A method and system for producing spunbonded nonwoven fabric

Abstract

The present invention relates to a production method and a production system for spunbond nonwoven fabrics, and belongs to the technical field of nonwoven fabrics. A production method for spunbond nonwoven fabrics, comprising: a process of melt-spinning a first thermoplastic resin to form continuous curled fibers, a process of gathering the continuous curled fibers to form a first fiber web and a second fiber web respectively, a process of melt-blowing a second thermoplastic resin to form hot short fibers and spraying them onto the first fiber web and / or the second fiber web, and a process of consolidating a laminate formed by the first fiber web and the second fiber web. The nonwoven fabric prepared by the present invention comprises two spunbond nonwoven fabric layers with relatively high strength and a meltblown nonwoven fabric layer with relatively good filtering performance, and not only has the advantage of good interlayer bonding, but also has the advantages of good structural strength of spunbond nonwoven fabrics and good filtering performance of meltblown nonwoven fabrics.

Description

Technical Field

[0001] The invention relates to a production method and a production system for spunbonded nonwoven fabrics, belonging to the technical field of nonwoven fabrics. Background Art

[0002] Non-woven fabrics have the advantage of good air permeability and are widely used in absorbent articles (such as diapers, sanitary napkins, etc.) and medical materials (bed sheets, gauze, covers, surgical gowns, etc.). In the field of filtration materials, non-woven fabrics are also used as support materials for filter membranes. In laminating, non-woven fabrics are directly used as materials for laminating with plastic films.

[0003] However, according to the classification of the prior art, non-woven fabrics are generally divided into spunbond non-woven fabrics and meltblown non-woven fabrics. Spunbond non-woven fabrics are made by bending continuous fibers and laying them into a fiber web and then undergoing subsequent processing. Meltblown non-woven fabrics are made by directly spraying out short fibers and capturing them with a special device to form a fiber web and then undergoing subsequent processing. Therefore, they have their own characteristics. Spunbond non-woven fabrics have high strength, but poor filtering performance, and can only be used as a supporting material for filter materials; meltblown non-woven fabrics have good filtering performance, but low strength, and can only be used as filter materials under low pressure conditions, such as disposable medical masks and daily protective masks; they cannot be used as filter materials for air filters and water treatment devices.

[0004] The invention patent with application number 2019800914649 discloses a method for manufacturing a spunbond nonwoven fabric and a spunbond nonwoven fabric. The manufacturing method includes: a process of melt-spinning a thermoplastic polymer to form a curled fiber; and a process of capturing the above-mentioned curled fibers and pressing the captured curled fibers with a linear pressure of more than 5N / mm using a compaction roller. The nonwoven fabric obtained by this method has the characteristics of not damaging softness and excellent anti-pilling properties. However, as mentioned above, the nonwoven fabric has poor filtering performance and can only be used as a supporting material for filter materials. Summary of the invention

[0005] In view of the problems raised in the background art, in a first aspect, the present invention provides a method for producing a spunbonded nonwoven fabric.

[0006] The technical solution of the present invention to solve the above problems is as follows:

[0007] A method for producing a spunbonded nonwoven fabric, comprising:

[0008] a step of melt-spinning a first thermoplastic resin to form continuous crimped fibers, and

[0009] a step of gathering the continuous crimped fibers to form a first web and a second web, respectively; and

[0010] The process of melt-blowing a second thermoplastic resin to form hot short fibers and spraying the hot short fibers onto the first fiber web and / or the second fiber web, and

[0011] The step of consolidating a stack formed by the first fiber web and the second fiber web.

[0012] In the above technical solution of the present invention, the process of melt-blowing the second thermoplastic resin to form hot staple fibers is different from the melt-blowing of the prior art. In the prior art, the staple fibers are usually at a temperature below 80°C because they have been forced to cool by cold air when melt-blown. In the above technical solution of the present invention, before melt-blowing from the spinneret, the melt only experiences the stretching and breaking effects of high-pressure hot air, but does not experience the cooling of strong high-pressure cold air or only experiences the cooling of weak high-pressure cold air, so the staple fibers are hot, and then they are only cooled by normal temperature and pressure air during the process of being sprayed from the spinneret to the first fiber web and / or the second fiber web. Therefore, they are still hot when they are captured by the web screen or web roller carrying the first fiber web and / or the second fiber web, and the temperature is usually between 90 and 110°C. The hot staple fibers have good adhesion and plasticity, so that they can be better compounded with the first fiber web and / or the second fiber web.

[0013] Preferably, the first thermoplastic resin is polypropylene or an olefin polymer containing polypropylene; and the second thermoplastic resin is polypropylene.

[0014] The olefin polymer, especially the propylene polymer, can be a homopolymer of propylene, a random copolymer of propylene and other short-chain olefins, and preferably a homopolymer of propylene or a random homopolymer of propylene and ethylene from the viewpoint of providing good adhesion and web-laying formability when melt-blown on the fiber web.

