JP2007197872A - Nonwoven fabric member and method for producing the same and duct composed of the nonwoven fabric member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a nonwoven fabric member having incompatible physical properties, e.g. acoustic properties and heat insulating properties and air permeability (aeration-blocking property) of air-conditioning duct, etc., at once and having sufficient stiffness and facilitating processing to an arbitrary shape and to provide a method for producing the nonwoven fabric member and to provide a duct composed of the nonwoven fabric member and to provide a nonwoven fabric enabling adequate control of physical properties and to provide a method for producing the nonwoven fabric. <P>SOLUTION: The nonwoven fabric member comprises a fiber group 13 including fibers 12 in which at least a part is composed of a thermoplastic synthetic resin. The nonwoven fabric member is composed of fiber areas 16 in which the fiber group 13 including the fibers 12 has a gathering state thinner than than that of nearly central part interposed between both-side surfaces of the nonwoven fabric member, in the vicinities of the both-side surfaces, and a dense area 18 in which the fiber group 13 containing the fiber 12 has a gathering state denser than that of the fiber areas 16. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a nonwoven fabric member, a method for producing the same, and a duct made of the nonwoven fabric member. More specifically, the invention is suitably used for a floor cushion material or a soundproof material for a vehicle such as an automobile. The present invention relates to a nonwoven fabric member that is excellent and can be easily manufactured while arbitrarily controlling the air flow rate, a manufacturing method thereof, and a duct manufactured from the nonwoven fabric member.

  In general, for vehicles represented by automobiles, noise reduction (sound absorption), heat insulation, ventilation (breathability prevention), and waterproofing due to sound absorption, such as air conditioning ducts, various insulators and door water seals, and various interior materials, etc. Alternatively, a large number of materials are used in which each characteristic such as rigidity is appropriately adjusted according to the purpose of use. For example, taking an air conditioning duct as an example, it is required to achieve a certain level of air permeability (ventilation shut-off) for suitable delivery of temperature-controlled air that circulates inside the duct, while at the same time the inner surface and outer On the surface, it is also required to prevent condensation due to a temperature difference between the inside and outside of the duct and to reduce noise related to ventilation. Either one of these requirements can be achieved basically by improving or decreasing the air blocking performance, but it is basically impossible to achieve both at the same time. Generally, (1) The same material is used by changing its density or the like, or (2) a method of using materials having different physical properties in a stacked manner.

  For example, as a material suitably used as a material for an air-conditioning duct, a non-woven fabric in which a large number of fine fibers are kneaded (constricted) can be cited. And the density is controlled by heat processing etc., and low air permeability and waterproofness are ensured by making it high density, and noise reduction and heat insulation can be secured by making it low density. That is, as shown in FIG. 7, the nonwoven fabric 14 having a low density is used as a basis, and pressing is performed on both sides of the nonwoven fabric 14 while being heated, thereby increasing the density only in the vicinity of the surfaces 14 a and 14 a on both sides, and in the thickness direction. A member 40 in which only the density in the vicinity of the center portion of the member 40 is kept low (see FIG. 7A; the density of dots in the figure indicates the density of the nonwoven fabric 14 in the member 40), or a material with different physical properties For example, a member 42 (see FIG. 7B) in which a non-breathable sheet member 44 such as PET is adhesively sandwiched between two nonwoven fabrics 14 and 14 or the sheet member 44 is used as a nonwoven fabric. Both of the above-described physical properties can be achieved by manufacturing the member 46 (see FIG. 7 (c)) bonded to one surface of 14.

  However, in the member 40 shown in (1), because the non-breathable regions are formed on both surfaces of the nonwoven fabric 14 because of the manufacturing method, the noise reduction due to the sound absorption required for the air conditioning duct and the like is preferable. It cannot be demonstrated. In addition, since the member 42 having the structure (2) has a so-called laminated structure such as two layers or three layers, the member cost and the manufacturing cost due to the increase in the process increase. Further, it is pointed out that problems such as peeling may occur during use.

