JP2012030571A - Biodegradable resin laminated foamed sheet, peripheral side frame material for lunch box and the lunch box - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a biodegradable resin laminated foamed sheet enabling manufacturing of a lunch box which includes a surface preventing a sharp tip of a bamboo skewer, a pick or the like from sticking into the surface and has excellent impact resistance, a peripheral side frame material for the lunch box made by using the biodegradable resin laminated foamed sheet, and the lunch box made by using the peripheral side frame material for the lunch box.SOLUTION: The biodegradable resin laminated foamed sheet is constituted by laminating a biodegradable resin film on one or both faces of a foamed base material sheet composed of a polystyrene-based resin foamed sheet, and has a piercing strength of 7.0 N or more.

Description

  The present invention relates to a biodegradable resin laminated foam sheet obtained by laminating a biodegradable resin film on a polystyrene resin foam sheet, a peripheral frame material for a folded box produced by using the laminated foam sheet, and a peripheral side for the folded box The present invention relates to a folded box made using a frame material.

Conventionally, as a folding box used for a lunch box or the like, a peripheral frame made of a strip-shaped thermoplastic resin foam sheet and subjected to a plurality of V-groove processing for bending and groove processing for fitting a bottom plate, There is provided a folded box formed by bending the V-shaped groove of the peripheral side frame, fitting the bottom plate and assembling it into a box shape, and joining both ends of the peripheral side frame.
The peripheral frame has a mechanical strength of the sheet surface layer portion remaining after the V-groove processing by appropriately adjusting the resin temperature at the time of extrusion foaming, the temperature of cooling air, etc. when producing a foamed sheet by the extrusion foaming method. What was manufactured using the improved thermoplastic resin foam sheet is known (for example, refer patent documents 1 and 2).

Patent Document 1 (Japanese Patent Laid-Open No. 6-297537) discloses a styrene resin extruded foam sheet having a density of 0.05 to 0.2 g / cm ³ and a thickness of 2 to 10 mm, and measured by static thermomechanical measurement. The maximum shrinkage in the extruding direction of at least one side surface layer part is 3% or more, and the tensile shear strength of the sheet when a V-cut at an angle of 90 ° is made from the other side of the sheet leaving 0.5 mm of the sheet thickness. There is disclosed a styrene resin extruded foam sheet characterized in that it is 14 kgf / 5 cm or more and the surface hardness of the V-cut surface is 70 or less.
In Patent Document 2 (Japanese Patent Laid-Open No. 2005-232300), the tensile strength of the sheet surface layer portion remaining when the V-groove is processed is in the range of 6.5 to 9.0 MPa, and the density of the sheet surface layer portion is A polystyrene-based resin foam sheet for folding boxes, which is within the range of 0.13 to 0.17 g / cm ³ , is disclosed.

In addition, in order to improve the mechanical strength and appearance of the peripheral frame, it is also proposed to use a thermoplastic resin laminated foam sheet in which a thermoplastic resin film is laminated on one or both surfaces of the thermoplastic resin foam sheet. (For example, see Patent Document 3).
Patent Document 3 discloses a lunch box in which a partition frame formed by processing a thin plastic sheet is housed in an outer box mainly made of a foamed styrene sheet, and the outer box has a rectangular bottom portion. And a container body composed of four trapezoidal sides that are respectively connected to the four sides and are raised obliquely upward and outward from the bottom, and a frame member attached to the outer periphery of the upper edge of the container body. The lunch box characterized by being comprised by this is disclosed. FIG. 3 of Patent Document 3 shows an outer box material in which plastic films 7 a and 7 b are attached to both surfaces of a foamed styrene sheet 6.

In addition, in a container for food packaging made by integral molding instead of a folded box, a container provided with a biodegradable resin film in a peelable manner has been proposed. s
Patent Document 4 (Japanese Patent Laid-Open No. 2002-187241) is formed by laminating a thermoplastic resin base sheet and a biodegradable resin film, and the peel strength between the two is 50 to 500 [g / 15 mm width]. A biodegradable resin film laminate, and a container formed by molding the biodegradable resin film laminate so that the biodegradable resin film is inside the container. It is disclosed.