[0015] Preferably, the melt index of the first thermoplastic resin is not less than 100 g / 10 min, and the melt index of the second thermoplastic resin is not less than 300 g / 10 min. The melt index is measured at 230° C., a load of 2160 g, and an inner diameter of a standard die of 2.095 mm.

[0016] Preferably, the melt index of the first thermoplastic resin is not less than 200 g / 10min and not more than 400 g / 10min; the melt index of the second thermoplastic resin is not less than 500 g / 10min and not more than 900 g / 10min.

[0017] Preferably, the hot staple fibers are formed by stretching a melt formed by the second thermoplastic resin until it breaks when being extruded from an outlet of the melt channel by high-pressure hot air.

[0018] Preferably, after being blown out, the hot staple fibers are captured by a web-forming curtain or a web-forming roller carrying the first fiber web or the second fiber web.

[0019] Preferably, a negative pressure extraction component is provided on the back side of the web-forming curtain or web-forming roller to improve the capture efficiency.

[0020] Preferably, when consolidation is performed using a press roll, the temperature of the press roll does not exceed the melting temperature of the first and second thermoplastic resins.

[0021] Preferably, the temperature of the pressing roller does not exceed 100°C.

[0022] In a second aspect, the present invention provides a system for producing nonwoven fabrics.

[0023] A nonwoven fabric production system, including a melt extruder, a melt filtration device, a nonwoven fabric forming machine and a roller press; the nonwoven fabric forming machine includes a first fiber web forming component, a second fiber web forming component, and a meltblowing component arranged between the first fiber web forming component and the second fiber web forming component; the first fiber web forming component includes a first spinning mechanism, a first airflow drafting mechanism and a first laying mechanism carrying a first web-forming curtain; the second fiber web forming component includes a second spinning mechanism, a second airflow drafting mechanism and a second laying mechanism carrying a second web-forming curtain; the meltblowing component includes a spinneret for spraying hot short fibers onto a nonwoven fabric web formed on the first web-forming curtain or the second web-forming curtain, and the spinneret holes of the spinneret face at least one of the two web-forming curtains.

[0024] Unlike the spinneret of the meltblown assembly in the prior art, in the prior art, the staple fibers are captured by a web-forming curtain or a web-forming roller, and a fiber web is formed directly after capture. Therefore, in addition to the hot air channel for stretching the melt, the spinneret also has a channel for cooling the melt to facilitate the capture of the staple fibers and the formation of the fiber web. When the staple fibers are sprayed onto the web-forming curtain or the web-forming roller, their temperature has dropped below 80°C. In the above technical solution of the present invention, since the staple fibers are sprayed onto the first fiber web or the second fiber web, the temperature of the staple fibers is designed to be hot, usually between 90 and 106°C, preferably 100 to 106°C. In this case, the spinneret does not include a cooling air channel that has a strong influence on the melt.

[0025] Preferably, the spinneret has a weakly affected cooling air channel, the air source of which is provided by room temperature gas around the spinneret and intervened by self-absorption formed based on the Bernoulli effect during the spinning process.

[0026] Preferably, the first mesh curtain and the second mesh curtain are symmetrically arranged.

[0027] Preferably, the spinneret comprises a melt channel and a high-pressure hot air channel surrounding the melt channel.

[0028] Preferably, the spinneret has first spinneret holes and second spinneret holes arranged in a row, wherein the first spinneret holes are arranged toward the first mesh-forming curtain, and the second spinneret holes are arranged toward the second mesh-forming curtain.

[0029] Preferably, the spinneret has a first melt channel and a second melt channel, the first spinneret hole is connected to the melt channel through the first melt channel; the second spinneret hole is connected to the melt channel through the second melt channel.

[0030] Preferably, the spinneret has a first high-pressure hot air channel and a second high-pressure hot air channel connected to the high-pressure hot air channel; the outlet of the first high-pressure hot air channel is arranged around the first spinneret hole; the outlet of the second high-pressure hot air channel is arranged around the second spinneret hole.

[0031] Preferably, the nonwoven fabric forming machine further comprises a web composite component for composite the first web carrying staple fibers and the second web into a nonwoven fabric.

[0032] Preferably, the first spinning box comprises a first spinneret arranged at the lower part of the box body and a first side-blowing box for blowing and cooling the continuous fibers melt-spun by the first spinneret.

[0033] Preferably, the roller press comprises an upper roller and a lower roller arranged in pair, the upper roller is an anilox roller, and the lower roller is a smooth roller.

