CN108884618B

CN108884618B - Apparatus for producing nonwoven fabric, method for producing nonwoven fabric, and nonwoven fabric

Info

Publication number: CN108884618B
Application number: CN201780021229.5A
Authority: CN
Inventors: 高久翔一; 铃木健一; 国本尚佑; 川田敦之; 田中乔之
Original assignee: Mitsui Chemicals Inc
Current assignee: Mitsui Chemicals Inc
Priority date: 2016-03-30
Filing date: 2017-03-24
Publication date: 2021-10-26
Anticipated expiration: 2037-03-24
Also published as: US20190106821A1; MY194230A; EP3438339A1; JP2020073749A; WO2017170241A1; JPWO2017170241A1; JP2022010113A; EP3438339A4; CN108884618A; EP3438339B1; KR20180117183A; DK3438339T3

Abstract

In a diffusion section of a nonwoven fabric manufacturing apparatus, a diffusion space is provided between a discharge nozzle and a moving belt of a collection section, an opening of a sub-nozzle is arranged in parallel with the opening of the discharge nozzle, and the sub-nozzle discharges gas from the opening. The discharge nozzle discharges a plurality of filaments together with gas toward the moving belt. The gas ejected from the ejection nozzle forms a transport stream flowing in a gradually expanding manner in the diffusion space, and the plurality of filaments are transported to the moving belt while being diffused by the transport stream and collected. The gas ejected from the sub-nozzle flows around the transport stream along the gas flow, and the air in the diffusion space is prevented from entering the transport stream.

Description

Apparatus for producing nonwoven fabric, method for producing nonwoven fabric, and nonwoven fabric

Technical Field

The present invention relates to a nonwoven fabric manufacturing apparatus, a nonwoven fabric manufacturing method, and a nonwoven fabric.

Background

Nonwoven fabrics such as spunbond nonwoven fabrics are used in many cases as medical and sanitary materials, civil engineering materials, packaging materials, and the like. The spunbond nonwoven fabric is produced from a web obtained by subjecting filaments obtained by melt-spinning a thermoplastic resin to a cooling treatment using a cooling air and a stretching treatment using a stretching air, and then collecting and accumulating the filaments while diffusing the filaments on a collecting medium.

Document 1 (japanese patent No. 2556953) discloses an apparatus having a cooling chamber whose cross section in the horizontal direction is rectangular and whose cross section is gradually reduced in the filament moving direction; a drawing nozzle connected to the cooling chamber and having a stepped recess formed in a wall of the discharge port; and a fiber carrying device connected with the drawing nozzle, wherein the spinning fiber tape sheet is manufactured by the synthetic resin filament which is aerodynamically drawn. The fiber placement device of document 1 has a cross section that is rectangular in the horizontal direction, and has a form of a jet pump that has a venturi-shaped flow field and a diffusion outlet in the longitudinal direction, and adjusts the amount of air sucked from a free air suction port by an air suction pipe that faces the diffusion outlet through a fiber tape piece placement filter.

Document 2 (japanese patent No. 3135498) discloses an apparatus for producing a spun lace web from endless thermoplastic resin fibers, the apparatus comprising: the apparatus includes a nozzle plate body having a plurality of nozzles, a processing shaft, a transport unit, and a transport conveyor, wherein processing air flows into the processing shaft and the transport unit, and an endless fiber group in a form of a mixture of air and fibers flows into the processing shaft by a discharge motion toward the transport conveyor while an endless fiber flows from the nozzle holes of the nozzle plate body, the transport unit includes a central inflow conduit for the endless fiber group and a diffusion conduit extending to the transport conveyor following the conduit, and forcibly imparts the discharge motion and a fluff forming motion overlapping with the discharge motion, and both conduits extend in a direction crossing a moving direction of the transport conveyor. In document 2, an introduction catheter and/or a distribution catheter includes: an aerodynamic uniform distribution device for mixing air and fibers, which is an aerodynamic uniform distribution device in a flow slit shape for additionally introducing air into a duct extending across the entire width of the duct across the moving direction of a transport conveyor and an aerodynamic uniform distribution device in an outflow slit shape for discharging air from the duct, wherein the flow rate to be additionally supplied separately and the flow rate of air to be flowed out are controlled or adjusted so as to affect the uniform distribution of fibers in the mixing of air and fibers. In patent document 2, the inner surface of the inflow duct and/or the diffuser duct is provided with an obstacle member in the vicinity of the surface in the longitudinal section of the duct, and a swirl region is formed behind the inflow duct and/or the diffuser duct with respect to the flow direction.

Document 3 (japanese patent No. 5094588) describes an apparatus for producing a spunbonded fabric (spunbond) formed of filaments, in which a spinneret for forming the filaments is provided, a cooling chamber for supplying process air for cooling the filaments is provided downstream of the spinneret, a drawing unit for drawing the filaments is connected to the cooling chamber, a connection region between the cooling chamber and the drawing unit is closed, the drawing unit has a drawing passage in which a passage wall branches off to at least a part of a length of the drawing passage, in the drawing unit, additional air is injected into the drawing passage at an upstream end of the branch drawing passage portion under conditions in which filament bundles are formed widely in a mechanical direction, and a deposition device for depositing the filaments of the spunbonded web is provided. Further, document 3 describes the following: downstream of the stretching unit there is a deposition unit formed by an upstream diffuser and an adjacent downstream diffuser, with a surrounding air inlet slit provided between the upstream and downstream diffusers.