JP-A-6-297537 JP-A-2005-232300 Utility Model Registration No. 3140522 JP 2002-187241 A

However, the conventional techniques described in Patent Documents 1 to 4 have the following problems.
The folding boxes disclosed in Patent Documents 1 and 2 are formed using a polystyrene resin foam sheet having improved surface layer mechanical properties during extrusion molding, and the inner surface of the resulting folding box is made of a polystyrene resin. The inner surface of this folding box is soft, and there is a problem that sharp tips such as bamboo skewers and toothpicks are easily pierced.

  Further, Patent Document 3 shows an outer box made of a plate material in which plastic films 7a and 7b are attached to both surfaces of a foamed styrene sheet 6. However, details regarding the material, thickness, mechanical strength, etc. of the plastic film are completely different. There is no description. Since this outer box stores a partition frame formed by processing a thin plastic sheet therein, and the food is configured to be stored in this partition frame, food containing bamboo skewers, toothpicks, etc. in the partition frame Even when the container is stored, the sharp tip does not pierce the outer box, and there is no need to consider the strength of the outer box surface.

  In addition, the biodegradable resin film laminate described in Patent Document 4 is formed by weakly bonding the biodegradable resin film to the base sheet so that the biodegradable resin film can be peeled off, and the laminate is heated and pressed between molds. Since the container is manufactured by a thermoforming method to form a container, even if this laminated body is cut or V-grooved to produce a peripheral frame, a biodegradable resin is produced from the base sheet. The film is easily peeled off, and it is very difficult to produce the peripheral side frame.

  The present invention has been made in view of the above circumstances, and a biodegradable resin laminated foam sheet that has a surface with a sharp tip such as a bamboo skewer or toothpick that is difficult to pierce and is excellent in impact resistance. It aims at provision of the folding box produced using the circumference side frame material for folding boxes manufactured using the sheet | seat, and this circumference side frame material for folding boxes.

  In order to achieve the above object, the present invention is formed by laminating a biodegradable resin film on one or both surfaces of a foamed base material sheet made of a polystyrene-based resin foam sheet, and has a puncture strength of 7.0 N or more. A biodegradable resin laminated foam sheet is provided.

In the biodegradable resin laminated foam sheet of the present invention, the foam base material sheet preferably has a density in the range of 0.035 to 0.105 g / cm ³ .

  In the biodegradable resin laminated foam sheet of the present invention, the mass ratio of the biodegradable resin film to the mass of the laminated foam sheet is preferably 25% by mass or more.

  In the biodegradable resin laminated foam sheet of the present invention, the biodegradable resin film is preferably made of a polylactic acid resin.

  In the biodegradable resin laminated foam sheet of the present invention, the foam base material sheet may be composed of a water absorbent foam sheet having an open cell ratio of 40% or more.

  The water-absorbent foam sheet may be configured by laminating a first foam layer having an open cell ratio of 40% or more and a second foam layer having an open cell ratio of 30% or less.

  In the biodegradable resin laminated foam sheet of the present invention, the foam base material sheet and the biodegradable resin film may be bonded to each other with an adhesive containing an isocyanate curing agent.

  The biodegradable resin laminated foam sheet of the present invention may have a configuration in which the foam base material sheet contains less than 50% by mass of the biodegradable resin.

  Further, the present invention provides a folding box peripheral frame material which is formed by cutting the biodegradable resin laminated foam sheet into a long rectangle and forming a plurality of folding V-grooves, and folding the V-grooves to constitute a folding box. I will provide a.

  In the peripheral frame material for folded boxes of the present invention, a groove for fitting the bottom plate may be provided along the longitudinal direction.

  The present invention also provides a folded box formed by bending the peripheral frame material for folded boxes and joining both ends thereof.

