JP2011083954A - Synthetic resin molding having two-layer sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a synthetic resin molding which is obtained by integral molding of synthetic resin sheets and is hard to cause warpage due to the difference of thermal expansion and contraction without apply ing any annealing. <P>SOLUTION: After charging the synthetic resin sheets by adjoining to a metal mold surface, a molten resin is injected into a metal mold to obtain the synthetic resin molding 1 in which welding joining of the synthetic resin sheets are carried out. The synthetic resin molding is equipped with a first synthetic resin sheet 20 at least on one surface of which an ink film layer 21 is formed, a synthetic resin plate 10 obtained by welding joining of the first synthetic resin sheet 20 with a first surface 10a and a second synthetic resin sheet 30 obtained by welding joining of the first surface 10a of the synthetic resin plate 10 with a second surface 10b thereof having a front and back relation. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a synthetic resin molded product obtained by integrally molding a synthetic resin sheet, and particularly to a synthetic resin molded product having a two-layer synthetic resin sheet.

  In automobile instrument panels and household appliance panels, light is often applied from the back side of the instrument panel and panels to make letters and patterns look bright and visible from the front (hereinafter referred to as “backlighting”). Backlighting characters and patterns are manufactured by printing on a synthetic resin molded product or by attaching a synthetic resin sheet on which characters and patterns are printed. Among these, it is advantageous from the viewpoint of production cost and the like to manufacture a synthetic resin sheet on which characters and patterns are printed by being attached to a synthetic resin molded product. Therefore, a synthetic resin sheet printed with characters and patterns is loaded into a mold, and a molten resin is injected to form a single piece. (For example, refer to Patent Document 1).

  In a synthetic resin molded product formed by integrating synthetic resin sheets, the material of the synthetic resin main body and the synthetic resin sheet are generally different, and similar to bimetal due to the difference in thermal expansion and contraction after injection molding. There was a problem of warping. Therefore, annealing was performed after the production of the synthetic resin molded product to correct warpage due to thermal expansion and contraction.

JP 2002-178362 A (4th, 5th page, FIG. 7)

  However, since the annealing process takes time, the production efficiency of the synthetic resin molded product is lowered by the annealing process, and the annealing process may become a bottleneck in productivity of the synthetic resin molded product.

  Then, an object of this invention is to provide the synthetic resin molded product which shape | molded the synthetic resin sheet | seat integrally and is hard to produce the curvature by the difference of thermal expansion / contraction without annealing.

  In order to achieve the above object, the synthetic resin molded product according to the first aspect of the present invention is loaded with a synthetic resin sheet adjacent to the mold surface, for example, as shown in FIG. A first synthetic resin sheet 20 having an ink film layer 21 formed on at least one side thereof, which is a synthetic resin molded article 1 formed by injecting a molten resin and welding and bonding the synthetic resin sheet; A synthetic resin plate 10 in which the resin sheet 20 is welded and bonded to the first surface 10a; a second synthetic resin in which the first surface 10a of the synthetic resin plate 10 is welded and bonded to the second surface 10b in a front-back relationship. A sheet 30.

  With this configuration, since the synthetic resin sheet is welded and bonded to both surfaces of the synthetic resin plate, the force that causes warpage due to the difference in thermal expansion and contraction between the synthetic resin plate and the synthetic resin sheet It becomes a synthetic resin molded product that is less prone to warpage due to differences in thermal expansion and contraction.

Further, the synthetic resin molded product according to the second aspect of the present invention is, for example, as shown in FIG. 3, in the synthetic resin molded product 2 according to the first aspect, the first synthetic resin sheet 22 is the first surface. The second synthetic resin sheet 32 covers a part of the second surface including a portion where the synthetic resin plate 12 is easily bent.
If comprised in this way, since the 2nd synthetic resin sheet only covers a part of 2nd surface including the part which is easy to bend of a synthetic resin board, the usage-amount of a 2nd synthetic resin sheet can be reduced. This is an economically superior synthetic resin molded product. Still, since the second synthetic resin sheet covers the portion of the synthetic resin plate that is easily bent, it is a synthetic resin molded product that is less likely to warp due to a difference in thermal expansion and contraction.

