JP5362471B2 - Molding method of composite fiber body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of molding a composite fiber body having mild gradient in change of density of a high density layer and a low density layer in the thickness direction, and effective as a sound absorbing interior material. <P>SOLUTION: Only the lower face side of a molding material 1A is compressed and molded as the high density layer 1a of a desired thickness under temperature control of a lower mold 2B, in a process of heating and pressurizing by a primary mold 2. The primary mold 2 is opened to restore the low density layer 1b on the upper surface of the molding material 1A, and in a state that hot air is sent to the molding material 1A and it is heated to a prescribed temperature, the molding material 1A is cold-pressed by a secondary mold 3, to thereby compress and mold the low density layer 1b to a prescribed thickness and density. Thus, the composite fiber body 1 is formed having mild gradient in the change of density of the high density layer 1a and low density layer 1b, and effective as the sound absorbing interior material. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a method for forming a composite fiber body in which a main fiber composed of natural fiber, chemical fiber or thermoplastic fiber and a thermoplastic fiber having a lower melting point as a binder are entangled and mixed in a non-woven manner, more specifically The present invention also relates to a method for forming a composite fiber body in which the density is changed between a high-density layer and a low-density layer in the thickness direction.

  The composite fiber body in which the density is changed between the high-density layer and the low-density layer in the thickness direction is used as a sound-absorbing interior material such as a dash insulator and a roof trim of an automobile.

  A dash insulator typified by the sound-absorbing interior material is configured as a two-layer structure in which one side surface is a low-density layer and the other side surface is a high-density layer, and the low-density layer is formed on the side surface of the dash panel on the vehicle interior side. They are placed in close contact with each other and attached with a fastening member such as a clip with the high-density layer exposed in the passenger compartment.

  In general, this dash insulator is formed by laminating a high-density fiber body that has been hot-press-molded in advance into a predetermined shape on a low-density fiber body through an appropriate adhesive, and then forming this into a predetermined shape and thickness using a thermoforming mold It is configured as a laminated structure formed by hot press molding.

  The dash insulator absorbs the noise on the engine room side with a low-density layer that is in close contact with the dash panel surface, and the required mounting rigidity is ensured by the shape retention function of the high-density layer that is exposed in the passenger compartment. There is also a demand for a sound absorbing effect that can also block noise from the engine room and absorb noise on the passenger compartment side to suppress reflection of the sound and improve the quietness of the passenger compartment comprehensively.

  However, if the dash insulator is a laminated structure of low-density fiber bodies and high-density fiber bodies as described above, the density change of these fiber bodies is abrupt. It has been pointed out that the amount of noise reflection increases, impairing the sound absorption performance of the dash insulator.

  On the other hand, in recent years, for example, as shown in Patent Document 1, a molding material in which a main fiber and a binder made of a thermoplastic binder are mixed is heated to the softening and melting temperature of the binder and pressed. A technique has been proposed in which one side of the molding material is pressed at a high temperature and the other side is pressed at a low temperature to form a plate having different densities on both sides.

JP 2001-322137 A

  According to the technique of Patent Document 1, it is possible to mold a plate-like fibrous body that changes in density into a high-density layer and a low-density layer in the thickness direction and has a gentle gradient in the density change. However, in order to heat press molding a molding material by setting the temperature of a pair of hot press molds to a high temperature and a low temperature, when forming a low density layer and a high density layer required for sound absorption in layers, It is difficult to control the temperature of these molds and pressurizing time of the molding material by the molds, and it is effective as a sound-absorbing interior material with excellent sound absorption performance and sound transmission loss like the dash insulator. It is not possible to easily obtain a fiber molded body in which the density changes to a low density layer and the density change gradient is gentle.

  Therefore, the present invention provides a composite fiber body that changes in density into a high density layer and a low density layer in the thickness direction by a simple method, and has a gentle gradient in density change, and is effective as a sound-absorbing interior material. A method of forming a composite fiber body that can be obtained is provided.