Disclosure of Invention

Problems to be solved by the invention

However, as important characteristics relating to the quality of the nonwoven fabric, there are uniformity and strength. For example, although the purpose of document 2 is to obtain a nonwoven fabric having a uniform mesh size, the nonwoven fabric having a high uniformity may have insufficient entanglement of filaments and a reduced strength.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a nonwoven fabric manufacturing apparatus, a nonwoven fabric manufacturing method, and a nonwoven fabric, which can improve uniformity while suppressing a decrease in strength of the nonwoven fabric.

Means for solving the problems

Specific means for achieving the above object include the following means.

The 1 st aspect is a nonwoven fabric manufacturing apparatus including:

a collecting section for collecting the filaments ejected toward a collecting medium on the collecting medium;

a diffusion section including a main nozzle that ejects gas supplied together with the filament to be collected in the collection medium toward the collection medium, and a diffusion space provided between the main nozzle and the collection medium, the diffusion space being configured to diffuse the filament by a gas flow that flows while diffusing the gas ejected together with the filament from the main nozzle; and

and a gas flow generating device that generates a gas flow that approaches and follows the gas flow ejected from the main nozzle to the diffusion space, around the gas flow.

The 2 nd mode is a method for producing a nonwoven fabric, which comprises the following operations: a diffusion space for diffusing the filament by an air flow flowing while diffusing the gas ejected from the main nozzle together with the filament is provided between the main nozzle for ejecting the gas together with the filament and a collecting medium for collecting the filament ejected from the main nozzle; ejecting the filaments together with the gas from the main nozzle to the collecting medium while generating a gas flow close to and along the gas flow around the gas flow ejected from the main nozzle to the diffusion space by a gas flow generating means; the filaments diffused in the diffusion space are collected and accumulated on the collection medium.

The 1 st and 2 nd aspects include: a spinning section for spinning filaments from molten resin or the like to derive a plurality of filaments (spinning step); a cooling section for cooling the plurality of filaments introduced from the spinning section by cooling air (cooling step); the nonwoven fabric is produced from the collected web by a drawing section (drawing step) in which the cooled filaments are drawn by a drawing air, and a collecting section (collecting step) in which the drawn filaments are collected and accumulated to produce a web. The manufacturing apparatus further includes a diffusing portion that diffuses the plurality of filaments introduced by the stretching portion and discharges the filaments to the collecting portion (diffusing step).

The diffusion section includes a main nozzle and a diffusion space provided between the main nozzle and the collection medium of the collection section. The diffusion space in the embodiments 1 and 2 is preferably a space that can naturally diffuse without preventing diffusion of the gas flow formed by the gas ejected from the main nozzle. The diffusion space may be surrounded by a partition wall, and in the case of being surrounded by a partition wall, it is sufficient if the partition wall is provided so as to be away from the gas flow so as to avoid an influence on the gas flow formed by the gas ejected from the main nozzle. Further, the plurality of filaments are arranged in the machine width direction, and the main nozzle is formed in a slit shape long in the machine width direction.

Thus, the gas ejected from the main nozzle becomes a gas flow (jet flow) that flows toward the collection medium while gradually expanding in the mechanical direction in the diffusion space. For a plurality of filaments ejected from the main nozzle together with the gas, the filaments are diffused in the machine direction by the gas flow formed in the diffusion space and are captured in the capturing medium.

Here, the diffuser section is provided with a gas flow generating device by which a gas flow close to and along the gas flow formed by the gas ejected from the main nozzle is generated around the gas flow, and by which the gas flow close to and along the gas flow of the main nozzle, the air (gas) in the diffusion space is suppressed from entering the gas flow formed by the gas ejected from the main nozzle together with the plurality of filaments. The flow velocity of the gas ejected from the main nozzle varies in the inside, and the air in the diffusion space enters the diffusion space, thereby creating a region in which the flow velocity variation is larger than that in the surroundings. In contrast, by generating a gas flow close to and along the gas flow formed by the gas ejected from the main nozzle, it is possible to suppress the air in the diffusion space from entering the gas flow formed by the gas ejected from the main nozzle, and it is possible to narrow the region where the flow velocity variation is larger than the surrounding, or to suppress the magnitude of the flow velocity variation in the region where the flow velocity variation is larger than the surrounding.

Since each filament has a region where the flow velocity variation is larger than the surrounding region, the filaments are entangled with each other more and the uniformity is reduced as the flow velocity variation in the region is larger.

In the 3 rd aspect, the gas flow generating means preferably includes a sub-nozzle for ejecting the gas into the diffusion space. In addition, according to the 4 th aspect, the airflow generation device includes: and a sub-nozzle having an opening arranged in parallel with the opening of the main nozzle and ejecting gas into the diffusion space.