[0034] In summary, the present invention has the following beneficial effects:

[0035] 1. The present invention sprays hot staple fibers between the double-layer fiber webs formed by two heads, and then consolidates them into the required non-woven fabrics through roller pressing; this not only improves the composite strength of the double-layer fiber webs, but also further solves the problem that the traditional spunbond non-woven fabrics have poor filtering ability and cannot be used as mask materials;

[0036] 2. The nonwoven fabric prepared by the present invention includes two spunbond nonwoven fabric layers with relatively high strength and one meltblown nonwoven fabric layer with relatively good filtering performance, and the three layers are pressure-consolidated in a hot state, which not only has the advantage of good interlayer bonding, but also has the advantages of good structural strength of the spunbond nonwoven fabric and good filtering performance of the meltblown nonwoven fabric;

[0037] 3. The nonwoven fabric of the present invention can be used in various types of masks, air purifier filter materials, engine air filters, vacuum cleaner filter materials and other occasions due to the above advantages. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 The production system of the spunbond nonwoven fabric of Example 1;

[0039] Figure 2 The production system of the spunbond nonwoven fabric of Example 2;

[0040] Figure 3 The production system of the spunbond nonwoven fabric of Example 3;

[0041] Figure 4 Schematic diagram of the structure of the spinneret in Example 1 and Example 2;

[0042] Figure 5 is a schematic structural diagram of the spinneret in Example 3;

[0043] The names of the components represented by the reference numbers in the figure are as follows:

[0044] 1. Melt extruder,

[0045] 2. Melt filtration device,

[0046] 3. Non-woven fabric forming machine,

[0047] 4. Roller press,

[0048] 5. Winding machine,

[0049] 31. a first web forming component,

[0050] 32. a second fiber web forming assembly,

[0051] 33. Meltblown components,

[0052] 311. The first spinning mechanism,

[0053] 312. a first air flow drafting mechanism,

[0054] 313. The first web laying mechanism,

[0055] 321. The second spinning mechanism,

[0056] 322. Second air flow drafting mechanism,

[0057] 323. The second web laying mechanism,

[0058] 332. Negative pressure adsorption mechanism,

[0059] 333. Negative pressure adsorption roller,

[0060] 334. Fiber-web composite mechanism,

[0061] 3111, the first spinneret,

[0062] 3112, first side blowing bellows,

[0063] 3211, the second spinneret,

[0064] 3212, second side blowing bellows,

[0065] 331, spinneret,

[0066] 331x, melt channel,

[0067] 3311, first melt channel,

[0068] 3312, second melt channel,

[0069] 332x, high pressure hot air channel,

[0070] 3321, the first high pressure hot air channel,

[0071] 3322, the second high pressure hot air passage,

[0072] 333x, weakly affected cooling air passages. DETAILED DESCRIPTION

[0073] The present invention is further explained below in conjunction with the accompanying drawings.

[0074] This specific implementation is only an explanation of the present invention, not a limitation of the present invention. Any changes made by those skilled in the art after reading the specification of the present invention will be protected by the patent law as long as they are within the scope of the claims.

[0075] Example 1

[0076] A method for producing a spunbonded nonwoven fabric, comprising:

[0077] a step of melt-spinning a first thermoplastic resin to form continuous crimped fibers, and

[0078] a step of gathering the continuous crimped fibers to form a first fiber web, and

[0079] The process of melt-blowing a second thermoplastic resin to form hot short fibers and spraying the hot short fibers onto the first fiber web, and

[0080] a step of gathering the continuous crimped fibers to form a second web, and

[0081] The step of consolidating a laminate formed by the first fiber web and the second fiber web to produce a nonwoven fabric.

[0082] [Preparatory step for the step of forming continuous crimped fibers]

[0083] Use Figure 1The production system shown in the figure is used for manufacturing, the first thermoplastic resin is melted by a melt extruder 1, impurities in the melt are intercepted by a melt filter 2, and the melt formed by the first thermoplastic resin is transported to a non-woven fabric forming machine 3 by a melt metering pump (not shown in the figure). In this example, the first thermoplastic resin is a mixture of polypropylene, a random copolymer of propylene and ethylene with a melt index of 178 g / 10min, wherein the polypropylene content is more than 95%.

[0084] [Step of forming continuous crimped fibers and step of forming a first fiber web]

[0085] Use Figure 1 The production system shown in the figure is manufactured, and the melt formed by the first thermoplastic resin delivered by the melt metering pump (not shown in the figure) is injected into the first spinning mechanism 311, and sprayed from the first spinneret 3111 at the lower part of the spinning box body to form continuous fibers. During the process, the cross wind from the first side blowing air box 3112 is used to preliminarily cool the newly formed fibers, and the fibers formed at this time are relatively thick; the thicker fibers are further stretched by the first air drafting mechanism 312 through the air flow to make the fibers gradually thinner during the cooling process; in this process, the flow rate and flow of the gas are controlled to prevent the fibers from breaking; the first fiber web is formed in the first web laying mechanism 313, and is transported by the first web laying mechanism 313 to the process direction of [the process of spraying to the first fiber web].

