Long fiber non-woven molding material and its preparation method

Abstract

The present invention discloses a method for preparing a long-fiber non-woven fabric molding material, comprising the following steps: filtering a melted polymer material and then feeding it into a composite spinning manifold; stretching the melted polymer material with a cooling airflow after spinning to form filaments; laying a web and needle-punching multiple bundles of composite filaments and single-structure filaments to form a non-woven fabric; the single-structure filament spinnerets eject PET single-structure filaments; and the composite filament spinnerets eject composite filaments comprising a core layer of PET coated with a sheath layer of CoPET; placing the cut non-woven fabric between the upper and lower molds of a molding machine; heating the molds to a temperature of 200 to 240°C; spraying steam at a temperature of 180 to 230°C into the molds; and, after molding and heating for 30 to 180 seconds, opening the upper and lower molds and removing the molded part. The long-fiber non-woven fabric molding material of the present invention has high structural strength, good noise absorption, and is lightweight, making it suitable for use as automotive underbody panels.

Description

Technical Field

[0001] The present invention relates to the production and processing of nonwoven fabrics and subsequent applications thereof, in particular to a long-fiber nonwoven fabric molding material and a production method and application of such nonwoven fabric molding material, belonging to the technical field of nonwoven fabric production. Background Art

[0002] Non-woven fabrics, also known as nonwovens, are fabrics that do not require spinning or weaving. During the non-woven fabric production process, textile staple fibers or filaments are simply aligned or randomly arranged, and then various web-forming methods and consolidation technologies, such as mechanical, thermal bonding, or chemical, are used to form a soft, breathable, and flat fiber product.

[0003] For a long time, non-woven fabrics have been widely used in many fields, such as: medical and health fabrics, surgical gowns, protective clothing, disinfection wraps, masks, diapers, sanitary napkins, etc.; home decoration fabrics, wall coverings, tablecloths, bed sheets, bedspreads, etc.; clothing fabrics, linings, adhesive interlinings, flakes, shaped cotton, various synthetic leather base fabrics, etc.; industrial fabrics, filter materials, insulation materials, cement packaging bags, geotextiles, covering fabrics, etc.; agricultural fabrics, crop protection fabrics, seedling cloths, irrigation fabrics, thermal insulation curtains, etc.; packaging industry, composite cement bags, luggage linings, packaging base linings, quilts, storage bags, mobile jacquard luggage fabrics, etc.; automotive industry, shock-absorbing felt, roofs, seat cushion linings, carpets, door linings, automotive filter elements, etc.; as well as reinforcement, reinforcement, filtration, drainage and roof waterproofing materials for construction projects, embankments, water slopes, sound insulation, heat protection and separation materials for railways, highways and ports, etc.

[0004] With the continuous development of non-woven fabric production technology, people have developed various non-woven fabrics with new features and high performance, which has enabled the subsequent application of non-woven fabric products to be further expanded. Among them, replacing glass fiber reinforced plastics and gradually replacing various injection molded parts has become an important direction for the development of non-woven fabric technology. In this development direction, how to make non-woven fabrics have good molding and processing performance while maintaining the inherent characteristics of non-woven fabrics is an important technical problem that must be solved. As far as the applicant knows, there are two problems in the existing technology: First, in order to meet the molding processing, other ingredients or auxiliary materials are often required, which leads to complicated molding procedures, increased processing costs, and the performance of non-woven fabrics cannot be fully utilized; second, composite fibers are directly used to produce non-woven fabrics, which reduces the performance of non-woven fabrics, affects the mechanical properties of subsequent molded products, and limits its scope of application. Summary of the Invention

[0005] The purpose of the present invention is to solve the above problems and provide a long-fiber non-woven fabric molding material with high structural strength, good noise absorption effect and light weight, as well as a preparation method and use of the long-fiber non-woven fabric molding material.

[0006] The technical solution of the present invention is: a method for preparing a long-fiber non-woven fabric molding material, comprising the following steps:

[0007] S1. The melted polymer material is filtered and then enters the composite spinning manifold. After being precisely metered by a metering pump, it enters the spinneret assembly for spinning. The spinneret assembly has two types of spinnerets on the same spinneret plate, one of which is a composite filament spinneret with a sheath-core coating structure, and the other is a single-structure filament spinneret. The various spinnerets are evenly distributed on the same spinneret plate; the number of composite filament spinnerets accounts for 30-50% of the total number of spinnerets, the single-structure filament spinneret ejects PET single-structure filaments, and the composite filament spinneret ejects a composite filament with a core layer of PET coated with a sheath layer of CoPET, and the amount of the sheath layer of CoPET ejected accounts for 15-50% of the total amount of the composite filament spinneret ejected;

[0008] S2. The filaments ejected from the same spinneret are cooled by air blowing and then stretched by air flow to form composite filaments and single-structure filaments with a single-filament linear density of ≤9 dtex. Multiple filaments are then laid and needle-punched to form non-woven fabrics.