In the 3 rd and 4 th aspects, a sub-nozzle having an opening arranged in parallel with the opening of the main nozzle is provided, and a gas ejected from the sub-nozzle generates a gas flow close to and along the gas flow formed by the gas ejected from the main nozzle.

This can suppress the entry of air in the diffusion space into the air flow formed by the gas ejected from the main nozzle, and therefore, the uniformity of the nonwoven fabric can be easily improved.

In addition, as for the 5 th aspect, in the 3 rd and 4 th aspects, the sub-nozzle is provided on the side of the main nozzle in the machine direction and on the side opposite to the machine direction.

In the 5 th aspect, the main nozzle is provided with the sub-nozzles on the side of the machine direction and on the side opposite to the machine direction. This can suppress the air in the diffusion space from entering the gas flow formed by the gas ejected from the main nozzle from the mechanical direction side and the opposite side to the mechanical direction, and thus can effectively suppress the increase in the flow velocity variation of the gas ejected from the main nozzle.

As for the 6 th aspect, in any one of the 3 rd to 5 th aspects, the flow velocity of the gas ejected from the sub-nozzle may be equal to or less than the flow velocity of the gas ejected from the main nozzle. In addition, according to the 7 th aspect, in the 6 th aspect, it is more preferable that the flow velocity of the gas ejected from the sub-nozzle is 1/10 or more of the flow velocity of the gas ejected from the main nozzle.

Each of the modes 1 to 7 is suitable for obtaining a nonwoven fabric in which the ratio of the strength at 5% elongation in the machine direction to the strength at 5% elongation in the direction perpendicular to the machine direction is 2.0 or less as a nonwoven fabric in which the uniformity is improved while suppressing the decrease in strength.

Each of the modes 1 to 7 is suitably used for producing a nonwoven fabric having a maximum strength of 35.0(N/25mm) or more when stretched in the machine direction. In each of aspects 1 to 7, the maximum strength of the produced nonwoven fabric when stretched in the machine direction is more preferably 37.5(N/25mm) or more, still more preferably 40.0(N/25mm), and most preferably 42.5(N/25 mm).

Further, each of the embodiments 1 to 7 is suitably used for producing a nonwoven fabric having a weight variation per unit area (%) of preferably 3.0% or less, more preferably 2.5% or less.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the embodiments of the present description, there is an effect that a nonwoven fabric having improved uniformity can be obtained while suppressing a decrease in strength.

Drawings

Fig. 1 is a schematic configuration diagram of a manufacturing apparatus according to the present embodiment.

Fig. 2 is a schematic configuration diagram showing a diffusion portion.

Fig. 3A is a distribution diagram showing an example of a simulation result of flow velocity fluctuation in the present embodiment.

Fig. 3B is a distribution diagram showing an example of the simulation result of the flow rate variation in the comparative example.

FIG. 4 is a graph showing a comparison between production conditions and physical properties in examples.

Detailed Description

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings. Fig. 1 shows a main part of a nonwoven fabric manufacturing apparatus 10 according to the present embodiment. The manufacturing apparatus 10 according to the present embodiment is used for manufacturing a spunbond nonwoven fabric. In the following description, the md (machine direction) direction indicates the machine direction (machine flow direction), and the UP direction indicates the upward direction in the vertical direction. In the following description, a direction (a direction perpendicular to the machine direction) perpendicular to each of the MD direction and the UP direction is referred to as a cd (cross machine direction) direction (a machine width direction, not shown).

The manufacturing apparatus 10 includes: the spun-bonded nonwoven fabric includes a spinning section 12 for spinning a molten resin obtained by melting a thermoplastic resin used for the spunbond nonwoven fabric to produce filaments, a cooling section 14 for cooling the filaments obtained by spinning, and a stretching section 16 for stretching the filaments. The manufacturing apparatus 10 further includes: the collecting section 18 collects the filaments subjected to the cooling treatment and the drawing treatment to obtain a web of nonwoven fabric, and the diffusing section 20 diffuses and discharges the plurality of filaments toward the collecting section 18.

The spinning section 12 includes a spinneret 22 in which a plurality of spinning nozzles are arranged, and a molten resin introduction pipe 24 is connected to the spinneret 22. The spinning section 12 spins the molten resin introduced into the spinneret 22 through the molten resin introduction pipe 24 by the spinning nozzle to produce filaments. In the spinning section 12, the spinneret 22 includes a plurality of spinning nozzles, and a plurality of filaments arranged in the CD direction are drawn out. The cooling section 14 includes a cooling chamber 26 for introducing a plurality of spun filaments, and a cooling air supply passage 28 is connected to the cooling chamber 26. The cooling unit 14 cools the plurality of filaments introduced into the cooling chamber 26 by the cooling air, using the gas supplied from the cooling air supply passage 28 as the cooling air.