  In the method for molding a composite fiber body according to the present invention, a fiber aggregate in which main fibers and a binder made of a thermoplastic fiber having a lower melting point than that are mixed is used as a molding material, and the molding material is used as a primary molding die. And compressing in a state where one side is heated to a required temperature required for compression molding, forming a high-density layer having a required thickness on one side of the molding material, and opening the primary mold. A step of restoring the non-densified low-density layer of the molding material, and a step of heating the restored low-density layer of the molding material to a required temperature required for the compression molding by a fluid heat medium And a step of pressure-molding a molding material in which the low-density layer is heated into a predetermined shape with a secondary molding die, and compression-molding the low-density layer to a required thickness. .

  According to the feature of the present invention, only one surface of the molding material is formed as a high-density layer having a required thickness in the process of heating and compressing by the primary mold, and thus a high-density layer having a required density is formed. The temperature control and processing time management of the mold can be easily performed.

  When a high-density layer is formed on one side of the molding material, the primary mold is opened to temporarily restore the low-density layer, and a fluid heat medium such as hot air is sent to this and heated to the required temperature. The heating temperature and the heating time of the low density layer can be easily managed, and the heating time can be shortened by spreading hot air over the entire low density layer.

  In this way, when the low density layer of the molding material is heated to a predetermined temperature with hot air throughout, the molding material is pressure-molded into a predetermined shape by the secondary mold, so that the required density is low. The layer can be easily compressed in a short time and the density of the low density layer can be stabilized, and the gradient of density change between the high density layer and the low density layer is gentle. A composite fiber body is obtained.

  In the method for molding a composite fiber body according to the present invention, a fiber aggregate in which a main fiber and a binder made of a thermoplastic fiber having a lower melting point than this fiber are used as a molding material. A step of compressing one side of the molding material in a state heated to a required temperature required for compression molding to form a high-density layer having a required thickness on one side of the molding material; A process of introducing cooling air entirely into the non-densified low-density layer of the molding material through the heating-side mold to keep the low-density layer at a low temperature, and the low-density layer is kept at a low temperature Pressing the molded material with a secondary mold to press-mold the high-density layer together with the low-density layer into a predetermined shape, and opening the secondary mold to increase the low-density layer of the molding material. And a step of restoring along the processing shape of the density layer. It is.

  According to the feature of the present invention, only one surface of the molding material is formed as a high-density layer having a required thickness in the process of heating and compressing by the primary mold, and thus a high-density layer having a required density is formed. The mold temperature control and pressurization time management can be easily performed.

  Then, after forming the high-density layer on one side of the molding material or in the process of forming the high-density layer, the whole of the molding material is not densified through the mold on the non-heating side of the primary molding die. Since cooling air is introduced to keep the low density layer at a low temperature, the progress of densification of the high density layer toward the low density layer is suppressed, and the high density layer having the required thickness can be easily formed. It becomes possible to form.

  In this way, the progress of densification of the high-density layer on one side of the molding material is suppressed, and the molding material is pressed into a predetermined shape by the secondary molding die while the low-density layer is kept at a low temperature. After molding, the secondary mold is opened to restore the low-density layer of the molding material along the processed shape of the high-density layer, so that the low-density layer with the required thickness and required density can be easily obtained. In addition to being able to be molded, it is possible to stabilize the density of the low-density layer, and a composite fiber body in which the density change gradient between the high-density layer and the low-density layer is gentle can be obtained.

  According to the present invention, since only one side of the molding material is first densified to form a high-density layer having a required thickness and required density, temperature control and pressurization of the molding die for forming the high-density layer are performed. Time management becomes easy.

  Following the formation of this high-density layer, the low-density layer of the molding material that has not been densified is suitable for compression molding in the low-density layer after the mold is opened and restored once. A fluid heat medium such as hot air at a temperature is sent, or cooling air is sent to the low-density layer when the high-density layer is formed, and the low-density layer is kept at a low temperature, so that the molding material is secondarily shaped into a predetermined shape. Therefore, it is possible to easily obtain a composite fiber body having a two-layer structure including a high-density layer and a low-density layer having a required density and thickness, and a gentle gradient of density change.