In addition, as in the invention “cylindrical nonwoven fabric” described in Patent Document 1 and the invention “Method of manufacturing an intake duct” described in Patent Document 2, the components are melted by heat and the like, and an adhesive action is exhibited. Some have disclosed the contents of ensuring the moldability and the like while improving the sound absorption performance and the heat insulation by adopting the heat-sealing fibers and the thermoplastic resin binder. However, in these configurations, while the effect obtained by making the nonwoven fabric sparse can be expected, the air permeability (air permeability blocking property) due to having a dense region cannot be expected.
JP 2002-302858 A JP-A-11-343938

  The present invention has been proposed in order to suitably solve this problem in view of the problems related to the prior art, and has contradictory physical properties such as sound-absorbing and heat-insulating and air-permeable properties (air-blocking properties) such as air-conditioning ducts. Another object of the present invention is to provide a non-woven fabric member that has both rigidity and sufficient rigidity and can be easily processed into an arbitrary shape, a method for producing the same, and a duct made of the non-woven fabric member.

In order to overcome the above-mentioned problems and achieve the intended purpose, the nonwoven fabric member according to claim 1 is a nonwoven fabric member comprising a group of fibers including at least a part of which is composed of a thermoplastic synthetic resin. Because
Near the surface on both sides, the fiber group containing the fibers is a fiber region that is in a sparsely aggregated state compared to the substantially central part sandwiched between the surfaces on both sides, and
The gist of the invention is that it is formed of a dense region formed in a substantially central portion sandwiched between the fiber regions and in which the fiber group including the fibers is in a dense aggregated state from the fiber region.

  Therefore, according to the first aspect of the present invention, the fibers have physical properties that are expressed by the presence of fibers in a sparsely assembled state in the vicinity of the surface, and the fibers are densely disposed in the vicinity of the substantially central portion in the other thickness direction. By providing the physical properties that are manifested by being in an aggregated state, it is possible to combine high sound absorption, heat insulation, anti-condensation and rigidity, and low air permeability that could only be achieved with laminated products. It also has a structural feature in which these two regions that exhibit different physical properties are not peeled off.

  The gist of the invention according to claim 2 is that, in the invention according to claim 1, the fiber group consists of only the fibers. Therefore, according to the invention which concerns on Claim 2, the structural characteristic of this invention can be expressed more suitably.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, the fiber includes a core portion made of a first thermoplastic synthetic resin having a required melting point, and the first thermoplastic resin. The gist is that the second thermoplastic synthetic resin having a melting point lower than that of the synthetic resin is used as a material and the sheath portion covers the outer periphery of the core portion. Therefore, according to the invention according to claim 3, compared to the case of using a fiber made of one kind of thermoplastic synthetic resin, excellent lightness, rigidity, heat insulation, anti-condensation and high sound absorption are provided. It can exhibit physical properties and can further facilitate temperature control during production.

  The invention according to claim 4 is the invention according to any one of claims 1 to 3, wherein the fiber region has a fiber structure in which a plurality of the fibers maintain a fiber state, and the dense region includes a plurality of dense regions. The gist is that the fibers are welded and solidified to form a dense state. Therefore, according to the invention which concerns on Claim 4, high non-breathability can be given to a nonwoven fabric member, and high sound-absorbing property, heat insulation, dew condensation prevention property, and rigidity can be combined.

