JP2014156037A - Sandwich structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sandwich structure which is relatively light and has rigidity.SOLUTION: A middle core 2 has a plurality of walls 6 erected in the lamination direction of a sandwich structure 1, and, in a planer view, a first belt-like area including no walls 6 and a second belt-like area which is adjacent to the first belt-like area and includes the walls 6 are arranged alternately so as to form a stripe pattern. At least one of the area ratio of the first belt-like area to the second belt-like area and the pitch of the first belt-like area is set to be such a value that the walls 6 are not buckled when a load in a range for first and second liners 4 to receive no compression force is applied in the lamination direction.

Description

  The present invention relates to a sandwich structure in which liners are provided on both sides of an inner core.

  Conventionally, various sandwich structures having a core and liners on both sides of the core are known (see, for example, Patent Document 1). The plastic hollow plate described as an example of this sandwich structure is more rigid than the thin plastic foam sheet frequently used in the field of cushioning packaging, and is an extruded polypropylene cap that is the core. A sheet, a polypropylene back sheet as the liner attached to the protrusion open side of the cap sheet, and a polypropylene liner sheet as the liner attached to the protrusion tip side of the cap sheet It is.

  By the way, in recent years, development of a sandwich structure having higher rigidity is expected. Therefore, the present inventors tried to make the liner that receives the load directly rigid. And if the liners on both sides are rigid plates, the core could be light and weak as long as the liner can be held.

  However, in reality, if the strength of the core is weak, the two liners cannot be held in a fixed position due to buckling of the core. For this reason, it was found that theoretical strength could not be achieved simply by making the two liners rigid. This is because the uniform core with a uniform thickness distribution formed by the batch method becomes a rigid plate simply by applying a liner on both sides, whereas the non-uniform medium with a poor thickness distribution made by the continuous method is used. This is clear from an experiment conducted by the present inventors that the core could not obtain the expected rigidity. That is, a core made continuously by extrusion such as the cap sheet often has a poor thickness distribution and a non-uniform sheet thickness. Therefore, buckling occurs in a portion where the thickness of the core sheet is smaller than that of the other, that is, a portion relatively weaker than the other, and the liner cannot be held. Thus, the present inventors have found that the quality of the wall thickness distribution is related as one factor that determines the strength of the core.

  However, apart from whether the thickness distribution is good or bad, it was discovered that a “strong portion” and a “weak portion” were formed in the core. That is, in general, when trying to make a sandwich structure, when one or more sheets are formed and processed, except for a specific case where the core is a foam block, the core is seen in a plane. The strong and weak parts are present in a striped pattern. That is, when the core is provided with a plurality of walls formed by forming one or a plurality of sheet-like materials and standing in the stacking direction of the sandwich structure, the walls are present in a plan view. The first belt-shaped region that is not to be formed and the second belt-shaped region that is adjacent to the first belt-shaped region and has the wall are alternately arranged so as to form a striped pattern.

  In such a case, when a load is applied in the stacking direction, the “strong portion (second strip region)” of the center core is used as a fulcrum, and the “weak” region is a region where no wall exists. There is a problem in that the liner positioned on the “part (first belt-like region)” tends to bend and the liner is strongly pulled on both sides. When the width dimension of the “weak part” is increased, compression occurs on the liner opposite to the liner where the tension is generated, that is, on the liner receiving the direct load. If the liner is made in particular of plastic, the compression becomes a big problem.

JP 2005-297323 A

  In view of the above-described problems, an object of the present invention is to provide a sandwich structure having relatively light weight and rigidity.

  The present invention employs the following configuration in order to solve the above-described problems. That is, the sandwich structure according to the present invention includes a core formed by molding one or a plurality of sheet-like materials, and a first liner having difficulty stretching attached to one surface side of the core. And a second liner having difficulty stretched attached to the other surface side of the core, wherein the core is erected in the stacking direction of the sandwich structure. When viewed in plan, the first belt-like region where the wall does not exist and the second belt-like region where the wall exists adjacent to the first belt-like region alternately form a stripe pattern. And at least one of the area ratio of the first belt-like region and the second belt-like region and the pitch of the first belt-like region does not exert a compressive force on the first and second liners. When the load in the range is received from the stacking direction, the wall is set to a value that does not buckle. Features that you are.

