Molded article and method for producing the same

Abstract

To provide a method for manufacturing a molded article which can reproduce a wood grain pattern such as a cross grain and a regular pattern.SOLUTION: A method for manufacturing a molded article includes the steps of: clamping a mold cavity and a mold core whose inner surfaces are rugged; injection molding a cellulose-based filler composite resin obtained by adding a cellulose-based filler to a base resin, to a cavity insides the mold cavity and the mold core, applying a rugged shape corresponding to the rugged shape on the inner surface of the mold cavity or the mold core, and forming a molded article having a layer containing furfurals derived from the cellulose-based filler provided in the vicinity of the surface; opening the mold cavity and the mold core after cooling and solidifying, and taking out a molded article from the mold cavity and the mold core; and removing a part of the rugged shape applied to the surface of the taken-out molded article, partially leaving the layer containing the furfurals and forming a pattern on the surface at a distribution of the layer containing the furfurals.SELECTED DRAWING: Figure 2A

Description

Technical Field

[0001] The present invention relates to a molded article, particularly a woody molded article having a woody texture and a method for manufacturing the same.

Background Art

[0002] As a conventional method for manufacturing a resin woody molded article, for example, a method of forming a woody texture on the outermost surface of a target shape by film decoration and painting, or a method of obtaining a woody texture with color unevenness and color shading (such as marble molding) using a coloring agent is common. However, the methods described above have problems such as difficulty in reproducing the surface touch, texture, and texture, leaving a plastic feeling, and low versatility due to shape constraints.

[0003] As methods for reproducing the above wood grain, methods as shown in Patent Document 1 and Patent Document 2 have been developed.

[0004] The two - headed injection device described in Patent Document 1 is composed of two injection cylinders arranged side by side and two injection screws housed in the cylinders. The molten resin outlets at the tips of the two cylinders merge to form a single nozzle. As the woody material, wood powder from which harmful volatile components have been sufficiently dried and removed is used, and it is mixed with a plastic raw material to prepare two types of molding raw materials, namely Material A and Material B, with different wood ratios, and they are respectively filled into the injection cylinders of the two - headed injection device. The wood ratio can be up to about 80%, and it is preferably as close to 80% as possible in order to obtain the texture of natural wood. Also, if necessary, coloring materials, pigments, colored inks, etc. are mixed into the two types of molding raw materials for coloring. Next, the molding method using the above two - headed injection molding machine will be described. First, the fixed mold and the moving mold of the two - headed injection molding machine are clamped. A predetermined amount of Material A is partially filled into the cavity in the mold by one cylinder, and subsequently, a predetermined amount of Material B is partially filled by the other cylinder. Then, the above - mentioned injections are alternately repeated, and sufficient pressure is applied in the final injection and then cooled. By repeating the alternating injection of the predetermined amounts of Material A and Material B, a grain pattern is formed. In this case, it is more desirable to appropriately keep the fixed mold and the moving mold warm with a heating and heat - retaining device (not shown).

[0005] In the method for manufacturing a wood - grained injection - molded product described in Patent Document 2, while a reinforcing member is set in the cavity, a molten resin containing a first material and a second material having a different color from the first material in an incompletely mixed state is prepared. The molten resin is supplied into the cavity in which the reinforcing member is set with a plurality of branch flows, and the reinforcing member is surrounded by the molten resin to form a solidified layer. Based on the action of the plurality of branch flows of the molten resin, in the molded product (product part) stage, a second - material solidified part with a substantially constant interval for each branch - flow trace is formed as a grain pattern on the solidified layer.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0007] However, the method described in Patent Document 1 requires a special molding machine such as a two-color molding machine, and for the materials to be injection-molded, it is also necessary to prepare two types of materials with different wood component addition concentrations. In addition, only the plank pattern within the wood grain pattern can be reproduced, and the high-class square grain pattern cannot be reproduced. Furthermore, there are problems such as difficulty in reproducing the uneven color and shade peculiar to wood by adding a colorant.

[0008] Also, in the method described in Patent Document 2, although significant improvements can be seen, such as the reproduction of the square grain pattern, which was a problem in Patent Document 1, and the ability to reproduce with an ordinary injection molding machine, there are problems such as an increase in the number of gate points for the product and difficulty in controlling each square grain pattern, and the width and direction of the square grain pattern cannot be arbitrarily set.

[0009] On the other hand, the inventor of the present application has developed a method for reproducing the uneven color, shade, touch, and woody texture peculiar to wood as described in Japanese Patent Application Laid-Open No. 2019-115989 in the past. According to this method, by generating furfural, which is a component that causes brownish coloration due to heat peculiar to cellulose-based fillers, it is possible to reproduce the uneven color, shade, and touch similar to natural wood. However, it is difficult to reproduce the wood grain pattern, and there are still problems to be overcome for further improvement of the woody texture quality, and the need to take measures for this has been found.

[0010] The present invention solves the above-mentioned conventional problems, and an object thereof is to provide a method for manufacturing a molded product capable of reproducing wood grain patterns such as plank patterns and square grain patterns.

Means for Solving the Problems

[0011] The manufacturing method of a molded product according to the present invention includes a step of clamping a mold cavity and a mold core having unevenness on the inner surface of the mold cavity and / or the mold core, and injecting a cellulose-based filler composite resin in which a cellulose-based filler is added to a base resin into the cavity inside the mold cavity and the mold core, so that an uneven shape corresponding to the unevenness on the inner surface of the mold cavity or the mold core is imparted to the surface, and a step of forming a molded product provided with a layer containing furfurals derived from the cellulose-based filler in the vicinity of the surface, a step of opening the mold cavity and the mold core after cooling and solidifying to take out the molded product from the mold cavity and the mold core, and a step of removing a part of the uneven shape imparted to the surface of the taken-out molded product and partially leaving the layer containing furfurals to form a pattern by the distribution of the layer containing furfurals.