[0009] S3. Place the cut non-woven fabric between the upper and lower molds of the molding machine, heat the mold to 200-240°C, spray steam at a temperature of 180-230°C into the mold, and heat the mold for 30-180 seconds. Open the upper and lower molds and remove the molded parts.

[0010] The sheath of the composite filament is CoPET (modified polyester) with a melting point of 200°C, the core is PET (polyethylene terephthalate) with a melting point of 265°C, and the single structure filament is PET (polyethylene terephthalate) with a melting point of 265°C. The total needle punch strength is 350 needles / cm 2 Water vapor injected into the mold at a temperature of 180-230°C improves the fluidity, adhesion, and demolding properties of the low-melting-point components, thereby improving the plasticization quality of the molded parts and enhancing molding efficiency. The resulting molded parts contain a large number of voids, resulting in lightweight and excellent sound absorption. The unmodified components in the monocomponent fibers and sheath-core composite fibers acquire excellent mechanical properties after stretching, resulting in excellent toughness and high strength, making them suitable for use as automotive underbody panels.

[0011] The sheath CoPET output accounts for 30-40% of the total output of the composite filament spinneret. The number of composite filament spinnerets accounts for 50% of the total number of spinnerets. Experiments have shown that when the sheath-core fiber ratio is too high, the molded part lacks toughness and is prone to brittle fracture. Therefore, the ratio of the number of single-structure filaments must be maintained, and the sheath-core fiber sheath ratio should not be too high.

[0012] The linear density of the composite filament and the single structure filament is 2 to 5 dtex. If the linear density is too high, the heat shrinkage of the needle-punched nonwoven fabric will be large, and if the linear density is too low, the difference in the void ratio inside the molded part will reduce the noise absorption capacity of the fiber after molding.

[0013] In step S2, the pressure is greater than 3 kg / cm 2 The compressed air is used as the power of the airflow stretching nozzle and stretching pipe to perform airflow stretching. Only by airflow stretching can the composite filaments and single structure filaments be fully stretched, the molecules are well oriented, and the linear density meets the production requirements, and only then can the molded parts with the required performance be obtained.

[0014] The mold closing heating temperature in step S3 is 220-236°C.

[0015] The non-woven fabric has a gram weight of 800 to 1400 g / m 2 As a car bottom guard plate, preferably 1000 ~ 1200g / m 2 .

[0016] The thickness of the molded part is 1.5 to 4.5 mm. The long-fiber non-woven fabric molding material of the present invention controls the thickness of the molded part by controlling the gap between the upper and lower molds, that is, the height of the mold cavity after the mold is closed. For example, the gap between the upper and lower molds is controlled at 2.3 mm, the non-woven fabric felt material becomes soft after the mold cavity is heated, and the CoPET with a lower melting point melts, achieving automatic demolding, and the thickness of the molded part is 2 mm. Non-woven fabric felt materials of the same gram weight are subjected to mold heating treatment. The larger the gap between the upper and lower molds, the greater the thickness of the molded part, the more voids therein, and a better sound absorption effect can be obtained; the smaller the gap between the upper and lower molds, the smaller the thickness of the molded part, the denser the structure within the molded part, and the better strength can be obtained.

[0017] The technical solution of the present invention is: a molded part prepared by the above-mentioned method for preparing the long-fiber non-woven fabric molding material.

[0018] The technical solution of the present invention is: a molded part prepared by the above-mentioned method for preparing the long-fiber non-woven fabric molded material is used as an automobile bottom guard plate.

[0019] The present invention aims to address the aforementioned issues by providing a nonwoven fabric that can be easily formed and processed, as well as a production method and uses for such a nonwoven fabric. By adjusting and optimizing the raw materials, key equipment, and production processes used in nonwoven fabric production, the present invention aims to produce a nonwoven felt material that can be directly formed and processed, exhibiting excellent performance, ensuring that the formed product meets or even exceeds the requirements for use in multiple industries and fields.

[0020] The technical solution of the present invention is: a non-woven fabric that is easy to directly shape and process, characterized in that: the non-woven fabric contains at least one composite filament and at least one single-structure filament; the composite filament has a two-component sheath-core coating structure, the melting point of the sheath component is at least 20°C lower than that of the core layer, and the melting point of the core component is the same as or similar to the melting point of the single-structure filament, or, the composite filament has a two-component bonding structure, in which the melting point of one component is at least 20°C lower than that of the other component, and the melting point of the high-melting-point component is the same as or similar to the melting point of the single-structure filament.