In order to overcome the above-mentioned problems and achieve the intended purpose, a method for producing a nonwoven fabric member according to the invention according to claim 5,
Preparing a non-woven fabric comprising a group of fibers including at least a part of a fiber composed of a thermoplastic synthetic resin;
After heating the whole of the nonwoven fabric so as to be within a temperature range that maintains the fiber structure at a temperature equal to or higher than the melting point of the thermoplastic synthetic resin having the lowest melting point in the fiber group constituting the nonwoven fabric,
By leaving it for a required time under a temperature below the melting point of the lowest-melting thermoplastic synthetic resin, it cools a portion to be a fiber region near the surface on both sides,
Next, the nonwoven fabric is pressed from the surfaces on both sides thereof, so that the thermoplastic resin having the lowest melting point still maintains the melting point or higher, and the substantially central portion sandwiched between the surfaces on both sides is formed as a dense region. The summary is as follows.

  Therefore, according to the fifth aspect of the invention, the fibers have physical properties that are manifested by the presence of fibers in a sparsely assembled state near the surface, and the fibers are densely disposed in the vicinity of the substantially central portion in the other thickness direction. By having the physical properties that are manifested by being in a complex state, a duct or a duct that has high sound absorption, heat insulation, anti-condensation and rigidity, and low air permeability, which could only be achieved with laminated products so far A non-woven member that can be used as a member such as a water seal can be easily manufactured.

  The gist of the invention described in claim 6 is that, in the invention described in claim 5, the non-woven fabric is prepared only from the fibers. Therefore, according to the invention which concerns on Claim 6, the nonwoven fabric member which expressed the structural characteristic of this invention more suitably can be manufactured.

  The gist of the duct according to the invention described in claim 7 is that the non-woven member described in any one of claims 1 to 4 is formed into a required shape. Therefore, according to the invention which concerns on Claim 7, the duct which has outstanding effects, such as the outstanding heat insulation and dew condensation prevention property, and high sound absorption property, ie, the outstanding low noise property, can be manufactured easily.

  As explained above, according to the nonwoven fabric member of the present invention and the manufacturing method thereof, and the duct composed of the nonwoven fabric member, the physical properties expressed by the presence of fibers in a sparsely assembled state in the vicinity of the surface are provided. It is possible to easily manufacture a nonwoven fabric member having physical properties that are manifested by the presence of the fibers in a dense aggregate state in the vicinity of the substantially central portion in the thickness direction. Moreover, by using such a nonwoven fabric member, it is possible to impart excellent heat insulating properties and anti-condensation properties and high sound absorption properties to the duct.

  Next, a non-woven fabric member according to the present invention, a method for producing the same, and a duct made of the non-woven fabric member will be described below with reference to the accompanying drawings by giving preferred examples. The inventor of the present application is composed of a group of fibers including the required fibers, and after applying the required heating to the nonwoven fabric having a single layer structure and allowing it to cool, press the nonwoven fabric in the vicinity of the surface. A region in which the fibers are present in a sparsely assembled state (hereinafter referred to as a fiber region) is provided, and the fibers are sandwiched between the fiber regions, that is, near the center of the nonwoven fabric in the thickness direction. The present inventors have found that a non-woven fabric member provided with a region (hereinafter referred to as a dense region) that exists in a proper aggregated state can be easily manufactured. Note that the `` temperature for maintaining the fiber structure '' means that when the fibers constituting the nonwoven fabric are fluidized (melted), there is no loss of the fiber structure due to the welding of a plurality of fibers depending on its own weight, but depending on the pressure from the outside The temperature at which the fiber structure disappears, “fiber structure” refers to the state in which individual fibers constituting the nonwoven fabric are entangled while maintaining their shape. Further, the terms “near the surface” and “near the substantially central portion” are relative, and their regions are not clarified.