Advantages of the Invention

[0012] As described above, according to the manufacturing method of a molded product according to the present invention, it is not necessary to use a plurality of materials, a special molding machine, or a complicated mold structure, and it is possible to reproduce a free wood grain pattern such as a plank grain or a square grain, or an arbitrary pattern according to the design of the unevenness of the mold. Thereby, it is possible to provide a molded product having more excellent appearance than before.

Brief Description of the Drawings

[0013]

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Mode for Carrying Out the Invention

[0014] The method for manufacturing a molded article according to the first aspect includes a step of clamping a mold cavity and a mold core having unevenness on the inner surface of the mold cavity and / or the mold core, and injecting a cellulose-based filler composite resin in which a cellulose-based filler is added to a base resin into the cavity inside the mold cavity and the mold core, so that an uneven shape corresponding to the unevenness on the inner surface of the mold cavity or the mold core is imparted to the surface, and a step of forming a molded article provided with a layer containing furfurals derived from the cellulose-based filler in the vicinity of the surface. After cooling and solidifying, the mold cavity and the mold core are opened, and the molded article is taken out from the mold cavity and the mold core. And a step of removing a part of the uneven shape imparted to the surface of the taken-out molded article and partially leaving the layer containing furfurals to form a pattern on the surface by the distribution of the layer containing furfurals.

[0015] The method for manufacturing a molded article according to the second aspect may control the input heat amount in the injection molding step and adjust the thickness of the layer containing furfurals derived from the cellulose-based filler in the vicinity of the surface in the first aspect.

[0016] The method for manufacturing a molded article according to the third aspect may arrange a heat source such as a heater in the mold cavity and / or the mold core and control the input heat amount in the injection molding step in the second aspect.

[0017] The method for manufacturing a molded article according to the fourth aspect may be in any of the first to third aspects, and the cellulose-based filler may be in a bleached pulp state.

[0018] The method for manufacturing a molded article according to the fifth aspect may be in any of the first to fourth aspects, and the addition rate of the cellulose-based filler in the cellulose-based filler composite resin may be 30 wt% to 95 wt%.

[0019] The method for manufacturing a molded article according to the sixth aspect may be in any of the first to fifth aspects, and the base resin to which the cellulose-based filler is added may be a thermoplastic resin having a melting point of 220°C or lower.

[0020] In the method for manufacturing a molded article according to the seventh aspect, in any of the first to sixth aspects, the inner surface of the mold cavity or the mold core has unevenness including a plurality of convex portions extending linearly and parallel to each other, and a straight grain pattern may be formed by removing a part of the uneven shape imparted to the surface of the molded article.

[0021] In the method for manufacturing a molded article according to the eighth aspect, in any of the first to sixth aspects, the inner surface of the mold cavity or the mold core has unevenness including a plurality of convex portions extending concentrically in an elliptical or semi-elliptical shape, and a plank grain pattern may be formed by removing a part of the uneven shape imparted to the surface of the molded article.

[0022] In the method for manufacturing a molded article according to the ninth aspect, in any of the first to sixth aspects, the inner surface of the mold cavity or the mold core has unevenness including convex portions having an arbitrary shape such as linear, radial, circular, square, or dot-like, and an arbitrary pattern may be formed by removing a part of the uneven shape imparted to the surface of the molded article.

[0023] The molded article according to the tenth aspect is a molded article made of a cellulose-based filler composite resin including a base resin and a cellulose-based filler dispersed in the base resin, and on the surface, there is a skin layer where the crystallinity and density of the base resin are higher than the surroundings and there are more furfurals derived from the cellulose-based filler than the surroundings, and a core layer where the crystallinity and density of the base resin are lower than those of the skin layer and there are fewer furfurals than the skin layer, and these are distributed to form a pattern.

[0024] In the molded article according to the eleventh aspect, in the tenth aspect, the boundary between the skin layer and the core layer may be a solid-liquid boundary layer where the crystallinity of the base resin changes.

[0025] The molded article according to the twelfth aspect, in the tenth or eleventh aspect, may have a boundary line with a color difference ΔE>3 in the Lab color space at the boundary between the skin layer and the core layer separated from the skin layer.

[0026] In the molded article according to the 13th aspect, in any of the 10th to 12th aspects, the pattern formed by the distribution of the skin layer and the core layer may be a wood grain pattern including a plank pattern and / or a square pattern.

[0027] In the molded article according to the 14th aspect, in any of the 10th to 12th aspects, the pattern formed by the distribution of the skin layer and the core layer may be other than a wood grain pattern.

[0028] In the molded article according to the 15th aspect, in any of the 10th to 14th aspects, there may be a step between the skin layer and the core layer.

[0029] In the molded article according to the 16th aspect, in any of the 10th to 14th aspects, the skin layer and the core layer may be flush without a step.

[0030] Hereinafter, the molded article and the method for manufacturing the molded article according to the embodiment will be described with reference to the accompanying drawings. In the drawings, substantially the same members are denoted by the same reference numerals.

[0031] (Embodiment 1) <Method for manufacturing a molded article> FIGS. 1A to 1E are schematic cross-sectional views showing each step of the method for manufacturing a molded article according to Embodiment 1. FIG. 2A is a detailed cross-sectional view showing the surface state immediately before processing for removing a part of the uneven shape on the surface of the molded article in one step of the method for manufacturing the molded article of FIG. 1D. FIG. 2B is a detailed cross-sectional view showing the surface state immediately after processing for removing a part of the uneven shape on the surface of the molded article in one step of the method for manufacturing the molded article of FIG. 1E. The manufacturing method of the molded product according to Embodiment 1 includes a step of clamping a mold cavity 101 and a mold core 102, a step of injecting a cellulose-based filler composite resin 105 into the cavity inside the mold cavity 101 and the mold core 102 to form a molded product, a step of opening the mold cavity 101 and the mold core 102 after cooling and solidifying to take out the molded product 107 from the mold cavity 101 and the mold core 102, and a step of removing a part of the uneven shape provided on the surface of the taken-out molded product to form a pattern.

