JP6562737B2 - Manufacturing method of injection molded product and injection molded product - Google Patents

Description

  The present invention relates to a method for manufacturing an injection molded product and an injection molded product. Specifically, at least a part of the surface is a region where a pattern formed by visually concavo-convex unevenness is formed, and a minute unevenness is formed in the pattern than the observable unevenness and is roughened. The present invention relates to a method for manufacturing an injection molded product having a region and an injection molded product obtained by the manufacturing method.

  Design properties are required for vehicle interior products such as console boxes, instrument panels, and cover members, and molded products such as building interior products. For this reason, a decorative pattern such as a leather pattern or a lattice pattern is often applied to the surface of the molded product using irregularities. Then, in order to reduce the gloss of the surface of the molded product (matte) and improve the appearance quality, the surface of the molded product with the decorative pattern may be roughened.

  As one method for producing a molded product having a roughened surface with a decorative pattern, a method of injection molding a polymer material using a mold having a decorative surface and a roughened molding surface Is mentioned. As a specific example, in Patent Document 1, a pattern forming uneven part for forming a decorative pattern with unevenness on the surface of a molded product is formed on the molding surface, and more than the average pattern unit of the decorative pattern. Disclosed is a method of injection-molding a polymer material using a molding die having a low-gloss processing portion in which countless micro-recesses or micro-projections having small planar dimensions are arranged in a pre-designed plane arrangement pattern. Has been.

JP 2006-68972 A

  However, in the technique described in Patent Document 1, in the case where the fluidity of the polymer material is poor, innumerable micro concave portions or micro convex portions on the molding surface of the molding die are designed in a plane arrangement pattern. The polymer material is less likely to flow into the low-gloss processing parts that are arranged, and as a result, the micro-recesses or micro-protrusions cannot be transferred to the injection molded product, and the surface with the decorative pattern is roughened. There is a problem that it is difficult to obtain a molded injection molded product. In order to increase the fluidity of the polymer material, a method of increasing the temperature of the mold is conceivable, but the molding apparatus becomes large and the cost increases. Therefore, a method for increasing the temperature of the mold is not practical as a solution.

  The present invention was created in order to solve the above-described problems, and its purpose is to easily produce an injection molded product having a roughened surface with a decorative pattern regardless of the fluidity of the polymer material. It is to provide a method that can be manufactured.

The invention of claim 1 created to solve the above-mentioned problem is an area where a pattern formed by the first concavo-convex that can be visually observed is provided on at least a part of the surface, and the pattern is formed in the pattern. This is a method for manufacturing an injection-molded article having a roughened region in which second unevenness smaller than the first unevenness is formed. The manufacturing method includes a filling step in which a molding material in which a polymer material and a thermally expandable capsule are mixed is injected and filled into a molding cavity of a predetermined shape of an injection mold, wherein at least one of molding surfaces of the molding cavity. The part is formed with third irregularities for applying a pattern formed by the first irregularities visible on the surface of the injection molded body; the filled molding material is cooled and solidified in the molding cavity Then, a molding step of obtaining an injection molded body having a region formed with a pattern formed by the first concavo-convex visible at least on a part of the surface; the obtained injection molded body from the injection mold A step of taking out; and heating at least a part of a region provided with the pattern formed by the first visible concavities and convexities on the surface of the taken-out injection-molded body, whereby the thermally expandable capsule The surface is roughened by thermally expanding to form a roughened region by forming second unevenness smaller than the first unevenness in the pattern formed by the first visible unevenness. It is characterized by including a process.
According to such a configuration, roughening of the surface on which the decorative pattern of the injection molded product, which is difficult when the flowability of the polymer material is poor, is performed using the thermal expansion of the thermally expandable capsule. Therefore, an injection-molded product having a roughened surface with a decorative pattern can be easily produced regardless of the fluidity of the polymer material.

According to a second aspect of the invention, in the invention of claim 1, in the roughened area, which the second maximum cross-sectional height Rt ₂ for irregularities, and less than than 30 [mu] m 200 [mu] m It is.
According to this configuration, since the surface of the injection molded product on which the decorative pattern has been applied is appropriately roughened, it is possible to obtain an injection molded product that is particularly excellent in appearance quality.

