Laminate and manufacturing method for laminate

Abstract

To provide a laminate that has a less environmental impact and does not impair the appearance.SOLUTION: A laminate comprises an upper layer 10, a lower layer 20, and an intermediate layer 30 laminated between the upper layer 10 and the lower layer 20. The intermediate layer 30 comprises: an upper intermediate layer 31 disposed on the upper layer 10 side; a lower intermediate layer 32 disposed on the lower layer 20 side; and a rib layer 33 that connects the upper intermediate layer 31 and the lower intermediate layer 32 so that those form a hollow part between the upper intermediate layer 31 and the lower intermediate layer 32, and is provided to connect the upper intermediate layer 31 and the lower intermediate layer 32, and has a cross-sectional shape that is constant regardless of which cutting surface is considered, with the cross-sectional shape being perpendicular to a direction perpendicular to a stacking direction. Materials of the upper layer 10, the lower layer 20, and the intermediate layer 30 are resin materials. At least one of the upper layer 10 and the lower layer 20 has a non-transparent property such that the intermediate layer 30 is not visible.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a laminate formed from a resin and a method for producing the laminate. [Background technology]

[0002] Conventionally, there have been laminates such as plastic corrugated cardboard having a structure in which a large number of ribs running parallel to each other are connected between liners made of two flat plates (for example, Patent Document 1). However, conventional laminates generally use only unused resin (virgin resin) as a material, which places a large burden on the environment. Furthermore, conventional laminates have had the problem that if recycled resins are used as materials in order to reduce the environmental impact, the aesthetic appearance is significantly impaired. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2003-334877 A Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present invention is to provide a laminate that does not impair the aesthetic appearance and has a small environmental impact, and a method for producing the laminate. [Means for solving the problem]

[0005] One form of the present invention is a laminate comprising an upper layer, a lower layer, and an intermediate layer laminated between the upper layer and the lower layer, the intermediate layer comprising an upper intermediate layer arranged on the upper layer side, a lower intermediate layer arranged on the lower layer side, and a connection portion connecting the upper intermediate layer and the lower intermediate layer so as to form a hollow portion between the upper intermediate layer and the lower intermediate layer, the upper layer, the lower layer, and the intermediate layer being made of a resin material, and at least one of the upper layer and the lower layer being opaque to a degree that the intermediate layer is not visible. [Brief description of the drawings]

[0006] [Figure 1] FIG. 1 is a diagram illustrating a configuration of a laminate 1 according to an embodiment. [Diagram 2] FIG. 2 is a diagram illustrating a configuration of an extrusion molding device 50 according to an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] (Embodiment) Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a diagram illustrating the configuration of a laminate 1 according to an embodiment. FIG. 1(A) is a perspective view of a portion of the laminate 1. FIG. FIG. 1(B) is a vertical cross-sectional view of the laminate 1 (a cross-sectional view cut along the ZX plane). In the embodiments and drawings, an XYZ orthogonal coordinate system is used for explanation as appropriate. This coordinate system represents the left-right direction X (left side X1, right side X2), the front-rear direction Y (front side Y1, rear side Y2), and the thickness direction Z (lower side Z1, upper side Z2) of the laminate 1 in the state shown in Fig. 1(A). The front-rear direction Y (one direction) is the extrusion direction when the laminate 1 is molded, and the thickness direction Z is the stacking direction of each layer of the laminate 1. The above directions are provided for the convenience of explanation and may be different from the directions in the usage form of the laminate 1. For example, the left-right direction X of the laminate 1 may be parallel to the vertical direction in the usage form, and the upper side Z2 and the lower side Z1 of the thickness direction Z may be the lower side and upper side in the vertical direction in the usage form. 1, the laminate 1 is made by laminating a plurality of resin plate materials like corrugated cardboard. The laminate 1 is also called plastic corrugated cardboard, plastic cardboard, or the like.

[0008] (Laminated structure) The laminate 1 comprises an upper layer 10, a lower layer 20, and an intermediate layer 30. The lower layer 20, the intermediate layer 30, and the upper layer 10 are laminated in this order from the lower side Z1 to the upper side Z2. The upper layer 10, the lower layer 20, and the intermediate layer 30 are each an extrusion molded product of a resin such as PE (polyethylene), PP (polypropylene), etc. As described later, the upper layer 10, the lower layer 20, and the intermediate layer 30 are integrally molded by extrusion molding, and the layers are welded together by thermal welding.