  The present invention also provides a folding box formed by bending the folding box peripheral frame member, fitting a bottom plate, and joining both end portions of the folding box peripheral frame member.

The biodegradable resin laminated foam sheet of the present invention is formed by laminating a biodegradable resin film on one or both surfaces of a foamed base material sheet made of a polystyrene resin foam sheet, and has a puncture strength of 7.0 N or more. The folding box made using this biodegradable resin laminated foam sheet has excellent puncture resistance against sharp edges, and even when storing food including bamboo skewers and toothpicks, The tip of the toothpick can be prevented from sticking into the inner wall of the folding box.
In addition, the biodegradable resin laminated foam sheet of the present invention is excellent in impact resistance, and a folded box made using the same is hardly broken by an impact such as dropping.

It is sectional drawing which shows embodiment of the biodegradable resin laminated foam sheet of this invention. It is sectional drawing which shows embodiment of the peripheral frame material for folding boxes of this invention. It is a perspective view which shows embodiment of the folding box of this invention.

(Biodegradable resin laminated foam sheet)
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view showing an embodiment of the biodegradable resin laminated foam sheet of the present invention.
This biodegradable resin laminated foam sheet 1 is formed by laminating biodegradable resin films 3a and 3b on both surfaces of a foam base sheet 2 made of a polystyrene resin foam sheet, and has a puncture strength of 7.0 N or more. It is characterized by being.

  The foam base sheet 2 is heated and melted by adding an additive such as a polystyrene resin and a foam nucleating agent to a resin supply means such as an extruder, and further added with a foaming agent and kneaded, and a foaming agent-containing resin is added. It is manufactured by an extrusion foaming method in which it is extruded from a slit of a die attached to the tip of the resin supply means, and then cooled after being foamed.

The foam base sheet 2 preferably has a density in the range of 0.035 to 0.105 g / cm ³ . If the density of the foam base sheet 2 is within the above range, the biodegradable resin laminated foam sheet 1 is lightweight and excellent in puncture strength and impact resistance in a state where the biodegradable resin films 3a and 3b are laminated. Obtainable. In addition, the density of the foam base material sheet 2 means the density measured by the following density measurement method.

<Density measurement method>
A specimen of 50 cm ³ or more (100 cm ³ or more in the case of semi-rigid and soft materials) was cut so as not to change the original cell structure of the material, its mass and volume were measured, and the total density was calculated by the following formula: .
Density (g / cm ³ ) = Test piece mass (g) / Test piece volume (cm ³ )
However, the test specimen for measurement is cut out from a sample that has passed 72 hours or more after molding, and is subjected to atmospheric conditions of 23 ° C. ± 2 ° C./50 RH% ± 5 RH% or 27 ° C. ± 2 ° C./65 RH% ± 5 RH% for 16 hours or more. It is what was left.

  Examples of the polystyrene resin used in the production of the foamed base sheet 2 include styrene monomers such as styrene, α-methylstyrene, vinyltoluene, chlorostyrene, ethylstyrene, i-propylstyrene, dimethylstyrene, and bromostyrene. A homopolymer or a copolymer thereof may be mentioned, and a polystyrene-based resin containing 50% by mass or more of styrene is preferable, and polystyrene is more preferable. Further, the polystyrene resin may be a copolymer of the styrene monomer and a vinyl monomer copolymerizable with the styrene monomer, the main component of which is the styrene monomer. As, for example, alkyl (meth) acrylate such as methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, cetyl (meth) acrylate, (meth) acrylonitrile, dimethyl maleate, dimethyl fumarate, diethyl In addition to fumarate and ethyl fumarate, bifunctional monomers such as divinylbenzene and alkylene glycol dimethacrylate are exemplified.