  A nonwoven fabric member 10 according to a preferred embodiment of the present invention is composed of a sheet-like and single-layer nonwoven fabric 14 as shown in FIG. And while the nonwoven fabric 14 maintains the fiber structure of the fiber 12 which makes the nonwoven fabric 14 in the vicinity of the surface 14a of the both sides, 14a, the fiber area | region 16 used as the sparse assembly state compared with the fiber area | region 16 mentioned later, 16 and a dense region 18 sandwiched between the fiber regions 16 and 16 in which the fibers 12 are in an aggregated state (hereinafter referred to as a dense state) closer to the fiber region 16, for example, substantially solid. The Here, the nonwoven fabric member 10 according to the present invention is not formed by laminating a plurality of layered nonwoven fabrics as described above, but is formed from a single sheet-shaped nonwoven fabric 14. Moreover, although the sheet-like thing is mentioned as an example here as the nonwoven fabric member 10, this invention is not limited to this, For example, complicated shape things, such as an air-conditioning duct for cars, and the internal structure of a door for cars Such a door water seal includes a shape that has been punched into a required shape. In the present embodiment, the nonwoven fabric 14 is composed of only the fibers 12, but in addition, as will be described later, a fiber group 13 that is an aggregate of various fibers including the fibers 12 may be used.

  Below, the manufacturing method of the nonwoven fabric member 10 which concerns on an Example is demonstrated with reference to FIG. 2 and FIG. Regarding the manufacturing apparatus used, a known apparatus such as a hot press for forming a nonwoven fabric composed of a large amount of fibers can basically be used as it is, so that detailed description thereof is omitted. The method for manufacturing the nonwoven fabric member 10 basically includes a nonwoven fabric preparation stage S1, a heating stage S2, a cooling stage S3, a pressing stage S4, and a final stage S5 (see FIG. 2).

  The nonwoven fabric preparation step S1 is a step of preparing a necessary amount of the fiber group 13 including the fibers 12 that are the constituent elements of the nonwoven fabric 14 constituting the nonwoven fabric member 10 according to the embodiment, and shrinking the fiber group 13 by a known method to obtain the nonwoven fabric 14. (See FIG. 3A). Here, the fiber 12 needs to be in a state where it can be melted and softened by heating in the heating step S2 and can be welded so that a suitable pressing can be performed in the pressing step S4 described later. The fiber group 13 refers to an aggregate of various fibers including at least the fibers 12. In order to form the nonwoven fabric 14 by welding and solidifying the entire fiber group 13 including the fibers 12 in these respects, a thermoplastic synthetic resin is preferably used as the material of the fibers 12, but at least one kind of thermoplastic synthesis is used. What is necessary is just to contain resin. For example, one fiber 12 is made of only a single thermoplastic synthetic resin, made of various types of thermoplastic synthetic resin, or other than thermoplastic synthetic resin, such as a thermosetting resin. A material to which a thermoplastic synthetic resin is added can be used. That is, the material composition of the fiber 12 is almost not limited as long as it contains at least one kind of thermoplastic synthetic resin. Furthermore, as described above, the constituent fibers of the fiber group 13 forming the nonwoven fabric 14 are not limited to the fibers 12, and a plurality of other fibers made of materials having different compositions can be used. As long as the fiber 12 is included, a fiber not containing a thermoplastic synthetic resin (for example, natural fiber) may be mixed.

  In this embodiment, the fiber group 13 consists of only a single fiber 12, and the fiber 12 is made of polypropylene (PP) resin (melting point 165 ° C.) as shown in FIG. A first resin), a polyethylene (PE) resin (melting point 130 ° C.) as a second thermoplastic synthetic resin (hereinafter simply referred to as a second resin), and a core portion made of the first resin inside 12a is located, and has a so-called core-sheath structure in which a sheath 12b made of a second resin having a lower melting point than the first resin is provided so as to cover the outer side (outer periphery) (FIG. 4). (See (a)). In addition to the configuration of the thermoplastic synthetic resins as described above, if the thermoplastic synthetic resin is disposed in the sheath portion 12b, the core portion 12a may be configured to include, for example, natural fibers that are not thermoplastic synthetic resins. . With such a configuration, the temperature range in which the fiber structure can be maintained in the heating step S2 is widened and molding becomes easy.

