle weaving process. The warp density is 10 threads / cm and the weft density is 2 threads / cm.

[0160] (C) Preparation of prepreg:

[0161] The narrow strip obtained in step (B) is impregnated in the adhesive solution (the impregnation process is as described above), and then dried (temperature 140℃, time 20min) to obtain a prepreg (adhesive content 55%).

[0162] The composition of the adhesive is as follows:

[0163] 55% phenolic resin;

[0164] Thermally conductive filler (dolomite) 15%;

[0165] Self-lubricating component (graphite) 2.0%;

[0166] Reinforcing filler (carbon nanotubes) 1%;

[0167] Interfacial coupling agent (KH-550 1%);

[0168] Solvent (ethanol) Balance.

[0169] (D) Molding:

[0170] The prepreg narrow strip obtained in step (C) is wound onto a ring mold and wound under a tension of 300N to form a ring sample with an inner diameter of 280mm and an outer diameter of 430mm. The above ring sample is then molded and cured at 140℃ and 10MPa (as described above) for 12 hours to obtain a stationary ring product. The axial length of the molded sample is approximately 90mm.

[0171] Example 3

[0172] (A) Preparation of the covered yarn fiber skeleton:

[0173] Aramid fibers are twisted in the Z direction, nylon fibers are twisted in the Z direction, and then the twisted aramid and nylon fibers are combined and twisted in the S direction to form a core yarn. Then, cotton and linen fibers are wrapped around the surface of the core yarn to obtain a covered yarn.

[0174] in:

[0175] Aramid fiber: linear density 400D;

[0176] Nylon fiber: linear density 1260D;

[0177] The mass ratio of aramid fiber to nylon fiber is 0.32:1; the linear density of the core wire is 1600D;

[0178] During the composite twisting process, the twist of the aramid fiber is 200Z, the twist of the nylon fiber is 200Z, and the twist of the composite twisting is 150S.

[0179] Cotton and linen fiber: cotton slivers are made of natural cotton and linen short fibers. The average length of a single fiber is 30mm, and the average diameter of the cotton slivers after aggregation is 4mm.

[0180] The mass ratio of cotton and linen fibers to core yarn is 6:1.

[0181] (B) Braided strip material:

[0182] Using the covered yarn obtained in step (A) as the warp and 800D nylon yarn as the weft, a narrow strip with a width of 120mm is woven by a shuttle weaving process. The warp density is 8 threads / cm and the weft density is 1 thread / cm.

[0183] (C) Preparation of prepreg:

[0184] The narrow strip obtained in step (B) is impregnated in the adhesive solution (the impregnation process is as described above), and then dried (temperature 140℃, time 20min) to obtain a prepreg (adhesive content 50%).

[0185] The composition of the adhesive is as follows:

[0186] Phenolic resin 60%;

[0187] Thermally conductive filler (dolomite) 13%;

[0188] Self-lubricating component (graphite) 2.0%;

[0189] Self-lubricating component (polytetrafluoroethylene) 2.0%;

[0190] Reinforcing filler (carbon nanotubes) 2%;

[0191] Interfacial coupling agent (KH-550 1%);

[0192] Solvent (ethanol) Balance.

[0193] (D) Molding:

[0194] The prepreg narrow strip obtained in step (C) is wound onto a ring mold and wound under a tension of 250N to form a ring sample with an inner diameter of 280mm and an outer diameter of 430mm. The above ring sample is then molded and cured at 140℃ and 5MPa (as described above) for 12 hours to obtain a stationary ring product. The axial length of the molded sample is approximately 90mm.

[0195] Example 4

[0196] The procedure was carried out as in Example 1, except that the thermally conductive filler dolomite in the adhesive was replaced with alumina.

[0197] Example 5

[0198] The method was implemented according to Example 1, except that the self-lubricating filler graphite in the adhesive was replaced with polytetrafluoroethylene, and the reinforcing filler carbon nanotubes were replaced with aramid short-cut fibers.

[0199] Comparative Example 1

[0200] The implementation follows Example 1, except that aramid fibers are replaced with nylon fibers (with the same specifications as the nylon fibers in Example 1), meaning that all core wire materials are made of nylon fibers.

[0201] Comparative Example 2

[0202] The implementation follows Example 1, except that nylon fibers are replaced with aramid fibers (with the same specifications as the aramid fibers in Example 1), meaning that all core wire materials are made of aramid fibers.

[0203] Comparative Example 3

[0204] The process was carried out according to Example 1, except that in the prepreg preparation process, the amount of adhesive on the prepreg was controlled at 70%, and the composition of the adhesive was not changed.

[0205] Performance testing :

[0206] Impact resistance, mechanical strength, water absorption, and abrasion resistance were tested on the samples of each embodiment and comparative example. The test results are shown in Table 1.

[0207] Compressive strength test method: GB / T 1448 "Determination of compressive properties of fiber reinforced plastics", the test direction is perpendicular to the compressive surface of the specimen.

[0208] Impact strength (IZOD) test method: GB / T1843-2008 "Determination of impact properties of plastic cantilever beams".

[0209] Water absorption rate test method: GB / T1034-2008 "Determination of water absorption rate of plastics", conduct a 72h water absorption test.

[0210] Coefficient of linear expansion: Refer to ISO 11359-2-1999 "Plastics - Thermal analysis methods - Part 2: Determination of coefficient of linear expansion and glass transition temperature".

[0211] Friction coefficient test method: GB / T3960-2016 "Plastics sliding friction and wear test method".