According to a third aspect of the present invention, in the first or second aspect of the present invention, in the surface roughening step, in the surface layer portion from the surface of the first convex portion of the first unevenness that forms the pattern to a predetermined reference depth. The average particle diameter (d _v ) of the thermally expandable capsule expanded in the surface layer portion from the surface of the concave portion of the first unevenness to the predetermined reference depth with respect to the average particle diameter (d _c ) of the expanded thermally expandable capsule Heating is performed so that the ratio (d _v / d _c ) is in the range of 0.80 to 1.20.
According to such a configuration, since the convex and concave portions of the first unevenness that can be visually observed are roughened to the same extent, an injection molded product that is particularly excellent in appearance quality and excellent in tactile sensation can be obtained.

The invention of claim 4 is an injection-molded article obtained by the manufacturing method according to any one of claims 1 to 3.
According to such a configuration, since the surface of the injection-molded product with the decorative pattern is roughened by using the expansion of the thermally expandable capsule, the surface with the decorative pattern is roughened in a texture. It becomes. Therefore, the injection molded product is particularly excellent in appearance quality and excellent in touch.

It is sectional drawing of an example of the injection molding die used for the manufacturing method of the injection molded product which concerns on one Embodiment of this invention. It is a fragmentary sectional view which shows the part in which the 1st unevenness | corrugation of the injection molded body was formed, and its vicinity part among the cross sections along the II-II direction of FIG. It is a perspective view which shows the heating process of the manufacturing method of the injection molded product which concerns on one Embodiment of this invention. It is a perspective view which shows typically the external shape of the injection molded product manufactured by the manufacturing method of the injection molded product which concerns on one Embodiment of this invention. It is sectional drawing which follows the VV line in FIG. It is a fragmentary sectional view which shows the part in which the 1st and 2nd unevenness | corrugation of the injection molded product was formed in the cross section along the VI-VI line in FIG. 5, and its vicinity part.

  Hereinafter, preferred embodiments of the present invention will be described. It should be noted that matters other than matters specifically mentioned in the present specification and necessary for carrying out the present invention can be grasped as design matters of those skilled in the art based on the prior art. The present invention can be carried out based on matters disclosed in the present specification and drawings and common general technical knowledge in the field.

  One embodiment of the present invention is a region in which a pattern formed by first concavo-convex that is visible is provided on at least a part of the surface, and the second that is smaller than the first concavo-convex in the pattern. It is a manufacturing method of the injection molded product which has the area | region where the unevenness | corrugation of this was formed and was roughened.

  In the method of manufacturing an injection-molded article disclosed herein, first, a filling step in which a molding material in which a polymer material and a thermally expandable capsule are mixed is injected into a molding cavity of a predetermined shape of an injection mold and filled. Is done. Here, at least a part of the molding surface of the molding cavity is provided with third irregularities for applying a pattern formed by the first irregularities visible on the surface of the injection molded body.

  The polymer material used in the method for producing an injection-molded article disclosed herein is a matrix (base material) in which the thermally expandable capsules are dispersed. As the polymer material, materials conventionally used for injection molded products can be used without any particular limitation. For example, various thermoplastic resins and thermoplastic elastomers can be used. Examples of the thermoplastic resin include polyolefin resins such as polyethylene and polypropylene; styrene resins such as polystyrene and acrylonitrile-styrene-butadiene resin (ABS); vinyl chloride resins; Examples of the thermoplastic elastomer include various thermoplastic elastomers such as styrene, olefin, ester, polyamide, vinyl chloride, and urethane. As the polymer material, a thermoplastic elastomer is preferably used.

  The heat-expandable capsule used in the method for producing an injection-molded article disclosed herein typically includes an inclusion substance (usually a gas, a solid, or a liquid that is vaporized by heating. It is configured as particles encapsulated in a shell made of thermoplastic resin. Examples of the material constituting the outer shell of the thermally expandable capsule include acrylic (co) polymer such as polyvinylidene chloride, vinylidene chloride-acrylonitrile copolymer, polyacrylonitrile, acrylonitrile copolymer, and polymethyl methacrylate. Examples thereof include thermoplastic resins such as coalescence and polyvinyl chloride. Examples of the inclusion substance include low-boiling hydrocarbons such as n-pentane, n-hexane, n-butane, isobutane, and isopentane. In addition, an inert gas such as air, carbon dioxide, nitrogen, and argon (which may be partially or entirely liquefied) may be used as the inclusion substance. When such a heat-expandable capsule is heated, the thermoplastic resin constituting the outer shell of the heat-expandable capsule softens, and the encapsulated substance accommodated in the outer shell expands in volume (that is, the above-mentioned The encapsulating substance functions as an expansion agent), whereby the thermally expandable capsule is thermally expanded. Furthermore, the thermally expandable capsule may be ruptured when a part or the whole of the outer shell is stretched beyond the expansion limit. Due to the expansion of the capsule and the rupture of the capsule after the expansion, fine irregularities are formed on the surface of the injection molded product.