The stretching section 16 includes a stretching shaft 30 extending in the vertical direction, and has an opening cross section having a narrow width that is long in the CD direction (in the front-back direction of the paper in fig. 1) and short in the MD direction. In the stretching section 16, a stretching shaft 30 is connected to the cooling chamber 26, and a plurality of filaments are introduced from the cooling chamber 26 to the stretching shaft 30. The stretching section 16 takes cooling air introduced together with the plurality of filaments or gas supplied into the stretching shaft 30 separately from the cooling air as stretching air, and draws out the filaments introduced from the cooling section 14 by the stretching air while stretching.

The trap unit 18 includes: a moving belt 32 as a collecting medium formed of mesh, punched metal, or the like, and a suction device, not shown, disposed below the moving belt 32. The diffuser 20 ejects the stretching air introduced from the stretching shaft 30 or the gas introduced separately from the stretching air toward the moving belt 32 of the trap 18. The collecting section 18 collects the ejected filaments on the collecting surface 32A of the moving belt 32 while sucking them by a suction device, and generates a web to be a nonwoven fabric. In addition, known configurations that perform the following operations can be applied to the spinning section 12, the cooling section 14, the stretching section 16, and the collecting section 18 of the manufacturing apparatus 10: the method includes the steps of spinning a molten resin to produce a plurality of filaments, cooling and drawing the produced plurality of filaments, and collecting the plurality of filaments.

Fig. 2 shows a schematic configuration of the diffusion portion 20 according to the present embodiment. The diffuser 20 includes a discharge nozzle 34 as a main nozzle. The discharge nozzle 34 has a tip opening 34A as an opening serving as a discharge port formed in a long slit shape in the CD direction and directed toward the moving belt 32 of the collecting section 18. The discharge nozzle 34 is connected to the stretching shaft 30 of the stretching unit 16 and introduces the cooled and stretched filaments. In the diffuser 20, a gas formed by the stretching wind is introduced into the discharge nozzle 34 or another gas is introduced separately from the gas of the stretching wind.

The diffuser 20 ejects the gas and the plurality of filaments introduced into the ejection nozzle 34 from the opening 34A onto the moving belt 32 of the collecting section 18. The diffuser 20 conveys the plurality of filaments discharged from the discharge nozzle 34 toward the collecting section 18 by the gas flow of the gas discharged from the discharge nozzle 34. Hereinafter, the gas flow generated by the gas ejected from the ejection nozzle 34 together with the plurality of filaments is referred to as a transport flow.

In the diffusing portion 20, a diffusion space 36 is provided between the discharge nozzle 34 and the collection surface 32A of the traveling belt 32 of the collection portion 18, and the transport flow flows in the diffusion space 36 toward the traveling belt 32. The diffusion space 36 is considered to be a space where no wall surface or the like for restricting the flow of the transport stream formed by the gas ejected from the ejection nozzle 34 is provided. That is, the diffusion space 36 is a space in which the transport stream discharged from the discharge nozzle 34 is not affected by structures such as wall surfaces other than the trap portion 18. The diffusion space may be divided by a partition wall as long as the partition wall does not interfere with the flow of the air stream.

Thus, in the diffusion part 20, the transport flow formed by the gas ejected from the ejection nozzles 34 flows in the diffusion space 36 while gradually (naturally) spreading in the MD direction and the direction opposite to the MD direction. Further, the transport stream gradually decreases in flow rate as it approaches the moving belt 32. The plurality of filaments discharged from the discharge nozzle 34 are spread in the spreading space 36 by the conveyance flow, and the filaments are spread in the MD direction and the direction opposite to the MD direction. Thus, in the manufacturing apparatus 10, the filaments spread to and are collected in a predetermined collection area on the collection surface 32A of the moving belt 32.

The manufacturing apparatus 10 defines the opening width and opening length of the discharge nozzle 34, the moving speed of the moving belt 32, the interval between the discharge nozzle 34 and the collection surface 32A of the moving belt 32, and the like, based on the nonwoven fabric to be produced, the manufacturing speed of the nonwoven fabric, the width of the web produced by collecting the filaments by the collection portion 18 in the CD direction, and the like. In the diffusing portion 20, the distance (height H) between the tip of the discharge nozzle 34 and the surface of the moving belt 32 of the collecting portion 18 is defined to be 0.1m or more and less than 1m, and the distance H becomes the height of the diffusion space 36.

The manufacturing apparatus 10 defines the flow rate of the gas ejected from the ejection nozzle 34 or the volume of the ejected gas per unit time, and hereinafter, the flow rate of the gas at the opening of the ejection nozzle 34 is referred to as the flow rate Vm of the transport stream. In the diffuser 20, the spread of the transport flow in the diffusion space 36 changes according to the flow velocity Vm, and when the flow velocity Vm is high, the spread of the transport flow becomes smaller than when the flow velocity Vm is low.

In the diffusing portion 20, the diffusion space 36 is provided, so that the transport stream ejected from the ejection nozzle 34 gradually spreads mainly in the MD direction and reaches the moving belt 32. In the following description, the region of the transport flow in the diffusion space 36 is referred to as a transport flow field 38. In fig. 2, the transport watershed 38 is virtually represented.

