JP4195043B2 - Method for forming fiber assembly and apparatus for forming fiber assembly - Google Patents

Description

  The present invention relates to a fiber assembly formed by processing a fiber body composed of a plurality of fibers, and particularly to a fiber assembly having a low density and a large thickness, a molding method thereof, and a molding apparatus.

  Conventionally, as a method for forming a fiber assembly, a needle punching method and a thermoforming method are generally used. These methods may be used independently or may be used in combination.

  The above two methods will be briefly described below.

(1) Needle punching method:
The needle punching method is a technique in which a laminated body of fiber materials is skewered by a needle punching machine using a needle called a felting needle, and fibers are entangled to continuously produce a sheet-like fiber aggregate.

(2) Thermoforming method:
The thermoforming method applies a desired heat to a laminate of a plurality of types of fiber materials having different melting points to melt fibers (adhesive material) having a relatively low melting point, thereby producing fibers (skeleton) having a relatively high melting point. This is a method of obtaining a fiber assembly by fixing the intersections of the materials. That is, in the thermoforming method, a skeleton is constituted by fibers having a relatively high melting point, and the fibers having a relatively low melting point have a function as an adhesive. Further, as a typical method for this thermoforming method, called a hot air conveyor furnace type, a method of continuously forming a fiber assembly by continuously supplying a fiber laminate to a hot air conveyor furnace, There is a method called “type” in which a fiber laminate is packed in a mold of a desired size and heated to obtain a fiber assembly of a desired size (shape / size) in a batch type.

  Hereinafter, the two methods will be further described.

(2-a) Hot air conveyor furnace type:
FIG. 4 is a schematic cross-sectional view of a conventional hot air conveyor furnace used in the thermoforming method. As shown in FIG. 4, the hot air conveyor furnace 500 has a predetermined vertical direction in order to transfer the fiber laminate 600 supplied from the right side in the figure to the left side in the vertical direction (fiber lamination direction). It has a pair of mesh belts 510 and 520 arranged to face each other with a gap. The fiber laminate 600 is formed by laminating webs that are produced by a card machine (not shown), a cross layer machine (not shown), or the like and that have substantially the same fiber direction, and have a desired basis weight (per unit area). Weight). Moreover, the fiber laminated body 600 is comprised from the multiple types of fiber material from which melting | fusing point differs.

  The distance h between the mesh belts 510 and 520 is substantially equal to the thickness of the fiber assembly 650 to be molded, and can be freely set as necessary. The thickness H of the fiber laminate 600 supplied to the hot-air conveyor furnace 500 is larger than the interval h between the mesh belts 510 and 520, and the fiber laminate 500 supplied into the hot-air conveyor furnace 500 is transferred by the mesh belts 510 and 520. It is compressed at a stretch to a thickness h, and is heat-molded in a compressed state to form a fiber assembly 650.

  In order to heat-mold the fiber laminate 600, a hot air conveyor furnace 500 is provided with a blower chamber 530 for blowing hot air and a wind receiving chamber 540 for sucking hot air blown from the blower chamber 530. The blower chamber 530 is disposed above the fiber laminate 600 that is transferred through the hot air conveyor furnace 500, and has a configuration in which hot air blown from the air supply port 531 is blown to the fiber laminate 600 through the plurality of openings 532. It has become. The wind receiving chamber 540 is disposed below the fiber laminate 600 and sucks hot air that has passed through the fiber laminate 600 through the plurality of openings 542 and exhausts the air from the suction port 541 to the outside.

  The fiber laminate 600 introduced into the hot air conveyor furnace 500 is heated to a desired temperature by hot air blown from the blower chamber 530. As described above, since the fiber laminate 600 is composed of a plurality of types of fiber materials having different melting points, the temperature of the hot air is higher than the melting point of the fibers having a relatively low melting point and higher than the melting point of the fibers having a relatively high melting point. By setting the temperature to a low temperature, the fibers having a relatively low melting point are melted, and the intersections of the fibers having a relatively high melting point are fixed by an adhesive (fibers having a relatively low melting point). A fiber assembly is obtained.

(2-b) Mold forming formula:
FIG. 5 is a diagram for explaining a method of forming a fiber assembly by a conventional mold forming method.

  The fiber laminate 610 is obtained by cutting out a fiber laminate similar to that used in the hot-air conveyor furnace type into a block shape. As shown in FIG. 5A, the fiber direction a substantially aligned in one direction. And a lamination direction b in a direction orthogonal to the fiber direction a. The fiber laminate 610 is inserted into an aluminum mold 700, and a lid 710 is formed as shown in FIGS. 5 (b) and 5 (c). In this state, the fiber laminate 610 is compressed in the lamination direction b and packed in the mold 700. In this state, the block 700 can be obtained by heating the mold 700 at the above-mentioned temperature.

  However, each of the above-described methods for producing a fiber assembly has the following problems.

(1) Needle punching method:
In the needle punching method, fibers are physically entangled with a felting needle, so that the obtained fiber aggregate is a sheet-like fiber aggregate having a high fiber density, a high hardness, and a thin thickness. Accordingly, it has been difficult to obtain a fiber assembly having a low fiber density, a soft, and thick fiber.

