US20200102678A1

US20200102678A1 - Method for producing fiber molded body

Info

Publication number: US20200102678A1
Application number: US16/699,747
Authority: US
Inventors: Hirokazu Terada; Masaru Nishijima
Original assignee: JNC Corp; JNC Fibers Corp
Current assignee: JNC Corp; JNC Fibers Corp
Priority date: 2014-08-29
Filing date: 2019-12-02
Publication date: 2020-04-02
Also published as: EP3187636A4; JP6375781B2; WO2016031894A1; US20170241053A1; EP3187636A1; EP3187636B1; JP2016050365A; CN107109744A

Abstract

Provided is a fiber molded body which has excellent durability against repeated compression and also has excellent flexibility and a cushioning property. The fiber molded body forms, on a surface of the fiber molded body, the ridges having a compressed and flattened shape in the thickness direction of the fiber molded body; or the fiber molded body forms a continuous curved surface with the fiber layer which forms the ridges and extends from both sides of the ridges in the thickness direction of the fiber molded body, and portions of the fiber layer of mutually adjacent ridges which form ridges and extend in the thickness direction of the fiber molded body come into close contact with each other in the thickness direction of the fiber molded body.

Description

This application is a divisional application of and claims the priority benefit of a prior application Ser. No. 15/506,250, filed on May 15, 2017. The prior application Ser. No. 15/506,250 is a 371 application of the international PCT application serial no. PCT/JP2015/074152, filed on Aug. 27, 2015, which claims the priority benefit of Japan application no. 2014-174719, filed on Aug. 29, 2014. The entirety of each of the above-mentioned patent applications is hereby incorporated by reference herein and made a part of this specification.

FIELD OF THE INVENTION

The present invention relates to a fiber molded body having a cushioning property and a product using the same.

DESCRIPTION OF RELATED ART

A fiber molded body which is used for cushioning materials is generally a needle-punched nonwoven fabric which is obtained by using a needle punch method, and by laminating a card web with a cross layer or the like. A needle-punched nonwoven fabric is a nonwoven fabric which is obtained by entangling and tightening fibers in a web by means of a plurality of needles. The needle-punched nonwoven fabric obtained using this method generally has a low degree of freedom of fibers in the nonwoven fabric, a small number of gaps, and a low thickness, and thus the cushioning, thermal insulation and sound insulation properties thereof are inevitably low.
A fiber molded body which is obtained using another fabrication method may be a nonwoven fabric which is obtained by forming short fibers into a web by using a card method and then folding the web (see, for example, Patent document 1). The term “folding” used herein refers to making a web enter a state of being folded in the MD direction of the web by pleating or the like. However, although the nonwoven fabric obtained by this method has an excellent cushioning property, it has problem in that it has low durability against repeated compression because it is composed of short fibers, and thus fluff and lint are generated when compression has been repeated.

PRIOR ART DOCUMENT

Patent Document

[Patent document 1] Japanese Patent Application Publication No. 2007-308831

SUMMARY OF THE INVENTION

Technical Problem

Accordingly, an object of the present invention is to provide a fiber molded body which has excellent durability against repeated compression and also has excellent flexibility, a cushioning property, and cushioning durability (a durable cushioning property).

