JP2013198984A - Fiber-reinforced thermoplastic resin structure and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fiber-reinforced thermoplastic resin structure integrated with a low-gravity core layer and a surface membrane in a uniform and desirable state, and to provide its manufacturing method.SOLUTION: There is provided a manufacturing method of a fiber-reinforced thermoplastic resin structure which is characterized in that: an uncontinuous fiber-reinforced thermoplastic resin having initial density A is made to serve as a core layer; a molding base material is formed by arranging a surface membrane comprising a non-expansive fiber-reinforced thermoplastic resin on at least one face of the core layer; the core layer and the surface membrane are integrated with each other by heating and melting the molding base material; the core layer is expanded so that the core layer may have density B lower than the initial density A by developing a restoration force to a shape before the molding of the core layer to an uncontinuous reinforced fiber in the core layer; after that, the molding base material is set into a molding mold; and the molding base material is press-molded in the molding mold so that the density of the core layer may become density C between the density B and the initial density A. There is also provided a fiber-reinforced thermoplastic resin structure manufactured by the method.

Description

  TECHNICAL FIELD The present invention relates to a fiber-reinforced thermoplastic resin structure and a method for producing the same, and in particular, a relatively large large-area structure with high mechanical properties while reducing the overall weight by reducing the specific gravity in the thickness of the structure. TECHNICAL FIELD The present invention relates to a method for producing a fiber-reinforced thermoplastic resin structure that can be easily produced in a state where the above is uniformly expressed, and a fiber-reinforced thermoplastic resin structure produced by the method.

  Fiber reinforced thermoplastic resin structures that are lightweight and have high mechanical properties are applied in various fields. Among them, the method of manufacturing a fiber-reinforced thermoplastic resin structure by heating and press-molding using a stampable base material made of a thermoplastic resin containing reinforcing fibers can easily manufacture a relatively large structure. For this reason, it has been adopted in the manufacture of various structures that require light weight and high rigidity.

  In this manufacturing method, in order to develop high mechanical properties such as high rigidity while maintaining the weight reduction characteristics of the structure and to give the structure surface a desired design, the inner layer has a low specific gravity (for example, foam A structure in which the core layer is composed of a fiber reinforced thermoplastic resin layer (with a body structure) and the surface layer is a skin layer (skin layer) composed of a solid, relatively thin fiber reinforced thermoplastic resin layer is preferable.

  As a technique for realizing such a structure, the skin material and a paper-making method fiber-reinforced thermoplastic resin sheet that has been preheated and expanded five times or more in the thickness direction are supplied between the pair of molds so as to overlap each other, and then expanded. Paper-making method Fiber-reinforced thermoplastic with mold-clamping and compression until the fiber-reinforced thermoplastic resin sheet is 40-80% thick, so that the base fiber-reinforced thermoplastic resin sheet (core layer) and skin material are integrated. A method for producing a resin molded body is known (Patent Document 1).

JP-A-8-238638

  However, in the method described in Patent Document 1, the core material that has been expanded (foamed) in advance by preheating and the skin material are set in a mold, and the contact surface of the skin material is set by the heat of the core material. Since both materials are integrated by melting, there is a possibility that the melting of the contact surface of the skin material at the time of integration may vary or local contact defects may occur locally. . For this reason, there is a risk of problems such as poor quality of the structure, such as poor adhesion, and uneven adhesion between the two layers. This problem becomes more apparent as the structure to be manufactured becomes larger and larger in area. come.

  Therefore, the object of the present invention is to integrate a core layer and a skin material with a uniform adhesive force without causing poor adhesion, etc., even with a relatively large large-area structure, A method of manufacturing a fiber reinforced thermoplastic resin structure that can be integrated with a skin material in a desirable and uniform state, and can easily and reliably express desired lightness and high mechanical properties, and manufactured by the method. Another object of the present invention is to provide an improved fiber reinforced thermoplastic resin structure.