  The shape before thermal expansion of the thermally expandable capsule disclosed here is not particularly limited. For example, various forms such as a substantially spherical shape, a spindle shape, an indefinite shape, and a cylindrical shape can be taken. From the viewpoint of dispersibility of the thermally expandable capsule and a decorative effect after the thermal expansion, the thermally expandable capsule is preferably substantially spherical. The average particle diameter of the thermally expandable capsule before thermal expansion is about 15 μm or more and 40 μm or less. The average particle diameter of the thermally expandable capsule after thermal expansion is about 50 μm or more.

  In addition, the said average particle diameter is an average value of the particle size of a thermally expansible capsule. Such an average particle diameter can be easily determined by observation using an optical microscope or an electron microscope (for example, a transmission electron microscope or a scanning electron microscope). For example, a predetermined number (for example, about 40) of thermally expandable capsules are randomly extracted from a micrograph of a cross section of an injection molded product, and the particle size of each thermally expandable capsule is measured. Here, when the thermally expandable capsule is spherical, the diameter is the particle diameter, and when it is non-spherical, the arithmetic average of the longest and shortest length of the thermally expandable capsule is the particle diameter. And let the average value of the particle diameter of each thermally expansible capsule measured be an average particle diameter of a thermally expansible capsule. The average particle diameter of the thermally expandable capsule before thermal expansion can be determined from a cross-sectional photograph of the region where the thermally expandable capsule of the injection molded product is not thermally expanded. The average particle diameter of the thermally expandable capsule after thermal expansion Can be obtained from a cross-sectional photograph of a region where the thermally expandable capsule of the injection molded product is thermally expanded.

  Examples of commercially available thermally expandable capsules (including those commercially available in a masterbatch state) include trade names “ADVANCEL (registered trademark)” manufactured by Sekisui Chemical Co., Ltd. , Trade name “EXPANSEL (registered trademark)” manufactured by Akzo Nobel, trade name “Matsumoto Microsphere (registered trademark)” manufactured by Matsumoto Yushi Seiyaku Co., Ltd. A trade name “Daiform (registered trademark)” and the like can be given.

  The amount of the thermally expandable capsule is, for example, about 0.1 to 10% by mass when the total amount of the molding material is 100% by mass, but is not particularly limited thereto.

  In addition to the polymer material and the thermally expandable capsule, the molding material can contain various subcomponents as necessary. As an example of such a subcomponent, a powdery and / or fibrous solid filler may be mentioned. Examples of such solid fillers include ceramic powder (including various inorganic compound powders such as talc; the same applies hereinafter), carbon powder (for example, carbon black), wood powder, ceramic fiber, carbon fiber, and the like. The amount of filler may vary depending on the type of filler used and the application of the injection molded product. Typically, when the total amount of the molding material is 100% by mass, the content is 1% by mass to 60% by mass. Or the molding material of the composition which does not contain a filler substantially may be sufficient. In addition to the solid filler, the molding material may contain an additive as an auxiliary component as necessary. Examples of such additives include antioxidants, light stabilizers, UV absorbers, plasticizers, lubricants, colorants (pigments, dyes), flame retardants, dispersants, antibacterial agents, and antistatic agents.

  The molding material can be prepared by mixing the polymer material, the thermally expandable capsule, and, if necessary, the subcomponent according to a known method.

  Next, the filling operation in the filling process will be specifically described with reference to the drawings. FIG. 1 is a schematic cross-sectional view of an injection mold 10 which is an example of an injection mold used in the method of manufacturing an injection molded product disclosed herein. The injection mold 10 includes a pair of molds 12 and 14 that can be opened and closed. The pair of molds 12 and 14 includes a fixed fixed mold 12 and a movable movable mold 14, and a predetermined molding cavity 26 is formed inside by closing the mold. The fixed mold 12 of the injection mold 10 has a locating ring 16 for inserting an injection nozzle (not shown) of the injection molding apparatus, and a sprue bush 20 in which a sprue 18 is formed. . When the mold is closed, a sprue 22, an injection gate 24, and a molding cavity 26 are roughly formed on the inner surface (divided surface) of the fixed mold 12 and the movable mold 14 of the injection mold 10 respectively. On one molding surface 28 of the molding cavity 26, there are formed third irregularities for applying a pattern formed by the first irregularities visible.