As shown in fig. 1 and 2, the diffuser 20 is provided with a sub-nozzle 40 as an airflow generating device. The sub-nozzle 40 is provided with a slit-shaped opening 40A that is long in the CD direction as an opening portion. In the diffusing portion 20, the sub-nozzles 40 are arranged on the MD direction side and the opposite side of the discharge nozzle 34, respectively, and the opening 40A of the sub-nozzle 40 is aligned with the opening 34A of the discharge nozzle 34.

The sub-nozzle 40 is connected to an air supply pipe 42, and ejects gas supplied through the air supply pipe 42 from the opening 40A. In the diffuser 20, the gas supplied to the sub-nozzle 40 via the air supply pipe 42 is controlled so that the gas flow formed by the gas ejected from the sub-nozzle 40 becomes a flow velocity Vs determined according to the flow velocity Vm of the transport stream ejected from the ejection nozzle 34. In the diffuser 20, the sub-nozzle 40 is provided so that the gas discharge direction is substantially parallel to the gas discharge direction from the discharge nozzle 34. Here, the flow rate Vs is preferably equal to or less than the flow rate Vm (Vs ≦ Vm), and more preferably equal to or greater than 1/10 (Vs ≧ Vm/10) of the flow rate Vm, and thus, in the diffuser 20, the supply of the gas to the sub-nozzle 40 is controlled so that the flow rate Vs becomes 1/2(Vs ═ Vm/2) of the flow rate Vm.

In the present embodiment, the opening 34A of the discharge nozzle 34 and the opening 40A of the sub-nozzle 40 are arranged in parallel, but the present invention is not limited thereto, and the openings may be arranged to have a step difference such that one of the opening 34A of the discharge nozzle 34 and the opening 40A of the sub-nozzle 40 is farther from the collection surface 32A of the moving belt 32 than the other.

As a result, as shown in fig. 2, in the diffuser portion 20, the gas ejected from the sub-nozzle 40 generates a gas flow that approaches and follows the transport flow (transport flow field 38) in the diffusion space 36. In fig. 2, a gas flow generated by the gas discharged from the sub-nozzle 40 is shown in a virtual manner as a gas flow layer 44.

In the manufacturing apparatus 10 configured as described above, a plurality of filaments spun from a molten resin and subjected to cooling treatment and drawing treatment are introduced into the discharge nozzle 34 of the diffuser 20. Further, a gas (a gas of a stretching wind or a gas supplied separately from the stretching wind) for generating a transport stream is introduced into the discharge nozzle 34.

In the diffuser section 20, a diffusion space 36 is provided between the discharge nozzle 34 and the moving belt 32 of the collecting section 18, and the gas and the plurality of filaments introduced into the discharge nozzle 34 are discharged from the opening 34A of the discharge nozzle 34 to the diffusion space 36. As a result, the filaments are sprayed onto the moving belt 32 of the collecting section 18 while being spread by the transport stream formed by the gas discharged from the discharge nozzle 34, and are collected on the collecting surface 32A.

Incidentally, the diffuser 20 is provided with a sub-nozzle 40 together with the discharge nozzle 34, and the sub-nozzle 40 discharges the gas supplied through the air supply pipe 42 to the diffusion space 36. This generates an airflow in the diffusion space 36, which flows along the transport flow while approaching the transport flow, and thus prevents the air in the diffusion space 36 from entering the transport flow (in the transport flow field 38).

The plurality of filaments transported in the diffusion space 36 by the transport flow generate a variation in flow velocity in the transport flow, but in a region where the variation in flow velocity is larger than that in the surroundings, the greater the variation in flow velocity, the more the filaments are entangled. This increases the tensile strength of the nonwoven fabric obtained from the fiber web produced by collecting the filaments. However, in the captured web, if entanglement of the filaments becomes large, uniformity of the nonwoven fabric is lowered.

In contrast, in the diffuser 20 provided with the sub-nozzle 40, the gas ejected from the sub-nozzle 40 forms an air flow close to and along the transport flow around the transport flow, and a region in which the flow velocity fluctuation generated inside the transport flow is large can suppress the magnitude of the flow velocity fluctuation. This can suppress the increase in entanglement of the filaments of the web collected by the collection unit 18, and can obtain a nonwoven fabric with improved uniformity.

Here, in fig. 3A and 3B, the simulation result of the flow velocity fluctuation (velocity fluctuation) of the air flow in the diffusion space 36 is shown by the distribution of the flow velocity fluctuation. Fig. 3A corresponds to the diffuser 20 of the present embodiment (hereinafter, example 1) provided with the discharge nozzle 34 and the sub-nozzle 40, and fig. 3B shows the diffuser 20A as a comparative example (hereinafter, comparative example 1) employing only the discharge nozzle 34 and not provided with the sub-nozzle 40.