[0021] Preferably, the non-woven fabric that is easy to directly shape and process, wherein: the non-woven fabric is mixed with a composite filament and a single structure filament, the composite filament accounts for 10-50% of the total weight of the filament; among the composite filaments, the low melting point component accounts for 10-90% of the total weight of the composite filament; the linear density of the composite filament and the single structure filament is 2-9 dtex, and the elongation at break is 20-100%; the gram weight of the non-woven fabric product is 15-2000 g / m 2 , the shrinkage rate under the test conditions of 200℃ and 10 minutes is ≤60%.

[0022] More preferably, the above-mentioned non-woven fabric that is easy to directly mold and process, wherein: the single structure filament is PET with a melting point of about 265°C; the composite filament is a sheath-core coated structure, the sheath component is CoPET, PBT or PA6 with a melting point ≤240°C, and the core layer component is PET with a melting point of about 265°C, or, the composite filament is a two-component bonding structure, the low melting point component is CoPET, PBT or PA6 with a melting point ≤240°C, and the high melting point component is PET with a melting point of about 265°C.

[0023] The present invention also provides a method for producing non-woven fabrics that are easy to directly form and process. Polymer chips are used as raw materials and are melt-extruded by a screw extruder. The melted polymer material is filtered and then enters a composite spinning box. After being accurately measured by a metering pump, it enters a spinneret assembly. After spinning, it is stretched to form filaments, which are then laid and consolidated, and then wound into rolls to obtain non-woven fabric products. The method is characterized in that: there are at least two types of polymer chips, and the melting point difference between them is not less than 20°C; there are at least two screw extruders; there are at least two types of spinnerets on the same spinneret in the spinneret assembly, one of which is a spinneret for forming a composite filament with a skin-core coating structure or a bonding structure, and the other is a spinneret for forming a single-structure filament. The various spinnerets are evenly distributed on the same spinneret.

[0024] Preferably, in the above-mentioned method for producing non-woven fabrics: in the same spinneret, the number of spinneret holes for forming composite filaments accounts for 10 to 50% of the total number of spinneret holes; in the spinneret holes, the amount of low-melting-point material ejected at the same time accounts for 10 to 90% of the weight of the total polymer material ejected from the hole.

[0025] More preferably, in the above-mentioned method for producing nonwoven fabrics: after the spinning assembly spins, the filaments are subjected to air cooling and stretching or hot roller stretching, and the formed filaments are consolidated by needle punching or thermal bonding after being laid on the web. In particular: the filaments ejected from the same spinneret are cooled by air blowing and then enter a machine with a pressure greater than 3kg / cm 2 Compressed air is used as the power source for the airflow stretching nozzle and stretching pipe, which form long fiber bundles with a linear density of ≤9dtex after stretching; multiple bundles are then laid, needle-punched or thermally bonded, and rolled to make non-woven fabrics.

[0026] Moreover, in the above-mentioned production method of non-woven fabrics, the raw materials fed to the screw extruder may further include color masterbatches, flame retardant masterbatches or various other functional auxiliary additives.

[0027] The non-woven fabric obtained by the present invention has new uses, namely: the non-woven fabric is directly molded or hot-pressed to be processed into profiles or plates suitable for interior and exterior automotive components and housings of household appliances or electronic office supplies; or processed into profiles or plates that replace plastic products or sound-absorbing and shock-absorbing materials for construction, decoration, office or household use; or processed into reinforcing sheets for textiles, clothing, shoes and hats.

[0028] In this way, a high-performance non-woven fabric product can be obtained by adopting the technical solution of the present invention, and the product can be directly used for subsequent molding and processing. During the molding process, no additional ingredients or auxiliary materials are needed. The low-melting-point component in the composite filaments melts, and the remaining filament structures are fully fused and bonded to each other and to the single-structure filaments. Among the product structures after molding, one part is the re-solidified structure after the low-melting-point component melts, and the other part is the fiber structure composed of high-melting-point filaments. The former can ensure the molding of the product, and the latter increases the strength and toughness of the molded product. Therefore, the non-woven fabric can be processed into a substitute for various existing plastic products or sound-absorbing and shock-absorbing materials, so that it has extremely broad application prospects in various industries such as automobiles, electrical appliances, construction, decoration, office or home use.