Moreover, the synthetic resin molded product according to the third aspect of the present invention is the same as the synthetic resin molded product according to the first or second aspect, wherein the first synthetic resin sheet and the second synthetic resin sheet are the same material. Formed with.
If comprised in this way, since the 1st synthetic resin sheet and the 2nd synthetic resin sheet are formed with the same raw material, the difference of thermal expansion and contraction between the 1st synthetic resin sheet and the 2nd synthetic resin sheet This is a synthetic resin molded product in which warpage due to a difference in thermal expansion and contraction does not occur.

Moreover, the synthetic resin molded product according to the fourth aspect of the present invention is the synthetic resin molded product according to the third aspect, wherein the synthetic resin plate is a material of the first synthetic resin sheet and the second synthetic resin sheet. It is made of a different material.
If comprised in this way, a 1st synthetic resin sheet and a 2nd synthetic resin sheet will be formed with the same raw material, and a synthetic resin board will be formed with a different raw material, but the 1st synthetic resin sheet and the 2nd synthetic resin are formed. There is no difference in thermal expansion and contraction between the resin sheet and the synthetic resin molded product is less likely to warp due to the difference in thermal expansion and contraction.

Moreover, the synthetic resin molded product according to the fifth aspect of the present invention is the synthetic resin molded product according to the fourth aspect, wherein the material of the first synthetic resin sheet and the second synthetic resin sheet is polycarbonate; The material of the synthetic resin plate is ABS resin.
If comprised in this way, since the raw material of a synthetic resin board is an ABS resin, it can shape | mold at low temperature and does not produce the ink flow of the ink film layer shape | molded by the synthetic resin sheet. Moreover, since the raw material of the first synthetic resin sheet and the second synthetic resin sheet is polycarbonate, it is a synthetic resin molded product that is excellent in transparency and strength, suitable for backlighting, and hardly damaged.

  According to the present invention, the synthetic resin molded article is a synthetic resin obtained by loading a synthetic resin sheet adjacent to the mold surface, injecting a molten resin into the mold, and welding the synthetic resin sheet. A molded article, a first synthetic resin sheet having an ink film layer formed on at least one surface, a synthetic resin plate in which the first synthetic resin sheet is welded and bonded to the first surface, and a first synthetic resin plate Since the second synthetic resin sheet welded and bonded to the first surface and the second surface of the front and back relationship is provided, the synthetic resin molded product is less prone to warp due to the difference in thermal expansion and contraction.

It is sectional drawing of the synthetic resin molded product as embodiment of this invention. It is a flowchart explaining the process of manufacturing the synthetic resin molded product which concerns on this invention. BRIEF DESCRIPTION OF THE DRAWINGS It is a figure of the synthetic resin molded product as embodiment of this invention, (a) is a top view, (b) is a bottom view, (c) is cc sectional drawing in (a) or (b). It is a bottom view of the synthetic resin molding which shows the example of the shape of a 2nd synthetic resin sheet.

  Embodiments of the present invention will be described below with reference to the drawings. In each figure, the same or equivalent devices are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 1 is a cross-sectional view of a synthetic resin molded product 1 as an embodiment of the present invention. The synthetic resin molded product 1 includes a synthetic resin molded plate 10, a first synthetic resin sheet 20 welded to the first surface (upper surface in FIG. 1) 10 a of the synthetic resin molded plate 10, and the synthetic resin molded plate 10. The second synthetic resin sheet 30 is welded and joined to a second surface (lower surface in FIG. 1) 10b that is in a front-back relationship with the first surface 10a. An ink film layer 21 is formed on at least one surface of the first synthetic resin sheet 10. In FIG. 1, the ink film layer 21 is illustrated by a broken line, but is generally a continuous film layer or may be partially formed.

  In the synthetic resin molded product 1, the ink film layer 21 is formed on the surface (the lower surface in FIG. 1) that is welded and joined to the synthetic resin molded plate 10 of the first synthetic resin sheet 20. (Top surface). Furthermore, although the ink film layer 21 is formed only on the first synthetic resin sheet 20, it may also be formed on the second synthetic resin sheet 30.