Process drawing which shows 1st Embodiment of this invention. Process drawing which shows 2nd Embodiment of this invention. Process drawing which shows 3rd Embodiment of this invention. The graph which shows the change gradient of the density of the thickness direction of the composite fiber body obtained by the method of this invention compared with the thing of the conventional laminated structure.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows a first embodiment of the method of the present invention, in which a high-density layer 1a is formed on one side of a molding material 1A of a composite fiber body 1 having a two-layer structure of a high-density layer and a low-density layer. A mold 2 and a secondary molding mold 3 that press-molds a molding material 1A having a high-density layer 1a formed on one side thereof into a predetermined shape are used.

  The composite fiber body in the present invention is a molded fiber body in which a main fiber made of natural fiber, chemical fiber or appropriate thermoplastic fiber and an appropriate thermoplastic fiber having a lower melting point than this are entangled and mixed in a non-woven form. The molding material means a fiber assembly in which the main fiber and the thermoplastic fiber having a melting point lower than the main fiber are used as a binder, and the main fiber and the binder are mixed at an arbitrary blending ratio. doing.

  In the first embodiment, as the primary mold 2, a mold formed in a flat plate shape is used for both the upper mold 2 </ b> A and the lower mold 2 </ b> B, and a hot plate capable of adjusting the heating temperature is used for the lower mold 2 </ b> B. .

  In the step (a) shown in FIG. 1, the molding material 1 </ b> A is compression-molded into a flat plate shape by the upper mold 2 </ b> A and the lower mold 2 </ b> B of the primary mold 2. In this step (a), the lower mold 2B is required for compression molding on the lower surface side of the molding material 1A, that is, the temperature at which the surface of the binder (thermoplastic fiber) used in the molding material 1A is softened and melted. The heating is adjusted as described above. The lower surface side of the molding material 1A in contact with the lower mold 2B is pressed for a predetermined time under heating by the lower mold 2B, so that the high-density layer 1a having a required thickness is compression molded on the lower surface side of the molding material 1A. The

  The density and molding thickness of the high-density layer 1a of the molding material 1A can be arbitrarily set by setting the heating temperature of the lower mold 2B and the pressure and pressing time of the molding material 1A by the lower mold 2B and the upper mold 2A. Adjusted.

  In the step (b) shown in FIG. 1, the upper mold 2A and the lower mold 2B of the primary mold 2 are opened, and the mold 1A is densified by the mold opening of the primary mold 2. The low-density layer 1b on the upper surface side that is not restored is restored to its original free thickness state by its own elasticity. Then, with the low density layer 1b restored, the required temperature required for compression molding of the low density layer 1b through a plurality of passages 2a formed through the upper mold 2A in the vertical direction. A heated fluid heat medium such as hot air is supplied. The supply of hot air is performed in the direction perpendicular to the low density layer 1b through the plurality of passages 2a penetrating the upper mold 2A in the vertical direction as described above, whereby hot air is supplied to every corner of the low density layer 1b. The low density layer 1b is heated to the required compression molding temperature within a short time.

  At this time, the heating state of the high-density layer 1a by the lower mold 2B may be continued, but the high-density layer 1a is maintained at the pressure molding temperature by introducing hot air into the low-density layer 1b. Therefore, the heating power of the lower mold 2B can be turned off to reduce power consumption.

  In this way, the molding material 1A in which the low density layer 1b is heated with hot air is cold-pressed by the secondary molding die 3 into a predetermined shape in steps (c) and (d) shown in FIG. Is done.

  The secondary mold 3 includes a core mold 3A that is an upper mold and a cavity mold 3B that is a lower mold.

  The molding material 1A in which the low-density layer 1b is heated with hot air to the required compression molding processing temperature in the step (b) is transferred to the step (c) and cold-pressed by the core die 3A and the cavity die 3B for a required time, For example, as shown in the step (c), it is pressure-molded into a required concavo-convex shape in which the thickness dimension of the low density layer 1b is different between the central portion and both side portions of the molding material 1A.

  When the high-density layer 1a and the low-density layer 1b of the molding material 1A are pressure-molded in this step (c) and cooled and solidified, the core mold 3A and the cavity mold 3B are opened in the step (d). Thus, a composite fiber body 1 of a predetermined shape having a two-layer structure having a high density layer 1a on the lower surface side and a low density layer 1b on the upper surface side is obtained by die cutting.

