JP2004216722A - Natural wood decorative sheet and method for producing resin molded article using the sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resin molded article which has no local discoloration in the grain pattern on its surface and reproduces a complicated shape such as unevenness or the like of a mold, and a natural wood decorative sheet for use in the production of the resin molded article. <P>SOLUTION: The natural tree decorative sheet is constituted by integrally laminating a surface transparent thermoplastic resin layer, a natural wood veneer, a heat-conductive sheet and a back thermoplastic resin layer from the surface side to the back side. After the sheet is arranged in an injection mold, a substrate resin is injected in the mold from the back side of the sheet and molded. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a natural wood decorative sheet and a method for producing a resin molded product using the natural wood decorative sheet.
[0002]
[Prior art]
2. Description of the Related Art In recent years, attention has been paid to excellent design properties of natural wood, and resin molded products having a woodgrain pattern using a natural wood veneer on the surface have been used for automobile interior parts, furniture, electric appliances, and the like. Such a wood-grain pattern resin molded product is obtained by placing a natural wood veneer of an arbitrary thickness in an injection molding die, injecting a synthetic resin from the back side of the veneer, and then molding the resin. It is manufactured by repeatedly painting and polishing the surface of a natural veneer veneer, and applying several layers of paint. However, in such a method, when the shape of the molded product becomes complicated, cracks occur in the natural wood veneer on the surface during injection molding, and product defects are likely to occur. Since it is necessary to repeatedly apply and polish the surface of the molded product, there is a problem that it takes time and effort and the production cost increases.
[0003]
Therefore, in order to solve the problem that cracks occur in the natural wood veneer, a surface material having a structure in which a wood veneer is laminated on both sides of a thin metal plate is arranged in a molding die, and then a synthetic resin is applied to the surface material. And a method of manufacturing a composite molded article characterized in that the surface material and the synthetic resin are integrated with each other by molding on the back side of the composite material. According to this method, the wood veneer is reinforced by a thin metal plate, so that even in the case of molding a resin molded product having a complicated shape, it is possible to obtain a wood-grained product without damage. I).
[0004]
On the other hand, in order to solve the problem of the complexity of painting and polishing, a transparent layer made of a thermoplastic resin composition, a wood layer mainly composed of natural wood, and a reinforcing layer made of the thermoplastic resin composition are sequentially formed on the surface. The laminated sheet was laminated and integrated from the side to the back side, the transparent layer was arranged along the inner surface of the cavity of the mold, and the thermoplastic resin composition was supplied to the molding space on the back side of the laminated sheet. A method of producing a laminate in which a molded article made of the thermoplastic resin composition and a laminated sheet are integrated with each other so as to directly contact the reinforcing layer with the reinforcing layer. (See, for example, Patent Document II). In this method, since the transparent layer made of the thermoplastic resin composition is adhered to the woody layer, there is no need to perform painting and polishing after injection molding as in the related art, and the wood-grain pattern resin can be formed at low cost. A molded article is obtained. However, in this method, at the time of injection molding, due to the high heat of the injected thermoplastic resin composition, the surface of the wood layer near the injection port causes discoloration, and the wood pattern on the surface of the manufactured resin molded product is locally localized. There is a place where discoloration occurs, and furthermore, the heat of the resin composition is easily confined only to the space close to the injection port, and is not quickly and uniformly transmitted to the entire laminated sheet. Therefore, it is difficult to manufacture a resin molded product that faithfully reproduces a complicated mold surface shape having irregularities and the like.
[0005]
[Patent Document I]
Japanese Patent Publication 5-58890 [pages 1-5]
[Patent Document II]
JP-A-2002-264216 [pages 1-8]
[0006]
[Problems to be solved by the invention]
The present invention has been made in consideration of such conventional circumstances, and has as its object to prevent local discoloration of the grain pattern on the surface of a molded product and to complicate the irregularities of a molding die. An object of the present invention is to propose a resin molded product that faithfully reproduces even a mold surface shape, and to provide a natural wood decorative sheet that enables production of such a resin molded product.