[0009] The upper layer 10 is a substantially flat layer that is laminated on the uppermost layer in the thickness direction Z. The lower layer 20 is a substantially flat layer that is laminated at the bottom in the thickness direction Z.

[0010] The intermediate layer 30 is laminated between the upper layer 10 and the lower layer 20 in the thickness direction Z. The intermediate layer 30 includes an upper intermediate layer 31, a lower intermediate layer 32, and a rib layer 33 (connecting portion). Although the upper intermediate layer 31, the lower intermediate layer 32, and the rib layer 33 are integrally formed, in the embodiment, each of these parts is also referred to as a "layer." The upper intermediate layer 31 is a substantially flat layer disposed on the upper layer 10 side. The lower intermediate layer 32 is a substantially flat layer disposed on the lower layer 20 side.

[0011] The rib layer 33 includes a plurality of flat plate-shaped rib portions 33a. The rib portion 33a is a portion that connects the upper intermediate layer 31 and the lower intermediate layer 32. The rib portion 33a is elongated in the front-rear direction Y and has a flat plate shape parallel to the YZ plane. The multiple rib portions 33a are arranged at equal intervals in the left-right direction X. Since the intermediate layer 30 is formed by extrusion molding, the cross section in the XZ plane has a constant shape. That is, the cross-sectional shape of the rib portion 33a in the XZ plane is constant at any position in the front-rear direction Y. In this manner, the rib layer 33 connects between the upper intermediate layer 31 and the lower intermediate layer 32 so as to form a hollow portion between the upper intermediate layer 31 and the lower intermediate layer 32 .

[0012] Due to the above-mentioned configuration of the rib layer 33, the stiffness of the laminate 1 is extremely stronger in bending in the front-rear direction Y (see arrow θY in FIG. 1(A)) than in bending in the left-right direction X (see arrow θX in FIG. 1(A)). For this reason, when the laminate 1 is used upright on a vertical surface, such as a bulletin board, it is preferable to install it so that the front-rear direction Y is vertical. In this way, the intermediate layer 30 has a hollow structure and is therefore lightweight, yet has sufficient strength.

[0013] (Resin material) Since the laminate 1 is manufactured by extrusion molding, the resin material of each layer is a thermoplastic resin, and the resin material of each layer may be a resin material mainly made of PE, PP, or the like. The resin material of each layer is made primarily from recycled resin in order to reduce the environmental impact. In the embodiment, the recycled resin refers to a resin that has been used for molding and then recovered, discarded, or the like, and is recycled as a molding resin. In the embodiment, a resin material whose main material is recycled resin is also simply referred to as recycled resin.

[0014] The upper surface of the upper layer 10 and the lower surface of the lower layer 20 are arranged on the exterior surface, and therefore the upper layer 10 and the lower layer 20 are formed from recycled resin with improved texture. Resin materials containing recycled resins are generally not white or transparent, and their texture is inferior to that of unused resins (which refers to resin materials that have never been used as molding resins after production from raw materials such as petroleum, and are also called virgin resins). The upper surface of the upper layer 10 and the lower layer 20 of the embodiment are made of such recycled resins, but in order to improve the texture, a master batch containing a large amount of titanium white (a white pigment containing titanium oxide) is mixed during molding. The master batch is a pellet containing a high concentration of dyes, etc., for the purpose of coloring molded products, etc. It should be noted that the recycled resin before mixing with the master batch is preferably a natural color other than black (for example, gray) from the viewpoint of coloring, etc.

[0015] In a usage state (a state in which the laminate 1 is used), the upper layer 10 and the lower layer 20 have a degree of non-translucency such that the intermediate layer 30 cannot be seen from the upper side Z2 and the lower side Z1, mainly due to the effect of titanium white. Therefore, the upper layer 10 and the lower layer 20 are colored (may be white) layers, and have the light concealing performance and light blocking performance having the above-mentioned non-translucency in a practical usage state. These properties may be adjusted as appropriate based on the texture and other properties of the material in actual use. In other words, the blending ratios of the resin materials of the upper layer 10, the lower layer 20, and the intermediate layer 30 may be adjusted as appropriate depending on the application of the laminate 1. The materials of the upper layer 10 and the lower layer 20 may contain an antistatic agent, a conductive agent, etc., depending on the intended use of the laminate 1.