[0029] The nonwoven fabric products produced using the technical solution of the present invention include single-structure filaments and composite filaments with a bicomponent sheath-core structure or a laminated structure. The latter serves as the basis for subsequent molding, while the former ensures the mechanical properties of the molded product and reduces the porosity of the finished product. The combination of the two can better leverage the inherent properties of the nonwoven fabric, enabling the molded product to achieve optimal mechanical properties, heat resistance, acoustic wave performance, and other aspects simultaneously, surpassing the performance of existing conventional plastic products or glass fiber reinforced plastics. This improvement in comprehensive performance enables the molded product to meet or even exceed its application requirements in various fields and different occasions.

[0030] The present invention adopts a "one-step" production process from sliced raw materials to non-woven fabric products, which has a short process, low cost, and is easy to operate and control. Using sliced raw materials, various modified ingredients such as masterbatch, flame retardant masterbatch, functional additives, etc. can be added at any time according to user needs; the number and form of the spinnerets on the spinneret assembly can be replaced and adjusted at any time according to requirements, and the number, form, and distribution of the spinnerets on the spinnerets can also be designed and replaced at any time according to the sliced raw materials and user needs. The post-spinning drawing process can freely choose between various methods such as airflow cooling drawing and hot roller drawing, while ensuring the performance of the filaments. All of the above greatly enhances the flexibility of the non-woven fabric production process and lays the foundation for energy conservation and consumption reduction, cost savings, and efficiency improvements for the entire production line.

[0031] Because the nonwoven fabric of the present invention comprises composite filaments and single-structure filaments, subsequent molding can be performed under a wide range of heating and pressurizing conditions, achieving excellent molding results. Hot pressing can be performed by either heating the nonwoven fabric and then extruding it through a room-temperature mold, or by heating the mold and then extruding the room-temperature nonwoven fabric. Compression molding can produce profiles for specific products, while hot pressing can yield high-performance boards or sheets for a variety of applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 A schematic diagram of the cross-sectional structure of filaments in the nonwoven fabric of the present invention;

[0033] Figure 2 This is another schematic diagram of the cross-sectional structure of the filaments in the nonwoven fabric of the present invention.

[0034] Figure 3 This is another schematic diagram of the cross-sectional structure of the filaments in the nonwoven fabric of the present invention;

[0035] Figure 4 A chart showing the sound absorption performance test data of Example 9 of the present invention.

[0036] In the figure: 1-composite filament, 2-single structure filament; A-low melting point component in the composite filament, B-high melting point component in the composite filament. DETAILED DESCRIPTION

[0037] The technical solution of the present invention is further described below with reference to the accompanying drawings to make it easier to understand and grasp. The melting point mentioned in this case refers to the value measured by DSC method.

[0038] The present invention provides a nonwoven fabric that is convenient for direct molding processing, comprising at least one composite filament and at least one single-structure filament. The composite filament has a bicomponent sheath-core structure, wherein the melting point of the sheath component is at least 20°C lower than that of the core component, and the melting point of the core component is the same as or similar to that of the single-structure filament; or the composite filament has a bicomponent laminating structure, wherein the melting point of one component is at least 20°C lower than that of the other component, and the melting point of the high-melting-point component is the same as or similar to that of the single-structure filament.

[0039] A more preferred solution is that the non-woven fabric contains one composite filament and one single structure filament; of course, it can also contain two composite filaments and one single structure filament, or one composite filament and two single structure filaments, or two composite filaments and two single structure filaments, and so on. Figure 1 、 Figure 2 and Figure 3 The diagram shows a typical case comprising a composite filament and a single structure filament; in the figure: 1 is the composite filament, 2 is the single structure filament, A is the low melting point component in the composite filament, and B is the high melting point component in the composite filament. Figure 1 Among them, the composite filament 1 is a two-component sheath-core structure, and the high melting point component B in the composite filament is the same as that of the single structure filament; Figure 2 Among them, the composite filament 1 is a two-component laminating structure, the laminating portion is a plane, and the high melting point component B in the composite filament is the same as the component of the single structure filament; Figure 3 Among them, composite filament 1 has a two-component laminating structure, the laminating portion is an arc surface, the cross-section of the low-melting-point portion of the composite filament is crescent-shaped, and the high-melting-point component B of the composite filament is different from the component of the single-structure filament. Due to the influence of the shape of the spinneret hole and the non-woven fabric processing process, in the actual product, the junction of the two components in the composite filament may not be as regular as shown in the figure, but this does not affect the implementation and application of the technical solution of this case. Moreover, due to the large number of spinnerets and spinnerets, and the fact that the web must undergo an interweaving and consolidation process after formation, in general, the composite filaments and single-structure filaments in the non-woven fabric can be considered to be evenly mixed in the running direction.