In order to solve the above-mentioned problems, a method for producing a fiber-reinforced thermoplastic resin structure according to the present invention uses a discontinuous fiber-reinforced thermoplastic resin having an initial density A having expandability when heated and melted as a core layer, and the core layer A base material for molding is formed by arranging a skin material made of a non-expandable fiber-reinforced thermoplastic resin on at least one surface of
By heating and melting the base material for molding, the core layer and the skin material are integrated, and the discontinuous reinforcing fibers in the core layer are made to develop a restoring force to the shape before molding the core layer. Expanding the core layer so that the core layer has a density B lower than the initial density A,
Thereafter, the molding base material in which the core layer is expanded is set in a molding die, and the molding base material has a density C between the density B and the initial density A. Is formed by press molding in a mold. Here, the initial density A is the density of the core layer before the core layer is expanded by heating and melting.

  In such a method for producing a fiber-reinforced thermoplastic resin structure according to the present invention, first, a core layer made of a discontinuous fiber-reinforced thermoplastic resin having an initial density A before expansion is disposed on at least one surface of the core layer. A base material for molding consisting of a non-expandable fiber-reinforced thermoplastic resin skin material is formed, and then the base material for molding is heated and melted outside the mold (mold), for example. As a result, the core layer and the skin material are integrated, and the discontinuous reinforcing fibers in the core layer are allowed to exhibit a restoring force (spring back) to the shape before the core layer is formed, so that the core layer is initially The core layer is expanded so that the density B is lower than the density A. That is, at the stage before being set in the molding die, a molding base material is formed in which the core layer and the skin material expanded so as to have a density B are integrated. In this integration, the contact surfaces of both the core layer and the skin material are melted by heating the entire molding base material, so that local melting defects and variations in melting are prevented from occurring between the two layers. The core layer and the skin material having a low specific gravity of density B are integrated with a uniform adhesive force in a desirable state without variation. After this integration, the molding base material is set in the mold, and the density of the core layer is a density C between the density B and the initial density A (that is, high mechanical properties as well as a desired weight reduction of the structure). The molding substrate is press-molded in a mold so as to achieve a density C) that can be realized. Since the core layer and the skin material are press-formed in a uniformly integrated state, the structure to be formed can also realize a uniform integrated form and uniform quality, particularly in the final formed form. In the final form, a core layer having a desired density C lower than the initial density A (that is, a desired expansion ratio) and an unexpanded skin material are integrated. Therefore, especially when the core layer has a desired low density C, the desired weight reduction of the structure is achieved, the core layer has a desired expansion ratio, and the thickness of the core layer is larger than the initial thickness before expansion. By being properly increased, the desired high mechanical properties of the structure, in particular the high stiffness associated with increased wall thickness, are achieved. In addition, by realizing the uniform integrated form, these excellent light weight and high mechanical properties are uniformly achieved throughout the entire structure, and uniform quality is realized.

  In the method for producing a fiber-reinforced thermoplastic resin structure according to the present invention, it is preferable that the discontinuous reinforcing fibers are randomly dispersed in the core layer. If the discontinuous reinforcing fibers are randomly dispersed, the base material for molding is heated and melted, and the discontinuous reinforcing fibers in the core layer develop a restoring force to the shape before forming the core layer and the core layer is expanded. In this case, uniform expansion is possible over the entire core layer, and uniform compression is also possible when a molding substrate having a uniformly expanded core layer is press-molded. As a result, a more uniform structure quality can be realized in the final molded form.

  The number average fiber length of the discontinuous reinforcing fibers of the core layer is preferably in the range of 3 to 50 mm. If the number average fiber length is less than 3 mm, the degree of entanglement between the fibers decreases, so that the restoring force described above decreases, and it may be difficult to expand the core layer to a desired thickness. Conversely, if the number average fiber length exceeds 50 mm, random dispersion of discontinuous reinforcing fibers may be difficult, and the uniformity of the structure quality may be impaired.

  In order to impart desirable dispersibility to the discontinuous reinforcing fibers before forming the core layer, for example, the discontinuous reinforcing fibers before impregnation with the thermoplastic resin are made of a reinforcing fiber mat manufactured by papermaking or carding. It is preferable. The reinforcing fiber mat manufactured by the papermaking method can easily obtain random dispersion of discontinuous reinforcing fibers, and the reinforcing fiber mat manufactured by the carding method can easily disperse random reinforcing fibers. It can also be obtained, or the dispersed discontinuous reinforcing fibers can be intentionally given appropriate directivity.