(2-a) Hot air conveyor furnace type:
In the hot air conveyor furnace type, hot air is blown from the upper side of the fiber laminate, so that the upper fiber is easier to soften than the lower side. End up. Therefore, the upper fiber density is higher than the lower fiber density, and it is difficult to obtain a uniform fiber assembly as a whole. In order to avoid this problem, the wind speed of the hot air may be reduced. However, if the wind speed of the hot air is reduced, the hot air cannot pass through the fiber laminate, causing a problem that the lower part of the fiber laminate is hardly heated.

  Therefore, similar to the needle punching method in the heat conveyer furnace type, a relatively high fiber density, a hard, sheet-like thin fiber assembly can be easily obtained, but a low fiber density, a soft, thick uniform fiber assembly. It was difficult to get a body. Further, since the fiber laminate is heated while being compressed by the mesh conveyor, there is also a problem that the trace (uneven shape) of the mesh conveyor is transferred to the surface layer of the fiber assembly.

(2-b) Mold forming formula:
A problem in forming a fiber assembly by a mold forming method will be described with reference to FIG. FIG. 6 is a diagram showing a state inside the mold when the fiber assembly is manufactured by the mold forming method.

  When the fiber laminate 610 is packed and when the mold 700 whose inside is sealed with the lid 710 starts to be heated, as shown in FIG. 6A, the fiber laminate 610 gradually follows the gravity direction from its peripheral portion. It will be crushed. This is not significant when the fibers constituting the fiber laminate 610 have greatly different melting points, such as a combination of polyethylene (PE) and polyethylene terephthalate (PET) blended fibers. However, when the olefin material alone is selected, the difference in melting point is relatively small, so that heat is transferred from around the mold 700 so that the influence of heat first appears around the fiber laminate 610.

  When the mold 700 is continuously heated, the heat is transferred to the inside of the fiber laminate 610, and the fiber laminate 610 is in a state where the entire bottom surface is crushed as shown in FIG. 6B. At this time, the fiber laminated body 610 is different in the fiber density state between the lower side and the upper side in the gravity direction. That is, the lower side of the fiber laminate 610 is affected by its own weight, so that the fiber density is high, and the upper side has a lower fiber density than the lower side. As a result, the fiber laminate 610 has a high density region 610b and a low density region 610a, and an unintended density gradient is generated. In FIG. 6B, the fiber laminate 610 is illustrated as being divided into two regions of a low density region 610a and a high density region 610b in order to simplify the illustration, but in actuality, the low density region 610a is illustrated. A continuous density gradient occurs from the high density region 610b to the high density region 610b.

  As described above, in the conventional molding method, a density gradient due to the effect of gravity is generated, so that the fiber density is relatively high and hard, like the hot air conveyor furnace type, a sheet-like fiber assembly. Can be easily obtained, but it has been difficult to obtain a uniform fiber assembly having a low fiber density, a soft, and thick thickness.

  In addition, the melted fiber (fiber having a function as an adhesive and a relatively low melting point) spreads in a plane along the inner surface of the mold 700 on the surface of the fiber laminate 610 in contact with the mold 700. A skin layer having a lower opening ratio than the inside is generated. Since this skin layer has a problem depending on its use, a step of peeling the skin layer is required, and there is also a problem that the material yield is deteriorated.

  An object of the present invention is to form a fiber assembly having a low fiber density, a uniform and thick thickness, particularly when the same kind of material, a material having a low melting point difference, or a material having a low melting point is used. It is providing the shaping | molding method and shaping | molding apparatus of a fiber assembly.

  In order to achieve the above object, the method for forming a fiber assembly of the present invention is a method for forming a fiber assembly in which a fiber body is subjected to heat treatment and a part of the fibers are fused. A first breathable sheet is disposed on a first mesh belt for transferring the fibrous body in one direction, the fibrous body is placed on the first breathable sheet, and the first breathable The fiber constituting the fibrous body is entangled with the sheet to regulate the posture of the fibrous body, and the first fibrous body against gravity by passing hot air from below to the fibrous body. A heating step of levitation from the mesh belt and melting a part of the fibers constituting the fibrous body in contact with the second mesh belt disposed opposite to the first mesh belt; and blowing of the hot air And maintain the second method The thickness of the heated fibrous body is set to a predetermined thickness by the first mesh belt and the third mesh belt disposed opposite to the first mesh belt on the downstream side of the schbert. A compression step of compressing, and a cooling step of cooling the compressed fiber body and solidifying the melted portion of the fiber on the downstream side of the third mesh belt.

  Further, the fiber assembly molding apparatus of the present invention is a fiber assembly molding device configured by heat-treating a fiber body and fusing part of the fibers, and placing the fiber body A first mesh belt for transferring the fibrous body in one direction in a heating furnace, hot air generating means for generating hot air blown upward from below the first mesh belt, and in the heating path On the upstream side of the second mesh belt disposed opposite to the first mesh belt, and on the downstream side of the second mesh belt disposed opposite to the first mesh belt. 3, and the first breathable sheet, the fibrous body, and the second breathable sheet are placed in this order on the first mesh belt, and the first breathable sheet is provided. The fibers constituting the fiber body are intertwined with each other The posture of the fiber body is regulated by the above, and the hot air generated by the hot air generating means is allowed to pass through the fiber body from below, so that the fiber body is separated from the first mesh belt against gravity. In a state where the fiber body is levitated and brought into contact with the second mesh belt, a part of the fibers constituting the fiber body is melted while the fiber body is transferred by the first and second mesh belts, While maintaining the air blowing, the fibrous body is transferred by the first and third mesh belts so that the heated vertical thickness of the fibrous body is set to a predetermined thickness by the third mesh belt. And compressing the fiber body by the first and third mesh belts, cooling the compressed fiber body downstream of the third mesh belt, Characterized by solidifying the molten point of the fibers.