[0040] According to the technical solution of the present invention, in a non-woven fabric formed by uniformly interweaving a composite filament and a single structure filament, the composite filament can account for 10 to 50% of the total weight of the filaments; and the low-melting point component in the composite filament can account for 10 to 90% of the total weight of the composite filament. The processed composite filament and single structure filament have a linear density of 2 to 9 dtex and an elongation at break of 20 to 100%. The resulting non-woven fabric has a gram weight of 15 to 2000 g / m2. 2 , the shrinkage rate under the test conditions of 200℃ and 10 minutes is ≤60%, so that the non-woven fabric can be directly used for subsequent molding processing.

[0041] Preferably, one specific embodiment of the present invention is: the single-structure filament uses PET with a melting point of approximately 265°C; the composite filament adopts a sheath-core structure, with the sheath component being CoPET, PBT, or PA6 with a melting point ≤240°C, and the core component being PET with a melting point of approximately 265°C. Another specific embodiment is: the single-structure filament uses PET with a melting point of approximately 265°C; the composite filament has a two-component laminated structure, with the low-melting-point component being CoPET, PBT, or PA6 with a melting point ≤240°C, and the high-melting-point component being PET with a melting point of approximately 265°C.

[0042] The above-mentioned non-woven fabric can be produced using a "one-step method," namely, polymer chips are used as raw materials and melt-extruded through a screw extruder. The melted polymer material is filtered and then enters a composite spinning manifold. After being precisely metered by a metering pump, it enters a spinneret assembly. After spinning, it is drawn into filaments, which are then laid and consolidated before being wound into rolls to obtain a non-woven fabric product. The polymer chips are of at least two types, with a melting point difference of at least 20°C, and there are at least two screw extruders. The spinneret assembly has at least two types of spinnerets on the same spinneret plate, one of which is a spinneret for forming composite filaments with a sheath-core coating or a laminated structure, and the other is a spinneret for forming single-structure filaments. The various spinnerets are evenly distributed on the same spinneret plate. When it is necessary to add masterbatches, flame-retardant masterbatches, and various functional modification components, they can be mixed and fed into the screw extruder together with the polymer chips.

[0043] In the "one-step" production process, the spinneret is a key component. The spinneret used in this case has 48 to 96 spinneret holes; in the same spinneret, the number of spinneret holes that form composite filaments accounts for 10 to 50% of the total number of spinneret holes, that is, 5 to 50 holes. In the spinneret holes, the amount of low-melting-point material ejected at the same time accounts for 10 to 90% of the total weight of the polymer material ejected from the hole. Different spinneret holes, as well as different parts of the composite spinneret holes, correspond to different flow channels for the output of the melt from the screw extruder. The composite spinneret holes correspond to at least two melt flow channels. After the spinneret assembly spins, filaments can be formed by airflow cooling drawing or hot roller drawing. The formed filaments are consolidated by needle punching or thermal bonding after laying the web, and then rolled up to form non-woven fabrics.

[0044] When air flow cooling and drawing is adopted, the filaments ejected from the same spinneret are cooled by air blowing and then enter the 2 Compressed air is used to draw the filaments through the nozzles and pipes, forming a continuous filament bundle with a linear density of ≤9 dtex. After laying, the bundles are preferably consolidated by needle punching, so that the various filaments are fully interwoven in three dimensions.

[0045] The nonwoven fabric produced by this invention can be directly molded or hot-pressed into profiles or sheets suitable for automotive interior and exterior trim, household appliance housings, or electronic office product housings; or profiles or sheets that replace plastic products or sound-absorbing and vibration-damping materials for construction, decoration, office, or household use; or reinforced sheets for textiles, clothing, shoes, and hats. These profiles or sheets exhibit a flexural modulus greater than 300 MPa, a flexural strength greater than 5 MPa, a tensile strength greater than 20 MPa, a temperature resistance of ≥80°C, and sound absorption coefficients greater than 0.09 at 1000 Hz, 0.41 at 3150 Hz, and 0.63 at 5000 Hz.

[0046] The specific applications of these profiles, plates or sheets can be: interior and exterior automotive components such as car linings, instrument panels, air-conditioning ducts, seat bodies, and bumpers; housings for household appliances or general office products such as vacuum cleaners, air conditioners, computers or printers; sound-absorbing or decorative panels for construction or decoration; main bodies and lining materials for various pallets, suitcases, and other bags; substitutes for insoles and other injection-molded products; reinforcing sheets for textiles, clothing, shoes and hats, and so on.

