JP4815622B2 - Method for producing synthetic resin molded article with improved decoration - Google Patents

Description

  The present invention provides a method for producing a synthetic resin molded product capable of improving the decorativeness of the design surface in a synthetic resin molded product having a design surface, and more specifically, an in-mold molding method and a liquid By combining the pressure transfer printing method, a method for producing a synthetic resin molded product having a high design surface is provided.

  In recent years, synthetic resin molded products that are directly touched by the user's eyes or directly touched by the user, such as automobile interior parts and home appliances, have a smooth surface on the surface of the synthetic resin in order to improve decorativeness and touch. It has come to provide a design surface with.

  As a method of forming such a design surface, a printing layer that forms a design surface is provided in advance on a sheet-like skin material, and this skin material is arranged on the surface of the molded article substrate by an in-mold molding method. There is a manufacturing method in which the base resin is fused and integrated.

  In addition, a soluble special film on which a pattern such as a wood grain pattern or a geometric pattern is printed in advance is floated on the liquid, and a synthetic resin molded body is pressed from above. A manufacturing method is also employed in which a design surface is formed on the surface of a molded body by a hydraulic transfer method in which a printed layer is attached.

  The in-mold molding method has a high degree of design freedom and can maintain a high design position accuracy. Transparent design (also referred to as backlighting, the design part where the printed design and characters appear brightly when viewed from the front and from the back or side of the molded product) It is also possible to provide. (See Patent Document 1) Further, it has an advantage that it is possible to adjust the degree of light transmission of the transmissive design portion by controlling the printing state of the design and characters. However, in this in-mold molding method, it is difficult to dispose a sheet-like skin material provided with a design surface up to the side surface (rising portion) of the molded product, and the surface texture of the design surface (for example, the fineness of the design or In terms of luxury, there is also a problem that it does not reach the hydraulic transfer method described later.

On the other hand, when the hydraulic pressure transfer method is used as it is, it is difficult to realize a transmissive design, and it is difficult to perform light control processing on the transmissive design portion. Further, the positional accuracy of the design and the degree of freedom of the design are not as good as the in-mold molding method. However, the hydraulic transfer method can provide a design surface up to the side surface (rising part) of the molded product, and it is possible to obtain an excellent surface texture of the design surface (for example, the fineness of the design and the sense of quality). is there. (See Patent Document 2)
JP 2002-178362 A JP 2005-231223 A

  As described above, in order to improve decorativeness and touch, there are in-mold molding method and hydraulic transfer printing method as methods for providing a high-quality design surface on the surface of synthetic resin. There has been a demand for a method for producing a synthetic resin molded product having both advantages.

  However, even if both methods are applied to the same synthetic resin molded product to form a design surface, the manufacturing cost is high, and it is difficult to put it to practical use. Also, if the hydraulic transfer printing method is applied as it is, it is difficult to form a transparent design. Therefore, a transparent design (such as an instrument panel or switch panel of an automobile or an electrical product, or an operation panel of an audio product) is used. It has been impossible to apply both of these methods to synthetic resin molded products that require backlighting.

  The present invention has been devised in view of such circumstances, and while suppressing the manufacturing cost, enhances the precision and luxury of the design applied to the surface of the synthetic resin molded product, and easily forms a transparent design. It is an object of the present invention to provide a method for producing a synthetic resin molded product that can be manufactured.

  In order to solve the problems as described above, in the invention described in claim 1, a step of providing a first printing layer on one side or both sides of the synthetic resin sheet, and a predetermined on either side of the synthetic resin sheet A step of printing the release ink on the region, a step of placing the synthetic resin sheet in the mold so that the surface on which the release ink is printed contacts the inner surface of the mold, and the surface of the synthetic resin sheet on which the release ink is printed Injecting molten synthetic resin into the space defined by the back surface of the mold and the mold, molding a synthetic resin molded product integrated with the synthetic resin sheet, and a second printed layer on the outer surface of the synthetic resin molded product A step of performing a hydraulic transfer, a step of melting and removing the second printed layer in a region where the release ink is printed by liquid washing the second printed layer surface, and a step of providing a clear layer on the second printed surface; Or Adopting a method of manufacturing a formed synthetic resin molded article.