[0032] Specifically, the manufacturing method of the molded product according to Embodiment 1 is carried out as follows. (1) First, clamp the mold cavity 101 and the mold core 102 with unevenness on the inner surface (Fig. 1A). The mold cavity 101 is provided with a sprue 103 for injecting a cellulose-based filler composite resin. (2) Next, inject a cellulose-based filler composite resin obtained by adding a cellulose-based filler to a base resin from the sprue 103 into the cavity inside the mold cavity 101 and the mold core 102 (Fig. 1B). Thereby, an uneven shape corresponding to the unevenness on the inner surface of the mold cavity or the mold core is imparted to the surface, and a molded product provided with a layer containing furfurals derived from the cellulose-based filler in the vicinity of the surface can be formed. (3) Then, after cooling and solidifying, open the mold cavity 101 and the mold core 102 to take out the molded product 107 (Fig. 1C). (4) Further, remove a part of the uneven shape provided on the surface of the taken-out molded product 107, and partially leave the layer containing furfurals to form a pattern with the distribution of the layer containing furfurals (Figs. 1D, 1E, 2A, 2B). According to this manufacturing method of the molded product, it is not necessary to use a plurality of materials, a special molding machine, or a complicated mold structure, and it is possible to reproduce a free wood grain pattern such as a plank pattern or a square pattern, or an arbitrary pattern according to the design of the unevenness of the mold.

[0033] Hereinafter, each step of this manufacturing method of the molded product and the members used will be described.

[0034] In the method for manufacturing a molded article according to Embodiment 1, a cellulose-based filler composite resin containing a cellulose-based filler is used as an injection molding resin for a base resin serving as a base material.

[0035] <Cellulose-based filler> The type of the cellulose-based filler may be any material from which a cellulose filler can be extracted, such as softwood, hardwood, hemp, bamboo, etc., and is not particularly limited. Also, the shape of the cellulose-based filler can be freely selected within the range of a diameter from the μm order to the nm order and a length from the mm order to the nm order. In order to prevent embrittlement due to the addition of the cellulose-based filler, a fiber shape with an aspect ratio (length / diameter) of 5 or more of the cellulose-based filler is preferable.

[0036] Also, the color of the cellulose-based filler is preferably white after being bleached and having the lignin component removed in order to expand the range of reproducible woody colors in the molded article. Preferably, pulp used as a raw material for paper or the like is used. As a white standard, it is preferable to use pulp having Lab color space measurement values by a spectroscopic measuring machine of L value: 50 or more, a value: -5 to 5, and b value: about 0 to 10.

[0037] <Base resin> As the base resin used for the base material, it is preferable to use a thermoplastic resin. For example, polypropylene (PP), polyethylene (PE), acrylonitrile-butadiene-styrene (ABS), acrylonitrile styrene (AS), polyamide (PA), polyacetal (POM), polylactic acid (PLA), polybutylene terephthalate (PBT), polyurethane (PU), polycarbonate (PC), polystyrene (PS), polyvinyl chloride (PVC), acrylic (PMMA), polyhydroxyalkanoate (PHA), etc. can be mentioned. More preferably, in order to prevent carbonization and deterioration of the cellulose-based filler during resin compounding, PP, PE, AS, ABS, PVC, POM, PMMA having a melting point of 220°C or lower are mentioned.

[0038] <Process of clamping the mold cavity and the mold core> In the mold structure, unevenness 104 is provided on the inner surface side of the mold cavity 101 and / or the mold core 102 so that the portions to be left in the texture (brown) for the final texture pattern become convex portions (i.e., concave portions on the molded product side where the shape is transferred) on the inner surface of the mold cavity 101 and / or the mold core 102. The mold cavity 101 and the mold core 102 are clamped (Fig. 1A).

[0039] <Regarding the unevenness provided on the inner surface of the mold cavity or the mold core> The convex portions provided on the inner surface of the mold cavity or the mold core become concave portions on the molded product side when transferred. On the other hand, the concave portions provided on the inner surface of the mold cavity or the mold core become convex portions on the molded product side when transferred. That is, the uneven shape on the surface of the molded product corresponds to the unevenness on the inner surface of the mold cavity or the mold core. Even if a part of the uneven shape on the surface of the molded product is removed, the browned layer in the concave portion remains to form a pattern. For example, when unevenness including a plurality of linearly extending convex portions parallel to each other is provided on the inner surface of the mold cavity or the mold core, a straight grain pattern is formed by removing a part of the uneven shape imparted to the surface of the molded product. Also, when unevenness including a plurality of concentric elliptical or semi-elliptical convex portions extending is provided on the inner surface of the mold cavity or the mold core, a plank grain pattern is formed by removing a part of the uneven shape imparted to the surface of the molded product. Further, when unevenness including convex portions of any shape such as linear, radial, circular, angular, or dot-shaped is provided on the inner surface of the mold cavity or the mold core, an arbitrary pattern is formed by removing a part of the uneven shape imparted to the surface of the molded product.

[0040] Also, although the size and shape of the unevenness can be set arbitrarily, it is preferable to unify the surface height so that the position of the tip of the convex portion of the convex shape on the mold side becomes the thickness of the final molded product. Moreover, by providing a heater and a temperature control circuit for controlling the mold temperature in the mold cavity and / or the mold core, it is possible to finely control the color tone of the texture pattern. In addition, in the present embodiment, unevenness is designed to reproduce the wood grain pattern on the appearance of the final molded product. However, the unevenness is not limited to the reproduction of the wood grain pattern, and any shape can be designed within the range that can be designed on the mold cavity and / or mold core.

[0041] <Step of injection molding a cellulose-based filler composite resin into the cavity inside the mold cavity and the mold core> The above-mentioned molten cellulose-based filler composite resin 105 is injection molded from the sprue 103 into the cavity inside the mold composed of the mold cavity 101 with unevenness on the inner surface and the mold core 102 (Fig. 1B). At this time, it is known that the cellulose-based filler generates a brownish component classified into furfurals according to the amount of heat input, and the color tone changes to brown. It gradually changes from brown to the original color of the resin from the surface of the molded product toward the center of the plate thickness, forming a browned layer. At this time, the surface of the molded product is most browned and the color becomes darker. Therefore, the browned layer formed on the surface of the molded product is called the skin layer. On the other hand, the part with the original color of the resin at the center of the plate thickness is called the core layer. Note that the molding conditions are controlled so that the surface of the molded product is uniformly browned, and the cellulose-based filler composite resin is filled into the shape of the molded product. Note that the expression of the brown color tone is for convenience and includes color expressions such as brown.