Technical Solution

The present inventors have repeated extensive research to overcome the above-described problems. As a result, the present inventors have found that a fiber molded body having a certain structure is fabricated using a fiber layer which is formed by opening a bundle of continuous fibers having crimps and extending in one direction, and thus a fiber molded body having excellent durability against repeated compression and also having an excellent cushioning property and excellent flexibility is obtained. Based on this finding, the present invention has been completed.
The present invention has the following configurations:
[1] A fiber molded body (1) having a structure in which a fiber layer (3) formed by opening a bundle of continuous fibers having crimps and extending in one direction is folded in the direction in which the continuous fibers extend so that ridges (2) repeatedly appear on a surface of the fiber layer (3); wherein the fiber molded body forms, on a surface of the fiber molded body (1), the ridges (2) having a compressed and flattened shape in the thickness direction (4) of the fiber molded body (1); or wherein the fiber molded body forms a continuous curved surface with the fiber layer (3) which forms the ridges (2) and extends from both sides of the ridges (2) in the thickness direction (4) of the fiber molded body (1), and portions of the fiber layer (3) of mutually adjacent ridges which form ridges and extend in the thickness direction (4) of the fiber molded body (1) come into close contact with each other in the thickness direction (4) of the fiber molded body (1).
[2] The fiber molded body (1) set forth in [1], wherein the continuous fibers are thermobondable continuous fibers, and the portions of the fiber layer of the mutually adjacent ridges come into close contact with each other in the thickness direction (4) of the fiber molded body by bonding through thermal bonding of the thermobondable continuous fibers of the fiber layer (3).
[3] The fiber molded body (1) set forth in [2], wherein at least a part of the thermobondable continuous fibers constituting the fiber layer (3) in close contact with each other in the thickness direction of the fiber molded body is entangled in the fiber layer of adjacent ridges, and the thermobondable continuous fibers constituting the fiber layer (3) and the entangled thermobondable continuous fibers are bonded to each other in the fiber layer of the ridges by thermal bonding.
[4] A fiber molded body (1), wherein an engraved pattern is additionally formed on the surface having the ridges (2) of the fiber molded body (1) set forth in any one of [1] to [3].
[5] The fiber molded body (1) set forth in any one of [1] to [4], wherein the continuous fibers are sheath/core type composite continuous fibers including polyester as a core and polyethylene as a sheath.
[6] A product obtained using the fiber molded body (1) set forth in any one of [1] to [5].

Advantageous Effects

The fiber molded body of the present invention has excellent flexibility and an excellent cushioning property. Furthermore, even when repeated compression has been performed, the amount of lint generated is small and fluffing resistance is desirable (it is difficult for fluff to be generated), and thus the fiber molded body has desirable durability against repeated compression. Furthermore, the fiber molded body of the present invention has a folded structure, and thus has high vertical resilience and provides a desirable tactile sensation. Moreover, the fiber molded body contains a large number of gaps, and thus has excellent thermal insulation and sound insulation properties.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic sectional view of a fiber molded body of the present invention.

FIG. 2 is a perspective view of the fiber molded body of the present invention.