  According to the present invention, at the time of heat treatment to the fiber body, the fiber body is levitated by blowing hot air from under the fiber body, and the posture of the fiber body is regulated at the time of ascent, so that the gravity of Impact is reduced. As a result, a low-density, uniform and thick fiber assembly can be easily obtained.

  In particular, by providing a breathable sheet above and below the fibrous body, it is possible to prevent a skin layer caused by the transfer of the surface state of the member that compresses the fibrous body when the fibrous body is compressed.

  According to the present invention, at the time of heat treatment to the fibrous body, the fibrous body is levitated by blowing hot air from under the fibrous body, and the posture of the fibrous body is regulated at the time of floating, so that the density is uniform at a low density and thickness. A thick fiber assembly can be easily obtained.

  Next, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic cross-sectional view of a fiber assembly forming apparatus according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along line AA of the forming apparatus shown in FIG.

  The molding apparatus of the present embodiment includes a first to third mesh belts 101, 102, and 103 in which a fiber laminate 150 sandwiched between upper and lower breathable sheets 111 and 112 in a heating furnace 100 that constitutes a main housing. Thus, the fiber assembly is molded while being transferred from the right side to the left side in the figure.

  The first mesh belt 101 is installed over the entire area in the transfer direction of the fiber laminate 150 in the lower part of the heating furnace 100, and the fiber laminate 150 supplied into the heating furnace 100 is the first mesh belt 101. The inside of the heating furnace 100 is transferred to the left in the figure and discharged from the heating furnace 100. With respect to the transfer direction of the fiber laminate 150, a carry-in conveyor is installed on the upstream side of the first mesh belt 101, and a carry-out belt is installed on the downstream side of the first mesh belt 101. The height level of the transfer line of the fiber laminate 150 of the first mesh belt coincides with the height level of the carry-in conveyor and the carry-out conveyor. As a result, the fiber laminate 150 is smoothly received from the carry-in conveyor to the first mesh belt 101 and sent from the first mesh belt 101 to the carry-out conveyor, and the fiber laminate 150 is continuously transferred. Is possible. As the first mesh belt 101, for example, a metal belt of about 4 mesh / cm is preferably used.

  The fiber laminate 150 is supplied to the heating furnace 100 with the air permeable sheets 111 and 112 laid on the lower surface and the upper surface, respectively. As shown in FIG. 2, the breathable sheet 111 laid on the lower surface of the fiber laminate 150 has a width larger than the width of the fiber laminate 150, and both side edges thereof are respectively pressed by the pressing members 113 to form the first mesh belt. 101. Further, the width of the air permeable sheet 112 placed on the fiber laminate 150 is equal to the width of the fiber laminate 150.

  Of these two breathable sheets 111 and 112, the lower breathable sheet 111 particularly has a function of holding the fiber laminate 150 that floats in the heating process described later, and therefore, the fibers constituting the fiber laminate 150 and the moderately appropriate amount. It is necessary to be entangled with each other and have elasticity in a heating environment. If there is no entanglement between the fibers of the fiber laminate 150 and the breathable sheet 111, the fiber laminate 150 peels off from the breathable sheet 111 when the fiber laminate 150 is levitated, and the breathable sheet 111 causes the fiber laminate 150 to be removed. It can no longer be held.

  The inside of the heating furnace 100 is divided into a heating unit 120 and a cooling unit 140 from the upstream side in the transfer direction of the fiber laminate 150.

  First, the heating unit 120 will be described. The heating unit 120 includes a second mesh belt 102 that is disposed so as to face the upper side of the first mesh belt 101. The second mesh belt 102 is synchronously moved around at the same speed as the first mesh belt 101, and the fiber laminate 150 is transferred by the first mesh belt 101 while holding the breathable sheet 112 from above. invite. The second mesh belt 102 can be moved in the vertical direction by an elevating mechanism (not shown) such as a hydraulic cylinder. The distance between the second mesh belt 102 and the first mesh belt 101 is larger than the thickness of the fiber laminate 150 including the air-permeable sheets 111 and 112, and the fiber laminate 150 has the first mesh as described later. The air-permeable sheet 112 is adjusted to an interval at which it can come into contact with the second mesh belt 102 by floating from the belt 101. As the second mesh belt 102, for example, a metal belt of about 4 mesh / cm is preferably used.

  Between the fiber laminate 150 transferred by the first mesh belt 101 and the second mesh belt 102, a first air blowing chamber 122 is disposed below the fiber laminate 150, and above the fiber laminate 150. The first wind receiving chamber 121 is disposed. The first blower chamber 122 has an air supply opening 122a opened on the side surface and a large number of ventilation holes 122b distributed on the upper surface. The first air receiving chamber 121 is also configured in the same manner as the first air blowing chamber 122. The air inlet 121a is open on the side surface, and a large number of air holes 121b are provided on the lower surface. Here, in FIG. 1, the conveyance roller 102 a around which the second mesh belt 102 is wound is depicted as being disposed in the wind receiving chamber 121, and this conveyance roller 102 a is illustrated in FIG. 2. Thus, since it arrange | positions at the both sides outside the wind receiving chamber 121, the conveyance roller 102a does not affect the flow of the hot air from the air supply port 122a mentioned later.