  The heating stage S2 is a stage in which the entire nonwoven fabric 14 obtained is uniformly raised to a required temperature. Generally, for the sheet-like nonwoven fabric 14 according to the present embodiment, the surfaces 14a and 14a on both sides thereof are arranged. The heaters 52 and 52 are arranged in the vicinity in a non-contact (indirect) manner (planar), and the heaters 52 are operated for a required time (see FIG. 3B). Here, the required temperature is within the range of the temperature that is equal to or higher than the melting point of the thermoplastic synthetic resin that forms the nonwoven fabric 14 and melts at the lowest temperature and maintains the fiber structure (hereinafter referred to as the structure maintaining temperature). The That is, through this stage, the nonwoven fabric 14 is easily crushed by an external stress such as pressing, and the fibers 12 and 12 are welded together in this state, and the fibers 12 are densely present (the dense region 18). It is possible to shift to the state (1). If heating is possible in a non-contact state, an instrument such as a thermostatic bath can be used. The heating time depends on various conditions such as the thickness of the nonwoven fabric 14, but heating for about 1 to 5 minutes is sufficient. In addition, the heating required here aims at the raise to the target temperature of nonwoven fabric 14 itself, and is not the temperature of the heater 52 grade | etc., Which heats this.

  Here, when considering the material forming the fiber 12, when the fiber 12 made of a single thermoplastic synthetic resin is used, the temperature is easily set in the main heating step S2 because the thermal properties are uniform as a whole. There is an advantage to become. On the other hand, as described above, in the present invention, it is necessary to carry out very precise management in which the heating temperature is equal to or higher than the melting point of the thermoplastic synthetic resin forming the fiber 12 and within the range of the structure maintaining temperature. If this management goes wrong and heating exceeds the temperature at which the structure of the single material constituting the fiber 12 can be maintained, the nonwoven fabric 14 will melt as a whole and become a simple solid material. If the heating temperature is less than the melting point, the nonwoven fabric member 10 having the structure according to the present invention cannot be obtained even if an excessive force is applied in the pressing step S4 described later.

  On the other hand, when the core-sheath structure fiber 12 made of two types of thermoplastic synthetic resins, the melting point of the core part 12a is relatively higher than the melting point of the sheath part 12b as in this embodiment, such a case is used. The problem is solved. That is, the temperature in the heating stage S2 may be set only for the sheath 12b made of a material having a lower structure maintaining temperature. In this embodiment, the material having a low structure maintaining temperature is a PE resin having a melting point of 130 ° C., and the other PP resin has a melting point of 165 ° C.

  This is made of PE resin by setting the temperature of the heating step S2 to 165 ° C., and the second fiber forming the sheath 12b completely reaches the melting point (melting temperature), so that the fibers 12 and 12 are welded together by pressing. While the dense region 18 can be formed, the first fiber made of PP resin and forming the core portion 12a does not reach a temperature at which the first fiber can be sufficiently melted, so that the fiber structure is maintained. Further, when the sheath portion 12b made of PE resin is welded to the sheath portion 12b forming the other fiber 12 by pressing, the first fiber (PP resin) that has not been melted is entrained and welded. Region 18 is formed (see FIG. 4B). Therefore, even if there is a slight deviation from the target temperature around 165 ° C., the fiber region 16 and the dense region 18 are reliably formed, and the temperature management is very easy. Note that FIG. 4 illustrates the case of the fibers 12 and 12, but even if one is the fiber 12 and the other is another fiber not containing the thermoplastic synthetic resin, Needless to say, the same effect is produced because the plastic synthetic resin is welded to the other fiber.

