JP2015201337A - Resin cover for lighting fixture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress heat conduction from molten resin to a molding die in an injection molding process, to prolong flowing length of the molten resin, and to achieve reduction in wall thickness and increase in size of a resin cover for a lighting fixture without causing underfill.SOLUTION: A transparent resin cover 1 used for a lighting fixture for a vehicle includes: a design part 2 visually recognizable from the outside of the lighting fixture; a peripheral edge part 3 spreading to the peripheral edge of the design part 2; and emboss processing surfaces 13, 14 formed by injection molding type minute irregularity parts. The outward emboss processing surface 13 is covered by a hard coat film 7, and high transparency, smoothness and surface hardness are imparted to an outer surface of the design part 2. The inward emboss processing surface 14 is covered by an antifogging film 8, and antifogging treatment is performed on an inner surface of the design part 2. In the injection molding, an air layer for heat insulation is formed between the minute irregularity of the molding die and a surface of the molten resin material, and flowing length is prolonged by suppressing cooling of the molten resin.

Description

  The present invention relates to a resin cover for a lamp that is injection-molded using a mold and a method for manufacturing the same.

  In recent years, resin molded products for vehicle lamps tend to increase in size due to demand for design. On the other hand, the weight of the vehicle body is required to be reduced due to functional restrictions such as improvement in fuel consumption. Therefore, conventionally, in the injection molding of a resin molded product for a lamp, a technique for reducing the thickness of the molded product has been proposed in order to satisfy both the demands for large size and light weight.

  For example, in Patent Document 1, by providing a rib on the inner wall surface of the lamp body and forming a runner at the time of molding (a passage of molten resin) inside the rib, cooling of the molten resin by the molding die is reduced, A technique for reducing the thickness of the lamp body and preventing the occurrence of sink marks is described. Patent Document 2 discloses a technique for devising the positions and lengths of the runner and the gate so that the entire cavity of the mold is included in the flow range of the molten resin.

Japanese Patent Laid-Open No. 10-247403 JP 2009-96105 A

  However, since the conventional thinning technology focuses on parts different from the mold surface, such as the runner and gate of the mold, there is room for improvement in order to suppress the heat removal effect of the mold surface on the molten resin. . In particular, in the injection molding of a resin cover for a lamp having a small thickness and a large surface area, the molten resin material at about 280 ° C. contacts the surface of the mold at about 40 to 120 ° C. And the flow path of the resin is narrowed, and as a result, the flow length of the resin is shortened.

  For this reason, in the resin cover for lamps provided with the flange and the seal leg at the periphery of the design portion, it is easy to cause a lack of thickness especially at the periphery. Therefore, conventionally, in the injection molding of a resin cover for a lamp, it has been necessary to design a thick wall in anticipation of a reduction in the flow length, and it has been difficult to reduce the thickness of the cover product.

  An object of the present invention is for a lamp that can suppress the heat conduction from a molten resin to a mold during injection molding, increase the flow length of the molten resin, and achieve a thin and large molded product without causing a lack of thickness. A resin cover and a manufacturing method thereof are provided.

  In order to solve the above problems, the present invention provides a resin cover for a lamp that is injection-molded using a molding die, a design portion that is visible from the outside of the lamp, a peripheral portion that extends around the periphery of the design portion, and a molding die And a textured surface formed by minute irregularities.

  Here, the textured surface is not limited to a specific part of the resin cover for a lamp, but is preferably included in a part where the cooling by the molding die is likely to proceed, particularly in the peripheral part of the cover. In addition, the textured surface can be provided on the design portion of the resin cover for lamps or on both the design portion and the peripheral portion. When the textured surface is provided in the design portion, it is preferable that the textured surface of the design portion is surface-treated with a coating film.

  A coating film is not limited to a specific material, According to the use of the resin cover for lamps, various surface treating agents can be used. For example, in the case of a transparent resin cover for a vehicular lamp, the outwardly embossed surface facing the outside of the lamp is covered with a hard coat film in the design portion, and the design portion is highly transparent (for example, 80% or more in linear transmittance) ) And smoothness and surface hardness. It is also possible to cover the inwardly textured surface facing the inside of the lamp in the design portion with an antifogging film, and to prevent the design portion of the transparent resin cover from being fogged from the inside of the lamp.

  The manufacturing method of the present invention is a method of injection molding a resin cover for a tree lamp provided with a design part visible from the outside of the lamp and a peripheral part spreading around the peripheral part of the design part, and a minute uneven part is formed on the molding surface. Including a step of preparing the formed mold and a step of molding the design portion and the peripheral portion with the molten resin material injected into the cavity of the mold, and in this molding step, the micro unevenness portion of the mold and the molten resin material A textured surface is formed on a resin cover for a lamp by a minute uneven portion of a molding die with a heat insulating air layer interposed between the surface and the surface of the lamp.