[0007]
[Means for Solving the Problems]
The above object is achieved by the present invention, that is, a natural wood decorative sheet in which a surface thermoplastic transparent resin layer, a natural wood veneer, a heat conductive sheet and a back thermoplastic resin layer are laminated and integrated from the front side to the back side, and This is solved by a method in which after the natural wood decorative sheet is placed in an injection mold, the base resin is injected and molded from the back side of the sheet.
[0008]
Therefore, a first subject of the present invention relates to a natural wood decorative sheet in which a surface thermoplastic transparent resin layer, a natural wood veneer, a heat conductive sheet and a back thermoplastic resin layer are laminated and integrated from the front side to the back side. . Further, the second subject of the present invention is to arrange the natural wood decorative sheet according to the first subject in a molding die, inject the base resin from the back side of the sheet, and mold the resin to be molded. Related to molded products.
[0009]
According to the sheet of the present invention, due to the high thermal conductivity of the heat conductive sheet in the natural wood decorative sheet, during injection molding, high heat conducted from the injected base resin is applied to the decorative sheet via the heat conductive sheet. Since it is quickly transmitted to the entire sheet and does not concentrate near the exit, the surface side of the natural wood decorative sheet facing the exit, that is, the surface of the veneer, does not undergo discoloration, and therefore has excellent local discoloration on the surface. A wood-patterned resin molded product is obtained, and the heat is quickly and uniformly transmitted to the entire natural wood decorative sheet, so that the thermoplastic transparent resin layer on the decorative sheet surface is sufficiently softened over the entire surface, Since the sheet can adhere to the details of the molding die, it becomes easy to manufacture a resin molded product that faithfully reproduces a complicated mold surface shape such as unevenness of the molding die. Furthermore, if the surface of the molding die is provided with a pattern of minute irregularities, etc., it becomes possible to produce a resin molded product having a higher commercial value than the conventional one having a surface resin layer provided with a three-dimensional decorative pattern, and If the surface of the molding die is a mirror surface without irregularities, it is possible to manufacture a mirror-finished resin molded product. Moreover, since the surface thermoplastic transparent resin layer is adhered to the natural wood veneer, there is no need to perform painting, polishing, etc. on the natural wood veneer after injection molding, and it is possible to reduce costs.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a cross-sectional view showing one embodiment of the natural wood decorative sheet of the present invention. FIG. 2 is a sectional view showing another embodiment of the decorative sheet for natural wood of the present invention. FIG. 3 is an arrangement diagram of the natural wood decorative sheet of the present invention in an injection mold. FIG. 4 is an arrangement diagram of a conventional laminate to an injection mold.
[0011]
In the natural wood decorative sheet 1 of the embodiment shown in FIG. 1, a surface thermoplastic transparent resin layer 2 is formed on a natural wood veneer 3, and a heat conductive sheet 4 is further provided on the lower surface of the natural wood veneer 3. The lower surface thermoplastic resin layer 5 is sequentially laminated thereunder via an adhesive, and these are laminated by laminating them by applying heat and pressure. This sheet was cut into a predetermined shape, punched out, and, as shown in FIG. 3, a backside thermoplastic resin layer 5, a heat conductive sheet 4, and a natural wood monolith in an injection mold 8 from the injection port 9 side. A resin molded product is manufactured by arranging the plate 3 and the surface thermoplastic transparent resin layer 2 in this order, and injecting a base resin 7 such as polypropylene or ABS resin from an injection port 9 on the back side of the sheet. You. The high heat conducted from the injected base resin 7 is transmitted to the entire decorative sheet, that is, the natural wood veneer 3 and the surface thermoplastic transparent resin layer 2 via the heat conductive sheet 4. Due to the high thermal conductivity of the heat conductive sheet, the high heat of the injected base resin does not concentrate near the outlet 9, so that the surface side of the natural wood decorative sheet facing the outlet, that is, the natural wood veneer 3 An excellent wood grain resin molded product having no discoloration on the surface portion 10 and no local discoloration on the surface can be obtained. In addition, since the heat is transferred to the entire natural wood decorative sheet 1 quickly and uniformly due to the high thermal conductivity of the heat conductive sheet, the surface thermoplastic transparent resin layer 2 is sufficiently softened to reach the details of the molding die 8. Since it can be in close contact, it becomes easy to manufacture a resin molded product that faithfully reproduces a complicated mold surface shape such as irregularities of a molding die, and furthermore, a pattern of minute irregularities is formed on the surface of the molding die 8. In addition, it is possible to produce a resin molded product having a higher commercial value than the conventional one having a surface resin layer provided with a three-dimensional decorative pattern, and if the surface of the molding die 8 is a mirror surface without irregularities, a mirror finish is achieved. Can be manufactured.