[0042] In addition, in the molding conditions during injection molding, in order to make the color tone of the browned layer darker (that is, closer to a dark color), it can be realized by increasing any one of the resin temperature, mold temperature, injection speed, or a plurality of factors. On the other hand, in order to make the color tone lighter, it can be realized by the reverse method.

[0043] In addition, the generation amount of the component classified into furfurals, which is a brown component, can be measured, for example, by converting the amount of gas generated in the vapor phase part of the vial into the amount per unit weight of the analysis sample by gas chromatography / mass spectrometry (GC / MS) component analysis using toluene d8 as a standard sample.

[0044] <Step of opening the mold cavity and the mold core after cooling and solidification to take out the molded product> After injection molding and after cooling and solidification, the mold cavity 101 and the mold core 102 are opened to take out the molded product 107 (Fig. 1C). At this time, the cured cellulose-based filler composite resin in the portion corresponding to the sprue 103 is called the runner 106. This runner 106 is taken out separately from the molded product 107.

[0045] <Step of removing a part of the uneven shape applied to the surface of the taken-out molded product to form a pattern> The uneven shapes 110, 112 (Fig. 2A) transferred to the surface of the taken-out molded product 107 are removed by removing means such as grinding or cutting, for example, with an unevenness removing tool 108 so that the surface of the molded product becomes flat (Figs. 1D, 1E, 2A, 2B). The surface of the taken-out molded product 107 is in a state of having a browned layer 113 and has convex portions 110 and concave portions 112. In the figure, a rotating polishing roller is used as the unevenness removing tool 108, but it is not limited to this. The portion that was the convex portion 110 on the surface of the molded product 107 has a larger amount removed than the portion that was the concave portion 112 on the surface of the molded product 107, so that the browned layer 113 is removed and the color approaches the original white color of the cellulose-based filler composite resin. This portion is the core layer 114 described above. On the other hand, the concave portion 112 has a smaller removal amount or is not removed compared to the convex portion 110, so that the surface at the time of molding is maintained in a state close to that at the time of molding and the browned layer 113 remains. The portion where the browned layer 113 remains is the skin layer 111 described above. An arbitrary pattern can be formed on the surface of the molded product by the difference in the remaining amount of this browned layer 113. That is, the pattern is constituted by the distribution of the skin layer 111 and the core layer 114 (Fig. 2B). The final molded product 109 is obtained by the above steps.

[0046] Further, the surface of the final molded product 109 after removing the uneven shapes 110 and 112 transferred to the surface of the molded product 107 is roughly divided into two states (Fig. 2B). First, for the part where the convex part 110 was originally formed during molding and the removal amount is larger than that of the concave part 112, the remaining amount of the skin layer 111 formed during the resin flow and cooling process is small, or the core layer 114 is exposed, and a resin structure with a high degree of crystallinity appears on the outermost surface. On the other hand, for the part where the concave part 112 was originally formed during molding and the removal amount is smaller than that of the convex part 110, or not removed, the skin layer 111 with a low degree of crystallinity appears on the outermost surface.

[0047] <Regarding the skin layer and the core layer> The definitions of the skin layer and the core layer will be described with reference to Figs. 3A and 3B. Fig. 3A is a schematic cross-sectional view showing the skin layer and the core layer in the thickness direction of the molded product during the injection molding of the cellulose-based filler composite resin. Fig. 3B is a schematic cross-sectional view showing the skin layer and the core layer in the thickness direction of the molded product after the injection molding of the cellulose-based filler composite resin.

[0048] In FIG. 3A, the cellulose-based filler composite resin injected into the cavity of the mold 501 flows within the cavity of the mold 501 while forming the core layer 502 and the skin layer 503, and is filled at the flow end to form a molded product. In FIG. 3B, when the cellulose-based filler composite resin is filled to the end, a skin layer 503 is also formed at the end. In the molded product after injection molding, there is a solid-liquid boundary layer 504 where the composition such as the degree of crystallinity and density changes between the core layer 502 and the skin layer 503. The skin layer 503 is formed at a position closer to the mold surface than the solid-liquid boundary layer 504, and the core layer 502 is formed inside the solid-liquid boundary layer 504 (inside the thickness of the molded product). As a feature, since the core layer 502 is at a relatively far distance from the mold surface, the cooling rate is slow and it is slowly cooled, while the skin layer 503 is in the immediate vicinity of the mold and the cooling rate is fast and it is rapidly cooled. Due to this difference in cooling rate, the rate of crystallization and the state of the pressure distribution change, and the core layer 502 has a high degree of crystallinity and a high density state, while the skin layer 503 has a low degree of crystallinity and a low density state. That is, the solid-liquid boundary layer 504 is formed due to the difference in the cooling rate of the cellulose-based filler resin in contact with the mold during injection molding, specifically, the difference in the degree of crystallinity caused by the difference in the cooling temperature between the rapid cooling near the mold surface and the slow cooling at the center of the plate thickness. The position of the solid-liquid boundary layer 504 varies depending on the injection molding conditions and the shape of the molded product, but it is often formed in a range of approximately 1 mm from the surface of the molded product inward in the thickness direction.

[0049] The states of the skin layer and the core layer in the molded product with the uneven shape provided on the surface after injection molding and the final molded product after removing the unevenness will be described with reference to FIGS. 4A and 4B. FIG. 4A is a schematic cross-sectional view showing the states of the skin layer and the core layer of the molded product with the uneven shape provided on the surface after injection molding. FIG. 4B is a schematic cross-sectional view showing the states of the skin layer and the core layer of the final molded product after removing the unevenness.