  If a polystyrene resin is the main component, other resins may be added. Examples of the resin to be added include the peripheral frame material for folding boxes and the resistance of the folding box produced using the laminated foam sheet. In order to improve impact, rubber-modified polystyrene resin, so-called high impact, to which diene rubbery polymer such as polybutadiene, styrene-butadiene copolymer, ethylene-propylene-nonconjugated diene three-dimensional copolymer is added. Examples include polystyrene. Alternatively, a polyethylene resin, a polypropylene resin, an acrylic resin, an acrylonitrile-styrene copolymer, an acrylonitrile-butadiene-styrene copolymer, and the like can be given. In addition, as a polystyrene resin as a raw material, a polystyrene resin that is not a recycled raw material, such as a normal polystyrene resin that is commercially available, a polystyrene resin newly produced by a method such as a suspension polymerization method, etc. can be used. Recycled raw materials obtained by reprocessing used polystyrene-based resin foamed molded products can be used. As this recycled material, used polystyrene-based resin foam moldings such as fish boxes, household appliance cushioning materials, food packaging trays, etc. are collected, and recycled materials that are regenerated by the limonene dissolution method or heating volume reduction method are used. Can do. Recyclable raw materials that can be used include home appliances (eg, TVs, refrigerators, washing machines, air conditioners) and office work, in addition to those obtained by reprocessing used polystyrene-based resin foam moldings. A non-foamed polystyrene resin molded product that has been separated and collected from an industrial machine (for example, a copying machine, a facsimile machine, a printer, etc.), pulverized, melt-kneaded, and repelletized can be used.

  As the foaming agent used for the production of the foamed base sheet 2, nitrogen dioxide, carbon dioxide, propane, n-butane, i-butane, n-pentane, i-pentane, and a mixture of two or more thereof are used. Of these, n-butane and i-butane are preferable. When using a hydrocarbon foaming agent such as butane, the addition amount is preferably in the range of 1 to 10 parts by mass, and in the range of 2 to 8 parts by mass with respect to 100 parts by mass of the polystyrene resin. More preferred.

  Examples of the foam nucleating agent used for the production of the foamed base sheet 2 include talc, sodium hydrogen carbonate, ammonium hydrogen carbonate, calcium carbonate, clay, citric acid and the like, and among these, talc is more preferable. The amount of the foam nucleating agent added is preferably in the range of 1 to 8 parts by mass, more preferably in the range of 2 to 6 parts by mass with respect to 100 parts by mass of the polystyrene resin.

  In addition, the foam base sheet 2 has additives that do not affect the circumferential effect of the container having desired properties, such as colorants, flame retardants, lubricants (hydrocarbons, fatty acids, fatty acid amides, esters, Alcohol-based, metal soap, silicone oil, wax such as low molecular weight polyethylene, etc.), spreading agents (liquid paraffin, polyethylene glycol, polybutene, etc.), dispersants and the like may be added.

  As the biodegradable resin films 3a and 3b laminated on the foam base material sheet 2, any of various conventionally known films formed of various biodegradable resins can be used. Examples of such biodegradable resins include polylactic acid (trade name Palgreen LC manufactured by Tosero Co., Ltd.), linear polyester of 3-hydroxybutyric acid and 3-hydroxyvaleric acid (trade name Bio manufactured by ICI). Paul, etc.), polyether, polyacrylic acid, ethylene / carbon monoxide copolymer, aliphatic polyester / polyamide copolymer, aliphatic polyester / polyolefin copolymer, aliphatic polyester / aromatic polyester copolymer (BASF) (Trade name Ecoflex, etc.), aliphatic polyester / polyether copolymer, polymer alloy of starch and modified polyvinyl alcohol (trade name Matterby, etc. manufactured by Novamont), starch and polyethylene polymer alloy (Amperset) Product name poly grade II), succinic acid ester (Akira Polymer, such as the trade name BIONOLLE Co., Ltd.) and the like. Among these, a polylactic acid (PLA) film is preferable.

  Although the thickness of biodegradable resin film 3a, 3b is not limited to this, It is preferable that it is 10-100 micrometers. If the thickness is less than 10 μm, the amount of elongation at the time of forming into the shape of the container is insufficient, and there is a possibility of breaking at the time of forming. Alternatively, it may be easily broken when it is separated, and the workability of fraction collection may be reduced. On the other hand, even if the thickness exceeds this range, no further effect is obtained, and the biodegradable resin is more expensive than the general-purpose resin, which may lead to an increase in the cost of the folded box. The thickness of the biodegradable resin film is preferably about 15 to 40 μm, more preferably about 20 to 35 μm, even within the above range.