  The 3rd unevenness | corrugation of the molding surface 28 is for transferring the pattern formed by the 1st unevenness | corrugation to an injection molded body. Therefore, the third unevenness of the molding surface 28 has a shape corresponding to the pattern formed by the first unevenness. That is, as for the 3rd unevenness | corrugation, a 1st unevenness | corrugation WHEREIN: A convex part and a recessed part become reverse, and a 3rd unevenness | corrugation and 1st unevenness | corrugation fit. There is no restriction | limiting in particular about the kind of pattern formed by the 1st unevenness | corrugation, What is necessary is just to determine suitably according to the shape of the pattern to apply to the injection molded product obtained. The pattern is typically a decorative pattern and may be a regular pattern or an irregular pattern. Specific examples include a wrinkle pattern such as a lattice pattern, a satin pattern, and a leather wrinkle pattern. In addition, according to the manufacturing method of the injection molded product disclosed here, since the pattern formed by the first unevenness is applied by injection molding, the pattern formed by the first unevenness is applied by extrusion molding. The pattern can be applied at a high transfer rate.

  The molding material 30 heated and melted is injected into the injection mold 10 as described above, and the molding material 30 is filled into the molding cavity 26 having a predetermined shape. At this time, the molten molding material 30 enters the molding cavity 26 from the injection gate 24 through the sprues 18 and 22 and is filled in the molding cavity 26.

  Next, the filled molding material is cooled and solidified in the molding cavity to obtain an injection-molded body having a region formed with a pattern formed by the first concavo-convex that is visible at least on a part of the surface. A process is performed.

  Specifically, for example, as shown in FIG. 1, the molding material 30 filled in the molding cavity 26 of the injection mold 10 is cooled to the glass transition temperature or lower of the polymer material and solidified. Thereby, the injection molded body 40 is obtained. A pattern formed by the third unevenness of the molding surface 28 is transferred to the injection-molded body 40 on the surface that is in contact with the molding surface 28 of the molding cavity 26 where the third unevenness is formed, and is visible. A pattern formed by the first irregularities is applied.

  In FIG. 2, the part in which the 1st unevenness | corrugation of the injection molded body 40 was formed in the cross section along the II-II direction of FIG. 1 and its vicinity part are shown. In FIG. 2, coarse rectangular first irregularities (that is, the convex portions 42 and the concave portions 44 of the first irregularities) can be seen. Thermally expandable capsules 34 are dispersed in the polymer material 32. Usually, the thermally expandable capsule 34 contained in the molding material 30 has a softening temperature (expansion start temperature: generally 160 ° C.) higher than the injection molding temperature (typically 150 ° C. to 250 ° C.) of the molding material 30. ~ 180 ° C) is low. However, the thermally expandable capsule 34 hardly undergoes thermal expansion at this stage. The reason is as follows. An internal pressure is applied to the molding material 30 filled in the molding cavity 26. Therefore, if the movable mold 24 is opened before being cooled and solidified, the pressure applied to the molding material 30 is released, so that the thermally expandable capsule 34 in the molding material 30 is thermally expanded. However, in the present embodiment, the molding material 30 is cooled and solidified with the internal pressure applied to the molding material 30, thereby substantially preventing thermal expansion of the thermally expandable capsule 34.

  Next, the extraction process which takes out the obtained injection molded object from the said injection mold is performed.

  Specifically, for example, the movable mold 14 of the injection mold 10 shown in FIG. 1 is moved to open the injection mold 10 and the injection molded body 40 formed in the molding cavity 26 is taken out.

  Next, by heating at least a part of a region (hereinafter, also referred to as “pattern region”) on which the pattern formed by the first visible projections and depressions on the surface of the extracted injection-molded body is heated, The expandable capsule is thermally expanded to form a roughened region by forming second irregularities smaller than the first irregularities in the pattern formed by the first irregularities that are visible. A roughening step is performed.