  Further, in the method for producing a fiber-reinforced thermoplastic resin structure according to the present invention, the density C is in the range of 1/3 times or more to less than 1 time of the initial density A depending on the conditions of press molding in the mold. It is preferable to control. If the density C is less than 1/3 times the initial density A, the expansion rate of the core layer in the final form is too high, and it may be difficult to maintain the strength of the core layer itself, and thus the strength of the structure, at a desired strength. There is. When the density C becomes 1 time the initial density A, the core layer returns to the state before expansion, so that the effect of increasing the structure thickness due to the expansion of the core layer is lost, and the effect of improving the mechanical properties due to the expansion is lost.

  It is preferable that the press pressure in the said press molding shall be 5 Mpa or less, for example. In general, when a pressing pressure of 6 MPa or more is applied, the expanded core layer may return to the state before expansion, and therefore, in order to properly compress the expanded core layer, press This is because the pressure needs to be controlled appropriately.

  The reinforcing fiber of the skin material is not particularly limited, but the skin material is made of a non-expandable fiber reinforced thermoplastic resin, constitutes the surface layer of the structure in the final molded form, and combines the strength of the structure with the core layer. It is preferable to have high rigidity (such as bending rigidity) with respect to a desired direction. For that purpose, it is preferable that the reinforcing fiber of the skin material is composed of continuous fibers.

  As the skin material, a skin material in which reinforcing fibers are aligned in one direction and impregnated with a thermoplastic resin can be used. If such a skin material is used, even if it is a comparatively large-sized large-area structure, a skin material can be easily arrange | positioned in a predetermined position. Further, in this case, the skin material can be in the form of a plate-like skin material obtained by laminating or knitting a tape-like base material in which reinforcing fibers are aligned in one direction and impregnated with a thermoplastic resin. If such a form is adopted, even if the structure is a relatively large large-area structure, the skin material can be easily arranged at a predetermined position, and desired mechanical properties can be easily imparted to the skin material.

  Moreover, the form containing a reinforced fiber fabric can be taken as a skin material. If such a form is adopted, it becomes possible to give a desired design property to the surface of the structure in the final formed form. In addition, by including the reinforced fiber fabric, it is possible to further improve the mechanical properties of the skin material itself constituting the surface layer of the structure, so that the mechanical properties of the entire structure can be improved.

  Moreover, in the manufacturing method of the fiber reinforced thermoplastic resin structure which concerns on this invention, a skin material can be arrange | positioned on both surfaces of the said core layer. If comprised in this way, since it will be what is called a sandwich structure which sandwiched the moderately expanded low specific gravity core layer from both sides with two non-expandable skin materials, the light weight and high mechanical characteristics of the structure are further increased. Easily achieved.

  The reinforcing fiber used in the structure according to the present invention is not particularly limited. For example, at least one selected from carbon fibers, glass fibers, and aramid fibers can be used as at least one reinforcing fiber of the core layer and the skin material. Among them, it is preferable to include carbon fiber in consideration of realization of high mechanical properties, ease of strength design, and the like.

  Further, the thermoplastic resin used in the structure according to the present invention is not particularly limited. For example, a form containing at least one of a polyphenylene sulfide resin, a polyamide resin, a polyolefin resin, a polyester resin, an ABS resin, a polycarbonate resin, a polyacetal resin, and a polyether ether ketone resin as at least one thermoplastic resin of the core layer and the skin material It can be.

  Further, when the thermoplastic resin of the core layer and the skin material is made of the same kind of resin, the two layers can be more easily integrated by fusion bonding.

  The present invention also provides a fiber reinforced thermoplastic resin structure produced by the method as described above, wherein the density of the core layer is lower than the initial density A of the core layer when forming the molding substrate.

  As described above, according to the present invention, a core layer and a skin material having a moderately low specific gravity can be integrated in a uniform and desirable state even in a relatively large large-area structure, and a desired lightweight property and high A fiber reinforced thermoplastic resin structure having both mechanical properties can be obtained easily and reliably.