[0012]
After the injection molding, since the surface thermoplastic transparent resin layer 2 is adhered to the natural wood veneer 3, there is no need to perform painting, polishing, etc. on the natural wood veneer 3.
[0013]
As the surface thermoplastic transparent resin layer 2, a resin such as acrylic, polycarbonate, polyethylene, EVOH, polypropylene, polyolefin, EMMA, nylon, PET, polyurethane, polyvinyl chloride, EVA, or the like, which is made into a single film, or these resins Is used. At the time of injection molding, a resin having a glass transition temperature of about 80 to 120 ° C. is preferable as the resin layer 2 so that the surface thermoplastic transparent resin layer 2 is appropriately softened by the heat of the injected base resin 7. Further, the natural wood decorative sheet 1 (surface thermoplastic transparent resin layer 2) is in close contact with the injection mold 8 and, in the manufactured resin molded product, the natural wood veneer 3 visible through the surface thermoplastic transparent resin layer 2 An acrylic resin having a thickness of 0.03 to 0.5 mm is preferable for good appearance.
[0014]
In addition, the surface thermoplastic transparent resin layer 2 is used to print patterns, characters, symbols, etc., apply transparent coloring to the whole or partially, or apply opaque coloring to improve the design. Partial application is possible.
[0015]
Any natural wood can be used as the above-mentioned natural wood veneer 3, but from the viewpoint of design, a wood grain pattern is preferable. At the time of injection molding, the thickness of the natural wood veneer 3 is 0.1 or more and 5.0 mm so that the natural wood decorative sheet 1 (natural wood veneer 3) adheres to the injection molding die 8 and does not crack. The following is preferable, and preferably about 0.1 to 0.3 mm.
[0016]
In addition, the natural wood veneer 3 may be subjected to bleaching, dyeing, and coloring to improve design.
[0017]
As the heat conductive sheet 4, the heat of the base resin 7 injected during the injection molding is transmitted well to the natural wood veneer 3 and the surface thermoplastic transparent resin layer 2, and the heat is applied to the inside of the injection mold 8. It is preferable that the heat conductive sheet 4 is visible through the natural wood decorative veneer 3 and does not impair the design of the wood grain pattern on the surface of the resin molded product. A metal foil having a thickness of about 0.01 to 0.1 mm, or a resin film of 0.1 mm or less or paper having a basis weight of about 10 to 60 g / m ^{2 on} both sides or one side thereof, with the metal foil as a core, A sheet obtained by laminating a nonwoven fabric, a woven fabric, or the like, or a resin sheet into which fine metal particles or fibers are kneaded is used. The more preferable heat conductive sheet 4 is a metal foil having a thickness of 0.01 to 0.1 mm.
[0018]
In the prior art, as shown in FIG. 4, a laminated body is arranged in an injection mold 15 from an injection port 16 side in the order of a reinforcing layer 13, a wood layer 12, and a transparent layer 11, and a sheet is formed. A resin molded product is manufactured by injecting a base resin 14 such as polypropylene or ABS resin from an injection port 15 on the back surface side. For this reason, the high heat conducted from the base resin 14 concentrates near the injection port 16, causing discoloration on the surface side of the laminate facing the injection port 16, that is, the surface portion 10 of the wooden layer 12, and the thermoplastic resin. Since the transparent layer 11 made of the composition does not soften sufficiently and does not adhere to the details of the molding die 15, it is possible to manufacture a resin molded product that faithfully reproduces a complicated mold surface shape such as unevenness of the molding die. There was a problem that it was difficult. However, in the present invention, this problem was solved by arranging the heat conductive sheet 4 below the surface thermoplastic resin layer 2 and the natural wood veneer 3.
[0019]
As the back thermoplastic resin layer 5, the same one as the front thermoplastic transparent resin layer 2 is used. The back thermoplastic resin layer 5 adheres well to the base resin 7, and the natural wood decorative sheet 1 is injected. A material having a thickness of 0.01 to 0.3 mm and a high fusion property with the base resin 7 is selected for convenience so as to be in close contact with the molding die 8.