[0086] [Step of spraying onto the first web]

[0087] Use Figure 1 The production system shown in the figure is used for manufacturing, and a melt formed by a second thermoplastic resin (not shown in the figure) is injected into the melt-blown component 33, and a large number of hot short fibers are sprayed out from the spinneret 331 to form on the surface of the first fiber web transmitted from the process of [forming continuous crimped fibers and forming the first fiber web]. In order to make the hot short fibers adhere better, a negative pressure adsorption mechanism 332 is provided on the side of the transmission component away from the spinneret 331. In this example, the second thermoplastic resin is a homopolypropylene with a melt index of 726 g / 10min.

[0088] [Step of forming continuous crimped fibers and step of forming a second fiber web]

[0089] Use Figure 1The production system shown in the figure is manufactured, and the melt formed by the first thermoplastic resin delivered by the melt metering pump (not shown in the figure) is injected into the first spinning mechanism 311 and the second spinning mechanism 321 at the same time, and is ejected from the second spinneret 3211 at the lower part of the spinning box body to form continuous fibers. During the process, the cross wind from the second side blowing air box 3212 preliminarily cools the newly formed fibers, and the fibers formed at this time are relatively thick; the thicker fibers are further stretched by the second air drafting mechanism 322, so that the fibers gradually become thinner during the cooling process; in this process, the flow rate and flow of the gas are controlled to prevent the fibers from breaking. The second fiber web is formed in the second laying mechanism 323, and is also formed on the first fiber web with a large number of hot short fibers attached to the surface formed by the process of [spraying to the first fiber web], forming a sandwich structure of the first fiber web (spunbond)-evenly laid hot short fibers (meltblown)-second fiber web (spunbond); and is transported by the second laying mechanism 323 to the process direction of [process of forming non-woven fabric].

[0090] [Process of forming nonwoven fabric]

[0091] Use Figure 1 The production system shown in the figure is used for manufacturing, and the sandwich structure delivered from the process of [the process of forming continuous crimped fibers and the process of forming the second fiber web] is consolidated by a roller press 4. The roller press is a cold roller press, and the surface temperature of the roller is heated up due to the working conditions, and the surface temperature of the roller is always controlled within 80°C.

[0092] [Reeling process]

[0093] Use Figure 1 The production system shown in the figure performs production, and the nonwoven fabric delivered from the step of [the step of forming the nonwoven fabric] is wound up by the winder 5 .

[0094] In this embodiment, the nonwoven fabric is manufactured using the following production equipment system.

[0095] Production systems for nonwovens, such as Figure 1 As shown, it includes a melt extruder 1, a melt filtering device 2, a non-woven fabric forming machine 3, a roller press 4 and a winder 5. Among them, the non-woven fabric forming machine 3 is the key part.

[0096] The nonwoven fabric forming machine 3 comprises a first web forming assembly 31 , a meltblowing assembly 33 and a second web forming assembly 32 .

[0097] The first web forming assembly 31 includes a first spinning mechanism 311, a first air drafting mechanism 312 and a first web laying mechanism 313. The first web forming assembly 31 forms a first thermoplastic melt into continuous fibers, and forms a first web on the web curtain of the first web laying mechanism 313. The melt-blowing assembly 33 includes a spinneret 331 for spraying hot short fibers onto the first web formed on the web curtain. The melt-blowing assembly 33 forms the first thermoplastic melt into hot short fibers, and sprays them uniformly on the surface of the first web. The second web forming assembly 32 includes a second spinning mechanism 321, a second air drafting mechanism 322 and a second web laying mechanism 323. The second web forming assembly 32 forms the first thermoplastic melt into continuous fibers, and forms a second web on the web curtain of the second web laying mechanism 323, and also on the first web with a large number of hot short fibers attached to the surface. The first spinning mechanism 311 includes a spinning box, a first spinneret 3111 disposed at the lower part of the box, and a first side blowing box 3112 for blowing and cooling the continuous fibers melt-spun by the first spinneret 3111; similarly, the second spinning mechanism 321 includes a spinning box, a second spinneret 3211 disposed at the lower part of the box, and a second side blowing box 3212 for blowing and cooling the continuous fibers melt-spun by the second spinneret. Figure 1 It can be seen that the first web laying mechanism 313 and the second web laying mechanism 323 are actually the same web laying mechanism, but they are located in different process positions.

[0098] like Figure 4 As shown, the spinneret 331 includes a melt channel 331x, a high-pressure hot air channel 332x surrounding the melt channel, and a weakly affected cooling air channel 333x. Since the cold air source of the cooling air channel is room temperature air, and the jetting power is based on the Bernoulli effect formed when the hot short fibers are jetted, it is a passive jetting form, so it is called a weakly affected cooling air channel.