  Specifically, for example, as shown in FIG. 3, the injection molded body 40 is placed on the belt 54 of the belt conveyor 52 provided with the heating device 50. At this time, the injection-molded body 40 is placed on the belt 54 in a state where the surface having the pattern region is the upper surface. And the pattern area | region of the upper surface of the injection molding 40 is heated with the heating apparatus 50. FIG. In the example shown in FIG. 3, a lattice pattern is formed by the first unevenness in the pattern region, and the entire upper surface of the injection molded body 40 is the pattern region.

  The surface of the injection molded body 40 is preferably heated using radiant heat. As a preferable example of the heating device 50, there is a near infrared irradiation device 50 capable of radiating radiant heat from the near infrared ray 56 to the surface of the injection molded body 40. The injection molded body 40 is moved in the direction of the arrow X1 in FIG. 3 by the belt conveyor 52, and the near infrared ray 56 is irradiated from the near infrared irradiation device 50 to the pattern area on the upper surface of the injection molded body 40 to be heated. At this time, the pattern area of the injection molded body 40 is heated to a temperature higher than the temperature at which the thermally expandable capsule 34 included in the injection molded body 40 thermally expands. As a result, the thermally expandable capsule 34 is thermally expanded, the polymer material 32 is thermally deformed, and a second unevenness smaller than the first unevenness is formed in the pattern formed by the visible first unevenness. It is formed. The region where the second unevenness is formed is roughened because the second unevenness is a minute one formed by the thermal expansion of the thermally expandable capsule 34. That is, the injection-molded body 40 is a region where a pattern formed by the first concavo-convex that can be visually observed is provided, and a second concavo-convex that is finer than the first concavo-convex is formed in the pattern and is rough. Surfaceized region 60 (hereinafter also referred to as design region 60) is formed.

  As described above, the surface of the injection-molded product with the decorative pattern, which is difficult when the fluidity of the polymer material 32 is poor, is roughened by utilizing the thermal expansion of the thermally expandable capsule 34. An injection-molded product having a roughened surface can be easily produced regardless of the fluidity of the polymer material 32.

  The heating condition of the pattern region of the injection-molded body 40 is not particularly limited as long as the surface temperature of the injection-molded body 40 reaches the temperature at which the thermally expandable capsule 34 is thermally expanded. The expansion temperature of the thermally expandable capsule 34 is not limited. It can be set appropriately depending on the situation. For example, the heating condition of the pattern region of the injection-molded body 40 can be set such that the surface temperature of the injection-molded body 40 is approximately 80 ° C. to 230 ° C.

  In FIG. 3, the near-infrared ray 56 is linearly irradiated with a width approximately equal to the width of the injection-molded body 40, but the near-infrared ray 56 is irradiated with a width wider or narrower than the width of the injection-molded body 40. Alternatively, the near-infrared ray 56 may be radiated in a dot shape. In the case of a structure in which the near-infrared irradiation device 50 is focused by a reflecting mirror attached thereto, the degree of focusing (focal range) can be changed by adjusting the reflecting mirror. Further, the near infrared irradiation device 50 is fixed and the injection molded body 40 is moved to irradiate the surface of the injection molded body 40 with the near infrared ray 56. The injection molded body 40 is fixed and the near infrared irradiation device 50 is fixed. The injection molded body 40 and the near infrared irradiation device 50 may be moved with respect to each other.

  Moreover, the heating apparatus 50 which heats the surface of the injection molded body 40 is not limited to a near infrared irradiation apparatus. For example, a burner that blows a flame onto the surface of the injection molded body 40, a hot air heater that blows hot air, a high-frequency heater that uses high frequency, a laser irradiation device, a mid-infrared irradiation device, or the like can be used.

  FIG. 4 shows an injection molded product 100 manufactured according to this embodiment. FIG. 5 shows a cross-sectional view of the injection molded product 100 along the line VV in FIG. As shown in FIGS. 4 and 5, the injection molded product 100 is molded in a box shape with one bottom surface opened. The entire upper surface of the upper wall of the injection molded product 100 is a design region 60 in which a region provided with a lattice pattern formed by the first unevenness is roughened by the minute second unevenness. The lower part and the side wall of the design area 60 on the upper wall of the injection-molded article 100 are non-expandable parts 62 in which the thermally expandable capsule 34 is not expanded. The design region 60 may be formed only on a part of the upper surface of the upper wall of the injection molded product 100. Further, the position of the design region 60 is not limited to the upper surface of the injection molded product 100 and may be formed on the side surface of the injection molded product 100. That is, the position and the width of the design region 60 are appropriately determined according to the application of the injection molded product 100, that is, according to the portion that is visible from the outside and is desired to be designed.