  According to the resin cover for a lamp of the present invention and the method for manufacturing the same, since the micro uneven portion of the molding die forms a textured surface at a required portion of the cover, at the time of injection molding, the molding die and the molten resin material A heat insulating air layer is formed between the two. Since the heat insulating air layer suppresses heat conduction from the molten resin to the mold, the flow length of the molten resin in the cavity can be increased. Therefore, there is an effect that the resin cover for a lamp can be formed thinner and larger without causing the molded product to be thin.

It is a front view of the resin cover for lamps which shows Example 1 of this invention. It is the sectional view on the AA line of FIG. It is sectional drawing which expands and shows the fine uneven | corrugated | grooved part of an injection mold. It is sectional drawing which shows the injection molding process using the shaping | molding die of FIG. It is sectional drawing which shows the state which opened the shaping | molding die. It is sectional drawing which shows the surface treatment process of a design part. It is a graph showing the temperature change of a molten resin with time. It is a graph showing the relationship between mold temperature and resin flow length. It is a front view of the resin cover for lamps which shows Example 2 of this invention. FIG. 10 is a sectional view taken along line B-B in FIG. 9.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, an embodiment in which the present invention is embodied in a transparent resin cover used for a vehicle lamp will be described with reference to the drawings. 1 to 8 show the transparent resin cover of Example 1, and FIGS. 9 and 10 show the transparent resin cover of Example 2. FIG. In the following description, “outside”, “outside surface”, and “outside” mean the outside, the outside, and the outside of the lamp with the transparent resin cover attached to the vehicular lamp. Similarly, “inside”, “inside surface”, and “inside” mean the inside, inside, and inside of the lamp with the cover attached to the lamp. In each drawing, the same reference numerals indicate the same or similar components.

  As shown in FIGS. 1 and 2, the transparent resin cover 1 according to the first embodiment enters the design portion 2 visible from the outside of the vehicle body 21 and the inside of the vehicle body 21 in a state where the vehicle lamp is assembled to the vehicle. The peripheral part 3 is invisible from the outside, and the whole is injection-molded with an amorphous transparent resin material such as acrylic or polycarbonate using a mold.

  The design portion 2 is formed in a shape that protrudes from the peripheral edge portion 3 so as to be exposed at the opening 22 of the vehicle body 21. The peripheral edge portion 3 is formed so as to spread along the peripheral edge of the design portion 2, and becomes a flange 23 concealed inside the vehicle body 21, a seal leg 25 attached to the lamp body 24, and a molten resin runway during molding. Part 6 is included. The runner portion 6 is thicker than the flange 23 and is formed to extend from the gate portion 5 to the design portion 2. As shown by a two-dot chain line in FIG. 1, the gate portion 5 and the runner portion 4 are cut off from the runner portion 6 after the transparent resin cover 1 is formed.

  On the inner surface and outer surface of the transparent resin cover 1, textured surfaces 13, 14 are formed by minute uneven portions of the molding die. In this embodiment, the inner and outer textured surfaces 13 and 14 are formed to spread over the entire region of the resin cover 1 including the design portion 2 and the peripheral edge portion 3. If necessary, the gate portion 5 and the runner portion 4 can be subjected to a textured process using minute uneven portions of the mold. The outwardly textured surface 13 of the design portion 2 is smoothed by the hard coat film 7, and the inwardly textured surface 14 of the design portion 2 is smoothed by the antifogging film 8.

  For the hard coat film 7, for example, a surface treatment agent composed of an acrylic or silicone ultraviolet curable resin and a solvent can be used, and a thermosetting surface hardener can also be used. For the antifogging film 8, for example, a surface treatment agent containing a hydrophilic acrylic resin and a surfactant can be used. In addition, the textured surfaces 13 and 14 may be provided only on the peripheral edge 3 (see Example 2), or may be provided only on the design part 3, and only on either the inner surface or the outer surface of the resin cover 1. It is also possible to provide it.

  When manufacturing the transparent resin cover 1 configured as described above, first, an injection mold in which minute uneven portions are formed on the molding surface is prepared. The injection mold 10 shown in FIG. 3 includes a core mold 10A and a cavity mold 10B, and a cavity 10C for filling a molten resin is formed between the core mold 10A and the mold 10B. A minute uneven portion 9 is provided for this purpose. The minute uneven portion 9 is not limited to a specific surface treatment method, but can be processed by, for example, blasting a mold forming surface.