  Here, “having difficult stretchability” means that the core does not stretch 20%, preferably 10% or more even when a maximum load is applied in a range where the core does not buckle.

  The term “wall” does not include those that are parallel to the liner or those that have a low degree of standing with respect to the liner. For example, when a load is applied in the stacking direction of the sandwich structure, the component force along the wall However, what was set so that it might become larger than the component force of the direction orthogonal to a wall etc. is mentioned.

  If it is such, it suppresses generation | occurrence | production of the malfunction that the said sandwich structure will be bent on the 1st strip | belt area | region weak to the load from a lamination direction compared with the 2nd strip | belt area | region of a center core. Can be a rigid sandwich structure. In other words, the sandwich structure of the present invention has a compressive force applied to the liner by setting the center strong and weak stripe pattern as fine as possible, or by setting the area of the weak part with respect to the strong part as small as possible. The center core is made to have sufficient strength. Therefore, it has rigidity despite having a large number of spaces between the first liner and the second liner. Further, the first liner and the second liner are each difficult to stretch when a tensile force is applied, and the relatively light core described above is sandwiched between these liners, so that the entire sandwich structure As described above, it can be light and strong against a load from the stacking direction.

  The area ratio of the first band-shaped region is preferably 50% or less of the area ratio of the second band-shaped region.

  The angles formed by the first liner, the second liner, and the wall are each preferably 45 degrees or more. In other words, when a load is applied in the stacking direction of the sandwich structure, the component force in the direction along the wall is set to be equal to or greater than the component force in the direction perpendicular to the wall. Is preferred.

  As the first liner and the second liner, a film sheet made of polyolefin resin can be cited as a preferred embodiment.

  The core is preferably made of a polyolefin resin.

  As a specific embodiment, the core is a cap sheet having a large number of cap-shaped protrusions, and the first liner is a flat back sheet attached to the protrusion open side of the cap sheet. And the second liner is a flat liner sheet attached to the tip end side of the protrusion of the cap sheet.

  Since this invention is the above structures, it can provide the sandwich structure which is comparatively lightweight and has rigidity.

The schematic of the sandwich structure concerning one embodiment of the present invention. The top view of the sandwich structure of the embodiment. XX sectional drawing in FIG. The front sectional view of the sandwich structure concerning other embodiments of the present invention. The top view of the sandwich structure of the embodiment. The front sectional view of the sandwich structure concerning other embodiment of the present invention.

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS.

  The sandwich structure 1 of the present embodiment includes a core 2 formed by molding one sheet-like material, a first liner 3 having a stretchability attached to one surface side of the core 2, and And a second liner 4 having difficulty in stretching attached to the other surface side of the core 2. More specifically, in the sandwich structure 1 of the present embodiment, the core 2 is a cap sheet having a large number of cap-shaped protrusions 5, and the first liner 3 is opened from the cap sheet. The second liner 4 is a three-layer plastic bubble board that is a flat liner sheet attached to the tip end side of the protrusion of the cap sheet.

  The core 2 that is the cap sheet is made of a polyolefin resin, which is an example of a thermoplastic resin, more specifically, a sheet made of polypropylene, and the thickness dimension is set to about 630 μm, for example. The core 2 is arranged such that a large number of protrusions 5 having a substantially circular shape in plan view are arranged in a straight line along the width direction and in a staggered pattern along the flow direction. The dimension of each part in each protrusion 5 is set to about 8 mm in length and about 4 mm in width, for example. The core 2 has a plurality of walls 6 standing in the stacking direction of the sandwich structure 1 in association with the protrusions 5.

Each wall 6 is a part of the cap-shaped protrusion 5 and serves as a part for maintaining a constant distance between the first liner 3 and the second liner 4. Each wall 6 has an angle θ ₁ , θ ₂ formed by the first liner 3 and the second liner 4 of the center core 2 of 45 degrees or more, respectively, in the stacking direction of the sandwich structure 1. When a load is applied, the component force N _{1 in the} direction along the wall 6 is larger than the component force N ₂ in the direction orthogonal to the wall 6 (in this embodiment, the component force N ₂ is almost zero). This is the part that is set. More specifically, the standing portion of the projection 5, that is, the portion where the angles θ ₁ and θ ₂ formed with the liners 3 and 4 are about 90 degrees, respectively, is the main portion of each wall 6 of the present embodiment. I am doing. The angles θ ₁ and θ ₂ formed by the wall 6 with the first liner 3 and the second liner 4, that is, the standing degree of the wall 6 is preferably 60 degrees or more.