  As shown in FIG. 2, the intake port 121a and the air supply port 122a are connected to the hot air generator 105 through ducts. In the hot air generator 105, there are provided a heater 107 and a blower fan 106 that generates an air flow from the intake port 121a side toward the air supply port 122a side. When the hot air generator 105 is driven, hot air toward the air supply port 122a is generated in the hot air generator 105. This hot air is sent into the blower chamber 122 through the air supply port 122a, and blown onto the fiber laminate 150 from below through the ventilation hole 122b. The hot air blown to the fiber laminate 150 passes through the fiber laminate 150 upward, is sucked into the wind receiving chamber 121 from the vent hole 121b, passes through the intake port 121a, and enters the hot air generator 105. Returned to That is, in the region where the fiber laminate 150 is being transferred, hot air that blows up from below is generated.

  As will be described later, in the present embodiment, the first air blowing chamber 122 and the first air receiving chamber are provided so that hot air can be blown toward the fiber laminated body 150 even during the compression operation of the fiber laminated body 150. Reference numeral 121 also projects below the most upstream conveying roller 103a around which a third mesh belt 103 of a cooling unit 140 described later is wound. Here, since the conveyance roller 103a is also arranged at both ends outside the wind receiving chamber 121, similarly to the above-described conveyance roller 102a, the conveyance roller 103a also affects the flow of hot air from the air supply port 122a. There is no effect.

  Next, the cooling unit 140 will be described. The basic configuration of the cooling unit 140 is the same as that of the heating unit 120. That is, the third mesh belt 103 disposed opposite to the upper side of the first mesh belt 101, the second air blowing chamber 142 disposed below the fiber laminate 150 to be transferred, and the upper side of the fiber laminate 150. And a second wind receiving chamber 141 disposed in the space. However, the cooling unit 140 performs cooling immediately after the fiber laminate 150 is compressed, and instead of the hot air generator, a cold air generator (not shown) includes the second air blowing chamber 142 and the second air blowing chamber 142. Are connected to the wind receiving chamber 141.

  The third mesh belt 103 is synchronously moved around at the same speed as the first mesh belt 101, and the fiber laminate 150 is transferred by the first mesh belt 101 while holding the breathable sheet 112 from above. invite. Similarly to the second mesh belt 102, the third mesh belt 103 can also be moved up and down by an elevating mechanism (not shown), and the thickness of the fiber laminate 150 is that of the fiber assembly to be finally formed. The distance from the first mesh belt 101 is adjusted so as to have a thickness. As the third mesh belt 103, for example, a metal belt of about 4 mesh / cm is preferably used.

  The second air blowing chamber 142 has air supply holes 142a and air ventilation holes 142b similar to the air supply holes 122a and air ventilation holes 122b of the first air blowing chamber 122, and the cold air generated by the cold air generator is fiber laminated. It is configured to blow up from below the body 150. The second air receiving chamber 141 has the same air inlet 141a and air vent 141b as the air inlet 121a and the air vent 121b of the first air receiving chamber 121, and is blown up from the second air blowing chamber 142 to laminate the fibers. The cool air that has passed through the body 150 is sucked and returned to the cool air generator.

  In the cooling unit 140, normal temperature air (outside air) may be used as cooling air for the heated fiber laminate 150. In this case, the cold air generator is simply a blower, sucks air from outside the heating furnace 100 and sends it to the second blower chamber 142, and discharges the sent air from the second wind receiving chamber 141 to the outside. Configured as follows. Here, if a blower or the like that forcibly exhausts the air in the second wind receiving chamber 141 to the outside of the intake port 141a of the second wind receiving chamber 141 is installed, an improvement in exhaust efficiency can be expected.

  Further, at least one of the rollers around which the first to third mesh belts 101 to 103 are wound is provided with a preheating means such as a heating wire, and the first to third mesh belts 101 to 103 are Before coming into contact with the fiber laminate 150, it is preheated to a temperature equivalent to that required by the heating unit 120.

  That is, since the temperature of the first mesh belt 101 is lowered by the passage of the cooling unit 140, the first mesh belt 101 is heated to a predetermined temperature before entering the heating unit 120 again. A reduction in heating efficiency with respect to 150 is prevented. Since the temperature of the second mesh belt 102 decreases from the time when the second mesh belt 102 is separated from the fiber laminate 150 until it comes into contact again, by heating to a predetermined temperature before contacting the fiber laminate 150, The heating part 120 is prevented from lowering the heating efficiency with respect to the fiber laminate 150. Since the temperature of the third mesh belt 103 decreases due to contact with the cooling air while passing between the second air blowing chamber 142 and the second air receiving chamber 141, the fiber laminate 150 By heating to a predetermined temperature before coming into contact with the substrate, a rapid temperature drop of the upper surface portion of the fiber laminate 150 to be compressed is prevented. Accordingly, since the entire fiber laminate 150 is uniformly compressed from the surface portion to the inside while being maintained at the temperature heated by the heating unit 120, the fiber laminate 150 that has been solidified due to a decrease in temperature is used. Inconveniences such as compression can be avoided.