[0099] Example 2

[0100] A method for producing a spunbonded nonwoven fabric, comprising:

[0101] a step of melt-spinning a first thermoplastic resin to form continuous crimped fibers, and

[0102] a step of gathering the continuous crimped fibers to form a first web and a second web respectively and simultaneously; and

[0103] The process of spraying hot short fibers formed by melt-blowing a second thermoplastic resin to a bell mouth formed by the first fiber web and the second fiber web when the first fiber web and the second fiber web are conveyed, and

[0104] The step of consolidating a laminate formed by the first fiber web and the second fiber web to produce a nonwoven fabric.

[0105] [Preparatory step for the step of forming continuous crimped fibers]

[0106] Use Figure 2 The production system shown in the figure is used for manufacturing, the first thermoplastic resin is melted by a melt extruder 1, impurities in the melt are intercepted by a melt filter 2, and the melt is then transported to a non-woven fabric forming machine 3 by a melt metering pump (not shown in the figure). In this example, the first thermoplastic resin is homopolypropylene with a melt index of 268 g / 10min.

[0107] [Step of forming continuous crimped fibers and step of forming a first fiber web]

[0108] Use Figure 2 The production system shown is manufactured, and the melt formed by the first thermoplastic resin delivered by the melt metering pump (not shown in the figure) is injected into the first spinning mechanism 311, and sprayed out from the first spinneret 3111 at the lower part of the spinning box body to form continuous fibers. During the process, the cross wind from the first side blowing air box 3112 is simultaneously used to preliminarily cool the newly formed fibers, and the fibers formed at this time are relatively thick; the thicker fibers are further stretched by the first air flow drawing mechanism 312 through the air flow to make the fibers gradually become thinner during the cooling process; in this process, the flow rate and flow rate of the gas are controlled to prevent the fibers from breaking; the first fiber web is formed in the first web laying mechanism 313, and is transported by the first web laying mechanism 313 in the process direction of [the process of spraying to the first and second fiber webs].

[0109] [Step of forming continuous crimped fibers and step of forming a second fiber web]

[0110] Use Figure 2The production system shown in the figure is used for manufacturing, and the melt formed by the first thermoplastic resin delivered by the melt metering pump (not shown in the figure) is injected into the second spinning mechanism 321 while being injected into the first spinning mechanism 311, and is ejected from the second spinneret 3211 at the lower part of the spinning box body to form continuous fibers. During the process, the crosswind from the second side-blowing air box 3212 preliminarily cools the newly formed fibers, and the fibers formed at this time are relatively thick; the thicker fibers are further stretched by the second air drafting mechanism 322, so that the fibers gradually become thinner during the cooling process; in this process, the flow rate and flow rate of the gas are controlled to prevent the fibers from breaking. The second fiber web is formed in the second web laying mechanism 323, and is transported by the second web laying mechanism 323 to the process direction of [the process of spraying to the first and second fiber webs]. Different from Example 1, the second web laying mechanism 323 and the first web laying mechanism 313 are relatively independent mechanisms. And in this example, the second web laying mechanism 323 and the first web laying mechanism 313 are arranged symmetrically.

[0111] [Step of Spraying to First and Second Webs]

[0112] Use Figure 2 The production system shown in the figure is used for manufacturing, and the melt formed by the second thermoplastic resin delivered by the melt metering pump (not shown in the figure) is injected into the meltblowing component 33, and a large number of hot short fibers are sprayed out from the spinneret 331 to form the surfaces of the first fiber web and the second fiber web that are simultaneously transmitted by [the process of forming continuous curled fibers and the process of forming the first fiber web] and [the process of forming continuous curled fibers and the process of forming the second fiber web]. At the same time, they are also formed on the two opposite surfaces of the first fiber web and the second fiber web to facilitate their consolidation in subsequent processes. After this process, a sandwich structure of the first fiber web (spunbond) - evenly laid hot short fibers (meltblown) - the second fiber web (spunbond) is finally formed. In this example, as Figure 2 As shown, the first fiber web and the second fiber web together form a gradually shrinking trumpet when they are conveyed to the bottom of the spinneret 331. Therefore, in this process, the corresponding relationship between the conveying rate of the first fiber web and the second fiber web and the injection amount of the spinneret 331 should be controlled to avoid the problem of premature closure of the opening. In this example, the second thermoplastic resin is homopolypropylene with a melt index of 726 g / 10min.

[0113] [Preliminary consolidation process]

[0114] Use Figure 2 The production system shown performs manufacturing by preliminarily consolidating the sandwich structure formed by the process of [the process of spraying onto the first and second fiber webs] using the fiber web composite mechanism 334.