  In the step (b), an example in which the restored low density layer 1b of the molding material 1A is heated with hot air is shown, but it is also possible to use water vapor or hot water as a fluid heat medium in addition to hot air. .

  According to the method of the first embodiment described above, since only the lower surface side (one surface) of the molding material 1A is formed as the high-density layer 1a having the required thickness in the process of heating and compressing with the primary molding die 2, the lower mold The heating temperature of 2B can be set appropriately, and the pressing force and pressurization time of the molding material 1A by the upper and lower molds 2A, 2B can be appropriately set. There is no need to consider the temperature balance and the balance between the heating temperature and the pressurization time, and the temperature control and pressurization time management of the mold for forming the high-density layer 1a having the required density and thickness are facilitated. can do.

  When the high-density layer 1b is formed on the lower surface side of the molding material 1A, the primary molding die 2 is opened to temporarily restore the lower-density layer 1b on the upper surface side, and a fluid heat medium such as hot air is applied thereto. Since it sends in and heats to required temperature, the heating temperature management and heating time management of this low density layer 1b can be performed easily.

  In addition, since the fluid heat medium is sent to the low density layer 1b once restored as described above, the fluid heat medium can be spread over the entire low density layer 1b to shorten the heating time. The heat retention of the temperature can also be improved.

  In this way, when the low density layer 1b of the molding material 1A is heated to a predetermined temperature by hot air (fluid heat medium) all over (to every corner), the secondary molding die 3 forms the molding material 1A into a predetermined shape. Therefore, the low density layer 1b having the required density and thickness can be easily compressed in a short time and the density of the low density layer 1b is stabilized. be able to.

  As a result, the density and thickness of the high-density layer 1a and the low-density layer 1b, which are suitable as a sound-absorbing interior material represented by, for example, automobile dash insulators, are stable, and the gradient of change in these densities is gentle. The composite fiber body 1 can be obtained easily. That is, FIG. 4 shows the density change gradient in the thickness direction of the composite fiber body 1 as a dash insulator obtained in this way. In the conventional dash insulator obtained as a laminated structure by hot press-molding a high-density fiber body and a low-density fiber body, as shown by a broken line b in FIG. On the other hand, in the dash insulator obtained by the method of the present invention, as shown by a solid line a in FIG. It turns out that it is loose.

  Incidentally, if the high-density layer 1a and the low-density layer 1b of the molding material 1A are to be molded in a single process by hot pressing, it becomes difficult to control the temperature and pressurization time of the mold as described above. It becomes difficult to heat the inside of the material 1A to an appropriate temperature, and not only the moldability is deteriorated and the molding time is increased, but also the density of each layer may become unstable.

  FIG. 2 shows a second embodiment of the method of the present invention. In this second embodiment, the primary mold 21 is composed of a core mold 21A as an upper mold and a cavity mold 21B as a lower mold. The primary molding die 21 preliminarily molds the molding material 1A into a required uneven shape.

  In the second embodiment, as in the first embodiment, only the lower surface side (one surface) of the molding material 1A is heated and compressed by the primary molding die 21 to form the high-density layer 1a having the required thickness. Yes.

  Therefore, the cavity side (lower mold) 21B is configured as a heating mold incorporating a proper heater.

  When the molding material 1A is supplied between the core mold 21A and the cavity mold 21B in the step (a) shown in FIG. 2, the molding material 1A is required by the core mold 21A and the cavity mold 21B in the step (b). Pre-formed into a concavo-convex shape. In this step (b), similarly to the first embodiment, the cavity mold 21B is heated and managed at the required temperature required for compression molding processing on the lower surface side (one surface) of the molding material 1A. Therefore, only the lower surface side of the molding material 1A is pressurized and compressed, and the high-density layer 1a having a required thickness is formed on the lower surface side.