  FIG. 6 shows a portion where the first and second concavo-convex portions of the injection-molded product are formed in the cross section taken along the line VI-VI in FIG. 5 and the vicinity thereof. In FIG. 6, a rough rectangular first unevenness (that is, the first unevenness convex portion 42 and the concave portion 44) can be seen. Although the heat-expandable capsules 34 are dispersed in the polymer material 32, the heat-expandable capsules 34A expanded in the surface layer portion can be seen. And on the surface of the convex part 42 and the concave part 44 of the 1st unevenness | corrugation, the circular-arc-shaped micro convex part based on the expanded thermal expansible capsule 34A is formed. In addition, on the surfaces of the convex and concave portions 42 and the concave portions 44 of the first concave and convex portions, a thermally expandable capsule 34B that is excessively expanded and ruptured is seen, and a small arc-shaped concave portion based on the ruptured thermally expandable capsule 34B is formed. Has been. Due to the arc-shaped minute convex portion based on the expanded thermal expandable capsule 34A and the arc-shaped minute concave portion based on the ruptured thermal expandable capsule 34B, the first concave-convex convex portion 42 and the concave portion 44 respectively. Minute second irregularities are formed.

  In addition, although the form in which the 2nd unevenness | corrugation is formed by expansion | swelling and rupture of a thermally expansible capsule is shown in FIG. 6, the 2nd unevenness | corrugation expanded without the expansible capsule exploding. The heat-expandable capsule may be formed only by a minute convex portion, or the heat-expandable capsule may be all ruptured and may be formed only by a minute recess based on the ruptured heat-expandable capsule. Therefore, in the method of manufacturing an injection molded product disclosed herein, the thermally expandable capsules are all expanded without rupture in the roughened region of the injection molded product, or all of the thermally expandable capsules are used. There may be a form in which is ruptured.

The maximum cross-sectional height of the roughness curve element defined in JIS B 0601: 2001 of the first unevenness is Rt ₁ , and the maximum cross-sectional height of the roughness curve element specified in JIS B 0601: 2001 of the second unevenness the When Rt _2, from the viewpoint of high appearance quality, Rt _1, it is preferable to adopt 1.5 times to 100 times the value of Rt _2. The value of Rt ₂ can be adjusted by appropriately adjusting the heating conditions. Rt ₁ is not particularly limited, but is, for example, 150 μm to 10 mm.

Further, the surface of the second unevenness formed (roughened region), JIS B 0601: maximum cross-sectional height Rt _second defined roughness curve in 2001, to be less than or 30 [mu] m 200 [mu] m preferable. If Rt ₂ is less than 30μm, the second concave-convex is not almost formed in the pattern area, there is a possibility that the pattern becomes substantially smooth. On the other hand, when Rt ₂ is larger than 200 μm, the second unevenness formed in the pattern region becomes too large, and the appearance quality may be impaired.

  The arithmetic mean roughness Ra of the roughness curve defined in JIS B 0601: 2001 is 7 μm or more and 25 μm or less (for example, 8 μm or more and 22 μm or less) with respect to the surface (roughened region) on which the second unevenness is formed. It is preferable that In addition, the maximum height roughness Rz of the roughness curve defined in JIS B 0601: 2001 is 40 μm or more and 140 μm or less (for example, 43 μm or more) for the surface (roughened region) on which the second unevenness is formed. 132 μm or less). Further, on the surface (roughened region) where the second unevenness is formed, the maximum peak height Rp of the roughness curve defined in JIS B 0601: 2001 is 25 μm or more and 65 μm or less (for example, 27 μm or more and 63 μm or less). ) Is preferable. Further, the 10-point average roughness Rzjis of the roughness curve defined in JIS B 0601: 2001 is 30 μm or more and 95 μm or less (for example, 32 μm or more, for example) on the surface (roughened region) on which the second unevenness is formed. 93 μm or less). On the surface (roughened region) on which the second unevenness is formed, the average length RSm of the roughness curve element defined in JIS B 0601: 2001 is 1050 μm or more and 1500 μm or less (for example, 1082 μm or more and 1482 μm). Or less). Each of the above parameters can be adjusted by appropriately adjusting the heating conditions.