  Here, the fiber laminate 150 will be described. The fiber laminate 150 is formed by laminating webs having substantially the same fiber direction, and is produced by a card machine (not shown) or a cross layer machine (not shown) with a predetermined basis weight according to the application. Yes. The stacking direction is parallel to the gravitational direction, which is the vertical direction of the drawing in FIG. The fiber direction is substantially perpendicular to the laminating direction, and in FIG. 1, it is the left-right direction or the depth direction of the drawing. In the present invention, the fiber laminate 150 is not necessarily a laminate having directionality, and may be a fiber body with random fiber orientation. In this case, it is desirable that the density of the fibrous body is substantially uniform.

  As the fiber constituting the fiber laminate 150, a double-sheathed core-sheath fiber including a core part made of polypropylene (PP) and a sheath part made of polyethylene (PE) around the core part was used. The melting point of polypropylene is about 180 ° C., and the melting point of polyethylene is about 130 ° C. Therefore, the melting point difference between them is about 50 ° C. A fiber diameter of about 5 μm to 50 μm is generally used, but in this embodiment, a fiber of about 18 μm (2 denier) was used.

  In this embodiment, the core-sheath fiber as described above is used. However, the structure of the fiber is not limited to this, and for example, a fiber having a single structure inside PP and PE (hereinafter referred to as a single yarn). May be blended, or single yarn and double structure fiber may be blended. When the core-sheath fiber is used, PE exists at all the intersections between the fibers, and most of the intersections are fixed with PE, so that a firm fiber assembly can be obtained. In the case of blended fiber, the ratio of the fixed intersection changes depending on the ratio of the PP fiber and the PE fiber, that is, only the intersection of the portion where the PE fiber exists is fixed, so that a relatively soft fiber aggregate is obtained. It is effective in some cases. In the present embodiment, PP and PE are used as the fiber material, but the present invention is not limited to this as long as the melting points of the fibers are different. Furthermore, the types of fibers are not limited to two, and may be three or more.

Next, using the molding apparatus shown in FIG. 1, a fiber assembly having an apparent density of 0.038 to 0.043 g / cm ³ and a thickness of 35 mm is continuously formed from a core-sheath fiber having a thickness of 2 to 6 denier. An example of forming will be described.

(1) Preparation process:
In order to form a fiber assembly having an apparent density of 0.038 to 0.043 g / cm ³ and a thickness of 35 mm from the above-described core-sheath fiber, the thickness of the fiber laminate 150 (uniform in the height direction) After being spread over, the thickness in a state in which it is lightly pressed from the upper side and is released is suitable to be around 120 mm (100 to 150 mm). Accordingly, a fiber laminate 150 having a thickness of 120 mm is prepared.

  Then, even if the fiber laminate 150 is placed on the first mesh belt 101 in a state where the second mesh belt 102 is moved up and down and overlapped with the two air permeable sheets 111 and 112, the fiber laminate 150 remains in the first state. The position of the second mesh belt 102 is adjusted to a position where it does not contact the second mesh belt 102. Further, since the thickness of the fiber assembly to be molded is 35 mm, the third mesh belt 103 is moved so that the third mesh belt 103 is moved up and down and the thickness of the fiber laminate 150 in the cooling unit 140 becomes 35 mm. The position of is adjusted. The rotation speeds of the mesh belts 101 to 103 are set so that the transfer speed of the fiber laminate 150 is 0.5 m / min.

  On the other hand, the heating unit 120 sets the temperature of the hot air, the wind speed, etc. on the premise of the physical property conditions of the fibers. That is, since the fiber laminate 150 is composed of PE and PP core-sheath fibers as described above, it is higher than the melting point of PE (about 130 ° C.) before being transferred to the downstream portion of the heating unit 120, And it is made into the conditions that it is heated to temperature lower than melting | fusing point (about 180 degreeC) of PP. Therefore, in this embodiment, the temperature of the hot air is set to about 145 ° C., and the wind speed is set to 0.3 to 0.8 m / sec. Note that the temperature of the hot air (about 145 ° C.) is higher than the softening point of PP (about 120 ° C.).

  In the cooling unit 140, it is assumed that the PE constituting the fiber is cooled to a temperature lower than its melting point before the heated and compressed fiber laminate 150 is transferred to the downstream portion of the compression unit. The temperature of the cooling air, the wind speed, etc. are set. The fiber laminate 150 is desirably cooled uniformly in the thickness direction from the lower surface (first mesh belt 101) side to the upper surface (third mesh belt 103) side. Therefore, in this embodiment, the temperature of the cooling air is set to about room temperature and the wind speed is set to 0.2 to 0.3 m / sec.

  Each part is set as described above, and the fiber laminate 150 is supplied into the heating furnace 100. At this time, the fiber laminate 150 is supplied with the upper and lower sides of the fiber laminate 150 sandwiched between the air-permeable sheets 111 and 112.