[0050] In FIG. 4A, in the molded product 107 taken out of the mold, the skin layer 503 and the core layer 502 are formed along the uneven shape with the unevenness of the mold transferred. Further, a solid-liquid boundary layer 504 exists between the skin layer 503 and the core layer 502. In FIG. 4B, the surface of the final molded product 109 after the removal of the unevenness is in a state where the skin layer 503 and the core layer 502 are each exposed on the surface according to the amount of removal as described above. In the final molded product 109, by the coexistence of the skin layer 503 and the core layer 502, it is possible to reproduce wood grain patterns such as straight grain and plank grain. Further, when the skin layer and the core layer are disordered, a matte feeling is felt visually and there is also a difference in touch, so that it has a random touch like real wood and also has the merit of looking like wood in terms of the light reflectance.

[0051] Hereinafter, a specific example of the method for manufacturing a molded product according to Embodiment 1 will be described with reference to the drawings.

[0052] (Specific Example) In the specific example of Embodiment 1, PP was used as the base resin, and bleached pulp derived from softwood was used as the cellulose-based filler. Further, the maximum uneven shape on the surface of the molded product was 0.3 mm, and the thickness of the molded product was 2.8 mm. Further, cooling circuits were arranged in the mold cavity and the mold core, and temperature control was performed with water.

[0053] FIG. 5A is a schematic view showing the appearance of a molded product 107 to which 55 wt% of a cellulose-based filler is added obtained by the method for manufacturing a molded product according to the specific example of Embodiment 1. FIG. 5B is a schematic view showing the appearance of the final molded product 109 obtained by removing the uneven shape of the molded product 107 in FIG. 5A. FIG. 5C is a schematic view showing the wood grain pattern 302, the white part 301, and the boundary line 303 thereof in the final molded product 109 in FIG. 5B. In FIG. 5A, the actual appearance of the molded article 107 including the uneven shape immediately after injection molding described in FIG. 2A in a cellulose filler composite resin (hereinafter referred to as PP-CeF55%) with 55 wt% of cellulose filler added is shown. In FIG. 5B, the actual appearance of the final molded article 109 after grinding described in FIG. 2B is shown. Further, in FIG. 5C, the portion where the convex portion 110 with a large removal amount was formed forms a white portion 301 (core layer), and the concave portion 112 that was not removed or had a small removal amount has a remaining browned layer 111 (skin layer) and forms a wood grain pattern portion 302. The color tone of the wood grain pattern portion 302 and the white portion 301 is different at the boundary line 303.

[0054] As a result of measuring the color difference in the Lab color space using a spectro-measuring instrument with the boundary line 303 between the wood grain pattern portion 302 and the white portion 301 of the obtained final molded article 109 as the boundary, the color difference ΔE = 4.75. From this, by this manufacturing method of the molded article, in the final molded article 109, a wood grain pattern having a color difference sufficient to be distinguishable even when visually observed by the human eye could be formed.

[0055] Further, as a result of analyzing the production amount of furfurals generated in the wood grain pattern portion 302 and the white portion 301 of the obtained final molded article by gas chromatography / mass spectrometry (GC / MS) component analysis, the average value of N = 3 was 0.21 μg / g in the wood grain pattern portion 302, while it was 0.12 μg / g in the white portion 301, and a difference of 0.09 μg was confirmed. From this, it was found that the color difference was due to the generated furfurals.

[0056] <Regarding the relationship between the uneven removal depth and the skin layer> i) When the uneven removal depth is smaller than the height of the convex portion FIG. 6A is a schematic cross-sectional view showing the remaining browned layer 111 and the whitened surface 114 in the final molded article when the uneven removal depth is smaller than the height of the convex portion. FIG. 6B is a schematic view showing the result of observing the surface of the final molded article 109 in FIG. 6A with a simple polarizing microscope. In FIG. 6A, a cross-section is shown when the convex portion 110 is removed by 0.29 mm with respect to the depth of the uneven shape of 0.3 mm so that the unevenness removing tool 108 does not contact (remove) the surface of the concave portion 112 shown in FIG. 2A. That is, the browned layer 113 formed on the surface of the concave portion 112 remains as the remaining browned layer 111 as it is. Also, in this case, a part of the uneven shape of the surface of the molded product remains as a step on the surface of the final molded product 109. In the actual observation photograph 701 taken with a simple polarizing microscope shown in FIG. 6B, since there is no removal process by the unevenness removing tool 108, the outermost surface is held as it is as a skin layer which is the remaining browned layer in which the browned layer formed at the time of molding remains, while on the other hand, it can be seen that the base resin crystals 704 which appear white are exposed at 10% or less of the surface of the final molded product 109. From this, it can be said that in the cases of FIGS. 6A and 6B, the crystallinity of the surface of the final molded product is low.

[0057] ii) When the depth of unevenness removal is approximately the same as the height of the convex portion FIG. 6C is a schematic cross-sectional view showing the remaining browned layer 111 in the final molded product when the depth of unevenness removal is approximately the same as the height of the convex portion. FIG. 6D is a schematic view showing the result of observing the surface of the final molded product 109 in FIG. 6C with a simple polarizing microscope. In FIG. 6C, a cross-section is shown when approximately 0.3 mm is removed with respect to the depth of the uneven shape of 0.3 mm so that the remaining browned layer 111 is slightly contacted by the unevenness removing tool 108 during the removal process. In this case, the unevenness on the surface of the molded product does not remain as a step on the surface of the final molded product 109. In the actual observation photograph 702 taken with a simple polarizing microscope shown in FIG. 6D, it can be seen that due to the slight removal process by the unevenness removing tool 108, the base resin crystals 704 are exposed in the range of 20% to 60% of the surface of the final molded product 109 as compared with the surface 701 (FIG. 6B) in the case where there is no removal process. From this, it can be said that in the cases of FIGS. 6C and 6D, the crystallinity of the surface of the final molded product is higher than that in FIGS. 6A and 6B.