It is a process flow figure showing a manufacturing method of a fiber reinforced thermoplastic resin structure concerning one embodiment of the present invention.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 shows a method for producing a fiber-reinforced thermoplastic resin structure according to an embodiment of the present invention. In the manufacturing method according to the present invention, first, as shown in FIG. 1 (A), for example, a reinforcing fiber mat manufactured by a papermaking method is impregnated with a thermoplastic resin, and has an initial density A having expandability when heated and melted. For example, continuous reinforcing fibers are aligned in one direction on at least one surface (both surfaces in the illustrated example) of the core layer forming base material 1 (that is, the core layer having an initial density A) made of the discontinuous fiber reinforced thermoplastic resin. A plate-like member knitted with a tape-like base material impregnated with a thermoplastic resin, and a skin material 2 made of a non-expandable fiber-reinforced thermoplastic resin at the time of heating and melting is arranged to form a base material 3 for molding. Is done.

  Next, as shown in FIG. 1B, a molding base material 3 in which a skin material 2 is arranged on both surfaces of a core layer forming base material 1 is positioned between, for example, heaters 4 and 4 as heating means. Thus, the entire molding substrate 3 is heated and melted by heating by the heaters 4 and 4. In this heating and melting, the contact surfaces of both the core layer forming base material 1 and the skin material 2 are melted over the entire surface, so that the core layer forming base material 1 and the skin material 2 are integrated in a uniform bonded state. . At the same time, as shown in FIG. 1C, the discontinuous reinforcing fibers in the core layer forming base material 1 exhibit a restoring force to the shape before forming the base material, and the restoring force (spring back) The core layer forming base material 1 is expanded so as to have a density B lower than the initial density A, whereby the core layer 5 having the expanded density B is formed. At this time, the skin material 2 made of a non-expandable fiber-reinforced thermoplastic resin is maintained in a substantially intact form.

  Next, the molding base material 3 in which the core layer 5 is expanded so as to have a density B is set in a mold 6 as a molding die, as shown in FIG. Thereafter, as shown in FIG. 1 (E), the mold 6 is closed and clamped, and press molding is performed on the molding substrate 3 with a pressing pressure of 5 MPa or less in the cavity 7 of the mold 6. Done. By this press molding, the core layer 5 is compressed so that the density of the core layer 5 becomes a density C between the density B and the initial density A, thereby forming the core layer 8 of the density C, and a predetermined shape along the shape of the cavity 7. The fiber reinforced thermoplastic resin structure 9 is molded. After this press molding, the mold 6 is opened, and the fiber reinforced thermoplastic resin structure 9 molded into a predetermined shape may be taken out.

  In the molding as described above, as described above, the core layer 5 and the skin material 2 that have been expanded so as to have the density B are integrated in the stage before being set in the mold 6. In forming the base material 3, the entire molding base material 3 is heated and the contact surfaces of both the core layer forming base material 1 and the skin material 2 are melted over the entire surface. Occurrence of defects and variations in melting are prevented, and the core layer 5 having a low density B with the density B and the skin material 2 are integrated with a uniform adhesive force in a desirable state without variations. Since it is press-molded in such a uniformly integrated state, the structure 9 to be molded also becomes a uniform integrated form in the final molded form, and uniform quality is realized.

  And the fiber reinforced thermoplastic resin structure 9 by which the core layer 8 of the desired density C between the initial density A and the density B and the unexpanded skin material 2 were integrated in the last shaping | molding form is shape | molded. However, particularly when the core layer 8 has the desired low density C, the desired weight reduction of the structure 9 is achieved, and an appropriate thickness of the core layer 8 is ensured. This achieves the desired high mechanical properties of the structure 9, in particular high stiffness due to the appropriate thickness of the core layer 8. In addition, these excellent lightweight properties and high mechanical properties are uniformly achieved throughout the entire structure 9, and uniform quality is achieved throughout the entire structure 9.