[0020]
Since the backside thermoplastic resin layer 5 has a high fusion property with the base resin 7, it is thermally fused with the injected base resin 7 at the time of injection molding to form the natural wood decorative sheet 1. Strong bonding of the material resin 7 is performed.
[0021]
In the embodiment shown in FIG. 2, a fibrous material 6 is further provided between the natural wood veneer 3 and the heat conductive sheet 4 in place of the embodiment shown in FIG. The layers are laminated so that they can be seen through the veneer 3 so as not to impair the design of the wood grain pattern.
[0022]
The front thermoplastic transparent resin layer 2, the natural wood veneer 3, the heat conductive sheet 4, and the rear thermoplastic resin layer 5 are the same as those exemplified in the description of FIG. 1, and the fibrous material 6 is paper The thickness can be arbitrarily set within a range that does not prevent the natural wood decorative sheet 1 from closely adhering to the injection mold 8 during injection molding. Further, the natural wood decorative sheet of the embodiment shown in FIG. 2 and the resin molded product manufactured using this sheet are also manufactured by the same method as described in the description of FIG.
[0023]
【Example】
(Example 1)
A surface thermoplastic transparent resin layer made of polycarbonate and having a thickness of 0.25 mm is formed on a 0.2 mm thick natural wood veneer obtained from a bird's eye maple with a beautiful grain pattern, and on the lower surface of the natural wood veneer. Then, a thin aluminum plate having a thickness of 0.05 mm as a heat conductive sheet and a polycarbonate having a thickness of 0.15 mm as a thermoplastic resin layer on the back side are sequentially laminated via a urethane-based adhesive, and these are heated and heated. A natural wood decorative sheet that is pressed and bonded and laminated and integrated is manufactured. This sheet is cut into a predetermined shape, punched out, and the inside of an injection molding die or the like having an uneven pattern or the like on its surface, the backside thermoplastic resin layer side (sheet backside) is injected by the injection molding die. It was arranged so as to face the outlet side, and an ABS resin was injected and molded as a base resin. The obtained resin molded product does not cause local discoloration of the grain pattern on the surface, and faithfully reproduces the complicated mold surface shape such as unevenness of the molding die. There was no one.
[0024]
【The invention's effect】
As can be seen from the above description, according to the method of the present invention, there is no local discoloration in the grain pattern of the surface of the resin molded product, and it is also possible to faithfully reproduce a complicated mold surface shape such as unevenness of a molding die. In addition, it is possible to easily and surely manufacture a resin molded product that does not require painting and polishing. And the natural wood decorative sheet of the present invention has an advantage that it is a material which enables production of such excellent resin molded products.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing one embodiment of a natural wood decorative sheet of the present invention.
FIG. 2 is a cross-sectional view showing another embodiment of the natural wood decorative sheet of the present invention.
FIG. 3 is a sectional view showing the arrangement of the natural wood decorative sheet of the present invention in an injection mold.
FIG. 4 is a layout view of a conventional laminate on an injection mold.
[Explanation of symbols]
1 Natural wood decorative sheet 2 Surface thermoplastic transparent resin layer 3 Natural wood veneer 4 Thermal conductive sheet 5 Back thermoplastic resin layer 6 Fibrous material 7 Base resin 8 Injection molding die 9 Injection port 10 Surface section 11 Transparent layer 12 wood layer 13 reinforcing layer 14 base resin 15 injection molding die 16 injection port

Claims (3)

A natural wood decorative sheet in which a surface thermoplastic transparent resin layer, a natural wood veneer, a heat conductive sheet and a back thermoplastic resin layer are laminated and integrated from the front side to the back side. The surface thermoplastic transparent resin layer is a resin layer having a glass transition temperature of 80 to 120 ° C., and the heat conductive sheet is a metal foil having a thickness of 0.01 to 0.1 mm. The natural wood decorative sheet according to claim 1. A resin molded product, wherein the decorative sheet of natural wood according to claim 1 or 2 is arranged in a molding die, and a base resin is injected from the back side of the sheet to be molded.

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