The tensile strength of the biodegradable resin films 3a and 3b is preferably in the range of 90 to 200 MPa, and more preferably in the range of 100 to 150 MPa.
Further, the elongation at break of the biodegradable resin films 3a and 3b is preferably in the range of 40 to 90%, and more preferably in the range of 55 to 85%.

The biodegradable resin films 3a and 3b are bonded to the foamed base sheet 2 via an adhesive. Examples of the adhesive include acrylic adhesives, polyurethane adhesives, and polyvinyl alcohol adhesives. A biodegradable pressure-sensitive adhesive mainly composed of natural compounds can also be used. Examples of the biodegradable pressure-sensitive adhesive include a rubber component having biodegradability, such as natural rubber and isoprene rubber, to which a natural tackifier such as rosin or terpene is added. It is done. Examples of rosin-based tackifiers include rosin and derivatives thereof (hydrogenated rosin, disproportionated rosin, polymerized rosin, rosin ester, etc.). Examples of the terpene-based tackifier include terpenes and derivatives thereof (α-pinene resin, β-pinene resin, dipentene resin, and hydrogenated products thereof).
As the adhesive, an adhesive containing an isocyanate curing agent is preferable.

  This adhesive is applied by applying a coating solution dissolved in an appropriate solvent on one side of the biodegradable resin films 3a and 3b using a bar coater, knife coater, roll coater, etc., and then drying and removing the solvent. The agent layer. The thickness of the adhesive layer formed on the biodegradable resin films 3a and 3b is not limited. However, considering that the foamed base sheet 2 and the biodegradable resin films 3a and 3b are bonded uniformly and evenly. 1 to 20 μm is preferable. The pressure-sensitive adhesive layer may be formed on both sides of the foam base material sheet 2.

  The biodegradable resin laminated foam sheet 1 may be provided with a printing layer or a colored layer (by coating, spraying, etc.) in order to give a color, a pattern or the like. In order to give a color, a pattern, or the like, the pigment is added to the adhesive layer or the foamed base sheet 2 or a colored layer is provided on the surface of the foamed base sheet 2, and this coloring and A pattern may be formed together with the print layers provided on the degradable resin films 3a and 3b. Further, the biodegradable resin films 3a and 3b may be colored by blending pigments. In particular, a method in which the biodegradable resin films 3a and 3b are coated with an adhesive that becomes a printed layer or a colored layer and is laminated on the foam base material sheet 2 is preferable.

  In order to manufacture the biodegradable resin laminated foam sheet 1, a foam base material sheet 2 and two biodegradable resin films 3a and 3b each provided with an adhesive layer are prepared. The adhesive layer side of the expandable resin films 3a and 3b is superposed on the surface of the foam base material sheet 2 and heated on a heat roll with the foam base material sheet 2 sandwiched between the two biodegradable resin films 3a and 3b. Press. As a result, the foam base sheet 2 and the biodegradable resin films 3a and 3b are firmly bonded, and the biodegradable resin laminated foam sheet 1 is continuously produced.

  At this time, the peripheral surface of the heat roll is preferably preliminarily subjected to chrome plating or fluororesin coating in order to prevent adhesion or stickiness to the biodegradable resin films 3a and 3b, respectively. Moreover, you may pre-heat the adhesive bond layer before supplying between heat rolls, for example by an infrared heater etc., without contact. In addition, as another manufacturing method of the biodegradable resin laminated foam sheet 1, an adhesive in a molten state extruded in a layer form from a T-die or the like between the foam base material sheet 2 and the biodegradable resin films 3a and 3b. And a method of adhering the foamed base sheet 2 and the biodegradable resin films 3a and 3b at the same time as forming an adhesive layer by superimposing them.