  The fiber reinforced thermoplastic resin structure and the method for producing the same according to the present invention can be applied to the production of any fiber reinforced thermoplastic resin structure having light weight and high mechanical properties. It is suitable for manufacturing a structure.

1 Core layer forming substrate (core layer with initial density A)
2 Skin material 3 Molding substrate 4 Heater 5 as heating means Density B core layer 6 Mold as mold 7 Cavity 8 Density C core layer 9 Fiber reinforced thermoplastic resin structure

Claims (15)

A discontinuous fiber reinforced thermoplastic resin having an initial density A that has expandability when heated and melted is used as a core layer, and a skin material made of a fiber reinforced thermoplastic resin that is non-expandable when heated and melted is disposed on at least one surface of the core layer. Forming a molding substrate,
By heating and melting the base material for molding, the core layer and the skin material are integrated, and the discontinuous reinforcing fibers in the core layer are made to develop a restoring force to the shape before molding the core layer. Expanding the core layer so that the core layer has a density B lower than the initial density A,
Thereafter, the molding base material in which the core layer is expanded is set in a molding die, and the molding base material has a density C between the density B and the initial density A. A method for producing a fiber-reinforced thermoplastic resin structure, characterized by press-molding in a mold.   The method for producing a fiber-reinforced thermoplastic resin structure according to claim 1, wherein the discontinuous reinforcing fibers are randomly dispersed in the core layer.   The manufacturing method of the fiber reinforced thermoplastic resin structure of Claim 1 or 2 whose number average fiber length of the said discontinuous reinforcement fiber of the said core layer is 3-50 mm.   The method for producing a fiber-reinforced thermoplastic resin structure according to any one of claims 1 to 3, wherein the discontinuous reinforcing fibers before forming the core layer are made of a reinforcing fiber mat manufactured by papermaking or a carding method. .   The fiber reinforced thermoplasticity according to any one of claims 1 to 4, wherein the density C is controlled in a range of 1/3 times or more and less than 1 time of the initial density A depending on the conditions of press molding in the mold. Manufacturing method of resin structure.   The manufacturing method of the fiber reinforced thermoplastic resin structure in any one of Claims 1-5 which sets the press pressure in the said press molding to 5 Mpa or less.   The manufacturing method of the fiber reinforced thermoplastic resin structure in any one of Claims 1-6 in which the reinforced fiber of the said skin material consists of continuous fibers.   The method for producing a fiber-reinforced thermoplastic resin structure according to any one of claims 1 to 7, wherein a skin material in which reinforcing fibers are aligned in one direction and impregnated with a thermoplastic resin is used as the skin material.   The fiber-reinforced thermoplastic resin structure according to claim 8, wherein the skin material is a plate-like skin material obtained by laminating or braiding a tape-like base material in which reinforcing fibers are aligned in one direction and impregnated with a thermoplastic resin. Body manufacturing method.   The manufacturing method of the fiber reinforced thermoplastic resin structure in any one of Claims 1-9 in which the said skin material contains a reinforced fiber fabric.   The manufacturing method of the fiber reinforced thermoplastic resin structure in any one of Claims 1-10 which arrange | positions the said skin material on both surfaces of the said core layer.   The fiber-reinforced thermoplastic resin structure according to any one of claims 1 to 11, comprising at least one selected from carbon fiber, glass fiber, and aramid fiber as at least one reinforcing fiber of the core layer and the skin material. Manufacturing method.   As the thermoplastic resin of at least one of the core layer and the skin material, including at least one of polyphenylene sulfide resin, polyamide resin, polyolefin resin, polyester resin, ABS resin, polycarbonate resin, polyacetal resin, polyether ether ketone resin, The manufacturing method of the fiber reinforced thermoplastic resin structure in any one of Claims 1-12.   The manufacturing method of the fiber reinforced thermoplastic resin structure in any one of Claims 1-13 in which the thermoplastic resin of the said core layer and the said skin material consists of the same kind of resin.   Fibers produced by the method for producing a fiber-reinforced thermoplastic resin structure according to any one of claims 1 to 14, wherein the density of the core layer is lower than the initial density A of the core layer when forming the molding substrate. Reinforced thermoplastic resin structure.

Images