In the simulation of the flow velocity fluctuation, the flow velocity of the gas ejected from the ejection nozzles 34 is set to the same flow velocity Vm for the

diffusion sections

20 and 20A, and 1/2(Vs ═ Vm/2) in which the flow velocity Vs of the gas ejected from the sub-nozzles 40 is set to the flow velocity Vm for the diffusion section 20 is set to eject the gas in parallel to the ejection direction of the gas from the ejection nozzles 34. Further, for the flow velocity fluctuation, a velocity difference of the flow velocity for each sampling time is obtained from the flow velocity for each sampling time set in advance, and a Root Mean Square (RMS) of the obtained velocity difference is used.

In the diffuser portion 20A of the comparative example shown in fig. 3B, a region in which the flow velocity fluctuation is extremely large as compared with the surroundings is generated inside the air flow ejected from the ejection nozzle 34. By forming such a region where the flow velocity greatly varies, the nonwoven fabric has improved tensile strength, but the uniformity of the mesh formed by the filaments is reduced.

In contrast, in the diffuser portion 20 of example 1 shown in fig. 3A, the flow velocity fluctuation in the region where the flow velocity fluctuation in the air flow ejected from the ejection nozzle 34 is large is suppressed as compared with the diffuser portion 20A. This suppresses entanglement of filaments in the web collected by the collecting section 18 in the diffusing section 20 as compared with the diffusing section 20A.

Therefore, the manufacturing apparatus 10 provided with the sub-nozzle 40 of the diffuser 20 can obtain a nonwoven fabric with improved uniformity as compared with the case where the sub-nozzle 40 is not provided. In the diffuser 20 of the present embodiment, a region having a flow rate fluctuation larger than that of the surrounding region remains in the transport flow, and thus the reduction in the tensile strength of the nonwoven fabric is suppressed.

In the present embodiment described above, the flow velocity Vs of the sub-nozzle 40 is 1/2 with respect to the flow velocity Vm of the discharge nozzle 34, but the present invention is not limited to this. The flow velocity Vs of the sub-nozzle 40 may be equal to or lower than the flow velocity Vm of the discharge nozzle 34, and thus, the flow velocity fluctuation in the transport stream can be suppressed without suppressing the spread of the transport stream in the diffusion space 36.

Further, the flow velocity Vs of the sub-nozzles 40 may be larger than the flow velocity Vm of the ejection nozzles 34 (Vs > Vm). In this case, if the discharge direction of the gas from the sub-nozzle 40 is made substantially parallel to the discharge direction of the gas from the discharge nozzle 34, the gas discharged from the sub-nozzle 40 may restrict the spread of the transport flow in the diffusion space 36. Therefore, when the flow velocity Vs of the sub-nozzle 40 is made larger than the flow velocity Vm of the ejection nozzle 34 (Vs > Vm), the orientation of the opening 40A or the ejection direction of the gas in the sub-nozzle 40 may be the direction along the transport stream around the transport stream formed by the gas ejected from the ejection nozzle 34, that is, the direction in which the gas flows in contact with the flow of the transport stream.

In the present embodiment, the sub-nozzles 40 are provided on the MD direction side and the opposite direction side with respect to the MD direction with respect to the discharge nozzles 34, but the sub-nozzles 40 may be provided on the MD direction side or the opposite direction side with respect to the discharge nozzles 34 with respect to the sub-nozzles 40. That is, the sub-nozzles 40 may be provided on at least one of the MD direction side and the direction opposite to the MD direction side of the discharge nozzles 34.

Further, in the present embodiment, the sub-nozzle 40 is provided as the air flow generating device, but the air flow generating device is not limited to the sub-nozzle 40, and may be any device as long as it generates a flow of air flow that approaches and follows the transport flow around the transport flow.

Examples

The present invention will be described in more detail with reference to examples. The present invention is not limited to these examples.

Physical properties in the present embodiment (hereinafter, referred to as example 1) and a comparative example (hereinafter, referred to as comparative example 1) to the present embodiment were measured by the following methods.

(1. weight per unit area [ g/m ]²〕)

5 test pieces of 100Mm (MD) X100 mm (CD) were collected from the nonwoven fabric. The sampling site (sampling position) of the test piece was set to 5 arbitrary positions.

Next, the mass of each test piece was measured using a dish electronic balance (manufactured by lapping industries) for each collected test piece, and the average value of the mass of each test piece was obtained. Converting the obtained average value into 1m²The mass [ g ] of (1) is determined by rounding off the 2 nd position (decimal 2 nd position) after the decimal point as the weight per unit area [ g/m ] of each test piece sample²〕。

(2. weight deviation per unit area [% ])

100 test pieces of 50Mm (MD) X50 mm (CD) were collected from the nonwoven fabric. The nonwoven fabric was collected 10 times in the flow direction (MD) at 10 spots in the width direction (CD) of the nonwoven fabric.

Then, the mass [ g ] of each test piece was measured using a dish-mounted electronic balance (manufactured by lapping industries, Ltd.) with respect to each collected test piece, and the average value and standard deviation of the mass of each test piece were obtained. The standard deviation was divided by the average value to obtain a weight deviation per unit area [% ] of each nonwoven fabric sample.