[0016] Since the intermediate layer 30 is laminated between the upper layer 10 and the lower layer 20, only the end faces are exposed to the outside. Furthermore, since the upper layer 10 and the lower layer 20 are non-translucent, the intermediate layer 30 can be hidden. Therefore, the intermediate layer 30 is basically formed from recycled resin that does not contain a masterbatch intended for the purposes of aesthetics, texture, coloring, etc. In other words, the material of the intermediate layer 30 does not contain additives that improve aesthetics, etc. With the above-mentioned configuration, although the laminate 1 of the embodiment is mainly made of recycled resin, the aesthetic appearance of the product is not impaired, and the texture is not significantly deteriorated.

[0017] (Cross-sectional shape) Since the laminate 1 is manufactured by extrusion molding, the cross-sectional shape thereof is constant at any position in the front-rear direction Y when cut. In fact, a laminate 1 having a total thickness of 5.0 mm and a pitch P33a between adjacent rib portions 33a of 5.0 mm was produced, and the cross-sectional area and thickness were measured as described below. By design, the cross-sectional shape of the laminate 1 is symmetrical in the thickness direction Z. The cross-sectional area, thickness, etc. are the average values ​​between adjacent rib portions 33a. Fig. 1(B) shows the center line of the rib portion 33a. The measurement was performed by displaying a captured image of a cross section (ZX cross section) perpendicular to the front-rear direction Y of the laminate 1 on a computer display device and analyzing the image. The main material of each layer is recycled PP resin, and the upper layer 10 and the lower layer 20 are mixed with a masterbatch containing titanium white, while the middle layer 30 is not mixed with a masterbatch containing titanium white.

[0018] (Cross-sectional area measurement results) Cross-sectional area S1 of upper layer 10: 0.5839 mm 2 Cross-sectional area S3 of intermediate layer 30: 2.6229 mm 2 Cross-sectional area S2 of upper layer 10: 0.5842 mm 2 From the above results, the cross-sectional area of ​​the laminate 1 roughly had the following ratio. S1:S3:S2=1:4.5:1...Equation 1

[0019] Here, the intermediate layer 30 functions mainly with respect to the strength of the laminate 1, while the upper layer 10 and the lower layer 20 function with respect to the aesthetics and quality of the front surface (upper side Z2 surface) and back surface (lower side Z1 surface) of the laminate 1. The above cross-sectional area ratio is set mainly to achieve such strength and aesthetic appearance. In other words, the uses of the laminate 1 as a plate material are generally limited to a certain extent, such as bulletin boards, boxes, curing sheets, etc. For this reason, the overall thickness is also limited to a certain extent, for example, about 1.5 mm to 10.0 mm. Because of this premise, in terms of design, the thickness, structure, etc. of the intermediate layer 30 are basically determined according to the strength of the intended use of the laminate 1. Then, the thickness of the upper layer 10 and the thickness of the lower layer 20 are determined so that the intermediate layer 30 of that thickness can be concealed.

[0020] For example, in a use form in which a light source is provided on the side (e.g., the lower surface of the lower layer 20) opposite to the observation surface (e.g., the upper surface of the upper layer 10), the light-blocking performance of the intermediate layer 30 itself must also be taken into consideration. In other words, the thicker the intermediate layer 30 is, the higher the light-blocking performance of the intermediate layer 30 itself is. For this reason, even if the thicknesses of the upper layer 10 and the lower layer 20 are relatively thin, the aesthetic appearance of the laminate 1 is good. On the other hand, the thinner the intermediate layer 30, the lower the light blocking performance of the intermediate layer 30 itself. For this reason, in order not to impair the aesthetic appearance, etc. of the laminate 1, it is necessary to make the thickness of the upper layer 10 and the thickness of the lower layer 20 thick to some extent.

[0021] As described above, the upper layer 10 and the lower layer 20 are formed using resin pellets containing a master batch containing titanium white in order to provide good hiding power and aesthetic appearance. The higher the titanium white content of the resin material, the higher the hiding power, but the resin fluidity during molding tends to be poor. Also, if the titanium white content of the upper layer 10 and the lower layer 20 is too high, the strength of the heat welding to the intermediate layer 30 decreases, and color unevenness and pinholes are likely to occur during molding. For reference, the titanium white content of the master batches of each color is in the following order: white>blue>green>gray. In order to ensure hiding power and stable molding while minimizing the amount of titanium white added, it is necessary to increase the thickness of the upper layer 10 and the lower layer 20. However, if the upper layer 10 and the lower layer 20 are made too thick, the ratio (volume ratio) of the rib portion 33a of the intermediate layer 30 in the entire laminate 1 decreases, which causes a problem of reducing the strength of the laminate 1.