(2) Heating process:
The fiber laminate 150 supplied into the heating furnace 100 is first transferred to the heating unit 120. The fiber laminate 150 is heated by hot air blown from below while passing through the heating unit 120, and the PE constituting the fiber sheath is melted so that the fibers are thermally bonded to each other. At this time, as shown also in FIG. 2, the fiber laminate 150 floats with respect to the first mesh belt 101, and the gravity applied to each fiber is canceled. Accordingly, the fiber laminate 150 is heat-bonded with the fibers while maintaining the state before heating.

  Further, the fiber laminate 150 is floated by the hot air, but the fibers of the fiber laminate 150 are appropriately intertwined with the breathable sheet 111, and both sides of the breathable sheet 111 are pressed by the first mesh belt 101 by the pressing members 113. Is held in. Therefore, the breathable sheet 111 is in a curved state as shown in FIG. 2, and the amount and the lifted posture of the fiber laminate 150 are regulated by the breathable sheet 111. In this way, by controlling the position and posture of the fiber laminate 150 when it floats, the fiber laminate 150 can be stably heated with hot air.

  In addition, floating the fiber laminate 150 with hot air has the following effects regardless of the presence or absence of the breathable sheet 111. When the fiber laminate 150 is not lifted, the heating state is different between the opening and the non-opening of the first mesh sheet 101. That is, since hot air blows out from the opening part of the 1st mesh sheet 101, since the hot air is ventilated more actively in the vicinity of the opening part, it is heated more rapidly and rapidly than the non-opening part. Therefore, the temperature rise state of the fiber laminate 150 becomes non-uniform, and it may be difficult to obtain a uniform fiber assembly. However, a space is created between the first mesh sheet 101 and the bottom surface of the fiber laminate 150 by floating the fiber laminate 150 as in the present embodiment. Since the space between the first mesh sheet 101 and the bottom surface of the fiber laminate 150 serves as a damper, the hot air blown from the opening of the first mesh sheet 101 is uniformly distributed from the bottom surface of the fiber laminate 150. Hot air can be ventilated, the fiber laminate 150 can be heated more uniformly than when heated without floating, and a more uniform fiber assembly can be obtained.

  When the pressing member 113 is not used, the fiber laminate 150 is pressed against the second mesh belt 102 when the wind speed of hot air blown from below is too high, and the upper fiber density is larger than the lower fiber density. It will be a thing. On the other hand, if the wind speed is too low, the fiber laminate 150 does not rise, the fibers softened by heating fall downward due to gravity, and the lower fiber density becomes larger than the upper fiber density. In any case, a uniform fiber density cannot be obtained unless hot air is blown at an appropriate wind speed. Note that the entire upper surface of the fiber laminate 150 is in contact with the second mesh sheet 102 almost uniformly without the fiber laminate 150 being lifted and pressed against the second mesh sheet 102 by the wind speed of the hot air. The pressing member 113 is not necessarily provided as long as it can be controlled appropriately.

  Further, since the air permeable sheet 111 is appropriately entangled with the fibers of the fiber laminate 150 and the friction resistance between the air permeable sheet 111 and the fiber laminate 150 is large, the fiber laminate 150 is horizontal with respect to the air permeable sheet 111. It becomes difficult to slip. As a result, physical deviation and shrinkage due to external force are suppressed during the heating step, the compression step and the cooling step described later, and a more uniform fiber assembly can be obtained.

  Here, the temperature rise characteristics of the fiber laminate 50 composed of core and sheath fibers of PP and PE will be described. In FIG. 3, the graph of the temperature rising characteristic of this fiber laminated body 150 is shown. In FIG. 3, the vertical axis represents temperature and the horizontal axis represents heating time.

When the fiber laminate 150 is put into the heating furnace 100 set to a temperature S ₃ lower than the melting point S ₂ (about 180 ° C.) of PP, the fiber laminate 150 will have a melting point S of PE after time T _{1. The} temperature is raised to ₁ (about 130 ° C.). When the temperature of the fiber laminate 150 reaches S ₁ , the PE starts to melt, and the temperature of the fiber laminate 150 remains at S ₁ until the melting of the PE constituting the sheath portion is completed.

When T ₂ time elapses, that is, when the melting of PE is completed, the fiber laminate 150 starts to rise again, and after T ₃ time elapses, reaches the set temperature S ₃ of the heating furnace 100. Since the temperature S ₃ is set to a temperature lower than the melting point S _{2 of} PP as described above, the PP does not melt and the fiber skeleton does not collapse.

In the case of a fiber assembly having a size of 1000 mm × 1000 mm, the values of T ₁ , T ₂ , and T ₃ are 10 to 15 minutes for T ₁ , 10 to 20 minutes for T ₂ , and 20 to 25 minutes for T _3. Is appropriate.

(3) Compression process:
The fiber laminate 150 heated by the heating unit 120 leaves the second mesh belt 102 and moves to the third mesh belt 103 side. As described above, the position of the third mesh belt 103 is adjusted on the premise of the thickness of the fiber assembly to be molded, so that the fiber laminate 150 that has reached the third mesh belt 103 is gradually compressed. The Further, at this time, hot air is blown up from the bottom to the fiber laminate 150 by the first air blowing chamber 122 and the first air receiving chamber 121, thereby preventing the fiber density from locally increasing. . Further, as described above, since the third mesh belt 103 is heated to a predetermined temperature before coming into contact with the fiber laminate 150, the third mesh belt 103 is compressed when the fiber laminate 150 is compressed. The temperature drop of the fiber laminate 150 by the belt 103 is prevented.