(3. fiber diameter [ mu.m ]

5 test pieces of 10Mm (MD) by 10mm (CD) were collected from the nonwoven fabric. The collection site is set to 1 arbitrary site.

Next, the test piece was photographed at a magnification of 200 times using an optical microscope, and the photographed image was analyzed by image size measuring software (Inotech, Pixs2000Version 2.0). For each test piece, the fiber diameter of 10 fibers was measured, and the average value of the fiber diameter of each test piece was obtained, and the 2 nd position after decimal point was rounded off to be the fiber diameter [ μm ] of each nonwoven fabric sample.

(4. yarn bundle of nonwoven cloth [ dot ]

1 test piece of 250Mm (MD) X200 mm (CD) was collected from a nonwoven fabric. The collection site is set to 1 arbitrary site.

Subsequently, the nonwoven fabric was visually checked, and the number of the portions (yarn bundles) where 2 or more fibers were entangled in a bundle shape was counted and evaluated according to the following criteria.

A: at the position of 0 part of the yarn bundle

B: the number of the yarn bundles is more than 1 and less than 20

C: the yarn bundle is more than 20

(5, MD 5% Strength and MD Strength [ N/25mm ]

5 pieces of MD test pieces of 25mm (CD) x 200Mm (MD) were collected from the nonwoven fabric. The number of collection sites is arbitrarily 5.

Next, each of the collected test pieces was elongated by stretching the test piece under the conditions of a chuck pitch of 100mm and a stretching speed of 100mm/min using a universal tensile tester (model IM-201 manufactured by Intesco corporation), and the load [ N ] and the maximum load [ N ] at a chuck pitch of 105mm were measured. The average value of each test piece was determined, and the 2 nd position after the decimal point was rounded off to obtain the MD 5% strength [ N/25mm ] and MD strength [ N/25mm ] of each nonwoven fabric sample. The MD 5% strength corresponds to the strength at 5% elongation in the machine direction, and the MD strength corresponds to the maximum strength at elongation in the machine direction.

(6.CD 5% Strength and CD Strength [ N/25mm ]

5 pieces of 25Mm (MD) X200 mm (CD) CD test pieces were collected from the nonwoven fabric. The number of collection sites is arbitrarily 5.

Next, each of the collected test pieces was elongated by stretching the test piece under the conditions of a chuck pitch of 100mm and a stretching speed of 100mm/min using a universal tensile tester (model IM-201 manufactured by Intesco corporation), and the load [ N ] and the maximum load [ N ] at a chuck pitch of 105mm were measured. The average value of each test piece was determined, and the 2 nd position after the decimal point was rounded off to obtain the CD 5% strength [ N/25mm ] and the CD strength [ N/25mm ] of each nonwoven fabric sample. The CD 5% strength corresponds to the strength when elongated by 5% in the direction perpendicular to the machine direction, and the CD strength corresponds to the maximum strength when elongated in the direction perpendicular to the machine direction.

(example 1)

As the 1 st propylene polymer, a propylene homopolymer having a melting point of 162 ℃ and an MFR (measured at 230 ℃ C. and a load of 2.16kg in accordance with ASTM D1238, the same shall apply hereinafter) of 60g/10 min was used. As the 2 nd propylene-based polymer, a propylene-ethylene random copolymer having a melting point of 142 ℃, MFR60g/10 min and an ethylene unit content of 4.0 mol% was used. A composite melt spinning was performed by a spunbond method using the 1 st propylene polymer and the 2 nd propylene polymer to obtain an eccentric core-sheath composite long fiber as a fiber (filament) in which the core portion was a propylene homopolymer and the sheath portion was a propylene-ethylene random copolymer (core portion/sheath portion: 20/80 (weight ratio)).

The obtained fibers were dispersed from a main nozzle (ejection nozzle 34) shown in fig. 1 and deposited on a collecting medium (moving belt 32). At this time, the velocity of the gas discharged from the discharge nozzle 34 (main nozzle) was 107.3m/sec, and the velocity of the gas discharged from the sub-nozzle 40 (discharge width 12mm) provided at a position 38mm away from the discharge port (opening 34A) of the discharge nozzle 34 in the horizontal direction with respect to the velocity of the gas discharged from the discharge nozzle 34 was 1/4(26.8 m/sec).

Then, the sheet was peeled from the collecting medium, and the area ratio of the embossed pattern was 6.7%, and the area of the embossing was 0.19m²The spunbonded nonwoven fabric was obtained by thermal bonding by embossing under the conditions of a heating temperature of 130 ℃ and a linear pressure of 60 kg/cm. The resulting spunbonded nonwoven had a basis weight of 20.0g/m². The obtained spunbond nonwoven fabric was evaluated by the method described above. The evaluation results are shown in fig. 4.

Comparative example 1

A spunbond nonwoven fabric was obtained in the same manner as in example 1, except that the gas ejected from the sub-nozzle 40 was changed to 0 (velocity 0 m/sec). The resulting spunbonded nonwoven had a basis weight of 20.2g/m². The obtained spunbond nonwoven fabric was evaluated by the method described above. The evaluation results are shown in fig. 4.