[0058] iii) When the depth of unevenness removal is greater than the height of the convex portion FIG. 6E is a schematic cross-sectional view showing a whitened surface 114 in the final molded product when the unevenness removal depth is greater than the height of the convex portion. FIG. 6F is a schematic view showing the result of observing the surface of the final molded product 109 of FIG. 6E with a simple polarizing microscope. In FIG. 6E, a cross-section is shown when 0.31 mm is removed from the depth of the uneven shape of 0.3 mm by the unevenness removal tool 108. In this case, the browned layer is completely removed and the whitened surface 114 is formed. In the actual observation photograph 703 taken with the simple polarizing microscope shown in FIG. 6F, the skin layer 503 including the browned layer is completely removed, and since the core layer is exposed on the outermost surface, it can be seen that the base resin crystals 704 are exposed on the surface of the final molded product 109 in the range of 70% to 99%. From this, in the cases of FIGS. 6E and 6F, it can be said that the crystallinity is higher than in FIGS. 6C and 6D, and the crystallinity increases as the amount of the skin layer decreases.

[0059] Table 1 in FIG. 7 is a table showing the results of investigating the cellulose-based filler addition rate and the color difference in the Lab color space between the wood grain pattern part and the white part in Examples 1-1 to 1-14 of Embodiment 1.

[0060] (Example 1) In Table 1 of FIG. 7, Example 1-1 is an example in which 30 wt% of softwood pulp was added, injection molding was performed at a resin temperature of 200°C and a mold temperature of 60°C, and then grinding was performed. As a result, it was possible to form a wood grain pattern and the color difference ΔE = 3.11.

[0061] (Example 2) In Table 1 of FIG. 7, Example 1-2 is an example in which 35 wt% of softwood pulp was added, injection molding was performed at a resin temperature of 205°C and a mold temperature of 60°C, and then grinding was performed. As a result, it was possible to form a wood grain pattern and the color difference ΔE = 3.49.

[0062] (Example 3) In Table 1 of FIG. 7, Example 1-3 is an example in which 40 wt% of softwood pulp was added, injection molding was performed at a resin temperature of 210°C and a mold temperature of 60°C, and then grinding was performed. As a result, it was possible to form a wood grain pattern and the color difference ΔE = 3.69.

[0063] (Example 4) In Table 1 of FIG. 7, Examples 1-4 are examples in which 45 wt% of softwood pulp was added, injection molding was performed at a resin temperature of 215°C and a mold temperature of 60°C, and then grinding was performed. As a result, it was possible to form a wood grain pattern and the color difference ΔE = 4.01.

[0064] (Example 5) In Table 1 of FIG. 7, Examples 1-5 are examples in which 50 wt% of softwood pulp was added, injection molding was performed at a resin temperature of 220°C and a mold temperature of 75°C, and then grinding was performed. As a result, it was possible to form a wood grain pattern and the color difference ΔE = 4.30.

[0065] (Example 6) In Table 1 of FIG. 7, Examples 1-6 are examples in which 55 wt% of softwood pulp was added, injection molding was performed at a resin temperature of 225°C and a mold temperature of 75°C, and then grinding was performed. As a result, it was possible to form a wood grain pattern and the color difference ΔE = 4.75.

[0066] (Examples 1-7) In Table 1 of FIG. 7, Examples 1-7 are examples in which 60 wt% of softwood pulp was added, injection molding was performed at a resin temperature of 230°C and a mold temperature of 75°C, and then grinding was performed. As a result, it was possible to form a wood grain pattern and the color difference ΔE = 5.06.

[0067] (Examples 1-8) In Table 1 of FIG. 7, Examples 1-8 are examples in which 65 wt% of softwood pulp was added, injection molding was performed at a resin temperature of 235°C and a mold temperature of 75°C, and then grinding was performed. As a result, it was possible to form a wood grain pattern and the color difference ΔE = 5.21.

[0068] (Examples 1-9) In Table 1 of FIG. 7, Examples 1-9 are examples in which 70 wt% of softwood pulp was added, injection molding was performed at a resin temperature of 240°C and a mold temperature of 75°C, and then grinding was performed. As a result, it was possible to form a wood grain pattern and the color difference ΔE = 5.40.

[0069] (Examples 1-10) In Table 1 of Figure 7, Examples 1-10 are examples in which 75 wt% of softwood pulp was added, injection molding was performed at a resin temperature of 245°C and a mold temperature of 90°C, and then grinding was performed. As a result, it was possible to form a wood grain pattern and the color difference ΔE = 5.66.

[0070] (Examples 1-11) In Table 1 of Figure 7, Examples 1-11 are examples in which 80 wt% of softwood pulp was added, injection molding was performed at a resin temperature of 250°C and a mold temperature of 90°C, and then grinding was performed. As a result, it was possible to form a wood grain pattern and the color difference ΔE = 5.93.

[0071] (Examples 1-12) In Table 1 of Figure 7, Examples 1-12 are examples in which 85 wt% of softwood pulp was added, injection molding was performed at a resin temperature of 255°C and a mold temperature of 90°C, and then grinding was performed. As a result, it was possible to form a wood grain pattern and the color difference ΔE = 6.23.

[0072] (Examples 1-13) In Table 1 of Figure 7, Examples 1-13 are examples in which 90 wt% of softwood pulp was added, injection molding was performed at a resin temperature of 260°C and a mold temperature of 90°C, and then grinding was performed. As a result, it was possible to form a wood grain pattern and the color difference ΔE = 6.65.

[0073] (Examples 1-14) In Table 1 of Figure 7, Examples 1-14 are examples in which 95 wt% of softwood pulp was added, injection molding was performed at a resin temperature of 265°C and a mold temperature of 90°C, and then grinding was performed. As a result, it was possible to form a wood grain pattern and the color difference ΔE = 6.89.

[0074] Table 2 of Figure 8 shows the results of investigating the possibility of forming a wood grain pattern when 30 wt% and 95 wt% of a cellulose-based filler were added to each base resin in Examples 2-1 to 2-8 of Embodiment 1.