  The core 2 includes a first belt-like region 7 where the wall 6 does not exist and a second belt-like region 8 adjacent to the first belt region 7 and including the wall 6 when viewed in plan. They are arranged alternately to form a striped pattern. The first belt-like region 7 is a portion where the rigidity with respect to the load in the stacking direction is weaker than that of the second belt-like region 8, and is shown with a pattern in FIG. In the present embodiment, the first belt-like regions 7 are formed at the same pitch in the flow direction, and have circular projections 5 arranged in a line in the width direction and a width direction adjacent to the projections 5. Are formed in a space between the protrusions 5 arranged in a row in a plan view, in other words, adjacent protrusions 5 in the flow direction, and extend in a band shape along the width direction. On the other hand, the second belt-like region 8 is a portion where the rigidity against the load in the stacking direction is stronger than that of the first belt-like region 7. In the present embodiment, the second belt-like regions 8 are formed at the same pitch in the flow direction, and are formed between the projections 5 having a circular shape in plan view arranged in a line in the width direction and the projections 5 adjacent in the width direction. And is formed in a portion including a space formed in the shape of a belt and extends in a band shape along the width direction. The boundary portion between the first belt-like region 7 and the second belt-like region 8 is not clear, and continuously changes between the first belt-like region 7 and the second belt-like region 8. ing.

  Therefore, the core 2 of the present embodiment is such that the area ratio of the first belt-like region 7 and the second belt-like region 8 is within a range in which a compressive force does not act on the first and second liners 3 and 4. When the wall 6 is received from the stacking direction, the wall 6 is set to a value that does not buckle. In the present embodiment, the area ratio of the first band-like region 7 is set to 50% or less, more specifically about 18% of the area ratio of the second band-like region 8. The area ratio of the first belt-like region 7 is preferably 20% or less of the second belt-like region 8, and more preferably 10% or less.

  The first liner 3 that is the back sheet is a film sheet made of polyolefin resin, and in the present embodiment, a flat flat yarn having a thickness dimension set to, for example, about 300 μm is used. A flat yarn is formed by stretching a strip formed by cutting an unstretched polyethylene-based resin film at a predetermined width in the length direction, or a uniaxially stretched polyethylene-based resin film in a direction perpendicular to the stretching direction. Various applications such as cutting to a predetermined width are applicable. The first liner 3 is difficult to stretch. Specifically, the first liner 3 is not stretched by 20% or more even when a maximum load of 100 N / 50 mm is applied in a range where the core 2 does not buckle. Yes. This is a value at which the area ratio and the pitch set in the core 2 change when the first liner 3 extends further, and when the first liner 3 is laminated, the first liner 3 does not have rigidity. Further, the first liner 3 has a small bending characteristic required by the three-point bending method. Specifically, when the load is applied to the first liner 3, the distance between the fulcrums (the distance between the fulcrums is set). The distance from the initial position of the upper surface or the lower surface of the first liner 3 at the center in the case of 100 mm is about 10 mm or less. This first liner 3 is attached to the protrusion opening side of the cap sheet, and a bubble 9 having a cylindrical shape is formed inside by the protrusion 5 of the cap sheet and the back sheet.

  The second liner 4 that is the liner sheet is a film sheet made of polyolefin resin similar to the first liner 3, and in this embodiment, a flat flat yarn having a thickness dimension set to, for example, about 570 μm. Is used.

  Therefore, as shown in FIG. 3, the sandwich structure 1 of the present embodiment is substantially the same as the liners 3 and 4 between the first liner 3 and the second liner 4, respectively. Intervened in an orthogonal state. In the sandwich structure 1, bubbles 9 are present in a space surrounded by the liners 3 and 4 and the core 2. The first liner 3 and the second liner 4 may be attached to the core 2 by a method of bonding a liner such as the flat yarn with an anchor effect using a resin having a low melt tension, an acid, etc. Various methods such as a method of adhering a polar liner such as a PET film with an adhesive resin having a polar group, a method of heat-sealing using a resin equivalent to the heated core 2 and a method of dry laminating using an adhesive Any suitable material can be selected depending on the material of the core 2 and the liners 3 and 4.