  The cooling step S3 to be performed next is a step of cooling the nonwoven fabric 14 sufficiently heated to a predetermined temperature to an intended state (see FIG. 3C). The state intended here refers to a state in which sufficient heat remains only in a portion that should be the dense region 18 and heat is released from other portions and does not become the dense region 18 even when pressed. That is, the nonwoven fabric 14 that has been uniformly heated up to a predetermined temperature is cooled to gradually decrease the temperature from the surfaces 14a and 14a on both sides thereof, and after a certain period of time, the surfaces 14a and 14a become sheath portions. Below the melting point of the second resin forming 12b. As the time further elapses, the temperature range below the melting point expands from the surface 14a to the inside in the thickness direction. Accordingly, although the nonwoven fabric 14 has a temperature gradient in the thickness direction due to the implementation of the cooling step S3, the vicinity of the surfaces 14a and 14a on both sides thereof is less than the melting point as shown in FIG. It becomes more than this temperature.

  If the cooling stage S3 is too long, even the heat of the portion to be the dense region 18 is released, so that it is not easy to set it appropriately. However, the calibration curve can be obtained by using a thermography or by making a prototype with varying cooling time. Reproducible implementation is possible by acquisition. Moreover, since the member property to be heated / cooled is a non-woven fabric, the heat dissipation on the surface 14a is relatively quick, but the internal heat dissipation proceeds slowly due to the high heat insulating property acquired by the property. The time margin for performing the pressing step S4 is large.

  In the next pressing step S4, the nonwoven fabric 14 in the temperature state shown in FIG. 5 is pressed from both sides, and the portion (near the substantially central portion) having a melting point or higher is defined as the dense region 18. (See FIG. 3D). Specifically, the nonwoven fabric 14 is moved from both sides thereof by the pressing plates 54 and 54 that are set to a temperature lower than the temperature at which the fibers 12 constituting the nonwoven fabric 14 are not thermally deteriorated (here, the melting point of the second resin forming the sheath portion 12b). Pressing. By this pressing, the fibers 12 constituting the nonwoven fabric 14 are compressed as a whole in the thickness direction. At this time, since the temperature of the nonwoven fabric 14 is different in the thickness direction, the vicinity of the surfaces 14a and 14a on both sides, which is less than the melting point, can be in a dense state while the fibers 12 continue to maintain the fiber state. However, in the vicinity of the substantially central portion that is at or above the temperature, the fibers 12 are welded while being crushed, and shift to a dense state. That is, the vicinity of the surfaces 14a and 14a on both sides remains as the fiber region 16, and the other regions, in particular, the dense region 18 becomes denser in the substantially central portion where the residual heat is large. In addition, since formation of the dense area | region 18 by implementation of this press step S4 is made instantaneously, implementation for about 10 to 40 seconds is enough fundamentally. As described above, the degree of the dense state can be advanced to make it a substantially solid state.

  Further, the amount of pressing here is related to the physical properties of the dense region 18 to be formed (breathability in the thickness direction of the nonwoven fabric member 10 (breathing blocking property)), and can be easily controlled by adjusting this amount. is there. And about the press plates 54 and 54 which press the nonwoven fabric 14, it is desirable for the surface temperature of the press side to be low. Specifically, as in the present embodiment, when there are a plurality of thermoplastic synthetic resins as the material of the fibers 12 (non-woven fabric 14 constituting the nonwoven fabric 14, the thermoplastic synthetic resin having the lowest melting temperature (the sheath portion 12b is formed). It is preferable to carry out a so-called cooling press at a temperature 10 ° C. or more lower than the melting point of the second resin)).

  Furthermore, the dense region 18 is formed by the execution of the main pressing step S4, and the dense region 18 is solidified by the subsequent heat dissipation to maintain the shape. In the nonwoven fabric 14 before pressing and the nonwoven fabric member 10 after pressing, The shape retention, that is, the rigidity of the entire member is greatly different. That is, the whole of the nonwoven fabric 14 is merely an aggregate of the fibers 12 and only receives external stress. On the other hand, in the nonwoven fabric member 10 in which the dense region 18 in a dense state exists, the dense region 18 It becomes the skeleton of the nonwoven fabric member 10 and produces a resistance against external stress. In addition, since the action associated with the change in properties appears for the first time after the pressing step S4, the shape of the pressing plate 54 described above is changed from a simple flat plate to a so-called mold having required irregularities, so that the required outer shape can be obtained at once. It is also possible to manufacture the non-woven fabric member 10 having the above structure.