  The blasting of the mold forming surface has been conventionally used as a means for improving the releasability. In this case, the surface roughness is usually about Ra: 0.01 to 0.03 μm. On the other hand, the roughness of the fine irregularities 9 forming the textured surfaces 13 and 14 is about Ra: 0.05 to 1.0 μm, and the depth and pitch shown in FIG. 3 is about d: 5 to 20 μm. , P: preferably about 2 to 10 μm. If the roughness of the fine unevenness portion 9 is smaller than Ra: 0.2 μm, the effect of improving the fluidity of the molten resin cannot be obtained, and if Ra: 1.0 μm is exceeded, smoothness is produced by the coating film. It becomes difficult. For this reason, the optimum value is about Ra: 0.25 μm.

  Next, as shown in FIG. 4, the molten resin material 11 is injected into the cavity 10 </ b> C of the mold 10, and the design portion 2 and the peripheral portion 3 of the transparent resin cover 1 are molded. According to the molding die 10 of this embodiment, since the fine irregularities 9 are provided on the molding surfaces of the core mold 10A and the cavity mold 10B, when the molten resin 11 is filled into the cavity 10C, the fine irregularities 9 and the molten resin are provided. An insulating air layer 12 is formed between the surface of the material 11. Then, with the heat insulating air layer 12 interposed, the surface shape of the minute uneven portion 9 is partially transferred to the surface of the molten resin material 11, and the textured surface is applied to both the inner and outer surfaces of the design portion 2 and the peripheral portion 3. 13 and 14 are formed. At this time, the surface shape of the micro uneven portion 9 is not faithfully transferred due to the surface tension of the molten resin material 11, and is transferred so that the uneven portions of the embossed surfaces 13, 14 are shallower than the micro uneven portion 9. The textured surfaces 13 and 14 can be formed to be somewhat smoother than the fine irregularities 9.

  When the molding process is completed, as shown in FIG. 5, the mold 10 is opened and the molded product (resin cover 1) is taken out from the cavity 10C. At this time, since the minute uneven portion 9 is processed with a larger surface roughness (Ra) than the conventional blast mold, the large transparent resin cover 1 for a vehicle lamp is more smoothly removed from the mold 10. Can be released.

  Subsequently, as shown in FIG. 6, the resin cover 1 is moved from the injection molding process to the painting process, and the surface hardening treatment liquid 17 is sprayed on the outwardly textured surface 13 of the design portion 2 by the first painting gun 16. The processed surface 13 is covered with the hard coat film 7 to impart transparency, smoothness, and surface hardness to the surface of the design portion 2. Further, the anti-fogging treatment liquid 19 is sprayed on the inwardly textured surface 14 of the design portion 2 with the second coating gun 18, and this textured surface 14 is covered with the antifogging film 8 to prevent fogging on the inner surface of the design portion 2. Is granted. Thereafter, a required finishing process is performed on the surface-treated molded product to complete a transparent resin cover product.

  According to the manufacturing method of this embodiment, the heat-insulating air layer 12 is formed between the minute irregularities 9 of the mold 10 and the surface layer (skin layer) of the molten resin material 11 in the injection molding process. Since air has a much lower thermal conductivity than a metal material, the amount of heat transferred from the molten resin 11 to the mold 10 can be reduced, and the solidification inside the molten resin (core layer) can be delayed. As a result, the flow length of the molten resin 11 can be increased, and the lack of the design portion 2 and the peripheral edge portion 3 can be prevented, thereby contributing to the thinning and enlargement of the transparent resin cover 1 for vehicle lamps.

  FIG. 7 shows resin temperature characteristics when a molding die (mirror surface molding die) whose molding surface is a mirror surface and a molding die 10 (rough surface molding die) including minute irregularities 9 on the molding surface are used. From this characteristic diagram, it can be seen that the rough surface mold maintains a higher resin temperature than the mirror mold during the period from injection filling of the molten resin to the end of pressure holding. In addition, since the rough surface mold has a large contact area with the resin due to the presence of the minute uneven portions, the temperature of the rough mold is significantly lower than that of the mirror mold during the period from the start of pressure holding to the end of pressure holding. Thereafter, the resin temperatures of both molds become substantially equal at the end of holding pressure, and the period from the end of holding pressure to the completion of cooling decreases to the same extent.

  FIG. 8 shows changes in the flow length of the molten resin accompanying changes in the mold temperature in the mirror surface mold and the rough surface mold. From this characteristic diagram, it can be seen that the rough surface mold has better characteristics than the mirror mold in the flowability of the molten resin. For example, the resin flow length when the mold temperature is 40 ° C. to 120 ° C. can be confirmed to be about 5% to 7% longer in the rough surface mold than in the mirror surface mold. Therefore, in the injection molding of the resin cover 1 for a lamp, the flow of the resin can be performed during the period from injection filling to the end of holding pressure without increasing the cycle time by using a rough surface mold in which minute uneven portions are formed. The effect that the length can be improved is obtained.