  As described above, the sandwich structure 1 according to the present embodiment has the core 2 formed by molding a single sheet-like material and the difficult stretchability attached to one surface side of the core 2. A first liner 3 having a second liner 4 attached to the other surface side of the core 2 and having a low stretchability, wherein the core 2 has the sandwich structure. 1 has a plurality of walls 6 standing in the stacking direction, and in plan view, the first belt-like region 7 where the walls 6 do not exist, and the wall 6 adjacent to the first belt-like region 7 are The existing second strip regions 8 are alternately arranged so as to form a stripe pattern, and the area ratio of the first strip region 7 and the second strip region 8 and the first strip region 7 When the pitch receives a load in a range in which a compressive force does not act on the first and second liners 3 and 4 from the stacking direction, 6 is set to a value that does not buckle. That is, the sandwich structure 1 of the present embodiment sets the strong and weak stripe pattern of the central core 2 as fine as possible and also has a relatively weak portion (first strip shape) with respect to a relatively strong portion (second strip region 8). Since the area 7) is set to a value as small as possible, the core 2 has sufficient strength within a range in which no compression force is applied to the liners 3 and 4. Therefore, the sandwich structure 1 has rigidity despite a large number of spaces between the first liner 3 and the second liner 4. Further, the first liner 3 and the second liner 4 are each difficult to stretch when a tensile force is applied, and the liner 3 described above is sandwiched between the liners 3 and 4. Therefore, the sandwich structure 1 as a whole can be lightweight and resistant to loads from the stacking direction.

  That is, as a point of the excellent sandwich structure 1, the core 2 has a sufficient strength, the strength and weak stripes of the core 2 are as fine as possible, or the area of the weak part is set as small as possible, It is important that the liners 3 and 4 are made of a material that is difficult to stretch. Factors related to the strength of the core 2 include the degree of standing of the wall 6 and the degree of the wall 6 of the core 2 in addition to the pitch of the strong and weak stripe pattern and the width of the weak portion (first strip region 7). The thickness dimension, the distance between adjacent walls 6, the material of the core 2, and the like are also included. Note that the pitch of the striped pattern is preferably 20% or less, more preferably 50% or less of the thickness dimension of the sandwich structure 1.

  The area ratio of the first belt-like region 7 is 50% or less of the area ratio of the second belt-like region 8, and particularly in the present embodiment, the area ratio is about 18%. The strength can be kept high.

The angles θ ₁ and θ ₂ formed by the first liner 3 and the second liner 4 and the wall 6 are 45 degrees or more, respectively. In this embodiment, particularly, the angles θ ₁ and θ ₂ are about Since it is 90 degrees, the load N applied from the stacking direction hardly acts as the component force N _{2 in} the thickness direction of the cap sheet of the core 2. Therefore, the first liner 3 and the second liner 4 can be held at appropriate positions.

  Since the first liner 3 and the second liner 4 are film sheets made of polyolefin resin, they are easy to handle. That is, it is difficult to stretch compared to a metal sheet, and it is easy to give rigidity while being relatively light. In the conventional one where the pitch of the core 2 is rough, compression may be applied to the liner on the opposite side to the liner to which the tension is applied, and it has been a problem that the compression that is most poor for the resin is applied. In the case of the core 2 as in the present embodiment, since the compression force is hardly applied to the liners 3 and 4, the strength of the liners 3 and 4 themselves can be maintained.

  Furthermore, since the core 2 is made of a polyolefin resin, the cap-shaped protrusion 5 can be easily formed, and it is easy to give rigidity although it is relatively light. Further, since the liners 3 and 4 are made of the same polyolefin resin, the liners 3 and 4 can be attached to the core 2 by a method such as heat welding.

  The core 2 is a cap sheet having a large number of cap-shaped protrusions 5, the first liner 3 is a flat back sheet attached to the protrusion open side of the cap sheet, and the second Since the liner 4 is a flat liner sheet attached to the protrusion tip side of the cap sheet, the sandwich structure 1 that is resistant to the load from the stacking direction can be obtained.