  Here, with reference to the flowchart of FIG. 2, the manufacturing method of the synthetic resin molded product 1 is demonstrated. The first synthetic resin sheet 20 is loaded into the upper mold as the first mold (S10). In this case, it is preferable to fix the first synthetic resin sheet 20 with pins or the like so as not to be displaced in the mold. An ink film layer 21 is formed on the first synthetic resin sheet 20 before loading into the mold, so that the synthetic resin molded product 1 has a desired appearance. When the first synthetic resin sheet 20 is transparent, the ink film layer 21 is disposed on the side in contact with the mold and becomes the back side of the first synthetic resin sheet 20 when the synthetic resin molded product 1 is obtained. It is preferable because damage to the ink film layer 21 can be suppressed. When the first synthetic resin sheet 20 is opaque, the first synthetic resin sheet 20 is arranged on the side not in contact with the mold, that is, on the surface side so that the first synthetic resin sheet 20 can be visually recognized when the synthetic resin molded product 1 is obtained. Note that “transparent” includes translucent, and “opaque” does not include translucent by shielding light.

  The second synthetic resin sheet 30 is loaded into the lower mold as the second mold (S12). The loading of the first synthetic resin sheet 20 and the loading of the second synthetic resin sheet 30 may be performed at the same time or either one may be performed first. When the synthetic resin plate 10 is transparent or when the synthetic resin molded product 1 is viewed from both sides, an ink film layer may be formed on the second synthetic resin sheet 30. Here, the description will be made assuming that the upper mold is used as the first mold and the lower mold is used as the second mold, but the lower mold and the second mold are used as the first mold. An upper mold may be used.

  After the first synthetic resin sheet 20 and the second synthetic resin sheet 30 are loaded into the upper mold and the lower mold, the upper mold and the lower mold are combined (S14). A cavity surrounded by the upper mold and the lower mold is a space for injection molding the synthetic resin plate 10.

Molten resin is injected into the cavity and the synthetic resin plate 10 is injection molded (S16). The injection molding may be a known method. The synthetic resin sheets 20 and 30 are preliminarily loaded into the upper mold and the lower mold and injection molded to produce the synthetic resin molded product 1 formed by integrating the synthetic resin sheets 20 and 30.
The molten resin injected into the cavity in the mold is cooled and solidified (S18). When the molten resin is cooled and solidified, the synthetic resin plate 10 is obtained, and the synthetic resin molded product 1 is completed.

  As materials of the first synthetic resin sheet 20 and the second synthetic resin sheet 30, polycarbonate (PC), polymethacryl (PMMA), polyethylene terephthalate (PET), PC / PET blend, polypropylene (PP), polyvinyl chloride Sheets such as (PVC) are preferred, but not limited thereto. However, when used for backlighting, it is preferable to use a transparent synthetic resin sheet as a material for the first synthetic resin sheet 20 and the second synthetic resin sheet 30. The material of the synthetic resin plate 10 may be any resin such as polycarbonate, acrylic, ABS resin, polypropylene (PP), but a transparent resin is preferable for backlighting.

In addition, when the synthetic resin plate 10 is injection-molded, it is preferable that the first and second synthetic resin sheets 20 and 30 loaded in advance in the mold do not melt or soften, and the material of the synthetic resin plate 10 Generally, the first and second synthetic resin sheets 20 and 30 are different from the raw material. As an example of a suitable combination, polycarbonate having a glass transition temperature _TG of 146 ° C. is used as a material for the first and second synthetic resin sheets 20, 30, and a glass transition temperature _TG is 97 ° C. as a material for the synthetic resin plate 10. ABS resin is used. Since the glass transition temperature _TG of the ABS resin used as the material of the synthetic resin plate 10 is as low as 97 ° C., the ink film layer 21 formed on the first synthetic resin sheet 20 and also on the second synthetic resin sheet 30 in some cases. Ink flow is less likely to occur. Moreover, since it is low temperature, the transparency (haze) of the first synthetic resin sheet 20 and the second synthetic resin sheet 30 made of polycarbonate is not adversely affected.

  Since the materials of the first synthetic resin sheet 20 and the second synthetic resin sheet 30 and the injected molten resin are different, there is a difference in thermal shrinkage due to cooling, and the synthetic resin molded product 1 may be warped. This is because different materials generally have different coefficients of thermal expansion. It is a sleigh similar to a so-called bimetal. Moreover, since different materials are used, the deflection temperature under load is different, and it is difficult to perform an annealing process after molding. However, in the synthetic resin molded product 1, the first and second synthetic resin sheets 20 and 30 are welded and bonded to both surfaces of the synthetic resin plate 10, so that tension or contraction is applied only to one surface of the synthetic resin plate 10. It does not occur. Since tension or shrinkage due to thermal expansion / contraction occurs on both sides, warpage similar to that of bimetal does not occur or is reduced.