In the present embodiment, the biodegradable resin films 3a and 3b are laminated on both surfaces of the foam base material sheet 2, but the biodegradable resin film is provided only on one surface of the foam base material sheet 2. Alternatively, a biodegradable resin film may be laminated on one surface of the foamed base sheet 2 and another resin film may be laminated on the other surface.
Although it does not specifically limit as another resin film laminated | stacked on the foaming base sheet 2, For example, polyester-type resin, such as a non-foaming film of a polystyrene-type resin, polyolefin-type resin films, such as polyethylene and a polypropylene, and a polyethylene terephthalate (PET) A film is mentioned and the non-foamed film of a polystyrene-type resin is preferable from the point which can be laminated | stacked on the foaming base material sheet 2 without an adhesive agent.

When this biodegradable resin laminated foam sheet 1 is used for producing folded boxes for food packaging, the thickness is preferably in the range of 1.0 to 10.0 mm, and in the range of 3.0 to 7.0 mm. It is more preferable. By sliding the thickness within the above range, it is possible to provide a folded box that is lightweight and excellent in mechanical strength.
Note that the use of the folded box is not limited to food packaging, but can also be used for packaging of machine parts, packaging for gift items, packaging for household appliances, and the like. When used for storing heavy objects, it is desirable to make the thickness of the biodegradable resin laminated foam sheet 1 thicker than the above range.

  In the biodegradable resin laminated foam sheet 1, the mass ratio of the biodegradable resin films 3a and 3b (mass ratio of the biodegradable resin) in the mass of the biodegradable resin laminated foam sheet 1 is 25% by mass or more. Preferably there is. If the mass ratio of the biodegradable resin is 25% by mass or more, it is possible to reduce environmental impact and reduce carbon dioxide emissions, thereby preventing global warming, saving fossil fuel resources, and protecting the natural environment. it can. Incidentally, if the mass ratio of the biodegradable resin is 25% by mass or more, it is possible to obtain “biomass plastic” certification as a biomass plastic product that conforms to the identification and display standards established by the Japan Bioplastics Association.

Since this biodegradable resin laminated foam sheet 1 is formed by laminating a biodegradable resin film on one or both surfaces of the foam substrate sheet 2, and has a puncture strength of 7.0 N or more, The folding box made using the biodegradable resin laminated foam sheet 1 has excellent puncture resistance against sharp edges, and even when food containing bamboo skewers or toothpicks is stored, the tips of bamboo skewers or toothpicks Can be prevented from sticking into the inner wall of the folding box. The puncture strength is preferably 10.0 N or more, and more preferably in the range of 10.0 to 15.0 N.
When the piercing strength is less than 7.0 N, the piercing resistance to the sharp tip becomes insufficient, and when a folded box is produced, the tip of the bamboo skewer or toothpick may pierce the inner wall of the folded box.

(Folding box peripheral frame material)
FIG. 2 is a cross-sectional view showing an embodiment of the peripheral frame material for a folded box of the present invention.
The peripheral frame material 10 for folding box is formed by cutting the biodegradable resin laminated foamed sheet 1 of the present invention into a long rectangle and forming a plurality of bending V-grooves 11, and folding the V-groove 11 to fold the box. 20 can be configured.

  The V groove 11 adjusts the angle θ according to the shape of the folded box 20 to be produced. In the illustration of FIG. 2, the case where the V-groove 11 having an angle θ of 90 degrees is formed to form a quadrilateral folded box as shown in FIG. 3, and the plan view shape is another polygonal shape. In the case of (for example, a triangle, pentagon, hexagon, octagon, rhombus, parallelogram, etc.), the optimum angle θ is set to form the planar view shape. The V groove 11 can be formed using a groove processing method and a groove processing apparatus conventionally used in the field of processing foamed resins such as polystyrene resin foam sheets.