  The invention described in claim 2 is the method for producing a synthetic resin molded product according to claim 1, wherein the synthetic resin molded product can be backlit, and the first printed layer has a light-transmitting property. Or the manufacturing method of the synthetic resin molded product of the structure by which the opaque design and character are printed is employ | adopted.

  Further, in the invention described in claim 3, in the method for producing a synthetic resin molded product according to claim 2, in the vicinity of a region where a translucent or non-translucent pattern or character is printed. Adopts a method of manufacturing a synthetic resin molded product having a configuration in which a hollow transparent window made of only a synthetic resin sheet is formed without a molten synthetic resin entering. This enables backlighting even when the molten synthetic resin is opaque or translucent.

  The invention described in claim 4 is the method for producing a synthetic resin molded article according to any one of claims 1 to 3, wherein the hydraulic transfer for forming the second printed layer is a hydraulic transfer. A method of manufacturing a synthetic resin molded product having a certain configuration was adopted.

  The invention described in claim 5 is the method for manufacturing a synthetic resin molded product according to any one of claims 1 to 4, wherein a design incorporating a gradation effect is applied to the first printed layer. The manufacturing method of the synthetic resin molded product of the structure which has it was adopted.

  Furthermore, in the invention described in claim 6, the method for producing a synthetic resin molded product according to any one of claims 2 to 5, wherein the translucent or non-translucent light printed on the first printing layer is provided. A method of manufacturing a synthetic resin molded article having a configuration in which a dimming process for adjusting the degree of light transmission is performed at the time of printing a pattern or a character is used.

  By applying the in-mold molding method and the hydraulic transfer printing method to the same synthetic resin molded product, surface decoration can be applied at a low cost. Synthetic resin molded products having a design surface with a high degree of sophistication and luxury can be produced at low cost.

  In addition, a manufacturing method is provided in which a surface design of a synthetic resin molded product is applied by applying an in-mold molding method and a hydraulic transfer printing method, and a transparent design (backlighting) can be formed on the synthetic resin molded product. It became possible to do.

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

  FIG. 1 shows a basic manufacturing process of a synthetic resin molded product according to the present invention. The manufacturing process of the synthetic resin molded product according to the present invention is roughly composed of the following seven processes.

(1) Step of printing the first print layer on the synthetic resin sheet 11
(2) Step of printing release ink on a predetermined area on any surface of the synthetic resin sheet 12
(3) Step of installing the synthetic resin sheet in the mold 13
(4) Step of molding a synthetic resin molded product integrated with the synthetic resin sheet by injection of molten synthetic resin 14
(5) Step of hydraulically transferring the second printed layer onto the outer surface of the synthetic resin molded product 15
(6) A step of melting and removing the second printed layer in the region where the release ink is printed by liquid cleaning.
(7) Applying a clear layer on the second printing surface 17
The synthetic resin sheet 21 used in the present invention is not particularly limited, but a thermoplastic synthetic resin sheet 21 having a thickness of about 0.1 mm to about 2.0 mm is desirable. If the plate thickness of the synthetic resin sheet 21 is too thin, the synthetic resin sheet 21 is weak when installed in the mold, and may be displaced from the mold surface depending on the structure of the mold. Moreover, depending on the temperature of the molten synthetic resin mentioned later, the synthetic resin sheet 21 may melt partially, and the shape may not be maintained. In addition, when the plate thickness of the synthetic resin sheet 21 is too thick, it is necessary to cut it according to the shape of the mold when it is mounted on the mold, but this cutting operation tends to be difficult. Furthermore, when the thickness of the synthetic resin sheet 21 is too thick, if the curved surface of the mold is strong or the curved surface has a complicated shape, the synthetic resin sheet 21 remains on the inner surface of the mold even when the molten synthetic resin is injected. Therefore, there arises a problem that a desired molded product cannot be obtained. Further, when performing backlighting, the synthetic resin sheet 21 must be transparent or translucent.