[0075] (Examples 2-1) In Table 2 of FIG. 8, Example 2-1 is an example in which 30 wt% of softwood pulp is added when the base resin is polyethylene (hereinafter referred to as PE). As a result, it was possible to form a wood grain pattern.

[0076] (Example 2-2) In Table 2 of FIG. 8, Example 2-2 is an example in which 95 wt% of softwood pulp is added when the base resin is PE. As a result, it was possible to form a wood grain pattern.

[0077] (Example 2-3) In Table 2 of FIG. 8, Example 2-3 is an example in which 30 wt% of softwood pulp is added when the base resin is acrylonitrile-styrene-butadiene (hereinafter referred to as ABS). As a result, it was possible to form a wood grain pattern.

[0078] (Example 2-4) In Table 2 of FIG. 8, Example 2-4 is an example in which 95 wt% of softwood pulp is added when the base resin is ABS. As a result, it was possible to form a wood grain pattern.

[0079] (Example 2-5) In Table 2 of FIG. 8, Example 2-5 is an example in which 30 wt% of softwood pulp is added when the base resin is polylactic acid (hereinafter referred to as PLA). As a result, it was possible to form a wood grain pattern.

[0080] (Example 2-6) In Table 2 of FIG. 8, Example 2-6 is an example in which 95 wt% of softwood pulp is added when the base resin is PLA, injection molded at a resin temperature of 200 °C and a mold temperature of 60 °C, and then subjected to grinding. As a result, it was possible to form a wood grain pattern.

[0081] (Example 3) In Table 2 of FIG. 8, Example 2-7 is an example in which 30 wt% of softwood pulp is added when the base resin is nylon (hereinafter referred to as PA). As a result, it was possible to form a wood grain pattern.

[0082] (Example 3) In Table 2 of FIG. 8, Examples 2-8 are examples in which 95 wt% of softwood pulp was added when the base resin was PA. As a result, it was possible to form a wood grain pattern.

[0083] According to such a configuration, a molded product having a wood grain pattern like real wood can be reproduced by a normal injection molding machine using a mold configured with a concavo-convex mold cavity and / or a mold core, and a cellulose-based filler composite resin.

[0084] In the above-described embodiments and examples, bleached softwood-derived pulp was used as the cellulose-based filler. However, any cellulose-based filler can be selected as long as carbonization and deterioration do not occur during the resin composite stage as described above, and there is no particular limitation.

[0085] In addition, in Embodiment 1, in order to clarify the difference from the prior art, the concavo-convex shape was designed to look like a wood grain pattern. However, any pattern other than the wood grain pattern can be realized as long as there is no problem with the mold structure.

[0086] (Embodiment 2) In Embodiment 2, for the purpose of making the color tone of the remaining browned layer 111 darker and forming a distinct wood grain pattern, injection molding was carried out with a mold structure in which a heater was arranged in the mold cavity and / or the mold core.

[0087] The base resin was polypropylene (PP), and a material with 55 wt% of cellulose filler (CeF) added (hereinafter referred to as PP-CeF55%) was used. The maximum unevenness on the surface of the molded product was 0.3 mm, and the plate thickness of the molded product was 2.8 mm.

[0088] In Embodiment 1, the mold temperature was set at 75°C in the cooling circuit using water. However, in Embodiment 2, high-speed heating and cooling between 140°C and 60°C was performed by controlling with a heater and increasing the maximum heating temperature (generally referred to as heat and cool molding). As a result, it is possible to improve only the input heat amount without increasing the molding cycle time.

[0089] Figures 9A to 9E are schematic cross-sectional views showing each step of the method for manufacturing a molded article according to Embodiment 2. The method for manufacturing a molded article according to Embodiment 2 is different from that of Embodiment 1 in that a mold structure is used in which a heater is arranged in the mold and an arbitrary position / area of the molded article can be locally heated. The method for manufacturing a molded article according to Embodiment 2 is carried out as follows. (1) First, the mold cavity 101 and the mold core 102, which have unevenness 104 on the inner surface and a heater 401 provided inside, are clamped (Fig. 9A). The mold cavity 101 is provided with a sprue 103 for injecting a cellulose-based filler composite resin. Note that the sprue 103 is not limited to being provided in the mold cavity 101 and may be provided in the mold core 102. (2) Next, the molten cellulose-based filler composite resin (PP-CeF30%) 402 is injected from the sprue 103 into the cavities inside the mold cavity 101 and the mold core 102 (Fig. 9B). At this time, the surface of the mold cavity is set at 140°C by the heater 401, and a larger amount of heat is input to an arbitrary area on the mold cavity side of the injected resin. As a result, an uneven shape corresponding to the unevenness on the inner surface of the mold cavity 101 or the mold core 102 is imparted to the surface, and a molded article can be formed in which a layer containing more furfurals derived from the cellulose-based filler is provided in the vicinity of the surface. (3) Next, the operation of the heater 401 is stopped and it is sufficiently cooled. After cooling and solidifying, the mold cavity 101 and the mold core 102 are opened and the molded article 403 is taken out (Fig. 9C). At this time, the runner 106 corresponding to the sprue 103 is separated from the molded article 403 and taken out. (4) Further, a part of the uneven shape imparted to the surface of the taken-out molded product 403 is removed with a grinding tool 108, and a layer containing furfurals is partially left to form a pattern based on the distribution of the layer containing furfurals (FIGS. 9D and 9E). Thus, the final molded product 404 is obtained.

[0090] Table 3 in FIG. 10 is a table comparing the characteristics of the molded products with and without the in-mold heater in Embodiment 2. In Table 3 in FIG. 10, as a result of measuring the color difference in the Lab color space between the grain pattern and the white part of the obtained final molded product 404, the color difference ΔE = 5.82, which is about 1.23 times improved compared to the molded product of Example 6 of the same PP-CeF55% obtained by the process of Embodiment 1.