  Next, another embodiment of the present invention will be described with reference to FIGS. In addition, the same code | symbol is attached | subjected to the part which is the same as that of embodiment mentioned above, or this, and detailed description is abbreviate | omitted.

  The sandwich structure 1 of the present embodiment includes a core 2 formed by molding one sheet-like material, a first liner 3 having a stretchability attached to one surface side of the core 2, and And a second liner 4 having difficulty in stretching attached to the other surface side of the core 2. More specifically, the sandwich structure 1 of the present embodiment is a corrugated sheet in which the core 2 has a number of protrusions 5 called “peaks”.

  The core 2 that is the cap sheet is made of a polyolefin resin, which is an example of a thermoplastic resin, more specifically, a sheet made of polypropylene, and the thickness dimension is set to about 900 μm, for example. The dimensions of each part of the protrusion 5 of the core 2 are set such that, for example, 1 pitch (distance from the upper vertex to the lower vertex) is 11.5 mm and the height is about 10 mm. The core 2 has a plurality of walls 6 standing in the stacking direction of the sandwich structure 1 in association with the protrusions 5.

Each wall 6 is a part of the wave-like protrusion 5 and is a part that plays a role in maintaining a constant distance between the first liner 3 and the second liner 4. Each wall 6 has an angle θ ₁ , θ ₂ formed by the first liner 3 and the second liner 4 of the center core 2 of 45 degrees or more, respectively, in the stacking direction of the sandwich structure 1. When the load N is applied, the component N _{1 in the} direction along the wall 6 is set to be larger than the component N ₂ in the direction perpendicular to the wall 6. More specifically, the standing portion of the projection 5, that is, the portion where the angles θ ₁ and θ ₂ formed with the liners 3 and 4 are about 70 degrees, respectively, is the main portion of each wall 6 of the present embodiment. I am doing.

  The core 2 includes a first belt-like region 7 where the wall 6 does not exist and a second belt-like region 8 adjacent to the first belt region 7 and including the wall 6 when viewed in plan. They are arranged alternately to form a striped pattern. The first belt-like region 7 is a portion where the rigidity against the load in the stacking direction is weaker than that of the second belt-like region 8, and is shown with a pattern in FIG. Further, in FIG. 5, portions corresponding to the upper and lower vertices of each protrusion 5 (the center of the first belt-like region 7) are indicated by a one-dot chain line. In this embodiment, the 1st strip | belt-shaped area | region 7 is formed in the flow direction at the same pitch, is formed in the vertex vicinity which exists on the upper and lower sides of the protrusion 5 adjacent to a flow direction, and is strip | belt-shaped along the width direction. Is growing. On the other hand, the second belt-like region 8 is a portion that is more rigid than the first belt-like region 7 with respect to the load in the stacking direction. In this embodiment, the 2nd strip | belt-shaped area | region 8 is formed in the flow direction at the same pitch, is formed in the inclined part of the protrusion 5 adjacent to a flow direction, and is extended in strip | belt shape along the width direction. . The boundary portion between the first belt-like region 7 and the second belt-like region 8 is not clear, and continuously changes between the first belt-like region 7 and the second belt-like region 8. ing.

  Thus, in the core 2 of the present embodiment, the area ratio of the first belt-like region 7 and the second belt-like region 8 is such that a load in a range where a compressive force does not act on the first and second liners 4 is described above. The wall 6 is set to a value that does not buckle when received from the stacking direction. In the present embodiment, the area ratio of the first band-like region 7 is set to 50% or less, more specifically about 50% of the area ratio of the second band-like region 8.

  If it is such, the effect similar to embodiment mentioned above is acquired.

  Next, still another embodiment of the present invention will be described with reference to FIG. In addition, the same code | symbol is attached | subjected to the part which is the same as that of embodiment mentioned above, or this, and detailed description is abbreviate | omitted.