  Screen printing is a typical printing method employed in the step 11 of printing the first printing layer 28 on the synthetic resin sheet 21. When a printing method other than screen printing is employed, only a film thickness of 1 μm or less can be obtained as a printed film thickness obtained by one-time printing, and defects such as pinholes are likely to occur in the printed layer. Therefore, in the case of backlighting, it is an essential requirement that defects such as pinholes do not occur in the printed layer, and a sufficient print film thickness (for example, 4 μm or more) that does not easily cause such defects can be obtained by one-time printing. A screen printing method that can be realized is desirable. In addition, if it is an area to be backlit and the printed part is black and forms a ground (when it is not a pattern or character), print by applying two layers of overprinting by screen printing It is desirable to make the film thickness sufficiently thick (for example, 8 μm or more). When the printed part is black and the ground is formed, unlike the printing of pictures and characters, the large area of the black ground part is likely to cause pinholes and light leakage due to backlighting is likely to occur. Because.

  The first printed layer 28 printed on the synthetic resin sheet 21 may be printed on only one side of the synthetic resin sheet 21 or may be printed on both sides to give a stereoscopic effect. Also good. Further, on the first printed layer 28, a design or the like rich in design that can give the synthetic resin molded product 23 a decorative property is printed. Furthermore, in the case of backlighting, it is possible to simultaneously print a translucent or non-translucent pattern or character on the backlit area (also referred to as a transparent design portion) of the first printing layer 28. I need it.

  In general, when a printing layer is applied by hydraulic transfer described later, it is difficult to transfer the printing layer only to a specific part of the surface of the synthetic resin molded product 23. In order to solve this problem, in the present invention, the step 12 of printing the release ink on the entire surface of any one of the surfaces of the synthetic resin sheet 21 where a printing layer by hydraulic transfer is not desired is provided. Provided. The release ink prevents the printing layer formed by hydraulic transfer from adhering to the surface of the synthetic resin molded product 23, and sol belt type silicone, solventless type ultraviolet curable silicone, or the like can be used.

  In particular, in the case of the synthetic resin molded product 23 having a transmissive design portion, it is inconvenient if a printing layer by hydraulic transfer adheres to the transmissive design portion. In such a case, printing the release ink on the transmissive design portion. As a result, it is possible to prevent the printing layer from adhering due to hydraulic transfer.

  By adopting such a method, it is possible to print a release ink that can be realized at low cost in an area where it is not desired to provide a printing layer by hydraulic transfer without performing a masking process that requires a large cost. It is possible to prevent the printing layer from adhering due to hydraulic transfer.

  In order to install the synthetic resin sheet 21 processed as described above in a mold as will be described later, the synthetic resin sheet 21 is cut in accordance with the shape of the opening of the mold. The synthetic resin sheet 21 can be cut by a scissor or a cutting machine (shearing), but may be cut by a press machine using a punching die. In addition, although the synthetic resin sheet 21 was cut and processed in accordance with the shape of the opening of the mold after each of the steps 11 and 12, the present invention is not limited to this. That is, after the synthetic resin sheet 21 is cut according to the shape of the opening of the mold, the process steps 11 and 12 may be performed on the synthetic resin sheet 21.

  Further, the synthetic resin sheet 21 cut and processed according to the shape of the opening of the mold may be formed in advance according to the shape of the inner surface of the mold. As a forming method, a hot plate type vacuum / pressure forming method can be used, or a hot press forming method can be used.