[0212] Table 1: Performance Test Results

[0213]

[0214] As can be seen from the test results in the table above, the impact strength of the products obtained in Examples 1-5 of this invention is above 75 MPa, the compressive strength is above 120 MPa, the water absorption rate is above 2.7%, and the coefficient of linear expansion is above 11 × 10⁻⁶. -5Below this, the coefficient of friction is below 0.21, exhibiting excellent mechanical properties, high water absorption, and friction resistance, ensuring the performance requirements of the ship's stern shaft sealing friction pair. Compared with Example 1, the performance of Comparative Examples 1-2 is significantly reduced, proving that the present invention uses a combination of aramid fiber and nylon fiber as the core wire to effectively improve product performance. Compared with Example 1, Comparative Example 1 replaced the core wire with pure nylon fiber, resulting in a significant decrease in the material's impact and compression properties; Comparative Example 2 replaced the core wire with pure aramid fiber, increasing the coefficient of friction, and the excessively high aramid fiber content made the material more difficult to machine, reducing the dimensional accuracy of the product; while Comparative Example 3 significantly increased the amount of adhesive applied during the prepreg preparation stage, resulting in a final product with a lower fiber component content and a higher resin content, increasing the material's brittleness, making it less impact-resistant, and increasing both the coefficient of linear expansion and the coefficient of friction.

[0215] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of these embodiments are merely to aid in understanding the method and core ideas of the present invention, including the best mode, and to enable any person skilled in the art to practice the present invention, including manufacturing and using any device or system, and implementing any combined method. It should be noted that those skilled in the art can make various improvements and modifications to the present invention without departing from its principles, and these improvements and modifications also fall within the scope of protection of the claims. The scope of protection of this patent is defined by the claims and may include other embodiments that can be conceived by those skilled in the art. If these other embodiments have structural elements similar to those expressed in the claims, or if they include equivalent structural elements that are not substantially different from those expressed in the claims, then these other embodiments should also be included within the scope of the claims.

Claims

1. A method for preparing a fiber-reinforced composite stationary ring, characterized in that, Includes the following steps: (A) Preparation of the covered yarn: Aramid fibers and nylon fibers are combined and twisted to form a core yarn. Then, cotton and linen fibers are wrapped around the surface of the core yarn to obtain a covered yarn. (B) Braided strip material: The covered yarn is woven into a strip using a weaving process; (C) Preparation of prepreg: The strip obtained in step (B) is impregnated with adhesive solution and then dried to obtain prepreg: The adhesive solution comprises the following components in the indicated mass ratios: Phenolic resin 50%~60%; Thermally conductive filler 10%~15%; Self-lubricating component: 1.0%~2.0%; Reinforcing filler 1%~3%; Interfacial coupling agent 0.3%~1.5%; Solvent balance; (D) Molding: The prepreg obtained in step (C) is wound onto a ring mold to form a ring-shaped sample; then, the ring-shaped sample is placed into the mold for compression molding to obtain a fiber-reinforced composite static ring.

2. The preparation method according to claim 1, characterized in that, In step (A): The linear density of the aramid fiber is 200~800D; The linear density of the nylon fiber is 800~1400D; The linear density of the core wire is 1000~2200D; The mass ratio of aramid fiber to nylon fiber is (0.3~1):

1.

3. The preparation method according to claim 1, characterized in that, In step (A): The composite twisting process preferably includes: applying Z-axis twist to aramid fibers, applying Z-axis twist to nylon fibers, then combining the twisted aramid and nylon fibers and applying S-axis twist to obtain the core wire; The twist of the Z-direction twist on aramid fibers is 100~300Z, the twist of the Z-direction twist on nylon fibers is 50~300Z, and the twist of the S-direction twist is 100~250S.

4. The preparation method according to claim 1, characterized in that, In step (A): The cotton and linen fiber is a cotton sliver made up of natural cotton and linen short fibers, with an average length of 25-33 mm for a single fiber and an average diameter of 4-8 mm for the sliver after aggregation. The mass ratio of cotton and linen fibers to core yarn is (3.5~6):

1.

5. The preparation method according to claim 1, characterized in that, In step (B): The width of the strip is 50~200mm; The weaving process uses the covered yarn as the warp and nylon yarn as the weft; wherein the linear density is 800D; the warp density is 8~15 threads / cm, and the weft density is 1~2 threads / cm.

6. The preparation method according to claim 1, characterized in that, In step (C): The thermally conductive filler is at least one of alumina, zinc oxide and dolomite; The self-lubricating component is at least one of graphite and polytetrafluoroethylene; The reinforcing filler is at least one of carbon nanotubes and aramid chopped fibers; The interface coupling agent is KH-550; The solvent is at least one of ethanol, methanol, acetone, and ethylene glycol.

7. The preparation method according to claim 1, characterized in that, In step (C), a continuous prepreg production equipment is used for impregnation. The prepreg production equipment includes an unwinding device, a tension control device, a glue tank, a drying tunnel, and a winding device; The impregnation process includes: the strip obtained in step (B) is discharged from the unwinding device, the tension control device applies tension to the narrow strip, the narrow strip enters one end of the glue tank at a set speed, and is impregnated with glue in the glue tank; The tension control device applies a tension of 80~150N to the narrow strip; the set speed is 2~5m / min. The drying temperature is 120~140℃ and the time is 15~20min.

8. The preparation method according to claim 1, characterized in that, In step (D), the winding tension of the winding process is 150~300N.

9. The preparation method according to claim 1, characterized in that, In step (D), the heating temperature for curing is 150~180℃, the pressure is 5~10MPa, and the time is 10~20h.

10. A fiber-reinforced composite static ring prepared by any one of claims 1 to 9.

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