DESCRIPTION OF THE EMBODIMENTS

<Fiber Molded Body>
The fiber molded body of the present invention has a structure in which a fiber layer formed by opening a bundle of continuous fibers having crimps and extending in one direction is folded in the direction in which the continuous fibers extend so that ridges repeatedly appear on a surface of the fiber layer.
The fiber molded body forms, on a surface thereof, the ridges having a compressed and flattened shape in the thickness direction of the fiber molded body. Alternatively, the fiber molded body forms a continuous curved surface with the fiber layer forming the ridges and extending from both sides of the ridges in the thickness direction of the fiber molded body, and portions of the fiber layer of the mutually adjacent ridges forming the ridges and extending in the thickness direction of the fiber molded body come into close contact with each other in the thickness direction of the fiber molded body.
The term “ridges” used in the prevent invention refers to a structure in which a corrugated state continues in a horizontal direction, as in ridges and furrows for the cultivation of crops which can be found in fields or the like, when viewed in a direction which is perpendicular to the thickness direction of the fiber molded body or in a direction in which the close contact state of the fiber layer and the state of the curved surface can be observed.
<Fiber Layer>
The fiber layer used in the present invention is formed by opening a bundle of continuous fibers which have crimps and extend in one direction. Using the bundle of continuous fibers, a fiber molded body having a structure in which the fiber layer is folded in a direction in which the continuous fibers extend so that ridges repeatedly appear on a surface of the fiber layer is obtained. The obtained fiber molded body has excellent durability against repeated compression in that it rarely generates fluff or lint even when compression has been repeated. Accordingly, the fiber molded body may be preferably used as a cushioning material.
Although the fiber layer formed by opening a bundle of continuous fibers having crimps and extending in one direction is not specifically limited, the fiber layer may use a fiber layer obtained by a known method, for example, a fiber layer fabricated by arranging continuous fibers in one direction by means of a spunbond method, a fiber layer fabricated by opening continuous fibers, particularly a tow of fibers, so that they extend in one direction by means of a tow opening method, or the like. In terms of cushioning and bulkiness properties, it is preferable to use the fiber layer obtained by means of the tow opening method.
<Continuous Fibers>
The continuous fibers which are used in the present invention are not specifically limited. In terms of durability against repeated compression, the continuous fibers preferably have thermobondability, and are particularly preferably thermobondable composite continuous fibers.
<Thermobondable Composite Continuous Fibers>
The thermobondable composite continuous fibers are preferably composite continuous fibers composed of a low-melting-point component and a high-melting-point component. Examples of a low-melting-point component/high-melting-point component combination include, but are not limited to, polyethylene/polypropylene, polypropylene copolymer/polypropylene homopolymer, polyethylene/polyethylene terephthalate, etc. Polypropylene which is used in the present invention is a polyethylene homopolymer, a copolymer of ethylene and propylene or other olefins, a copolymer of ethylene with other copolymerizable components, or the like. Polypropylene which is used in the present invention is a polypropylene homopolymer, a copolymer of propylene and ethylene or other olefins, a copolymer of propylene and other copolymerizable components, or the like. Polyester which is used in the present invention is polyethylene terephthalate, polybutylene terephthalate, a copolymer thereof, or the like. In particular, thermobondable composite continuous fibers composed of a combination of polyethylene/polyethylene terephthalate are preferable because they have rigidity, i.e., a property of polyethylene terephthalate resin, and a final molded product has an excellent cushioning property.
Examples of composite type of thermobondable composite continuous fibers may include sheath/core type composite continuous fibers or parallel type composite continuous fibers. In the case of the sheath/core type composite continuous fibers, it is generally preferred that a low-melting-point component is configured to be mixed with a sheath component in order to exhibit thermal bondability. Examples of the sheath/core type composite continuous fibers include concentric sheath/core type composite continuous fibers and eccentric sheath/core type composite continuous fibers, etc. In the present invention, in terms of a cushioning property, eccentric sheath/core type composite continuous fibers in which three-dimensional crimps can be easily manifested are preferable.
In the case where the continuous fibers are thermobondable composite continuous fibers, the ratio of a low-melting-point component to a high-melting-point component is preferably in the range from 30/70 to 70/30 on a volume basis, and more preferably in the range from 40/60 to 60/40 on a volume basis. In the case where the percentage of the low-melting-point component is 30 vol % or more, when a fiber molded body, such as a mat, is formed, the obtained mat has a desirable bonding state, and thus has a desirable cushioning property without breakage of its thermally bonded part even when it is compressed. When the percentage of the high-melting-point component is 30 vol % or more, this is preferable because the low-melting-point component which contributes to bonding is used in a small amount, and thus the degree of freedom of the fibers does not decrease even after thermal bonding, and the obtained fiber molded body has excellent flexibility (softness) and maintains its cushioning property.