[0115] [Process of forming nonwoven fabric]

[0116] Use Figure 2 The production system shown is used for manufacturing, and the structure formed by the process of [preliminary consolidation process] is consolidated by a roller press 4. The roller press is a cold roller press, and the surface of the roller is heated due to the working conditions, and the temperature is controlled within 80°C.

[0117] [Reeling process]

[0118] Use Figure 2 The production system shown is used for manufacturing, and the nonwoven fabric delivered from the step of [step of forming nonwoven fabric] is wound up by the winder 5 .

[0119] In this embodiment, the nonwoven fabric is manufactured using the following production equipment system.

[0120] Production systems for nonwovens, such as Figure 2 As shown, it includes a melt extruder 1, a melt filtering device 2, a non-woven fabric forming machine 3, a roller press 4 and a winder 5. Among them, the non-woven fabric forming machine 3 is the key part.

[0121] The nonwoven fabric forming machine 3 includes a first web forming assembly 31, a meltblowing assembly 33 and a second web forming assembly 32. The first web forming assembly 31 includes a first spinning mechanism 311, a first air drafting mechanism 312 and a first web laying mechanism 313. The first web forming assembly 31 forms a first thermoplastic melt into continuous fibers, and forms a first web on a first web-forming curtain of the first web laying mechanism 313. The second web forming assembly 32 includes a second spinning mechanism 321, a second air drafting mechanism 322 and a second web laying mechanism 323. The second web forming assembly 32 forms a first thermoplastic melt into continuous fibers, and forms a second web on a second web-forming curtain of the second web laying mechanism 323. When the first web and the second web are transported to the bottom of the spinneret 331, they jointly form a gradually shrinking bell mouth. The meltblowing assembly 33 includes a spinneret 331 for spraying hot short fibers to the bell mouth jointly formed by the first web and the second web. In order to avoid premature closure of the first fiber web and the second fiber web, it is necessary to control the transmission rate of the first fiber web and the second fiber web, and also to control the spraying amount per unit time of the melt-blown staple fibers accordingly.

[0122] The melt-blowing assembly 33 makes the first thermoplastic melt into hot short fibers and sprays them evenly on the surfaces of the first fiber web and the second fiber web. Figure 2 It can be seen that the first web laying mechanism 313 and the second web laying mechanism 323 are two sets of independent mechanisms and are symmetrically arranged. A fiber web composite mechanism 334 is arranged below the web laying mechanism, and the main working part of the fiber web composite mechanism 334 is a pair of rollers, which provide preliminary pressing effect.

[0123] like Figure 4As shown, the spinneret includes a melt channel 331x, a high-pressure hot air channel 332x surrounding the melt channel, and a weakly affected cooling air channel 333x. Since the cold air source of the cooling air channel is room temperature air, and the jet power is based on the Bernoulli effect formed when the hot short fibers are jetted, it is a passive jet form, so it is called a weakly affected cooling air channel.

[0124] Example 3

[0125] A method for producing a spunbonded nonwoven fabric, comprising:

[0126] a step of melt-spinning a first thermoplastic resin to form continuous crimped fibers, and

[0127] a step of gathering the continuous crimped fibers to form a first web and a second web, respectively; and

[0128] The process of melt-blowing a second thermoplastic resin to form hot short fibers and spraying the hot short fibers onto the first fiber web and the second fiber web, and

[0129] The step of consolidating a laminate formed by the first fiber web and the second fiber web to produce a nonwoven fabric.

[0130] [Preparatory step for the step of forming continuous crimped fibers]

[0131] Use Figure 3 The production system shown in the figure is used for manufacturing, the first thermoplastic resin is melted by a melt extruder 1, impurities in the melt are intercepted by a melt filter 2, and the melt is then transported to a non-woven fabric forming machine 3 by a melt metering pump (not shown in the figure). In this example, the first thermoplastic resin is homopolypropylene with a melt index of 268 g / 10min.

[0132] [Step of forming continuous crimped fibers and step of forming a first fiber web]

[0133] Use Figure 3 The production system shown in the figure is manufactured, and the melt formed by the first thermoplastic resin delivered by the melt metering pump (not shown in the figure) is injected into the first spinning mechanism 311, and sprayed from the first spinneret 3111 at the lower part of the spinning box body to form continuous fibers. During the process, the cross wind from the first side blowing air box 3112 is simultaneously used to preliminarily cool the newly formed fibers, and the fibers formed at this time are relatively thick; the thicker fibers are further stretched by the first air drafting mechanism 312 through the air flow to make the fibers gradually thinner during the cooling process. In this process, the flow rate and flow of the gas are controlled to prevent the fibers from breaking; the first fiber web is formed in the first web laying mechanism 313, and is transported by the first web laying mechanism 313 to the process direction of [the process of spraying to the first and second fiber webs].