[0022] As a result of repeated verification and prototyping, it was confirmed that if the overall thickness is 5.0 mm and the pitch P33a of the rib portion 33a is approximately 5.0 mm, the strength, concealment properties, aesthetics, etc. of the laminate 1 can be excellent by using a layer structure of "S1:S3:S2=1:4.5:1... formula 1". Furthermore, after repeated testing and prototyping, When the overall thickness is 3.0 mm and the pitch P33a of the rib portion 33a is about 3.0 mm, If the resin color of the upper layer 10 and the lower layer 20 is white, the layer structure is "S3 / S1 = 2.6, and S3 / S2 = 3.0". In addition, if the resin color of the upper layer 10 and the lower layer 20 is gray, the layer structure will be "S3 / S1 = 3.2, and S3 / S2 = 3.5". It was confirmed that the strength, hiding power, aesthetic appearance, etc. of the laminate 1 were excellent. Furthermore, from these verifications, if the total thickness of the laminate 1 is 1.5 mm or more and 10.0 mm or less, 2≦S3 / S1≦5, and 2≦S3 / S2≦5... Equation 2 If it satisfies the above criteria, it can be assumed that it is appropriate for general use. Document "About the layer area ratio of 3mm R board" I understood and explained that the white and gray were the resin colors of the top layer 10 and bottom layer 20 (not the resin color of the middle layer 30).

[0023] (Extrusion molding device 50) FIG. 2 is a diagram illustrating the configuration of an extrusion molding device 50 according to the embodiment. FIG. 2A is a diagram illustrating the overall configuration of the extrusion molding device 50. As shown in FIG. FIG. 2B is an enlarged view of a part of the transverse cross section of the die 72 (cross section taken along line BB in FIG. 2A). In the following explanation, the mold structure is explained as a "feed block + die" concept (I apologize for my lack of knowledge about this structure). If the "feed block" itself includes a die, please let us know. The extrusion molding apparatus 50 includes two heating devices 61 and 63 , a feed block 71 , and a die 72 . The heating device 61 and the feed block 71 are connected by two pipes 51 and 52 , and the heating device 63 and the feed block 71 are connected by a pipe 53 . The resin melted in the heaters 61 and 63 is sent to the feed block 71 through the pipes 51 , 52 , and 53 .

[0024] The heating device 61 is a device for molding the upper layer 10 and the lower layer 20. In other words, the upper layer 10 and the lower layer 20 are molded from the same material, and therefore, are molded by the same heating device 61. The heating device 63 is a device for molding the intermediate layer 30. The heating devices 61 and 63 are devices that heat resin pellets placed in hoppers 61a and 63a in heating cylinders, knead the resin pellets with a screw, and then send the molten resin to the pipes 51, 52, and 53 by rotating the screw. The feed block 71 is a block that receives the molten resin sent from the pipes 51 , 52 , and 53 . The die 72 is connected to the feed block 71 and is a metal mold that molds the molten resin sent from the feed block 71 into a shape corresponding to each layer. As shown in FIG. 2(B), the cross-sectional shape of the die 72 corresponds to the upper layer 10, the lower layer 20, and the middle layer 30.

[0025] (Manufacturing method) When molding the laminate 1, resin pellets of recycled resin are placed in the hopper 61a of the heating device 61 corresponding to the upper layer 10 and the lower layer 20, and resin pellets of recycled resin are placed in the hopper 63a of the heating device 63 corresponding to the intermediate layer 30. At this time, in addition to the resin pellets of the recycled resin, a master batch is mainly charged for the purpose of coloring into the hopper 61a. At this time, the master batch is mixed so that the content of the master batch in the resin material is 10 ppm or more and 20 ppm or less so that the upper layer 10 and the lower layer 20 can exhibit sufficient opacity, etc.

[0026] As a result, the master batch such as resin pellets is mixed in the hopper 61a, and is also mixed by the rotation of the screw in the heating cylinder (mixing process).

[0027] On the other hand, for the purpose of coloring, etc., no master batch is charged into the hopper 63a of the heating device 63 corresponding to the intermediate layer 30. This makes it possible to reduce the number of steps for charging the resin pellets.