A bundle of continuous fibers is opened (also referred to as “width-expanded”) to thus form a fiber layer. The term “opening” refers to an operation of separating continuous fibers in a bundle of continuous fibers (a bundle formed by converging continuous fibers) and allowing the continuous fibers to be present individually. As a result, the bundle of continuous fibers is separated into individual fibers so that the width of the bundle is increased, thereby forming a fiber layer.
In the opening of the bundle of continuous fibers, the width of the bundle may be uniformly expanded by suitably applying tension and relaxation to the fiber bundle by means of the fiber opening effect of wince rolls, the speed ratio between the rolls, and a Z bar (a swing tension bar). When tension is applied to the fiber bundle, it is important not to apply excessive tension that causes the crimps of the width-expanded fiber bundle to extend.
Manifested crimps, potential crimps, or a combination of manifested crimps and potential crimps may be used as the crimps that the bundle of continuous fibers has. Although two-dimensional crimps having a zigzag shape, such as a peak/valley shape, or three-dimensional crimps having a coil shape or a spiral shape may be used as the manifested crimps, the two-dimensional crimps are preferable in terms of workability. In terms of both opening and bulkiness properties, the number of crimps of continuous fibers in the fiber molded body is preferably in the range from 5 to 25 peaks/2.54 cm, more preferably 10 to 20 peaks/2.54 cm.
The bundle of continuous fibers preferably has manifested crimps, and the number of the crimps is preferably 8-70 peaks/25 mm, more preferably 9-65 peaks/25 mm, even more preferably 10-50 peaks/25 mm. In the case where the number of the crimps is 8 peaks/25 mm or more, the convergence of the tow is desirable, and the fiber bundle does not undergo excessive transverse cracking when the tow is pulled up, and thus high-speed opening becomes easy. In the case where the number of the crimps is 70 peaks/25 mm or less, it is difficult for excessive entanglement between continuous fibers or an increase in the density of the fibers to occur, and high-speed opening also becomes easy.
In the case where the bundle of continuous fibers, which is used in the fabrication of the fiber molded body, has manifested crimps together with potential crimps attributable to an eccentric sheath/core composite structure or the like, the potential crimps are expressed (manifested) due to a difference in stress strain occurring between the composite structure and each composite component by the tension which is applied in an opening process. By heating a fiber layer, obtained by opening the fiber bundle, in a later process, potential crimps may further be expressed (manifested) using a difference in thermal shrinkability between the composite structure of the fiber and each composite component.
In the case where the continuous fibers in the fiber molded body have potential crimps, this is preferable because crimp shapes, such as spiral crimps, i.e., three-dimensional crimps, can be manifested, and thus cushioning and bulkiness properties are desirable. In this case, two-dimensional crimps, such as zigzag type crimps or the like, may remain at a proportion lower than the majority of the continuous fibers.
The single yarn fineness of the continuous fibers is preferably 0.5-100 dtex. In the case where the single yarn fineness is 0.5 dtex or more, single-yarn breakage in the opening process or fluff rarely occurs, and high-speed opening is also possible. In the case where the single-yarn fineness is 100 dtex or more, the convergence of a tow is desirable and opening workability becomes desirable, and thus high-speed opening is possible and wide expansion can be performed for various purposes.
The total fineness of the fiber bundle is preferably 10,000-500,000 dtex, more preferably 30,000-200,000 dtex. In the case where the total fineness is 10,000 dtex or more, a cushioning property by fiber density can be maintained. In the case where the total fineness is 500,000 dtex or less, width expansion becomes desirable.
The weight per unit area of the fiber layer obtained by width-expanding the fiber bundle is preferably 10-150 g/cm², more preferably 20-100 g/cm². In particular, in the case where the weight per unit area is low, the folding distance in the folded structure becomes shorter to thus provide a structure in which ridges having a low height are present at high density and the wall surfaces of adjacent ridges are strongly pressed against each other to form a dense structure. In contrast, in the case where a fiber layer having a high weight per unit area is used, the folding distance in the folded structure becomes longer to thus provide a structure in which the width of the ridges is wide. In the case of the former structure, the fiber molded body has high strength. In the case of the latter structure, gaps remain in the fiber layer. Accordingly, the fiber molded body is soft, and it may be expected that thermal insulation and sound insulation properties are excellent due to the structure. A cushioning material suitable for use can be obtained by changing the weight per unit area within the above-described range.
The fiber layer obtained by opening (width-expanding) a bundle of continuous fibers having crimps and extending in one direction, which is used in the present invention, is preferably a fiber layer in which continuous fibers constituting a fiber layer are not bonded to each other. For example, the fiber layer is preferably a fiber layer in which continuous fibers are not partially bonded to and integrated with each other (not formed into a nonwoven fabric) by a plurality of bonding lines in a direction perpendicular to the lengthwise direction of the continuous fibers.
When the fiber layer in which the continuous fibers extending in one direction are not bonded to each other is configured such that portions of the fiber layer constituting the mutually adjacent ridges come into close contact with each other by folding the fiber layer in a direction in which the continuous fibers extend so that ridges repeatedly appear on a surface of the fiber layer, a state in which a part of the fibers of the fiber layer forming adjacent ridges is entangled in (penetrates into) the fiber layer forming the ridges is easily formed. When heating is performed in this state, thermal bonding between portions of the fiber layer constituting both ridges enables robust and strong thermal bonding than that in a case in which thermal bonding is performed using only contact points of fiber axes only on the contact interface between both portions of a fiber layer. Therefore, durability against repeated compression can be enhanced.