  The final process S5 that is finally performed is a stage in which the nonwoven fabric member 10 obtained through the above steps is taken out from the pressing plate 54 and further subjected to necessary post-processing and inspection. By passing through this stage, the nonwoven fabric member 10 is completed as a product. When the air-conditioning duct is manufactured using the nonwoven fabric member 10 according to the present invention manufactured as described above, the surface, that is, the fiber region 16 in the nonwoven fabric member 10 expresses sound absorption and heat insulation (condensation prevention), At the same time, the inside, that is, the dense region 18 in the nonwoven fabric member 10 develops a ventilation barrier property of the duct wall surface.

  Moreover, in the manufacturing method of the nonwoven fabric member 10 which concerns on this invention, since the nonwoven fabric member 10 obtained is manufactured from the nonwoven fabric 14 of a single layer, the several nonwoven fabric member manufactured by the prior art which has a dense area | region on one surface is included. Therefore, a complicated procedure such as separate lamination is not necessary. Further, if the temperature control of the nonwoven fabric 14 before the pressing step S4 is densified, it is not limited to the rough division into two regions such as the fiber region 16 and the dense region 18, but from both side surfaces 14a, 14a in the center in the thickness direction. Therefore, it is also possible to obtain a so-called gradient material-like nonwoven fabric member 10 whose density and the like increase at a required ratio.

(Experimental example)
The experiment example about the nonwoven fabric member which concerns on this invention below is shown. The present invention is not limited to this experimental example.

(Experiment 1) Relationship between set temperature in each stage, fiber region and dense region A core portion employing PP resin with a melting point of 165 ° C. as the material and a sheath portion employing PE resin with a melting point of 130 ° C. as the material A non-woven fabric having a basis weight of 500 g / m ² and a thickness of 5 mm was obtained. And the nonwoven fabric member which concerns on the Example which implemented heating step S2 (heating temperature 165 degreeC, 3 minutes), cooling step S3 (2-3 seconds), and pressing step S4 which were mentioned above to this nonwoven fabric was made into thickness 1mm. . At the same time, using the same nonwoven fabric, pressing was performed under heating at 145 ° C. using the same press machine as in the example to produce a nonwoven fabric member according to a comparative example having a thickness of 1 mm. The conditions at each stage at this time are described below.

(Result of Experiment 1)
Regarding the manufactured Examples and Comparative Examples, the surface state was confirmed by visual observation. As for the Examples, the fiber structure was ensured and raised, whereas in the Comparative Examples, a dense layer was formed and the film was formed. It was in the shape.

(Experiment 2) Breathability and sound absorption of the nonwoven fabric member obtained in Experiment 1 Nonwoven fabric members according to the examples and comparative examples in Experiment 1 described above were prepared and processed into necessary test pieces. The test piece was measured for the air flow rate in the thickness direction (cm ³ / cm ² · S) and the sound absorption coefficient (%) in the frequency range of 400 to 5000 Hz. The measurement method is based on JIS L 1096A (Fragile method) with respect to the air flow rate, and the prepared test piece is sandwiched and fixed between two rings having an inner hole of φ100 mm, and the upper 250 Pa is provided here. The measurement was performed under conditions where air was circulated. The sound absorption coefficient was measured based on JIS A 1405 (measurement method of sound absorption coefficient using an impedance tube).

(Result of Experiment 2)
As a result of the experiment, as for the air permeability, the nonwoven fabric member according to the example is 0 to 3.0 cm ³ / cm ² · S, which is a preferable numerical range as the above-described air conditioning duct, while the comparative example is 8 0.5 to 20.0 cm ³ / cm ² · S, 3 to 7 times as much as the air permeability of the examples, and as an air conditioning duct, it was confirmed that the air permeability of the duct wall surface is low. As for the sound absorption, the results shown in the graph of FIG. 6 are obtained, and the results of the example are more preferable in the entire frequency range, and the remarkable and good effect is confirmed particularly in the high frequency range exceeding 4000 Hz. .