  In step 13 of placing the synthetic resin sheet 21 in the mold, the printing surface of the release ink of the synthetic resin sheet 21 faces the mold inner surface from the opening of the mating mold, that is, the outer surface of the synthetic resin molded product 23 (design). Insert and set so that In order to hold the synthetic resin sheet 21 at an appropriate position in the mold, a minute hole is provided in the mold in advance, and the hole and a vacuum source such as a vacuum pump are connected to form the mold. A space between the inner surface and the synthetic resin sheet 21 may be maintained in a vacuum state.

  As described above, after the synthetic resin sheet 21 is mounted in the mold and the mold is closed, the process proceeds to step 14 of molding the synthetic resin molded product 23 integrated with the synthetic resin sheet 21. This process is basically the same as the general injection molding process using thermoplastic resin, but the molten thermoplastic resin (hereinafter simply referred to as “molten synthetic resin”) passes through the gate and is already mounted. It is press-fitted into the space formed by the back surface of the synthetic resin sheet 21 and the mold. Therefore, for example, the direction of the gate should not be perpendicular to the synthetic resin sheet 21 so that the synthetic resin sheet 21 mounted in the mold in advance is not broken by the molten synthetic resin that is press-fitted. Such considerations are necessary. Thus, after the molten synthetic resin is press-fitted into the space formed by the back surface of the synthetic resin sheet 21 and the mold, when the temperature of the molten synthetic resin decreases to some extent, the synthetic resin molded product 23 integrated with the synthetic resin sheet 21 is formed. The (Hereinafter, the portion where the injected molten synthetic resin has solidified will be referred to as “base resin”.) In this case, the outer surface (design surface) of the synthetic resin molded product 23 is provided on the synthetic resin sheet 21. The first print layer 28 is visible.

  Based on FIGS. 2-4, the process 14 which shape | molds the synthetic resin molded product 23 integrated with the synthetic resin sheet 21 is demonstrated in detail.

  FIG. 2 shows the state of the mold in part B of the synthetic resin molded product 23 shown in FIG.

  The synthetic resin sheet 21 is mounted on the inner surface side of the mold 27a, and the molten synthetic resin 22 is press-fitted into a space defined between the back surface of the synthetic resin sheet 21 and the mold 27b. The molten synthetic resin 22 is introduced into the molds 27 a and 27 b through the injection molding nozzle 26, the sprue 25, and the gate 24. The synthetic resin sheet 21 to be mounted on the inner surface side of the mold 27a can be molded in advance according to the inner surface shape of the mold 27a. The molten synthetic resin 22 press-fitted into the space between the back surface of the synthetic resin sheet 21 and the mold 27b is welded and joined to the synthetic resin sheet 21, and is cooled and solidified by a relatively low temperature mold. As a result, a synthetic resin molded product 23 in which the synthetic resin sheet 21 and the base resin 22 (the solidified molten synthetic resin 22) are integrated as shown in FIG. 3 is completed.

  FIG. 4 is an enlarged view of portion A in FIG. A first print layer 28 is provided on the outer surface of the base resin 22, and a release ink layer 30 is provided on the first print layer 28.

  In the case where a backlighting part (transmission design part) is provided in a part of the synthetic resin molded product 23 and the base resin 22 is made of an opaque or translucent resin, the light transmission for the backlighting A translucent window 31 is provided to enable the above. (Refer to FIG. 3.) The translucent window 31 is provided in the vicinity of a region where a translucent or non-translucent pattern or character printed on the synthetic resin sheet 21 is printed. In this part, the mold shape is such that the molten synthetic resin 22 does not enter. Therefore, a recessed light-transmitting window 31 made of only the synthetic resin sheet 21 is formed in the backlighting portion of the synthetic resin molded product 23 that has been molded. When the base resin 22 is made of a transparent resin, a light-transmitting window is not always necessary. However, in order to prevent unnecessary light from leaking during backlighting, the base resin 22 or a synthetic resin is not necessary. The coating which shields light in the predetermined position of the resin sheet 21 is needed.