  In addition, each said parameter in the surface (roughened area | region) in which the 2nd unevenness | corrugation was formed can be measured using the brand name "SURFCOM 1400D (trademark)" by Tokyo Seimitsu Co., Ltd., for example. it can. The value of each parameter is selected within a range in which the second unevenness is smaller than the first unevenness.

In the roughening step, the average particle diameter of the thermally expandable capsules 34 expanded in the surface layer portion from the surface (upper surface) of the first concavo-convex convex portion 42 that forms the pattern to the predetermined reference depth ( the ratio of the average particle diameter of d _c) to the first thermal expansion capsules 34 from the surface (lower surface) were expanded in the surface layer portion up to the predetermined reference depth of the recess 44 of the uneven _{(d v) (d v /} d c ) Is preferably within a range of 0.80 to 1.20. That the ratio (d _v / d _c ) is 0.80 or more and 1.20 or less means that the thermally expandable capsule that has expanded in the surface layer portion from the surface of the convex portion 42 of the first unevenness to a predetermined reference depth. This means that the expansion coefficient of the thermal expansion capsule 34 expanded in the surface layer portion from the surface of the concave portion 44 of the first unevenness to the predetermined reference depth is substantially the same. The ratio (d _v / d _c ) is preferably 0.85 or more and 1.15 or less, and more preferably 0.90 or more and 1.10 or less.

Here, if the manner in which the thermally expandable capsule 34 expands in the first concavo-convex convex portion 42 is the same as the manner in which the thermally expandable capsule 34 expands in the first concavo-convex concave portion 44, a predetermined reference depth is obtained. However, at any depth, the ratio (d _v / d _c ) shows a similar value. From the viewpoint of ease of measurement, the predetermined reference depth is, for example, from the surface of the first concavo-convex convex portion 42 and the surface of the concave portion 44 to the place where the thermally expandable capsule 34 is expanded. The depth can be 1/2 of the depth.

When the ratio (d _v / d _c ) is 0.80 or more and 1.20 or less, the degree of expansion of the thermally expandable capsule 34 in the first concavo-convex convex portion 42 is the first concavo-convex concave portion 44. Since the degree of expansion of the thermally expandable capsule 34 in this embodiment is the same, it has a particularly excellent appearance quality with a sense of unity between the convex portions 42 and the concave portions 44 of the first concave and convex portions and an excellent tactile sense with a sense of unity. An injection molded product 100 is obtained.

In addition, the average particle diameter (d _c ) and average particle diameter (d _v ) of the expanded thermally expandable capsule 34 can be measured by the above-described method.

Further, in order to set the ratio (d _v / d _c ) to 0.80 or more and 1.20 or less, for example, a near infrared irradiation device is used for the heating device 50 and the infrared irradiation amount is adjusted, and the above-described visual observation is possible. A region in the pattern formed by the first unevenness is heated. Specifically, among the regions in the pattern formed by the first unevenness, the thermally expandable capsule 34 sufficiently expands at a position that is farthest from the infrared irradiation device during heating, and the infrared irradiation device The infrared irradiation amount and the focal range are adjusted so that the polymer material 32 is heated to such a degree that it is not thermally decomposed at the closest position. Further, the surface of the first concave-convex is formed, JIS B 0601: a maximum cross-sectional height Rt ₁ of the roughness curve element as defined in 2001 may be a 10mm or less.

  It should be noted that in the portion where the thermally expandable capsule 34 is thermally expanded, the density is low, and therefore the mechanical strength is weakened. In consideration of securing the rigidity of the injection-molded article 100, the heating of the injection-molded body 40 is less than half the average thickness of the surface of the injection-molded body 40 having the pattern region, that is, the injection-molded body 40. It is preferable that the temperature and time be such that the thermally expandable capsule 34 included in the portion on the surface side of the surface in the thickness direction of the surface having the pattern region thermally expands.

  According to the above-described method for manufacturing an injection-molded product, the surface of the injection-molded product on which the decorative pattern is applied is roughened by utilizing the expansion of the thermally expandable capsule. Therefore, the surface on which the decorative pattern is applied is roughened to a texture. Therefore, the obtained injection molded product is particularly excellent in appearance quality and excellent in touch.

  Therefore, from another viewpoint, another embodiment of the present invention is an injection-molded product manufactured by the above-described manufacturing method. The injection molded product is useful in applications requiring high design properties, and can be suitably used for vehicle interior products such as console boxes, instrument panels, cover members, and building interior products.