[0047] In this way, the technical solution of the present invention can be used to obtain a high-performance non-woven fabric product, which can be directly used for subsequent molding and processing. During the molding process, no additional ingredients or auxiliary materials are needed. The low-melting-point component in the composite filaments melts, and the remaining filament structures are fully fused and bonded to each other and to the single-structure filaments. The structure of the molded product consists of a resolidified structure after the low-melting-point component melts, and a fiber structure composed of high-melting-point filaments. The former ensures product molding, while the latter increases the strength and toughness of the molded product. Therefore, the non-woven fabric can be processed into a substitute for various existing plastic products and sound-absorbing and shock-absorbing materials, giving it extremely broad application prospects in various industries such as automobiles, electrical appliances, construction, decoration, office or home use.

[0048] The nonwoven fabric products produced using the technical solution of the present invention include single-structure filaments and composite filaments with a bicomponent sheath-core structure or a laminated structure. The latter serves as the basis for subsequent molding, while the former ensures the mechanical properties of the molded product and reduces the porosity of the finished product. The combination of the two can better leverage the inherent properties of the nonwoven fabric, enabling the molded product to achieve optimal mechanical properties, heat resistance, acoustic wave performance, and other aspects simultaneously, surpassing the performance of existing conventional plastic products or glass fiber reinforced plastics. This improvement in comprehensive performance enables the molded product to meet or even exceed its application requirements in various fields and different occasions.

[0049] The present invention adopts a "one-step" production process from sliced raw materials to non-woven fabric products, which has a short process, low cost, and is easy to operate and control. Using sliced raw materials, various modified ingredients such as masterbatch, flame retardant masterbatch, functional additives, etc. can be added at any time according to user needs; the number and form of the spinnerets on the spinneret assembly can be replaced and adjusted at any time according to requirements, and the number, form, and distribution of the spinnerets on the spinnerets can also be designed and replaced at any time according to the sliced raw materials and user needs. The post-spinning drawing process can freely choose between various methods such as airflow cooling drawing and hot roller drawing, while ensuring the performance of the filaments. All of the above greatly enhances the flexibility of the non-woven fabric production process and lays the foundation for energy conservation and consumption reduction, cost savings, and efficiency improvements for the entire production line.

[0050] Because the nonwoven fabric of the present invention comprises composite filaments and single-structure filaments, subsequent molding can be performed under a wide range of heating and pressurizing conditions, achieving excellent molding results. Hot pressing can be performed by either heating the nonwoven fabric and then extruding it through a room-temperature mold, or by heating the mold and then extruding the room-temperature nonwoven fabric. Compression molding can produce profiles for specific products, while hot pressing can yield high-performance boards or sheets for a variety of applications.

[0051] Table 1: Main technical contents of several preparation examples of the present invention

[0052]

[0053]

[0054] (*The shrinkage rate is tested at 200°C for 10 minutes.)

[0055] Table 2: Specific applications of various embodiments of the present invention

[0056]

[0057] Example 7

[0058] The method for preparing the long-fiber non-woven fabric molding material of this embodiment includes the following steps:

[0059] After filtration, the melted polymer material enters the composite spinning manifold. After being precisely metered by a metering pump, it enters the spinneret assembly for spinning. The spinneret assembly consists of multiple identical spinnerets, each with two types of spinneret holes: one for composite filaments with a sheath-core structure, and one for single-structure filaments. These various types of spinnerets are evenly distributed on the same spinneret. The number of spinneret holes for composite filaments accounts for 50% of the total number of spinneret holes. The single-structure filament spinnerets produce PET single-structure filaments, while the composite filament spinnerets produce composite filaments with a core layer of PET coated with CoPET. The amount of CoPET produced from the sheath accounts for 35% of the total number of spinneret holes for composite filaments.

[0060] S2. The filaments ejected from the same spinneret are cooled by air at 25℃ and then heated to a pressure greater than 3kg / cm 2 The compressed air is used as the power of the airflow stretching nozzle and stretching pipe. After airflow stretching, composite filaments and single structure filaments with a linear density of 4.2dtex are formed. Multiple filament bundles are then laid and needle-punched to form non-woven fabrics with a gram weight of 1200g / m 2 The cross-sectional structure of composite filaments and single structure filaments in non-woven fabrics is as follows: Figure 1 shown.

[0061] S3. Place the cut non-woven fabric between the upper and lower molds of the molding machine. The upper and lower molds are closed and heated with thermal oil to a temperature of 230°C. Steam at a temperature of 220°C is sprayed into the mold. After molding and heating for 60 seconds, the upper and lower molds are opened and the molded parts are sucked out with a negative pressure suction cup. The thickness of the molded parts is 2mm. After cooling, they are trimmed and punched to form the car underbody guard.