  When the synthetic resin sheet 21 and the base resin 22 are integrally molded, the synthetic resin molded article 23 is completed. Then, the second printing layer 32 is hydraulically transferred onto the outer surface of the synthetic resin molded article 23. Move.

  Here, the hydraulic transfer is also referred to as a hydraulic transfer printing method, and a solvent such as thinner is sprayed on a pattern portion of a transfer sheet on which a pattern or pattern to be printed has been printed in advance, and paint or ink constituting the pattern is applied. After making it into a dissolved state, the transfer sheet is floated on the liquid surface so that the pattern faces upward, and the outer surface (that is, the design surface) of the synthetic resin molded product 23 that is the part to be coated is pressed against the pattern portion of the transfer sheet. However, the transfer sheet is submerged in the liquid, and the design is transferred from the transfer sheet to the portion to be coated by liquid pressure. A liquid using water as a liquid to be used is referred to as a water pressure transfer or water pressure transfer printing method.

  Here, the transfer sheet refers to a sheet on which a printed pattern is printed with a transfer ink on a water-soluble or water-swellable base film. The base film includes, for example, polyvinyl alcohol as a main component. A mixture of polyacrylic acid amide, other water-soluble polymer, starch, gelatin, glue and the like as required is used.

  After transferring the second printed layer 32 of the pattern or pattern to the outer surface of the synthetic resin molded article 23 by the hydraulic transfer printing method as described here, the release ink is removed by liquid washing (for example, washing with water). It moves to the process 16 which removes the 2nd printing layer 32 of the printed area | region. In the liquid washing step 16, the transfer sheet that is no longer necessary is removed, and moisture and solvent adhering to the transfer are removed. Further, in the region where the release ink is printed on the surface of the synthetic resin molded product 23, the second print layer 32 formed by the hydraulic transfer is removed, and the release ink layer 30 attached to the surface is also washed away. After the liquid cleaning is completed, excess water (cleaning liquid) adhering to the surface is dried and removed.

  After the liquid washing step 16, a step 17 for applying the clear layer 33 on the second printing surface 32 of the synthetic resin molded product 23 is performed. The clear layer 33 protects the second printed layer 32 (having a function as a so-called top coat) and smoothes the surface of the synthetic resin molded product 23 by filling the region of the second printed layer 32 that has been washed away. To finish. (See FIG. 5.) As the clear layer 33, for example, a two-component urethane paint can be used.

  FIG. 5 schematically shows a part of the synthetic resin molded product 23 after the step 17 of applying the clear layer 33 on the second printed layer 32 is performed (that is, in a completed state). It is a representation.

  As described above, in the production of the synthetic resin molded article 23, the in-mold molding method and the hydraulic transfer printing method or the hydraulic transfer printing method are adopted while applying the technical idea of the present invention. By adopting the method of printing the release ink on the ground surface, it is possible to eliminate the masking and masking process that has been performed manually, and the surface texture of the unprecedented advanced design surface. It has become possible to produce a synthetic resin molded article 23 having a high degree of design (for example, a fine design or a high-class feeling) at low cost. In addition, the surface of the synthetic resin molded product 23 is decorated by applying the in-mold molding method and the hydraulic transfer printing method, while any transmission design can be applied to the synthetic resin molded product 23 without being obstructed by the printing layer by the hydraulic transfer. It has become possible to establish a manufacturing method capable of forming (backlighting).

  In addition, although the 1st printing layer 28 shown in FIG.4 and FIG.5 showed what was printed on the outer surface (surface on the opposite side of the base resin 22) side of the synthetic resin sheet 21, synthetic resin sheet 21 is shown. May be printed on the inner surface (the surface on the base resin 22 side), or may be printed on both surfaces of the synthetic resin sheet 21.

  In addition, by incorporating the gradation effect into the first printing layer 28 described above, the gradation effect of the first printing layer 28 and the design and pattern of the second printing layer 32 are superimposed, so that the light and shade that could not be expressed conventionally. It becomes possible to express a certain design.