<Method for Fabricating Fiber Molded Body>
A method for forming a folded structure by pushing a fiber layer into a stuffing box, a method for forming a folded structure by using pleating, or the like may be used as a method for fabricating a fiber molded body, having a folded structure so that ridges repeatedly appear, by using a fiber layer that is formed by opening (width-expanding) a bundle of continuous fibers extending in one direction.
The method for pushing a fiber layer into a stuffing box may be exemplified by the following method:
1) A fiber layer is pushed into a box having a structure in which an opening area decreases from the inlet thereof toward the outlet thereof so that the fiber layer is not easily discharged from the outlet side thereof. The fiber layer is accumulated in the box and folded.
2) Furthermore, the folded fiber layer is discharged from the outlet side by continuously pushing the fiber layer into the box from the inlet side. A folded structure is imparted to the discharged fiber layer.
3) Thereafter, in order to mold the fiber layer into a fiber molded body, portions of the fiber layer in close contact with each other are bonded to each other. For example, in the case where thermobondable continuous fibers are used as the continuous fibers, a method for bonding portions of a fiber layer is preferably to bond portions of a fiber layer, in close contact with each other, to each other by the thermal bonding of the thermobondable continuous fibers using hot air by means of, for example, a hot-air circulation-type suction dryer. Thermobondable composite continuous fibers may be preferably used as the thermobondable continuous fibers, and are bonded to each other and formed by hot air having a temperature within a temperature range which is equal to or higher than the melting point of the low-melting-point component of the thermobondable composite continuous fibers and is lower than the melting point of the high-melting-point component thereof.
The height of the folded fiber layer may be preferably adjusted depending on the internal volume of the box. For example, the internal volume of the box may be changed by fixing the inlet side of the upper surface of the box and allowing the outlet side to descend. In this case, a folded structure may be made smaller by reducing the volume and, in contrast, a folded structure may be made larger by increasing the volume. This fabrication method is preferable because it is possible to efficiently obtain a fiber molded body in which ridges are formed such that portions of the fiber layer of the mutually adjacent ridges extending in the thickness direction of the fiber molded body come into close contact with each other in the thickness direction of the fiber molded body.
Another method for fabricating a fiber molded body is, for example, pleating. However, the method for fabricating a fiber molded body is not limited to these methods.
According to the above-described method, generally, it is possible to considerably suitably obtain a fiber molded body in which ridges form a continuous curved surface with a fiber layer which extends from both sides of the ridges in the thickness direction of the fiber molded body. Furthermore, the fiber molded body obtained as described above may be compressed from both sides thereof in the thickness direction thereof by means of plates or the like so that the ridges have a compressed and flattened shape in the thickness direction of the fiber molded body.
In addition, various engraved patterns may be formed on a surface side of the filer molded body that is obtained as described above and has the ridges. Such an engraved pattern may be obtained by, for example, pressing a mold, on which the pattern has been engraved, onto the surface side of the fiber molded body having the ridges while heating the mold as desired.
The present invention will be described in greater detail below with reference to examples, but the scope of the present invention is not limited thereto.
The evaluation of property of the fiber molded body of the present invention was carried out by the following method.
<Method for Evaluation of Cushioning Property>
The cushioning property was evaluated by 10 panelists based on the following evaluation criteria:
⊙: the number of panelists who felt resilience was 8 or more.
◯: the number of panelists who felt resilience was 5 to 7.
X: the number of panelists who felt resilience was 4 or less.
In this evaluation method, the fiber molded body rated ◯ or ⊙ was evaluated as having an excellent cushioning property.
<Method for Evaluation of Flexibility>
The flexibility was evaluated by 10 panelists based on the following evaluation criteria:
⊙: the number of panelists who felt flexibility was 8 or more.
◯: the number of panelists who felt flexibility was 5 to 7.
X: the number of panelists who felt flexibility was 4 or less.
In this evaluation method, the fiber molded body rated ◯ or ⊙ was evaluated as having excellent flexibility.
<Method for Evaluation of Durability Against Repeated Compression>
The fiber molded body was cut into a size of 100 mm×100 mm, and was repeatedly compressed 10 times with a compressor under a pressure of 3 kgf/cm²(29.4 Pa). Thereafter, evaluation was performed based on the following criteria by using the fiber molded body. The 10 panelists who had performed the evaluation of flexibility were employed for this evaluation.
⊙: the number of panelists who evaluated the fiber structure as having no or little fluff and lint was 8 or more.
◯: the number of panelists who evaluated the fiber structure as having no or little fluff and lint was 5 to 7.
X: the number of panelists who evaluated the fiber structure as having no or little fluff and lint was 4 or less.
In this evaluation method, the fiber molded body rated ◯ or ⊙ was evaluated as having little fluff and lint and also having desirable durability against repeated compression.