Here, the weight variation per unit area was 3.5 [% ], while that of example 1 was 2.0 [% ]. Further, with respect to the evaluation of the yarn bundle [ point ] in the nonwoven fabric, example 1 was evaluation B, while comparative example 1 was evaluation C. At this time, the MD 5% strength was 4.3 [ N/25mm ] for example 1 and 5.2 [ N/25mm ] for comparative example 1, and the CD 5% strength was 2.7 [ N/25mm ] for example 1 and 1.2 [ N/25mm ] for comparative example 1. In addition, the MD 5% strength/CD 5% strength was 1.6 for example 1, while 4.3 for comparative example 1. From this, it is understood that example 1 suppresses the decrease in strength and improves the uniformity as compared with comparative example 1.

Therefore, the apparatus and method for producing a nonwoven fabric according to the present embodiment are suitable for producing a nonwoven fabric in which the strength reduction is suppressed and the uniformity is improved. The apparatus and method for producing a nonwoven fabric according to the present embodiment are suitable for producing a nonwoven fabric in which the ratio (MD 5% strength/CD 5% strength) of the strength at 5% elongation (MD 5% strength) in the machine direction (MD direction) to the strength at 5% elongation (CD 5% strength) in the direction perpendicular to the machine direction (CD direction) is 2.0 or less.

Further, the apparatus and method for producing a nonwoven fabric according to the present embodiment are suitable for producing a nonwoven fabric having a weight variation per unit area of preferably 3.0 [% ] or less, more preferably 2.5 [% ]orless.

The apparatus and method for producing a nonwoven fabric according to the present embodiment are suitable for producing a nonwoven fabric having a maximum strength (MD strength) when stretched in the machine direction of more preferably 37.5 [ N/25mm ] or more, still more preferably 40.0 [ N/25mm ] or more, and most preferably 42.5 [ N/25mm ] or more.

The disclosure of Japanese patent application 2016-020144 is incorporated in its entirety by reference into the present specification.

All documents, patent applications, and technical standards described in the present specification are incorporated by reference into the present specification to the same extent as if each document, patent application, and technical standard was specifically and individually indicated to be incorporated by reference.

Claims

1. An apparatus for manufacturing a nonwoven fabric, comprising:

a diffusion section including a main nozzle that ejects gas supplied together with the filaments to be collected in the collection medium toward the collection medium, and a diffusion space provided between the main nozzle and the collection medium, the diffusion space being configured to diffuse the filaments by a gas flow that flows together with the gas ejected from the main nozzle together with the filaments while diffusing; and

a gas flow generating device that generates a gas flow close to and along the gas flow ejected from the main nozzle to the diffusion space around the gas flow,

the gas flow generating apparatus includes: a sub-nozzle having an opening portion arranged in parallel with the opening portion of the main nozzle and configured to discharge the gas into the diffusion space, the opening portion of the main nozzle extending toward the sub-nozzle,

the diffusion space is a space that can be naturally diffused without preventing diffusion of a gas flow formed by the gas ejected from the main nozzle.

2. The apparatus according to claim 1, wherein the secondary nozzle is provided on a side of the main nozzle in the machine direction and on a side opposite to the machine direction.

3. The apparatus according to claim 1 or 2, wherein the flow rate of the gas ejected from the secondary nozzle is equal to or lower than the flow rate of the gas ejected from the main nozzle.

4. The nonwoven fabric production apparatus according to claim 3, wherein the flow rate of the gas ejected from the secondary nozzle is 1/10 or more of the flow rate of the gas ejected from the main nozzle.

5. A method for manufacturing a nonwoven fabric, comprising the operations of:

a diffusion space for diffusing the filament by a gas flow flowing while diffusing together with the gas ejected from the main nozzle together with the filament is provided between the main nozzle for ejecting the gas together with the filament and a collecting medium for collecting the filament ejected from the main nozzle, wherein the diffusion space is a space capable of naturally diffusing without preventing diffusion of the gas flow formed by the gas ejected from the main nozzle,

ejecting gas into the diffusion space from a sub-nozzle having an opening arranged in parallel with the opening of the main nozzle, wherein the opening of the main nozzle is expanded toward the sub-nozzle, and a gas flow close to and along the gas flow ejected from the main nozzle into the diffusion space is generated around the gas flow,

ejecting the filaments together with gas from the primary nozzle toward the trapping medium,

collecting and accumulating the filaments diffused in the diffusion space on the collection medium.

6. The method of manufacturing a nonwoven fabric according to claim 5, wherein the secondary nozzle is provided on the side of the main nozzle in the machine direction and on the side opposite to the machine direction.

7. The method of manufacturing a nonwoven fabric according to claim 5 or 6, wherein the flow rate of the gas ejected from the secondary nozzle is set to be equal to or lower than the flow rate of the gas ejected from the main nozzle.

8. The method of producing a nonwoven fabric according to claim 7, wherein the flow rate of the gas ejected from the secondary nozzle is set to be not less than 1/10 of the flow rate of the gas ejected from the main nozzle.