[0091] According to such a configuration, by arranging the heater in the mold and increasing the input heat amount, a clearer grain pattern could be formed without problems such as an increase in the molding cycle time.

[0092] Note that in the present disclosure, it includes appropriately combining any of the various embodiments and / or examples described above, and the effects possessed by each embodiment and / or example can be achieved.

Industrial Applicability

[0093] The molded product according to the present invention can reproduce the texture and grain pattern like real wood in a cycle equivalent to injection molding. For this reason, it can be applied to the replacement of products that have been applied by cutting wood over a long period of time, and also to parts that cannot use real wood such as those around water, which have been difficult to adopt due to durability problems.

Explanation of Signs

[0094] 101 Mold cavity 102 Mold core 103 Sprue 104 Surface unevenness 105 Molded object 106 Runner 107 Molded product 108 Uneven removal tool 109 Final molded product 110 Convex part 111 Remaining browned layer 112 Concave part 113 Browned layer 114 Whitened surface 301 White part 302 Grain pattern part 303 Boundary line 401 Heater 402 Molded object 403 Molded product 404 Final molded product 501 Mold 502 Core layer 503 Skin layer 504 Solid-liquid boundary layer 20 Fixed mold plate 21 Moving mold plate 22 Fixed mold fixed to the fixed mold plate 20 23 Moving mold fixed to the moving mold plate 21 24 Two-headed injection device 25 Injection cylinder 25’ Injection cylinder 26 Injection screw 26’ Injection screw 27 Nozzle 28 Sprue provided in the fixed mold 22 29 Parting surface between the fixed mold 22 and the moving mold 23 30 Cavity formed inside the fixed mold 22 and the moving mold 23 31 Molded product 1201 Cavity 1202 Reinforcing member 1203 First material 1204 Second material with a different color from the first material 1205 Molten resin 1206 Split flow 1207 Solidified layer 1208 shunt trace

Claims

1. A step of clamping the mold cavity and / or the mold core having unevenness on the inner surface of the mold cavity and the mold core; Injecting a cellulose filler composite resin in which a cellulose filler is added to a base resin into the cavities inside the mold cavity and the mold core, and forming an uneven shape corresponding to the unevenness on the inner surface of the mold cavity or the mold core is provided on the surface, and a step of forming a molded product provided with a layer containing furfurals derived from the cellulose filler in the vicinity of the surface; After cooling and solidifying, a step of opening the mold cavity and the mold core and taking out the molded product from the mold cavity and the mold core; Removing a part of the uneven shape provided on the surface of the taken-out molded product, and partially leaving the layer containing furfurals to form a pattern on the surface by the distribution of the layer containing furfurals; A method for manufacturing a molded product, comprising:

2. The method for manufacturing a molded product according to claim 1, wherein the input heat amount in the injection molding step is controlled to adjust the thickness of the layer containing furfurals derived from the cellulose filler in the vicinity of the surface.

3. The method for manufacturing a molded product according to claim 2, wherein a heat source of a heater is arranged in the mold cavity and / or the mold core to control the input heat amount in the injection molding step.

4. The method for manufacturing a molded product according to any one of claims 1 to 3, wherein the cellulose filler is in a bleached pulp state.

5. The method for manufacturing a molded product according to any one of claims 1 to 4, wherein the addition rate of the cellulose filler in the cellulose filler composite resin is 30 wt% to 95 wt%.

6. The method for manufacturing a molded product according to any one of claims 1 to 5, wherein the base resin to which the cellulose filler is added is a thermoplastic resin having a melting point of 220 ° C or lower.

7. having unevenness including a plurality of convex portions extending linearly and parallel to each other on the inner surface of the mold cavity or the mold core, The method for manufacturing a molded article according to any one of claims 1 to 6, wherein a straight grain pattern is formed by removing a part of the uneven shape imparted to the surface of the molded article.

8. having unevenness including a plurality of convex portions extending concentrically in an elliptical or semi-elliptical shape on the inner surface of the mold cavity or the mold core, The method for manufacturing a molded article according to any one of claims 1 to 6, wherein a plank grain pattern is formed by removing a part of the uneven shape imparted to the surface of the molded article.

9. having unevenness including convex portions of any shape such as linear, radial, circular, angular, or dot-shaped on the inner surface of the mold cavity or the mold core, The method for manufacturing a molded article according to any one of claims 1 to 6, wherein an arbitrary pattern is formed by removing a part of the uneven shape imparted to the surface of the molded article.

10. A molded article made of a cellulose-based filler composite resin including a base resin and a cellulose-based filler dispersed in the base resin, on the surface, there is a skin layer in which the crystallinity and density of the base resin are lower than the surroundings and furfurals derived from the cellulose-based filler are more than the surroundings, and a core layer in which the crystallinity and density of the base resin are higher than those of the skin layer and the furfurals are less than those of the skin layer, and a pattern is formed by their distribution, A molded article in which the pattern formed by the distribution of the skin layer and the core layer is a wood grain pattern including a plank grain and / or a straight grain pattern.

11. A molded article made of a cellulose-based filler composite resin including a base resin and a cellulose-based filler dispersed in the base resin, On the surface, there is a skin layer where the crystallinity and density of the base resin are lower than those of the surroundings and the furfurals derived from the cellulose-based filler are more than those of the surroundings, and a core layer where the crystallinity and density of the base resin are higher than those of the skin layer and the furfurals are less than those of the skin layer, and they are distributed to form a pattern. At the same time, A molded article in which the pattern formed by the distribution of the skin layer and the core layer is other than a wood grain pattern.

12. The boundary between the skin layer and the core layer is a solid-liquid boundary layer where the crystallinity of the base resin changes. The molded article according to claim 10 or 11.

13. The boundary between the skin layer and the core layer away from the skin layer has a boundary line with a color difference ΔE>3 in the Lab color space. The molded article according to any one of claims 10 to 12.

14. There is a step between the skin layer and the core layer. The molded article according to any one of claims 10 to 13.

15. There is no step between the skin layer and the core layer and they are flush. The molded article according to any one of claims 10 to 13.

Images