(Example 1) Sample A

A bundle of continuous fibers, in which concentric sheath/core type composite fibers (whose sheath/core ratio was 50/50 on a volume ratio; 3.3 dtex), including high-density polyethylene (HDPE; melting point: 130° C., MI: 16) as a low-melting-point component and polyethylene terephthalate (PET; melting point: 250° C., IV: 0.68) as a high-melting-point component, subjected to mechanical crimpling, and having zigzag crimps with 10-20 peaks/2.54 cm, extend in one direction, was uniformly opened by tensioning and relaxing it by using a tow opening method. An obtained fiber layer having a weight per unit area of 20 g/m², a thickness of 1 mm, and a width of 500 mm was pushed into a box whose opening area decreases from the inlet thereof toward the outlet thereof and which has an outlet opening size of 10 mm×500 mm, thereby obtaining a fiber layer in which a folded structure has been formed inside the box.
This fiber layer having a folded structure was heat-treated under the conditions of a circulating air speed of 1.5 m/s, a hot air temperature of 130° C. and a conveyor speed of 8.5 m/min by using a hot air circulation-type heat-treatment apparatus, thereby obtaining a fiber molded body.
The obtained fiber molded body formed a continuous curved surface with the fiber layer which formed ridges and extended from both sides of the ridges in the thickness direction of the fiber molded body. In addition, adjacent portions of the fiber layer forming the ridges and extending in the thickness direction of the fiber molded body were bonded to each other by thermal bonding based on the low-melting-point component of the fibers, and came into close contact with each other. When an attempt was made to peel portions of the fiber layer of mutually adjacent ridges from each other, it was observed that a part of the fibers of a portion of the fiber layer penetrated into (was entangled in) and was thermally bonded to another adjacent portion of the fiber layer, which contributed to an increase in strength against peeling.

(Example 2) Sample B

A tow of eccentric sheath/core type composite fibers (whose sheath/core ratio was 50/50 on a volume ratio; 3.3 dtex), including high-density polyethylene (HDPE; melting point: 130° C., MI: 16) as a low-melting-point component and a polypropylene (PP) homopolymer (melting point: 160° C.; MFR: 16) as a high-melting-point component and having potential crimps, was uniformly opened by tensioning and relaxing it by using a tow opening method. A fiber molded body was obtained by a method that is similar to the method for fabricating sample A except that the layer of a bundle of fibers having a weight per unit area of 25 g/m², a thickness of about 2.5 mm, and a width of about 500 mm was obtained. Spiral crimps with 10-15 peaks/2.54 cm were manifested in fibers constituting the fiber molded body.
The obtained fiber molded body formed a continuous curved surface with the fiber layer which formed ridges and extended from both sides of the ridges in the thickness direction of the fiber molded body. In addition, adjacent portions of the fiber layer forming the ridges and extending in the thickness direction of the fiber molded body were bonded to each by thermal bonding based on the low-melting-point component of the fibers, and came into close contact with each other. When an attempt was made to peel portions of the fiber layer of mutually adjacent ridges from each other, it was estimated that a part of the fibers of one portion of the fiber layer penetrated into (were entangled in) and was thermally bonded to another adjacent portion of the fiber layer, and thus strength against peeling was improved.

(Comparative Example 1) Sample C

Concentric sheath/core type composite short fibers (whose sheath/core ratio was 50/50 on a volume ratio; 3.3 dtex×51 mm), including high-density polyethylene (HDPE; melting point: 130° C., MI: 16) as a low-melting-point component and polyethylene terephthalate (PET; melting point: 250° C., IV: 0.68) as a high-melting-point component), subjected to mechanical crimpling, and having zigzag crimps with 10-20 peaks/2.54 cm, were processed by a card processing method to thereby obtain a fiber layer having a weight per unit area of 20 g/m², a thickness of about 1.5 mm, and a width of 500 mm. Thereafter, a fiber molded body having a folded structure was obtained by a method similar to the method for sample A.