  In this compression step, the hot air is not stopped, and the fiber laminate 150 is compressed in a state where the gravity applied to each fiber is canceled. Thereby, the fiber laminate 150 is compressed while maintaining a uniform fiber density as a whole. Along with the compression of the fiber laminate 150, the fiber density of the fiber laminate 150 gradually increases, and the air permeability and the heat transfer performance of the hot air deteriorate. Therefore, it is desirable that the hot air is slightly weakened when the fiber laminate 150 is compressed. This is because the fiber density is increased and the air permeability and the heat permeability are deteriorated, so that the entire fiber laminate 150 is blown up by the hot air and pressed against the second mesh belt 102, and as a result, the upper fiber density is reduced. This is because problems such as local increase occur.

  As means for changing the wind speed of the hot air depending on the portion of the fiber laminate 150 that is continuously fed as in the present embodiment, for example, a method of changing the size and dispersion density of the ventilation holes 122b between the compression unit and the heating unit, There is a method of providing the air supply port 122a at a position relatively far from the compression unit.

(4) Cooling process:
The fiber laminate 150 compressed by the first mesh belt 101 and the third mesh belt 103 is transferred through the cooling unit 140 while being compressed by the mesh belts 101 and 103. In the cooling unit 140, the cooling air is blown up from below, whereby the fiber laminate 150 is gradually cooled, and PE is solidified until the compression is released.

And the fiber laminated body 150 which passed the cooling part 140 is discharged | emitted from the heating furnace 100, breathable sheet 111,112 is peeled, apparent specific gravity 0.038-0.043g / cm < ³ >, thickness is 35 mm. A continuous fiber assembly is obtained. The obtained fiber assembly is appropriately cut into a size and is put into practice.

  As described above, according to the present embodiment, immediately after the fiber laminate 150 placed and supplied on the conveyor is heated in a natural state without compression and heated to a predetermined temperature, Since continuous cooling is performed while continuously compressing, a fiber assembly having a desired fiber density and thickness can be continuously formed.

  In addition, although the case where the fiber assembly which consists of a core sheath fiber of PP and PE which has said apparent specific gravity and thickness was described here was described, the kind, thickness, and physical property of the fiber assembly which should be shape | molded Each condition such as the temperature setting in the heating furnace 100 and the wind speed of the hot air is changed according to the conditions.

  Since such a fiber assembly has appropriate elasticity, it is suitably used as an interior material such as a passenger car seat, armrest, or headrest, or a cushion material for furniture such as a bed or sofa. be able to. Moreover, since the fiber assembly is excellent in water retention, it can be suitably used as a water retention member or the like stored in a container product that stores and holds various liquids and moisture.

  According to the method for forming a fiber assembly of the present embodiment using the heating furnace 100, in the heating process, hot air is blown from below to the fiber laminate 150 in an uncompressed state. As the inside of the fiber laminate 150 rises smoothly while exchanging heat with it, the heating effect is enhanced and the heating time is shortened, and a fiber assembly having a low density and a large thickness can be formed.

  Here, supplementary explanation will be given for the air-permeable sheets 111 and 112.

  As described above, the lower breathable sheet 111 prevents the fiber laminate 150 from being detached from the first mesh belt 101 in the heating process, thereby reducing the thickness of the thick fiber having a low and uniform fiber density. It works effectively to obtain an aggregate. Considering only this point, the upper air-permeable sheet 112 is unnecessary. However, this breathable sheet 112 causes unintentional density distribution due to disturbance of the upper surface of the fiber laminate 150 during the floating heating of the fiber laminate 150 and sudden heat transfer from the heated second mesh belt 102. There is an effect to prevent. In addition, considering the compression step after the heating step, in this compression step, the fiber laminate 150 is compressed by the first mesh belt 101 and the second mesh belt 102 in a state where PE is melted. Therefore, when the breathable sheets 111 and 112 are not used, the surface states of the first mesh belt 101 and the second mesh belt 102 are transferred to the fiber laminate 150, and so-called skin layers are formed on the fiber laminate 150. It is formed on the lower surface. In order to prevent the occurrence of such a skin layer, it is effective to interpose the breathable sheets 111 and 112 between the members that compress the fiber laminate 150.

  As is apparent from the above, the air-permeable sheets 111 and 112 are desirably materials that are appropriately entangled with the fibers of the fiber laminate 150, have elasticity in a heating environment, and do not melt in the heating process. . In addition, since the surface state of the air permeable sheets 111 and 112 is transferred to the fiber laminate 150, the air permeable sheets 111 and 112 have the same opening state as the opening state inside the fiber laminate. The material is desirable. Therefore, as the breathable sheets 111 and 112, foamed polyurethane sheets having about 16 cells / cm can be used.

  In addition, a structure obtained by removing a cell membrane after foaming, such as foamed polyurethane foam, has a small difference in local ventilation resistance on a cell (about 300 to 600 μm) scale with respect to fibers. If expressed two-dimensionally, the fibrous body can be compared to a large room (pillar is a fiber) that has been removed from the fence, but the urethane sponge cells have different sizes (cell sizes). In addition, each partition (tub) is partially closed, and the ventilation resistance is locally increased. By arranging such a foam as a breathable sheet above or below the fiber laminate, a rectifying effect on the entire vent surface can be obtained.