  FIG. 3 is a view of a synthetic resin molded product 2 as an embodiment of the present invention, in which (a) is a top view, (b) is a bottom view, and (c) is cc in (a) or (b). It is sectional drawing. In the synthetic resin molded product 2, the first synthetic resin sheet 22 is welded to the upper surface of the synthetic resin plate 12, and the second synthetic resin sheet 32 is welded to the lower surface. The synthetic resin molded product 2 as a whole has a shape in which an elliptic hole 14 is formed in a rectangular synthetic resin plate 12. For example, for an automobile instrument, a scale may be printed around the hole 14 and a movable needle may be fitted into the hole 14. In this case, the synthetic resin molded product 2 is preferably used so as to be viewed from the upper surface side. The rectangular synthetic resin plate 12 may be a plate having a curvature instead of a flat plate.

  As can be seen from FIG. 3A, the first synthetic resin sheet 22 covers the entire upper surface of the synthetic resin plate 12. When used for backlighting, an ink film layer (not shown) is formed on the first synthetic resin sheet 22 before being welded to the synthetic resin plate 12, thereby printing desired colors, patterns, and characters. can do. Further, by forming a hard coat layer on the upper surface of the first synthetic resin sheet 22 (the surface opposite to the surface to be welded and bonded to the synthetic resin plate 12), the synthetic resin molded product 2 that is not easily damaged can be manufactured. it can.

  Referring to FIG. 3B, the second synthetic resin sheet 32 does not cover the entire lower surface of the synthetic resin plate 12. That is, the second synthetic resin sheet 32 has an elongated rectangular shape and is arranged along the longitudinal side of the rectangular synthetic resin plate 12.

  Here, there is a possibility that the shape of the synthetic resin plate 12, that is, the synthetic resin molded product 2, is caused by a difference in thermal expansion / contraction between the first synthetic resin sheet 22 or the second synthetic resin sheet 32 and the synthetic resin plate 12. Consider sledding. The synthetic resin plate 12 has a uniform thickness. The synthetic resin plate 12 is a rectangle whose horizontal direction is the longitudinal direction in FIG. A hole 14 is formed at the center. Therefore, the upper and lower portions of the hole 14 in FIG. 3B are the narrowest portions. That is, it becomes a part which is easy to bend. Therefore, in the synthetic resin molded product 2, the upper and lower portions of the hole 14 bend, thereby causing a warp in which the end in the longitudinal direction of the synthetic resin molded product 2 is deformed in the out-of-plane direction of FIGS. there is a possibility.

  Therefore, as shown in FIG. 3B, the second synthetic resin sheet 32 is disposed so as to cover the upper and lower portions of the hole 14 in the longitudinal direction of the synthetic resin plate 12. In the portion where the upper and lower portions of the hole 14 are easily bent, the first synthetic resin sheet 22 and the second synthetic resin sheet 32 are arranged on the upper and lower surfaces of the synthetic resin plate 12, as described in the synthetic resin molded product 1. Warpage due to differences in thermal expansion and contraction is suppressed. Thus, even if the second synthetic resin sheet 32 is covered with only a part of the synthetic resin plate 12 including a portion that is easily bent, the synthetic resin molded product 2 that is less likely to warp due to a difference in thermal expansion and contraction. Become. Here, the portion that is easily bent is, as the synthetic resin molded product 2, if warpage occurs due to the difference in thermal expansion and contraction between the synthetic resin plate 12 and the first and second synthetic resin sheets 22 and 32, This is a portion where stress for generation is concentrated, such as the periphery of the hole 14, a portion where the width is narrow, a portion where the plate pressure is thin, and the like. The part including the portion that is easily bent refers to the portion including the easily bent portion and the periphery thereof.