[0134] [Step of forming continuous crimped fibers and step of forming a second fiber web]

[0135] Use Figure 3 The production system shown in the figure is used for manufacturing, and the melt formed by the first thermoplastic resin delivered by the melt metering pump (not shown in the figure) is injected into the second spinning mechanism 321 while being injected into the first spinning mechanism 311, and is ejected from the second spinneret 3211 at the lower part of the spinning box body to form continuous fibers. During the process, the crosswind from the second side-blowing air box 3212 preliminarily cools the newly formed fibers, and the fibers formed at this time are relatively thick; the thicker fibers are further stretched by the second air drafting mechanism 322, so that the fibers gradually become thinner during the cooling process. During this process, the flow rate and flow rate of the gas are controlled to prevent the fibers from breaking. The second fiber web is formed in the second web laying mechanism 323, and is transported by the second web laying mechanism 323 to the process direction of [the process of spraying to the first and second fiber webs]. Different from Example 1, the second web laying mechanism 323 and the first web laying mechanism 313 are relatively independent mechanisms. And in this example, the second web laying mechanism 323 and the first web laying mechanism 313 are arranged symmetrically.

[0136] [Step of Spraying to First and Second Webs]

[0137] Use Figure 3 The production system shown in the figure is used for manufacturing, and the melt formed by the second thermoplastic resin delivered by the melt metering pump (not shown in the figure) is injected into the meltblown component 33, and a large number of hot short fibers are sprayed out from the spinneret 331 to form the surfaces of the first fiber web and the second fiber web that are simultaneously transmitted by [the process of forming continuous curled fibers and the process of forming the first fiber web] and [the process of forming continuous curled fibers and the process of forming the second fiber web]. At the same time, they are also formed on the two opposite surfaces of the first fiber web and the second fiber web to facilitate their consolidation in subsequent processes. After this process, a sandwich structure of the first fiber web (spunbond) - evenly laid hot short fibers (meltblown) - the second fiber web (spunbond) is finally formed. In this example, as Figure 3 As shown, when the first fiber web and the second fiber web are transported to the bottom of the spinneret 331, they jointly form a gradually shrinking bell mouth. Different from Example 2, the hot staple fibers are not sprayed toward the bell mouth, but are sprayed toward the first fiber web and the second fiber web by the two nozzles of the spinneret 331 respectively before the bell mouth is formed. In this way, the problem of premature closing can be avoided without limiting the vehicle speed. In this embodiment, in the application scenario of early spraying, the roller needs to be modified. Figure 3As shown, a negative pressure adsorption roller 333 is provided below the spinneret 331 at a position corresponding to the first web laying mechanism 313 and the second web laying mechanism 323. In this example, the second thermoplastic resin is homopolypropylene with a melt index of 726 g / 10min.

[0138] [Preliminary consolidation process]

[0139] Use Figure 3 The production system shown performs manufacturing by preliminarily consolidating the sandwich structure formed by the process of [the process of spraying onto the first and second fiber webs] using the fiber web composite mechanism 334.

[0140] [Process of forming nonwoven fabric]

[0141] Use Figure 3 The production system shown is used for manufacturing, and the structure formed by the process of [preliminary consolidation process] is consolidated by a roller press 4. The roller press is a cold roller press, and the surface of the roller is heated due to the working conditions, and the temperature is controlled within 80°C.

[0142] [Reeling process]

[0143] Use Figure 3 The production system shown is used for manufacturing, and the nonwoven fabric delivered from the step of [step of forming nonwoven fabric] is wound up by the winder 5 .

[0144] In this embodiment, the nonwoven fabric is manufactured using the following production equipment system.

[0145] Production systems for nonwovens, such as Figure 3 As shown, it includes a melt extruder 1, a melt filtering device 2, a non-woven fabric forming machine 3, a roller press 4 and a winder 5. Among them, the non-woven fabric forming machine 3 is the key part.

[0146] The nonwoven fabric forming machine 3 comprises a first web forming assembly 31 , a meltblowing assembly 33 and a second web forming assembly 32 .

[0147] The first web forming assembly 31 includes a first spinning mechanism 311, a first air drafting mechanism 312 and a first web laying mechanism 313. The first web forming assembly 31 forms a first thermoplastic melt into continuous fibers, and forms a first web on a first web-forming curtain of the first web laying mechanism 313. The second web forming assembly 32 includes a second spinning mechanism 321, a second air drafting mechanism 322 and a second web laying mechanism 323. The second web forming assembly 32 forms a first thermoplastic melt into continuous fibers, and forms a second web on a second web-forming curtain of the second web laying mechanism 323. When the first web and the second web are conveyed to the bottom of the spinneret 331, they jointly form a gradually shrinking bell mouth.

[0148] The melt-blowing assembly 33 comprises a spinneret 331 for respectively spraying hot short fibers to the first fiber web and the second fiber web before the bell mouth is formed. The melt-blowing assembly 33 makes the first thermoplastic melt into hot short fibers and sprays them uniformly on the surfaces of the first fiber web and the second fiber web.