[0062] Example 8

[0063] The method for preparing the long-fiber non-woven fabric molding material of this embodiment includes the following steps:

[0064] After filtration, the melted polymer material enters the composite spinning manifold. After being precisely metered by a metering pump, it enters the spinneret assembly for spinning. The spinneret assembly consists of multiple identical spinnerets, each with two types of spinneret holes: one for composite filaments with a sheath-core structure, and one for single-structure filaments. These various types of spinnerets are evenly distributed on the same spinneret. The number of spinneret holes for composite filaments accounts for 40% of the total number of spinneret holes. The single-structure filament spinnerets produce PET single-structure filaments, while the composite filament spinnerets produce composite filaments with a core layer of PET coated with CoPET. The amount of CoPET produced from the sheath accounts for 30% of the total number of spinneret holes for composite filaments.

[0065] S2. The filaments ejected from the same spinneret are cooled by air at 25℃ and then heated to a pressure greater than 3kg / cm 2 The compressed air is used as the power of the airflow stretching nozzle and stretching pipe. After airflow stretching, composite filaments and single structure filaments with a linear density of 3.6dtex are formed. Multiple filament bundles are then laid and needle-punched to form non-woven fabrics with a gram weight of 1000g / m 2 .

[0066] S3. Place the cut non-woven fabric between the upper and lower molds of the molding machine. The upper and lower molds are closed and heated to 220°C using thermal oil. Steam at a temperature of 210°C is sprayed into the mold. After molding and heating for 120 seconds, the upper and lower molds are opened and the molded parts are sucked out using a negative pressure suction cup. The thickness of the molded parts is 1.5mm. After cooling, the parts are trimmed and punched to form the car underbody guard.

[0067] Example 9

[0068] The method for preparing the long-fiber non-woven fabric molding material of this embodiment includes the following steps:

[0069] After filtration, the melted polymer material enters the composite spinning manifold. After being precisely metered by a metering pump, it enters the spinneret assembly for spinning. The spinneret assembly consists of multiple identical spinnerets, each with two types of spinneret holes: one for composite filaments with a sheath-core structure, and one for single-structure filaments. These various types of spinnerets are evenly distributed on the same spinneret. The number of spinneret holes for composite filaments accounts for 30% of the total number of spinneret holes. The single-structure filament spinnerets produce PET single-structure filaments, while the composite filament spinnerets produce composite filaments with a core layer of PET coated with CoPET. The amount of CoPET produced from the sheath accounts for 40% of the total number of spinneret holes.

[0070] S2. The filaments ejected from the same spinneret are cooled by air at 25℃ and then heated to a pressure greater than 3kg / cm 2The compressed air is used as the power of the airflow stretching nozzle and stretching pipe. After airflow stretching, composite filaments and single structure filaments with a linear density of 4.2dtex are formed. Multiple filament bundles are then laid and needle-punched to form non-woven fabrics with a gram weight of 1200g / m 2 .

[0071] S3. Place the cut non-woven fabric between the upper and lower molds of the molding machine. The upper and lower molds are closed and heated with thermal oil to a temperature of 236°C. Steam at a temperature of 230°C is sprayed into the mold. After molding and heating for 30 seconds, the upper and lower molds are opened and the molded parts are sucked out with a negative pressure suction cup. The thickness of the molded parts is 4mm. After cooling, they are trimmed and punched to form the car underbody guard.

[0072] Comparative Example

[0073] The preparation method of the short fiber nonwoven fabric molding material of this comparative example comprises the following steps:

[0074] After filtration, the melted polymer material enters the composite spinning manifold. After being precisely metered by a metering pump, it enters the spinneret assembly for spinning. The spinneret assembly consists of multiple identical spinnerets. The spinnerets on each spinneret have two types of spinnerets: a composite spinneret with a sheath-core structure and a single-structure spinneret. The various spinnerets are evenly distributed on the same spinneret. The composite spinnerets account for 50% of the total number of spinnerets. The single-structure spinnerets produce PET single-structure filaments, while the composite spinnerets produce composite filaments with a core layer of PET coated with CoPET. The amount of CoPET produced from the composite spinnerets accounts for 35% of the total.

[0075] S2. The fiber length of the tows sprayed from the same spinneret is 55±10mm, the linear density is 4.2dtex, and the composite yarn and single structure yarn are made. The multiple tows are then laid and needle-punched to form a non-woven fabric with a gram weight of 1200g / m 2 .

[0076] S3. Place the cut non-woven fabric between the upper and lower molds of the molding machine. Close the upper and lower molds and heat them with thermal oil to 230°C. Spray steam at 220°C into the molds. After molding and heating for 60 seconds, open the upper and lower molds and use a negative pressure suction cup to suck out the molded part. The thickness of the molded part is 2 mm.