As shown in FIG. 3, grooves 12 for fitting a bottom plate serving as a bottom portion of the folding box 20 may be formed in the folding-side peripheral frame member 10 along the longitudinal direction.
Further, one or more grooves (not shown) for fitting a partition plate attached to the folded box may be provided in the folded box peripheral side frame member 10 along the width direction.

  In a preferred embodiment of the folding box peripheral frame member 10, the foam base material sheet 2 constituting the folding box peripheral frame member 10 has an average cell diameter (L1) in the short direction and an average cell diameter in the longitudinal direction. It is preferable to have a bubble structure in which the ratio (L1 / L2) to (L2) is in the range of 1.10 to 1.55. The ratio (L1 / L2) is more preferably in the range of 1.21 to 1.55, and further preferably in the range of 1.21 to 1.45.

Here, the average bubble diameter (L1) in the short direction and the average bubble diameter (L2) in the longitudinal direction of the foam base material sheet 2 constituting the peripheral frame material 10 for folded boxes are calculated by the following measurement methods. Say the value you did.
<Method for measuring bubble diameter ratio (L1 / L2)>
The average cell diameters (L1, L2) are those calculated based on the average chord length measured according to the test method of ASTM D2842-69. Specifically, the peripheral frame material for the folding box is cut in a direction perpendicular to the surface (thickness direction), and is divided into approximately four equal parts in the thickness direction on the cut surface, and approximately ½ of the central portion of the thickness. The thickness of was photographed with a scanning electron microscope (S-3000N, manufactured by Hitachi, Ltd.) at a magnification of 17 to 20 times (in some cases 200 times).
Next, the average chord length (t) of each bubble is expressed by the following formula 1 from the number of bubbles that are 60 mm in length in the photograph and that are in a straight line oriented in the thickness direction of the peripheral frame material for folding boxes. Based on the calculation. And the average bubble diameter D was computed by following formula 2. In addition, when the layer of the peripheral frame material for folding boxes is thin and a straight line having a length of 60 mm cannot be drawn on the photograph, a straight line having the longest possible length is drawn on the photograph, and the length of this straight line is set to 60 mm. The average bubble diameter D was calculated by conversion.
Average chord length (t) = 60 / (number of bubbles × photo magnification) Formula 1
Average bubble diameter D = t / 0.616 Formula 2
The measurement and calculation of the average bubble diameter are respectively performed on the cut surface along the short side and the long side of the peripheral frame material for the folded box (number of measurement points n = 6 or more). The average bubble diameter (L1) in the hand direction and the average bubble diameter (L2) in the longitudinal direction were determined, and the bubble diameter ratio (L1 / L2) was calculated from Equation 3.
Bubble diameter ratio (L1 / L2) = L1 (μm) ÷ L2 (μm) Formula 3

  In the foam base material sheet 2 constituting the folding box peripheral frame member 10, the ratio (L1 / L2) of the average cell diameter (L1) in the short direction and the average cell diameter (L2) in the longitudinal direction is 1. In the range of 10 to 1.55, the bubbles are long in the short direction and short in the long direction, so that it is easy to bend when bending the peripheral frame material 10 for folding boxes along the long direction. In addition, the surface of the folded box peripheral side frame material 10 that has been bent is less likely to be crushed or broken. When the ratio (L1 / L2) is less than 1.10, small wrinkles and folds are likely to occur when bending, and when the ratio (L1 / L2) exceeds 1.55, the peripheral frame material 10 for folded boxes. Both the elastic modulus and the maximum point displacement are reduced, the flexibility is lost, and the brittleness becomes brittle.

  The peripheral frame material 10 for folding box is heated and melted by adding an additive such as a polystyrene resin and a foam nucleating agent to a resin supply means such as an extruder, and further added with a foaming agent and kneaded, and contains a foaming agent. A foam base material sheet 2 (hereinafter referred to as a primary sheet) is manufactured by an extrusion foaming method in which resin is extruded from a slit of a die attached to the tip of a resin supply means, foamed (primary foaming), and then cooled, and is described above. In this way, the biodegradable resin laminated foamed sheet 1 produced by stacking two biodegradable resin films 3a and 3b having an adhesive layer formed on one side and heating and press-bonding them is cut into an oblong shape having an appropriate size. In addition, the V-shaped groove 12 for bending and the groove for fitting the bottom plate can be formed and manufactured.