  In the step (c) shown in FIG. 2, the core die 21A and the cavity die 21B are opened, and the low-density layer 1b on the upper surface side which has not been densified in the step (b) of the molding material 1A is once temporarily formed. It is restored to the original free thickness state by the elasticity of. Then, in a state where the low density layer 1b is restored, the required temperature required for the compression molding process of the low density layer 1A through the plurality of passages 21a formed through the core mold 21A in the vertical direction. A heated fluid heat medium such as hot air is supplied. This is exactly the same as the step (b) shown in FIG. 1 in the first embodiment, and the hot air is sent into the low-density layer 1A in a substantially perpendicular direction.

  In this way, the molding material 1A in which the low-density layer 1b is heated with hot air is cold-pressed by the secondary molding die 31 into a predetermined final shape in the step (d) shown in FIG. .

  Similar to the primary mold 21, the secondary mold 31 includes a core mold 31 </ b> A that is an upper mold and a cavity mold 31 </ b> B that is a lower mold. As shown in FIG. 4D, high-density layer molding in which convex portions 31a are formed at the center position and both end positions of the mold surface, and the mold clearance is partially made extremely small in the secondary molding die 31. The part is made up.

  The molding material 1A in which the low density layer 1b is heated with hot air to the required compression molding processing temperature in the step (c) is transferred to the step (d), and is cold pressed by the core die 31A and the cavity die 31B for a required time, It is pressure-molded into the required final uneven shape. At this time, since the mold clearance is extremely small in the portion where the convex portion 31a of the core mold 31A is formed, the degree of compression of the low density layer 1b is different in the portion corresponding to the convex portion 31a of the molding material 1A. Therefore, the density of the low-density layer 1b is increased in the portion, and the thickness of the high-density layer 1a is increased over the upper and lower surfaces of the molding material 1A.

  Therefore, according to the method of the second embodiment, the same effect as that of the first embodiment can be obtained, and the obtained composite fiber body 1 has a high density layer 1a partially over the front and back surfaces. A highly rigid portion 1a ′ having an increased thickness is formed. Therefore, by using the high-rigidity portion 1a ′ as a fixing portion to the mating member to the dash panel or the like, it is possible to obtain the composite fiber body 1 that can increase the attachment rigidity.

  In both the first and second embodiments, the lower molds 2B and 21B of the primary molds 2 and 21 are used as heating molds, and hot air that is a fluid heat medium is fed from the upper molds 2A and 21A. Of course, the upper molds 2A and 21A may be heated, and hot air may be sent from the lower molds 2B and 21B.

  FIG. 3 shows a third embodiment of the present invention. The primary molding die 2 and the secondary molding die 3 used in the third embodiment are those used in the molding method of the first embodiment. Is the same.

  The method of the third embodiment is different from the method of the first embodiment in that the lower surface of the molding material 1A is formed by the upper mold 2A and the lower mold 2B of the primary mold 2 in the step (a) shown in FIG. The low density layer 1b on the upper surface side of the molding material 1A is formed through the passage 2a of the upper mold 2A in the molding process of the high density layer 1a or immediately after the molding at the time of molding the high density layer 1a having the required thickness on the side (one side). This is the point that the cooling air is entirely introduced to keep the low density layer 1b at a low temperature.

  In the step (a) shown in FIG. 3, after the high-density layer 1a is formed, the upper mold 2A and the lower mold 2B are opened, and the low-density layer 1b on the upper surface side of the molding material 1A is once restored. The cooling air is sent to the low-density layer 1b in the direction perpendicular to the plane, but it is also possible to send the cooling air to the low-density layer 1b in the molding process of the high-density layer 1a.

  When the molding material 1A is cold-pressed with the core mold 3A and the cavity mold 3B by the secondary molding die 3 in the step (b) shown in FIG. 1a is formed into the concavo-convex shape of the mold surfaces of the core mold 3A and the cavity mold 3B. At this time, since the low density layer 1b is kept at a low temperature, even if it is compressed, it retains its self-restoring property by elasticity. Therefore, after the high-density layer 1a is cooled and solidified, when the core mold 2A and the cavity mold 2B are opened in the step (c) shown in FIG. 3, the low-density layer 1b follows the processed shape of the high-density layer 1a. Thus, the composite fiber body 1 restored to the required thickness is obtained.