  EXAMPLES Examples relating to the present invention will be described below, but the present invention is not intended to be limited to those shown in the specific examples.

<Example>
95% by mass of “actimer (registered trademark)” manufactured by Riken Technos Co., Ltd., which is a styrenic thermoplastic elastomer as a polymer material, and “ADVANCELL (registered trademark) manufactured by Sekisui Chemical Co., Ltd. as a thermally expandable capsule. ) ”Was prepared in a mixture with 5% by mass. The molding material prepared above was melted, filled into an injection mold having a grid pattern unevenness on one molding surface of the molding cavity, and injected. After the molding material was cooled and solidified without opening the mold, the mold was opened to obtain an injection molded body. A lattice pattern was transferred to one surface of the molded injection molded body.

Next, the product name “HYL25-14” manufactured by Hi-Beck Co., Ltd. was used as the near-infrared device, and the molded injection molded body was placed on a belt conveyor to heat the surface of the injection molded body. When heating, adjust the irradiation distance (distance between the near infrared device and the injection molded body), the moving speed of the belt conveyor, and the voltage of the near infrared device so that the convex portions and concave portions of the lattice pattern are about the same. Infrared irradiation amount to be heated. Thereby, an injection molded product according to this example having a surface roughened by fine irregularities in the lattice pattern was obtained. When the cross section of the obtained injection-molded product was observed with an optical microscope, the lattice with respect to the average particle diameter (d _c ) of the thermally expandable capsule expanded in the surface layer portion from the surface of the convex portion of the lattice pattern to a predetermined reference depth The ratio (d _v / d _c ) of the average particle diameter (d _v ) of the thermally expandable capsules expanded in the surface layer portion from the surface of the pattern concave portion to the predetermined reference depth was about 1. Further, the maximum cross-sectional height Rt was 93.3 μm for minute irregularities in the lattice pattern.

  As mentioned above, although the specific example of this invention was demonstrated in detail, referring drawings, these are only illustrations and do not limit a claim. The technology described in the claims includes various modifications and changes of the specific examples illustrated above.

10 injection mold 12 fixed mold 14 movable mold 16 locate ring 18 sprue 20 sprue bush 22 spru 24 injection gate 26 molding cavity 28 molding surface 30 molding material 32 polymer material 34 thermally expandable capsule 40 injection molding body 42 Convex part 44 First concave / convex concave part 50 Near infrared irradiation device (heating device)
52 belt conveyor 54 belt 56 near infrared ray 60 design area 62 non-expandable part 100 injection molded product

Claims (3)

At least a part of the surface is a region where a pattern formed by the first concavo-convex that can be visually observed is provided, and a second concavo-convex that is finer than the first concavo-convex is formed in the pattern and rough. A method for producing an injection-molded article having a surfaced area,
A filling process in which a molding material in which a polymer material and a heat-expandable capsule are mixed is injected into a molding cavity of a predetermined shape of an injection mold, and at least a part of the molding surface of the molding cavity is injected. 3rd unevenness | corrugation for giving the pattern formed by the 1st unevenness | corrugation visible to the surface of a molded object is formed;
A molding step of cooling and solidifying the filled molding material in the molding cavity to obtain an injection molded body having a region formed with a pattern formed by the first concavo-convex visible at least on a part of the surface. ;
A step of taking out the obtained injection-molded body from the injection mold; and heating at least a part of a region provided with a pattern formed by the first concavo-convex pattern visible on the surface of the taken-out injection-molded body By thermally expanding the thermally expandable capsule, a second unevenness smaller than the first unevenness is formed in the pattern formed by the first visible unevenness, and a rough surface is formed. A method for producing an injection-molded article, comprising: a roughening step for forming a roughened region. 2. The manufacturing method according to claim 1, wherein in the roughened region, a maximum cross-sectional height Rt ₂ for the second unevenness is 30 μm or more and less than 200 μm. In the roughening step, the average particle diameter (d _c ) of the thermally expandable capsules expanded in the surface layer portion from the surface of the first concavo-convex convex portion that forms the pattern to a predetermined reference depth The ratio (d _v / d _c ) of the average particle diameter (d _v ) of the thermally expandable capsules expanded in the surface layer portion from the surface of the concave portion of the first unevenness to the predetermined reference depth is 0.80 or more. The manufacturing method according to claim 1, wherein the heating is performed so as to be within a range of 20 or less.

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