1 is a perspective view schematically showing an internal structure of a nonwoven fabric member according to a preferred embodiment of the present invention, partly cut away. It is process drawing which shows the manufacturing method of the nonwoven fabric member which concerns on an Example. It is explanatory drawing which shows each step which concerns on manufacture of the nonwoven fabric member which concerns on an Example. In the fiber which comprises the nonwoven fabric which concerns on an Example, (a) The state before a heating, (b) The state after a heating is each partially cut away, and it is a perspective view which shows. It is the schematic which shows the temperature distribution inside the nonwoven fabric before pressing in the press step S4 in the cross section along the thickness direction. It is a graph which shows the sound absorption characteristic of the nonwoven fabric member which concerns on this invention measured in Experiment 2, and the nonwoven fabric member which concerns on a prior art. It is the schematic which shows the structure of the nonwoven fabric member which concerns on a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Nonwoven fabric member, 12 fibers, 12a Core portion, 12b Sheath portion, 13 Fiber group 14 Nonwoven fabric, 14a Surface, 16 Fiber region, 18 Dense region

Claims (7)

A non-woven fabric member comprising a fiber group (13) including a fiber (12) at least part of which is composed of a thermoplastic synthetic resin,
In the vicinity of the surfaces (14a, 14a) on both sides, the fiber group (13) containing the fibers (12) is a sparse aggregated state as compared to the substantially central portion sandwiched between the surfaces (14a, 14a) on both sides The fiber region (16, 16), and
A dense region (18) formed in a substantially central portion sandwiched between the fiber regions (16), wherein the fiber group (13) including the fibers (12) is in a dense aggregate state than the fiber region (16). The nonwoven fabric member characterized by being comprised from these.   The nonwoven fabric member according to claim 1, wherein the fiber group (13) comprises only the fiber (12).   The fiber (12) includes a core portion (12a) made of a first thermoplastic synthetic resin having a required melting point, and a second thermoplastic synthetic resin having a melting point lower than that of the first thermoplastic synthetic resin. The non-woven fabric member according to claim 1 or 2, comprising a sheath portion (12b) covering the outer periphery of the core portion (12a).   The fiber region (16) has a fiber structure in which a plurality of the fibers (12) maintain a fiber state, and the dense region (18) is formed by welding and solidifying a plurality of the fibers (12, 12). The nonwoven fabric member according to any one of claims 1 to 3, which is in a dense state. Preparing a non-woven fabric (14) comprising a fiber group (13) including fibers (12) at least part of which is composed of a thermoplastic synthetic resin;
The entirety of the nonwoven fabric (14) is within the temperature range above the melting point of the lowest melting thermoplastic synthetic resin in the fiber group (13) forming the nonwoven fabric (14) and maintaining the fiber structure. After heating so
By cooling the portion to be the fiber region (16) in the vicinity of the surfaces (14a, 14a) on both sides by leaving it for a required time under a temperature lower than the melting point of the thermoplastic resin having the lowest melting point,
Next, by pressing the nonwoven fabric (14) from the surfaces (14a, 14a) on both sides thereof, the thermoplastic resin having the lowest melting point still maintains the melting point or higher, and the surfaces (14a, 14a) on both sides are maintained. A method for producing a non-woven fabric member, characterized in that a substantially central portion sandwiched between them is a dense region (18).   The said nonwoven fabric (14) is a manufacturing method of the nonwoven fabric member of Claim 5 prepared only from the said fiber (12). A duct, wherein the nonwoven fabric member according to any one of claims 1 to 4 is molded into a required shape.

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