  According to the method of the third embodiment, as in the first and second embodiments, only the lower surface side (one surface) of the molding material 1A has a high required thickness in the process of heating and compressing by the primary mold 2. Since it is formed as the density layer 1a, temperature management and pressurization time management of the mold for forming the high density layer 1a having the required density and thickness can be facilitated.

  Then, after or during the formation of the high-density layer 1a on the lower surface side (one surface) of the molding material 1A, the high density of the molding material 1A passes through the upper mold 2A that is a non-heating-side mold of the primary molding die 2. In order to keep the low-density layer 1b at a low temperature by introducing cooling air entirely into the low-density layer 1b on the upper surface side that is not formed, the density of the high-density layer 1a toward the low-density layer 1b is increased. Is suppressed, and the high-density layer 1a having a required thickness can be easily formed.

  In this way, the progress of the densification of the high-density layer 1a on the lower surface side (one surface side) of the molding material 1A is suppressed, and the molding material 1A is secondarily placed in a state where the low-density layer 1b is kept at a low temperature. After being pressure-molded into a predetermined shape by the molding die 3, the secondary molding die 3 is opened to restore the low density layer 1b of the molding material 1A along the processed shape of the high density layer 1a. Therefore, the low density layer 1b having the required thickness and the required density can be facilitated.

  That is, since the low density layer 1b is restored to the state before compression by the mold opening of the secondary mold 3, the substantially uniform thickness and density are maintained in a stable state, and the high density layer 1a and the low density layer 1b are maintained. Thus, it is possible to obtain a composite fiber body 1 having a gentle gradient in density.

  In particular, according to the method of the third embodiment, as described above, the low density layer 1b of the molding material 1A is restored to the state before compression by the mold opening after the pressure molding by the secondary molding die 3. This is effective for obtaining a sound-absorbing interior material having a low-density layer 1b having a uniform thickness and density.

  In the first to third embodiments, trimming and piercing of the molded body may be performed at the same time when the secondary molding dies 2, 21, 3 are cold-formed by cold pressing.

DESCRIPTION OF SYMBOLS 1 ... Composite fiber body 1A ... Molding material 1a ... High density layer 1b ... Low density layer 2 ... Primary mold 2A ... Upper mold 2a ... Passage 2B ... Lower mold 3 ... Secondary mold 3A ... Core mold (upper mold)
3B ... Cavity mold (lower mold)
21 ... Primary mold 21A ... Core mold (upper mold)
21a ... passage 21B ... cavity type (lower mold)
31 ... Secondary mold 31A ... Core mold (upper mold)
31a ... convex part (high density layer molding part)
31b ... Cavity mold (lower mold)

Claims (3)

As a molding material, a fiber assembly in which the main fiber and a binder made of thermoplastic fiber having a lower melting point than this are mixed,
Compressing the molding material with a primary mold in a state where one side is heated to a required temperature required for compression molding, and forming a high-density layer with a required thickness on one side of the molding material;
Opening the primary mold and restoring the non-densified low density layer of the molding material;
Heating the restored low density layer of the molding material to a required temperature required for the compression molding by a fluid heat medium;
A step of pressure-molding a molding material in which the low-density layer is heated by a fluid heat medium into a predetermined shape using a secondary molding die, and compression-molding the low-density layer to a required thickness. A method for forming a composite fiber body.   A high-density layer molding part in which the mold clearance is partially reduced is set in the secondary molding die, and the compression density of the low-density layer of the molding material is partially increased in the high-density layer molding part to increase the density, The method for molding a composite fiber body according to claim 1, wherein the thickness of the high-density layer is increased. As a molding material, a fiber assembly in which the main fiber and a binder made of thermoplastic fiber having a lower melting point than this are mixed,
Compressing the molding material with a primary mold in a state where one side is heated to a required temperature required for compression molding, and forming a high-density layer with a required thickness on one side of the molding material;
Through the inside of the mold on the non-heating side of the primary molding die, introducing a cooling air entirely into the non-densified low-density layer of the molding material to keep the low-density layer at a low temperature;
Pressing the molding material in which the low density layer is held at a low temperature by a secondary molding die to press the high density layer into a predetermined shape together with the low density layer;
And a step of opening the secondary mold and restoring the low density layer of the molding material along the processed shape of the high density layer.

Images