  The amount of the second synthetic resin sheet 32 used can be reduced by covering the second synthetic resin sheet 32 with only a part of the synthetic resin plate 12. Therefore, it can contribute to cost reduction. In addition, if the synthetic resin molded product 2 is viewed from the upper surface (the first synthetic resin sheet 22 side), the second synthetic resin sheet 32 may be covered even if only a part of the synthetic resin plate 12 is covered. Does not deteriorate, and it does not drop in strength, such as being easily damaged.

  FIG. 4 is a diagram showing a modification of the shape of the second synthetic resin sheets 33 and 34 when the synthetic resin molded products 3 and 4 having the same shape as FIG. 3 are manufactured. FIG. 4A shows a second synthetic resin sheet 33 that is wider than FIG. By expanding the width of the second synthetic resin sheet 33, it overlaps with the hole 14, so the portion corresponding to the hole 14 is deleted according to the shape of the hole 14. The effect of suppressing warpage due to the difference in thermal expansion and contraction is improved by the amount that the width is wider than that of the second synthetic resin sheet 32 shown in FIG. In FIG. 4B, instead of deleting the portion corresponding to the hole 14 of the second synthetic resin sheet 33 shown in FIG. Yes. By deleting in this way, the processing of the shape of the second synthetic resin sheet 34 becomes easy, and the positioning at the time of welding and joining to the synthetic resin plate 12 becomes easy.

  In the above description, the first synthetic resin sheet 22 covers the entire surface of the synthetic resin plate 12. However, depending on the application, the first synthetic resin sheet 22 may not cover the entire surface of the synthetic resin plate 12. Good.

  Further, in the description so far, the portion where the synthetic resin molded products 2, 3, and 4 are easily bent is one place (specifically, two portions that are symmetrical in the vertical direction of the hole 14). 4 may be configured such that a plurality of easily bent portions are recognized and the second synthetic resin sheets 32, 33, and 34 are welded and bonded to the respective portions. For example, the second synthetic resin sheets 32, 33, and 34 may be welded and joined to the left and right portions of the hole 14 in FIG. Alternatively, the second synthetic resin sheets 32, 33, 34 may be welded and joined to other portions.

  In the description so far, the second synthetic resin sheets 32, 33, and 34 have been described as covering a part of the synthetic resin plate 12, but as with the first synthetic resin sheet 22, The entire surface may be covered. By covering the entire surface of the synthetic resin plate 12 with the second synthetic resin sheets 32, 33, and 34, warpage due to the difference in thermal expansion and contraction does not occur even in the second and third flexible portions. In addition, even if it does not cover small parts, such as a projection part and a notch part, with the 2nd synthetic resin sheet 32, 33, 34, a curvature will not arise substantially and there is no influence.

  The synthetic resin molded products 1 to 4 according to the present invention may be annealed after production. In this case, annealing may be performed not only for the purpose of reducing the residual stress and stabilizing the shape, but also for the purpose of improving the deflection temperature under load and mechanical properties.

1, 2, 3, 4 Synthetic resin molded article 10, 12 Synthetic resin plate 10a, 10b First and second surfaces 14 of synthetic resin plate Holes 20, 22 First synthetic resin sheet 21 Ink film layers 30, 32, 33, 34 Second synthetic resin sheet

Claims (5)

After the synthetic resin sheet is loaded adjacent to the mold surface, a molten resin is injected into the mold, and the synthetic resin sheet is welded and joined.
A first synthetic resin sheet having an ink film layer formed on at least one surface;
A synthetic resin plate in which the first synthetic resin sheet is welded and bonded to the first surface;
A second synthetic resin sheet welded and bonded to the second surface of the first and second surfaces of the synthetic resin plate;
Synthetic resin molded product. The first synthetic resin sheet covers the entire surface of the first surface;
The second synthetic resin sheet covers a part of the second surface including a portion where the synthetic resin plate is easily bent;
The synthetic resin molded product according to claim 1. The first synthetic resin sheet and the second synthetic resin sheet are formed of the same material;
The synthetic resin molded product according to claim 1 or 2. The synthetic resin plate is formed of a material different from a material of the first synthetic resin sheet and the second synthetic resin sheet;
The synthetic resin molded product according to claim 3. The material of the first synthetic resin sheet and the second synthetic resin sheet is polycarbonate;
The material of the synthetic resin plate is ABS resin;
The synthetic resin molded product according to claim 4.

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