  Furthermore, by adjusting the thickness of the ink layer of the translucent or non-translucent pattern or the character portion printed on the transmissive design portion of the first printed layer 28 and the type of ink, the transmission of light in the transmissive design portion can be achieved. It is possible to easily perform the dimming process of adjusting the degree.

  INDUSTRIAL APPLICABILITY The present invention can be applied to synthetic resin molded products used in a wide range of fields such as building interior parts and sunday miscellaneous goods, as well as instrument panels and switch panels for automobiles and electrical products, and operation panels for audio products.

FIG. 1 shows a basic manufacturing process of a synthetic resin molded product according to the present invention. FIG. 2 shows the state of the mold in part B of the synthetic resin molded product shown in FIG. FIG. 3 is an example of a synthetic resin molded product molded according to the present invention, and schematically shows a cross section thereof. FIG. 4 is a schematic enlarged view of a cross-section portion of A part in FIG. FIG. 5 shows a completed state of the synthetic resin molded product, and schematically shows a cross-sectional portion of the A part in FIG.

Explanation of symbols

11 Step of printing the first printed layer on the synthetic resin sheet 12 Step of printing the release ink on any surface of the synthetic resin sheet 13 Step of installing the synthetic resin sheet in the mold 14 Integrated with the synthetic resin sheet Step 15 for molding the synthetic resin molded product Step 16 for hydraulically transferring the second printed layer onto the outer surface of the synthetic resin molded product 16 Step 17 for cleaning and removing the second printed layer in the area where the release ink is printed 17 On the second printed surface Step 21 of applying clear layer to synthetic resin sheet 22 Molten synthetic resin (or base resin)
23 Synthetic resin molded product 24 Gate 25 Sprue 26 Nozzle 27a, 27b Mold 28 First printing layer 30 Peeling ink layer 31 Translucent window 32 Second printing layer 33 Clear layer

Claims (6)

A method for producing a synthetic resin molded article,
(1) providing a first printed layer on one or both sides of the synthetic resin sheet;
(2) printing a release ink on a predetermined region on any surface of the synthetic resin sheet;
(3) installing the synthetic resin sheet in the mold so that the surface on which the release ink is printed contacts the inner surface of the mold;
(4) injecting a molten synthetic resin into a space defined by the back surface of the surface on which the release ink of the synthetic resin sheet is printed and a mold, and molding a synthetic resin molded product integrated with the synthetic resin sheet; ,
(5) hydraulically transferring the second printed layer onto the outer surface of the synthetic resin molded article;
(6) melt-removing the second printed layer in the region where the release ink is printed by liquid cleaning the second printed layer surface;
(7) providing a clear layer on the second printed surface;
A method for producing a synthetic resin molded product comprising: A method for producing a synthetic resin molded article according to claim 1,
The method for producing a synthetic resin molded product, wherein the synthetic resin molded product is capable of backlighting, and a light-transmitting or non-translucent pattern or character is printed on the first printed layer.   3. The method for producing a synthetic resin molded article according to claim 2, wherein the molten synthetic resin does not enter in the vicinity of a region where the translucent or non-translucent pattern or character is printed. A method for producing a synthetic resin molded product, wherein a hollow light-transmitting window composed only of a sheet is formed.   4. The method for producing a synthetic resin molded product according to claim 1, wherein the hydraulic transfer for forming the second printed layer is a hydraulic transfer. Method.   5. The method for producing a synthetic resin molded product according to claim 1, wherein a design incorporating a gradation effect is applied to the first printed layer. Method.   The method for producing a synthetic resin molded article according to any one of claims 2 to 5, wherein light is transmitted through a translucent or non-translucent pattern or character printed on the first printing layer. A method for producing a synthetic resin molded product, characterized in that the light control processing for adjusting the degree is performed when the pattern or the character is printed.

Images