[0077] The long fiber nonwoven molded material of Example 7 and the short fiber nonwoven molded material of the comparative example were subjected to tensile performance measurement (ISO527), bending performance measurement (ISO178), tear strength measurement (GB / T 529 right angle type) and 24h water absorption measurement (100*100mm sample was placed in a water pool with a depth of 30cm, and the water on both sides was dried after being taken out to measure the weight gain). The test data are shown in Table 3.

[0078] Table 3: Performance measurement comparison data

[0079]

[0080]

[0081] As can be seen from Table 3, the long fiber non-woven molded material has significantly improved tensile properties, bending properties and tear strength compared with the short fiber non-woven molded material. The short fiber non-woven molded material is easy to absorb water, while the long fiber non-woven molded material greatly reduces the water absorption.

[0082] The sound absorption performance of the long fiber non-woven fabric molded material of Example 9 was tested using an Alpha-Cabin instrument. The test conditions were 1200mm*1000mm*4mm plate + 20mm air layer. The test results are as follows: Figure 4 As shown, the horizontal axis is the sound frequency, the vertical axis is the absorption coefficient αs, the absorption coefficient α s The higher the value, the better the sound absorption performance. The test results are shown in Table 4.

[0083] Table 4: Sound absorption performance test data

[0084] Frequency (Hz) 315 400 500 630 800 1000 <![CDATA[Sound absorption coefficient α s > 0.124 0.129 0.258 0.287 0.363 0.461 Frequency (Hz) 1250 1600 2000 2500 3150 4000 <![CDATA[Sound absorption coefficient α s > 0.622 0.746 0.836 0.863 0.98 0.926

[0085] The above describes the technical solutions and implementation effects of the present invention in detail. To further illustrate the technical solutions and innovative effects of the present invention, several specific preparation examples, molding processes, and applications are listed below. It should be noted that the examples listed are only typical examples of the present invention. In addition, the present invention may also have many other specific implementations. Any technical solutions formed by equivalent substitution or equivalent transformation fall within the scope of protection claimed by the present invention.

Claims

1. A method for preparing a long fiber nonwoven molding material, characterized in that: The following steps are involved: S1. The melted polymer material is filtered and then fed into a composite spinning manifold. After being precisely metered by a metering pump, it enters a spinneret assembly for spinning. The spinneret assembly has two types of spinnerets: one for forming composite filaments with a sheath-core structure, and one for forming single-structure filaments. These types of spinnerets are evenly distributed on the same spinneret. The number of spinnerets for composite filaments accounts for 30-50% of the total number of spinnerets. The single-structure filament spinnerets produce PET single-structure filaments, while the composite filament spinnerets produce composite filaments with a core layer of PET coated with CoPET sheath. The amount of CoPET sheathed accounts for 15-50% of the total number of spinnerets. S2. The filaments ejected from the same spinneret are cooled by air blowing and then stretched by air flow to form composite filaments and single structure filaments with a single filament linear density of ≤9 dtex. The multiple filaments are then laid and needle-punched to form a non-woven fabric; the non-woven fabric has a gram weight of 800 to 1400 g / m 2 ; S3. Place the cut nonwoven fabric between the upper and lower molds of a molding machine. Heat the molds to a temperature of 220-236°C. Spray steam at a temperature of 180-230°C into the mold. After heating for 30-180 seconds, open the upper and lower molds and remove the molded part. The thickness of the molded part is 1.5-4.5 mm.

2. The method for preparing the long-fiber nonwoven molding material according to claim 1, wherein: The ejection amount of the skin layer CoPET accounts for 30-40% of the total ejection amount of the composite filament spinneret.

3. The method for preparing the long fiber nonwoven molding material according to claim 1, characterized in that: The proportion of the number of the composite filament spinnerets to the total number of the spinnerets is 50%.

4. The method for preparing the long-fiber nonwoven molding material according to claim 1, wherein: The single-filament linear density of the composite filament and the single-structure filament is 2 to 5 dtex.

5. The method for preparing the long fiber nonwoven molding material according to claim 3, characterized in that: In step S2, the pressure is greater than 3 kg / cm 2 The compressed air is used as the power of the air flow stretching nozzle and the stretching pipe to perform air flow stretching.

6. A molded part prepared by the method for preparing a long-fiber non-woven fabric molding material according to claim 1.

7. Use of a molded part prepared by the method for preparing a long-fiber non-woven fabric molding material according to claim 1 as an automobile underbody guard.

Images