The sandwich structure 1 has the core 2 provided with the plurality of wavy projections 5 described above, and a plurality of walls 6 erected in the stacking direction of the sandwich structure 1 in relation to the projections 5. Have. Each wall 6 is a part of the wave-like protrusion 5 and is a part that plays a role in maintaining a constant distance between the first liner 3 and the second liner 4. Each wall 6 has an angle θ ₁ , θ ₂ formed by the first liner 3 and the second liner 4 in the core 2 of about 45 degrees, respectively, in the stacking direction of the sandwich structure 1. When the load N is applied, the component N _{1 in the} direction along the wall 6 is set to be substantially the same as the component N ₂ in the direction perpendicular to the wall 6. If it is such, the effect similar to embodiment mentioned above is acquired.

  The present invention is not limited to the embodiment described above.

  For example, the liner may be any material that does not stretch easily, such as the above-mentioned stretched yarn cloth such as flat yarn, stretched film sheet such as PET, filler kneaded sheet such as carbon or glass fiber, etc. preferable. The material of the liner is not limited to resin, but may be metal. The core may also be made of metal in addition to the resin described above.

  Among the materials of the core or liner, as the resin, an α-olefin copolymer, polybutadiene, or the like may be used in addition to the above-described polypropylene and polyethylene.

  In the sandwich structure, the plurality of walls existing between the first liner and the second liner may not be orthogonal to the respective liners, and the walls may be the first, The angle formed with the second liner may be larger than 90 degrees or smaller than 90 degrees.

  The shape of the core may be any shape such as a twin cone, a honeycomb shape, a protrusion having a rectangular shape in plan view, or a different shape such as a heart shape. Further, the core may be formed by molding a plurality of sheet-like materials.

  In the embodiment described above, the plastic bubble board having the columnar protrusion has been described, but other “plastic hollow plate” may be used. Here, the “plastic hollow plate” is a concept including “plastic bubble board”, “plastic corrugated cardboard”, and “plastic folded honeycomb board”.

  “Plastic foam board” means, for example, that a large number of cap-shaped protrusions are vacuum-formed on a sheet extruded from a die such as polypropylene, and a flat back on each of the bottom and top surfaces of the cap sheet. A molded product formed by fusing a sheet and a liner sheet to form a plate having a hollow structure. “Plastic corrugated cardboard” refers to a molded product comprising two sheets formed by melt extrusion of plastic and a large number of ribs that run in parallel by connecting them. The “plastic folded honeycomb board” refers to a molded article having a honeycomb structure formed by giving a vertical portion to a plastic sheet at a predetermined pitch and sequentially folding the plastic sheet in the longitudinal direction.

  In addition, you may change variously in the range which does not impair the meaning of this invention.

DESCRIPTION OF SYMBOLS 1 ... Sandwich structure 2 ... Core 3 ... 1st liner 4 ... 2nd liner 5 ... Protrusion 6 ... Wall 7 ... 1st strip | belt-shaped area | region 8 ... 2nd strip | belt-shaped area | region (theta) ₁ ... angle (theta) ₂ ... angle

Claims (6)

A core formed by molding one or a plurality of sheet-like materials, a first liner having difficulty in stretching attached to one surface side of the core, and attached to the other surface side of the core A sandwich structure comprising a second liner having a reduced stretch ability,
The core has a plurality of walls standing in the stacking direction of the sandwich structure, and is adjacent to the first belt-like region where the wall does not exist when seen in a plan view. The second belt-like regions where the walls exist are alternately arranged so as to form a stripe pattern,
At least one of the area ratio of the first belt-like region and the second belt-like region and the pitch of the first belt-like region applies a load in a range in which a compressive force does not act on the first and second liners from the stacking direction. A sandwich structure characterized in that the wall is set to a value that does not buckle when received. The sandwich structure according to claim 1, wherein an area ratio of the first band-shaped region is 50% or less of an area ratio of the second band-shaped region. The sandwich structure according to claim 1 or 2, wherein an angle formed by the first liner, the second liner, and the wall is 45 degrees or more. 4. The sandwich structure according to claim 1, wherein the first liner and the second liner are film sheets made of polyolefin resin. The sandwich structure according to claim 1, 2, 3, or 4, wherein the core is made of a polyolefin resin. The core is a cap sheet having a large number of cap-shaped protrusions, the first liner is a flat back sheet attached to the protrusion opening side of the cap sheet, and the second liner is The sandwich structure according to claim 1, 2, 3, 4, or 5, wherein the sandwich structure is a flat liner sheet attached to the tip end side of the cap sheet.

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