  Further, according to the transparent resin cover 1 for a lamp of Example 1, the outward and inward textured surfaces 13 and 14 of the design portion 2 are smoothly surface-treated by the hard coat film 7 and the antifogging film 8, respectively. Therefore, there is no risk of impairing the transparency of the design portion 2 due to the embossing process, and the original appearance and functionality of the transparent cover can be maintained.

  As shown in FIGS. 9 and 10, in the vehicle lamp resin cover 31 of the second embodiment, the textured surface 32 is formed only on the peripheral edge portion 3, but not on the design portion 2. On the embossed surface 32 of the peripheral edge portion 3, the embossed portion 323 of the runner portion 6, the embossed portion 324 of the flange 23 (see FIG. 10), the embossed portion 325 of the standing wall 26 extending from the flange 23 to the design portion 2, A textured portion 326 of the seal leg 25 is included. A textured portion can be provided in the gate portion 5 and the runner portion 4 as necessary.

  In the injection molding of the resin cover 31 for lamps, a core mold 10A and a mold mold 10B (see FIG. 3) in which minute uneven portions 9 are formed on a molding surface corresponding to the peripheral edge portion 3 are prepared. Similarly, the molten resin material 11 is injected into the cavity 10C, and the design portion 2 and the peripheral portion 3 are molded. At this time, in the peripheral edge portion 3, a heat insulating air layer 12 (see FIG. 4) is formed between the minute uneven portion 9 of the mold 10 and the surface of the molten resin material 11, and this air layer 12 is interposed. Then, the surface shape of the minute uneven portion 9 is transferred shallowly to the resin surface, and a textured surface 32 is formed at a required portion of the peripheral edge portion 3.

  Usually, since the peripheral part 3 of the resin cover 31 for lamps is set thinly compared with the design part 2, the fluidity | liquidity of molten resin falls. However, according to the lamp resin cover 31 of the second embodiment, the heat insulating air layer 12 corresponding to the textured surface 32 delays solidification accompanying cooling of the molten resin and lengthens the resin flow length in the peripheral edge portion 3. . Therefore, without increasing the thickness of the design portion 2, the molten resin can be spread to the end portion 33 (see FIG. 9) far from the gate 5, and the lack of thickness can be eliminated from the peripheral portion 3.

  In addition, the surface treatment of the peripheral part 3 is arbitrary, A hard coat film | membrane, an antifogging film | membrane, and another surface treatment coating film can be provided or omitted according to the use and installation place of a lamp. In addition, the resin cover for a lamp of the present invention is not limited to a vehicle lamp, and can be applied to various lamps such as indoor and outdoor lighting lamps, street lamps, road sign lamps, and signal lights. In addition, the present invention is not limited to the above embodiment, and can be embodied by appropriately changing the shape and configuration of each part without departing from the spirit of the invention.

DESCRIPTION OF SYMBOLS 1 Resin cover for lamps 2 Design part 3 Peripheral part 7 Hard coat film 8 Anti-fogging film 9 Minute uneven part 10 Mold 11 Molten resin 12 Air layer 13 for heat-insulation 13 Outward wrinkle processing surface 14

Claims (6)

A resin cover for a lamp that is injection-molded using a mold,
A resin cover for a lamp, comprising: a design portion that is visible from the outside of the lamp; a peripheral portion that extends around the periphery of the design portion; and a textured surface that is formed by the minute uneven portions of the mold.   The resin cover for a lamp according to claim 1, wherein the textured surface is included in the peripheral edge.   The resin cover for a lamp according to claim 1, wherein the textured surface is included in the design portion, and the textured surface of the design portion is smooth-treated with a coating film.   The resin cover for a lamp according to claim 3, wherein the coating film includes a hard coat film that covers an outwardly textured surface facing the outside of the lamp in the design portion.   The resin cover for a lamp according to claim 3 or 4, wherein the coating film includes an antifogging film that covers an inwardly textured surface facing the inside of the lamp in the design portion. A method for producing a resin cover for a lamp comprising a design part visible from the outside of the lamp and a peripheral part extending to the periphery of the design part,
Including a step of preparing a mold in which a minute uneven portion is formed on a molding surface, and a step of molding the design portion and the peripheral portion with a molten resin material injected into a cavity of the mold,
In the molding step, a textured surface is formed on the lamp resin cover by the minute irregularities with a heat insulating air layer interposed between the minute irregularities of the mold and the surface of the molten resin material. A method for producing a resin cover for a lamp.

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