(Comparative Example 2) Sample D

Concentric sheath/core type composite fibers (whose sheath/core ratio was 50/50 on a volume ratio), including high-density polyethylene (HDPE; melting point: 130° C., MI: 16) as a low-melting-point component and polyethylene terephthalate (PET; melting point: 250° C., IV: 0.68) as a high-melting-point component), were accumulated on a conveyor by a spunbond method. A fiber layer (fleece; 2.2 dtex) having a weight per unit area of 20 g/m², a thickness of about 0.3 mm, and a width of about 500 mm was obtained. Thereafter, a fiber molded body having a folded structure was obtained by a method similar to the method for sample A.
The results of the evaluation of the examples and the comparative examples are shown in Table 1 below:

	TABLE 1

	Durability against
	repeated compression

		Cushioning			Amount of
Example	Sample	property	Flexibility	Fluffiness	Lint

Example 1	A	⊚	⊚	⊚	⊚
Example 2	B	⊚	⊚	◯	◯
Comparative	C	⊚	⊚	X	X
Example 1
Comparative	D	X	X	⊚	◯
Example 2

INDUSTRIAL APPLICABILITY

The fiber molded body having a cushioning property according to the present invention has excellent flexibility. Furthermore, even when compression has been repeated, fluffing resistance is desirable and the amount of lint generated is small, and thus the fiber molded body can be very suitably used in, for example, the medical field, the automobile industry, the architectural field, etc. Furthermore, the fiber molded body of the present invention has a folded structure, and thus it has high vertical resilience and provides a desirable tactile sensation, with the result that it can be very suitably used for cushioning materials, etc. Moreover, the fiber molded body of the present invention contains a large number of gaps and has excellent thermal insulation and sound insulation properties, and thus can be very suitably used for thermal insulation and sound insulation materials, etc.

Claims

What is claimed is:

1. A method for producing a fiber molded body having a structure in which a fiber layer formed by opening a bundle of thermobondable continuous fibers having crimps and extending in one direction is folded in a direction in which the continuous fibers extend so that ridges repeatedly appear on a surface of the fiber layer, the method comprising:

obtaining a fiber layer by uniformly opening the bundle of continuous fibers extending in one direction by tensioning and relaxing by a tow opening method;

continuously pushing the fiber layer in a box in which the opening area decreases from an inlet of the box toward an outlet of the box, so that the fiber layer is accumulated in the box and folded; and

bonding with each other portions of the fiber layer in direct contact with each other to form the fiber molded body, by performing a heat treatment process on the fiber layer having the folded structure by using a hot-air circulation-type heat treatment apparatus,

wherein a number of crimps of continuous fibers in the fiber molded body is in the range from 5 to 25 peaks/2.54 cm;

wherein the fiber molded body forms, on a surface of the fiber molded body, the ridges having a compressed and flattened shape in a thickness direction of the fiber molded body; or

wherein the fiber molded body forms a continuous curved surface with the fiber layer which forms the ridges and extends from both sides of the ridges in the thickness direction of the fiber molded body, and

portions of the fiber layer of mutually adjacent ridges which form ridges and extend in the thickness direction of the fiber molded body come into direct contact with each other in the thickness direction of the fiber molded body.

2. The method of claim 1, wherein the portions of the fiber layer of the mutually adjacent ridges come into direct contact with each other in the thickness direction of the fiber molded body by bonding through thermal bonding of the thermobondable continuous fibers of the fiber layer.

3. The method of claim 2, wherein at least a part of the thermobondable continuous fibers constituting the fiber layer in direct contact with each other in the thickness direction of the fiber molded body is entangled in the fiber layer of adjacent ridges, and the thermobondable continuous fibers constituting the fiber layer and the entangled thermobondable continuous fibers are bonded to each other in the fiber layer of the ridges by thermal bonding.

4. The method of claim 1, wherein an engraved pattern is additionally formed on the surface having the ridges of the fiber molded body.

5. The method of claim 1, wherein the thermobondable continuous fibers are sheath/core type composite continuous fibers comprising polyester as a core and polyethylene as a sheath.

6. The method of claim 1, wherein a single yarn fineness of the continuous fibers is 0.5-100 dtex.

7. The method of claim 1, wherein a total fineness of the fiber bundle is 10,000-500,000 dtex.