[0028] As described above, the resin pellets fed into the hoppers 61 a and 63 a are heated and kneaded, and then sent to the feed block 71 as molten resin. The die 72 sends out the molten resin sent from the feed block 71 in a molded state from an opening at the tip (molding process). Inside the die 72, the upper layer 10, the intermediate layer 30, and the lower layer 20 are welded together by thermal welding (interlayer welding process). This produces a plate-shaped laminate 1. The molded laminate 1 is then cut to a size (length in the front-rear direction Y and left-right direction X) according to product specifications.

[0029] As described above, the laminate 1 of this embodiment has a small environmental impact because it contains recycled resin as a material, but does not impair the aesthetic appearance or significantly reduce the texture.

[0030] Although the embodiment of the present invention has been described above, the present invention is not limited to the above-mentioned embodiment, and various modifications and changes are possible, such as the modified forms described below, which are also within the technical scope of the present invention. Furthermore, the effects described in the embodiment are merely a list of the most preferable effects resulting from the present invention, and the effects of the present invention are not limited to those described in the embodiment. Note that the configurations of the above-mentioned embodiment and the modified forms described below can be used only in part, or in appropriate combination, but detailed description will be omitted.

[0031] (Variations) (1) In the embodiment, both the upper layer and the lower layer are non-transparent layers, but the present invention is not limited to this. Only one of the upper layer and the lower layer may be non-transparent. For example, in the case where the laminate is attached so that one of the upper layer and the lower layer is in contact with a wall surface, only the other layer may be a non-light-transmitting layer, because the one layer is not exposed to the outside when the laminate is in use. In this case, the coloring master batch may be mixed only in the hopper of the heating device for forming the other layer. In this case, it is only necessary that either the upper layer or the lower layer satisfies one of the above "2≦S3 / S1≦5 and 2≦S3 / S2≦5... formula 2".

[0032] (2) In the embodiment, the connecting layer of the intermediate layer has a plate-like rib portion, but is not limited thereto. The connecting layer of the intermediate layer may have any structure as long as it can partially connect the upper layer and the lower layer and can be formed by extrusion molding, and may have, for example, a honeycomb structure or a corrugated plate structure.

[0033] (3) In the embodiment, the upper layer and the lower layer are formed from recycled resin, but the present invention is not limited to this. The upper layer and the lower layer may be formed from unused resin, and only the middle layer may be formed from recycled resin. Here, molded products made from recycled resins may have foreign matter exposed or may have dents or the like caused by foreign matter, but molded products made from virgin resins almost never experience such phenomena. For this reason, by forming the upper and lower layers from virgin resin, the aesthetics of the laminate can be further improved. The amount of the master batch containing titanium white may be different depending on whether virgin resin is used or recycled resin is used. [Explanation of symbols]

[0034] 1: Laminate 10: Upper layer 20: Lower layer 30: Middle class 31: Upper middle class 32: Lower middle class 33: Rib layer

Claims

1. The upper layer and The lower layer and an intermediate layer laminated between the upper layer and the lower layer, The intermediate layer is An upper middle layer disposed on the upper layer side; A lower middle layer disposed on the lower layer side; a connection portion that connects the upper intermediate layer and the lower intermediate layer so as to form a hollow portion between the upper intermediate layer and the lower intermediate layer, the upper layer, the lower layer, and the intermediate layer are made of a resin material; At least one of the upper layer and the lower layer is opaque to such an extent that the intermediate layer cannot be seen. A laminate comprising:

2. When the cross-sectional area of ​​the upper layer perpendicular to one direction is S1, the cross-sectional area of ​​the lower layer perpendicular to one direction is S2, and the cross-sectional area of ​​the intermediate layer perpendicular to one direction is S3, At least one of 2≦S3 / S1≦5 and 2≦S3 / S2≦5 is satisfied. The laminate according to claim 1 .

3. The resin material of the intermediate layer contains recycled resin.

3. The laminate according to claim 1 or 2.

4. A method for producing the laminate according to claim 1 or 2, comprising the steps of: a mixing step of mixing a master batch with at least one molding resin of the upper layer and the lower layer; a molding step of molding the upper layer, the lower layer, and the intermediate layer by extrusion molding; an interlayer welding step of heat-welding the resin layers heated in the molding step; A method for producing a laminate, comprising:

5. In the mixing step, the master batch is mixed so that the content of the master batch in the molding resin is 10 ppm or more and 20 ppm or less. The method for producing a laminate according to claim 4 .

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