  By the way, in the synthetic fiber, various oil agents are generally adhered to the fiber surface in the spinning process for the purpose of ensuring the convergence and smoothness of the fiber and preventing static electricity. However, in the medical field and precision instrument field, there are cases where such oils are extremely disliked. In such a case, the oil agent may be extremely reduced. When such a fiber is applied to the present invention, various problems such as unintentional entanglement of the fiber due to static electricity and disturbance of density may be caused. Therefore, as a countermeasure against this, it is desirable to carry out static elimination blow over the entire web when producing a fiber laminate. In addition to this, it is also effective to provide a step of spraying the fibers with ion exchange water or an aqueous solution of a nonionic surfactant.

It is a schematic sectional drawing of the shaping | molding apparatus of the fiber assembly by one Embodiment of this invention. It is the sectional view on the AA line of the shaping | molding apparatus shown in FIG. It is a graph which shows the temperature rising characteristic of the fiber laminated body which consists of core sheath fiber of PE and PP. It is a schematic sectional drawing of the conventional hot-air conveyor furnace used for a thermoforming method. It is a figure explaining the shaping | molding method of the fiber assembly by the conventional mold shaping type | mold. It is a figure explaining the subject in the shaping | molding method of the fiber assembly by the conventional die shaping type | mold.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Heating furnace 107 Heater 106 Blower fan 111,112 Breathable sheet 150 Fiber laminated body 101,102,103 Mesh belt 102a, 103a Conveying roller 105 Hot air generator 113 Holding member 120 Heating part 121,141 Air receiving chamber 122,142 Air blowing Chamber 140 Cooling unit

Claims (9)

In the method of forming a fiber assembly that is configured by heat-treating a fiber body and fusing part of the fibers together,
A first breathable sheet is disposed on a first mesh belt for transferring the fibrous body in one direction in a heating furnace, the fibrous body is placed on the first breathable sheet, and the first The fiber constituting the fiber body is entangled with one air-permeable sheet to regulate the posture of the fiber body, and the fiber body is resisted against gravity by allowing hot air to pass through the fiber body from below. A heating step of levitating from the first mesh belt and melting a part of the fibers constituting the fibrous body in a state of being in contact with the second mesh belt disposed opposite to the first mesh belt;
The blowing of the hot air is maintained and heated by the first mesh belt and the third mesh belt disposed opposite to the first mesh belt on the downstream side of the second mesh belt. A compression step of compressing the thickness of the fibrous body in a vertical direction to a predetermined thickness;
A cooling step of cooling the compressed fiber body on the downstream side of the third mesh belt and solidifying the melted portion of the fiber;
A method for forming a fiber assembly, comprising:   2. The method for forming a fiber assembly according to claim 1, wherein the first air-permeable sheet is held against the first mesh belt by a pressing member.   The method for molding a fiber assembly according to claim 1 or 2, wherein the breathable sheet has a melting point higher than that of the fibers constituting the fibrous body.   The method for forming a fiber assembly according to claim 1 or 2, wherein the breathable sheet has elasticity even in the heating step.   The fibers constituting the fibrous body are made of a plurality of materials having different melting points, and the temperature of the hot air that passes through the fibrous body in the heating step is relatively higher than that of the material having a relatively low melting point. 2. The method for forming a fiber assembly according to claim 1, wherein the method is higher than a softening point of a material having a high melting point and lower than a melting point of a material having a relatively high melting point.   The method for forming a fiber assembly according to claim 5, wherein the fibers are made of an olefin-based material. A fiber assembly forming apparatus configured by heat-treating a fiber body and fusing part of the fibers,
A first mesh belt for placing the fibrous body and transferring the fibrous body in one direction in a heating furnace;
Hot air generating means for generating hot air blown upward from below the first mesh belt;
A second mesh belt disposed on the upstream side in the heating path and facing the first mesh belt;
A third mesh belt disposed on the downstream side of the second mesh belt and facing the first mesh belt;
With
On the first mesh belt, the first breathable sheet, the fibrous body, and the second breathable sheet are placed in this order, and the fibers constituting the fibrous body are placed on the first breathable sheet. By restricting the posture of the fiber body by entanglement, the hot air generated by the hot air generating means is passed from below to the fiber body, thereby allowing the fiber body to resist the gravity against the first mesh belt. In a state where the fiber body is floated and in contact with the second mesh belt, a part of the fibers constituting the fiber body is melted while the fiber body is transferred by the first and second mesh belts,
While maintaining the blowing of the hot air, the fibrous body is formed by the first and third mesh belts so that the heated fibrous body has a predetermined thickness by the third mesh belt. Compressed while transporting,
The fiber body is transferred by the first and third mesh belts, the compressed fiber body is cooled on the downstream side of the third mesh belt, and the melted portion of the fibers is solidified. A device for forming a fiber assembly. The fiber aggregate molding apparatus according to claim 7, wherein the first air-permeable sheet is held against the first mesh belt by a pressing member. The first and second breathable sheets have elasticity in a heating environment by the hot air generating means, and a melting point thereof is higher than a melting point of fibers constituting the fibrous body. 8. The apparatus for forming a fiber assembly according to 7.

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