[0149] like Figure 5 As shown, the spinneret includes a melt channel, a high-pressure hot air channel surrounding the melt channel, and a weakly affected cooling air channel 333x. Since the cold air source of the cooling air channel is room temperature air, and the jet power is based on the Bernoulli effect formed when the hot short fibers are jetted, it is a passive jet form, so it is called a weakly affected cooling air channel. Further, the melt channel is bifurcated into a first melt channel 3311 and a second melt channel 3312, and the high-pressure hot air channel is bifurcated into a first high-pressure hot air channel 3321 and a second high-pressure hot air channel 3322. The spinneret 331 has a first spinneret hole and a second spinneret hole arranged in a row, and the first spinneret hole is connected to the melt channel through the first melt channel 3311; the second spinneret hole is connected to the melt channel through the second melt channel 3312. The outlet of the first high-pressure hot air channel 3321 is arranged around the first spinneret hole; the outlet of the second high-pressure hot air channel 3322 is arranged around the second spinneret hole.

Claims

1. A production system for spunbonded nonwoven fabrics, comprising a melt extruder, a melt filtration device, a nonwoven fabric forming machine, a roller press and a winder; The nonwoven fabric forming machine comprises a first web forming component, a meltblowing component and a second web forming component; The first fiber web forming assembly includes a first spinning mechanism, a first air drafting mechanism and a first web laying mechanism; the first fiber web forming assembly forms a first thermoplastic melt into continuous fibers, and forms the first fiber web on a first web forming curtain of the first web laying mechanism; The second fiber web forming assembly includes a second spinning mechanism, a second air drafting mechanism and a second web laying mechanism; the second fiber web forming assembly forms the first thermoplastic melt into continuous fibers, and forms the fibers into a second fiber web on a second web forming curtain of the second web laying mechanism; The melt-blowing component forms the second thermoplastic melt into hot short fibers and evenly sprays the hot short fibers onto the surfaces of the first fiber web and the second fiber web; The meltblowing assembly includes a spinneret; Features: When the first fiber web and the second fiber web are conveyed to the bottom of the spinneret, they jointly form a gradually shrinking bell mouth; The spinneret is used to spray hot short fibers to the first fiber web and the second fiber web respectively before forming a bell mouth; The spinneret includes a melt channel, a high-pressure hot air channel surrounding the melt channel, and a weak-impact cooling air channel; The air source of the weakly affected cooling air channel is provided by the room temperature gas around the spinneret, and intervenes by the self-absorption effect formed based on the Bernoulli effect during the spinning process; The melt channel is bifurcated into a first melt channel and a second melt channel, and the high-pressure hot air channel is bifurcated into a first high-pressure hot air channel and a second high-pressure hot air channel; The spinneret has first spinneret holes and second spinneret holes arranged in a row, the first spinneret holes are connected to the melt channel through the first melt channel; the second spinneret holes are connected to the melt channel through the second melt channel; the outlet of the first high-pressure hot air channel is arranged around the first spinneret holes; the outlet of the second high-pressure hot air channel is arranged around the second spinneret holes.

2. A method for producing a spunbonded nonwoven fabric for filter material according to the production system of claim 1, comprising: a step of melt-spinning a first thermoplastic resin to form continuous crimped fibers, and a step of gathering the continuous crimped fibers to form a first web and a second web, respectively; and The process of melt-blowing a second thermoplastic resin to form hot short fibers and spraying the hot short fibers onto the first fiber web and the second fiber web, and a step of consolidating a laminate formed by the first fiber web and the second fiber web; The first thermoplastic resin is polypropylene or an olefin polymer containing polypropylene; the second thermoplastic resin is polypropylene; The melt index of the first thermoplastic resin is not less than 200 g / 10 min, and the melt index of the second thermoplastic resin is not less than 300 g / 10 min; The temperature of the hot staple fibers is between 90 and 110°C.

3. The method for producing a spunbonded nonwoven fabric for filter material according to claim 2, characterized in that: The hot staple fibers are formed when the melt formed by the second thermoplastic resin is stretched to break by high-pressure hot air when being extruded from the outlet of the melt channel.

4. The method for producing a spunbonded nonwoven fabric for filter material according to claim 3, characterized in that: After being blown out, the hot staple fibers are captured by a web-forming curtain carrying the first fiber web or the second fiber web.

5. The method for producing a spunbonded nonwoven fabric for filter material according to claim 4, characterized in that: A negative pressure extraction component is arranged on the back side of the mesh curtain.

6. The method for producing a spunbonded nonwoven fabric for filter material according to claim 4, characterized in that: When consolidation is performed using a press roll, the temperature of the press roll does not exceed the melting temperature of the first thermoplastic resin and the second thermoplastic resin.

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