  Moreover, the peripheral side for folding boxes having a cell structure in which the ratio (L1 / L2) of the average cell diameter (L1) in the short direction to the average cell size (L2) in the longitudinal direction is in the range of 1.10 to 1.55 In order to manufacture the frame member 10, when the primary sheet is manufactured, the sheet surface is stretched in either the vertical or horizontal direction, and when cutting, the bubbles in the primary sheet are long in the short direction and long It is desirable to cut the primary sheet in a direction that is short in the direction. The amount of stretching is appropriately adjusted so that the ratio (L1 / L2) of the average bubble diameter (L1) in the short direction and the average bubble diameter (L2) in the longitudinal direction is in the range of 1.10 to 1.55. It is desirable to do.

  As a method for producing the peripheral frame material 10 for folding box, when producing a primary sheet by extrusion foaming, it is cooled and stabilized by applying a tension such that the primary sheet is stretched in the extrusion direction (MD direction). Then, the biodegradable resin laminated foam sheet 1 is manufactured by laminating two biodegradable resin films 3a and 3b, and then the obtained laminated foam sheet is heated and subjected to secondary foaming to obtain a desired thickness and density. A laminated foam sheet (hereinafter, referred to as a secondary sheet) having a sheet length, and then the secondary sheet is cut into a rectangular shape having a predetermined length, and then the printed rectangular sheet is changed in the MD direction of the original sheet. A method of obtaining the peripheral frame material 10 for folded boxes by cutting into a long rectangular shape so that the direction perpendicular to the MD direction on the sheet surface (hereinafter referred to as the TD direction) is the longitudinal direction in the short direction is preferable.

  When the primary sheet is subjected to secondary foaming, the amount of secondary foaming is preferably in the range of 1.3 to 2.5 times in the thickness direction. If it is less than 1.3 times, it is not soft and difficult to bend even if pressed, and if it exceeds 2.5 times, the cell shape of the epidermis is rounded, the directionality of the bubbles is reduced, and bending is not preferred. In addition, it is compressed and bubble buckling is less likely to bend.

  A heat source is used for secondary foaming of the primary sheet. As the heat source, one used for molding a foam base material sheet for general molding can be used. The conditions for the secondary foaming were 22 to 30 m / min. In an oven having an atmospheric temperature of 160 to 190 ° C. A desired secondary sheet can be obtained by passing at a moderate speed. Steam may also be used.

Since the peripheral frame material 10 for folding box is formed by cutting the biodegradable resin laminated foamed sheet 1 into a long rectangular shape and providing a V-shaped groove 11 for bending, the piercing strength is 7.0 N or more. The folding box 20 produced using can prevent the tip of the bamboo skewer or toothpick from sticking into the inner wall of the folding box even when food containing bamboo skewers or toothpicks is stored.
In addition, a groove structure in which the ratio (L1 / L2) of the average bubble diameter (L1) in the short direction and the average bubble diameter (L2) in the longitudinal direction is in the range of 1.10 to 1.55 is obtained. Occurrence of folds and wrinkles can be prevented in the processed portion.

(Fold box)
FIG. 3 is a diagram showing an embodiment of the folding box of the present invention.
The folding box 20 of the present embodiment is configured by bending the above-described folding box peripheral frame material 10 into a bent portion 13 by bending the V groove 11 and joining both ends.
3 illustrates a case where the four V-grooves 11 are bent by 90 degrees to form a quadrangular folded box 20 in plan view, but the shape of the folded box 20 is not limited to this, for example, a plane Various shapes such as a viewing triangle, a pentagon, a hexagon, an octagon, a rhombus, a parallelogram, and a trapezoid can be used.

  The bent portion 13 is connected by a biodegradable resin film 3b which is left inside the V-shaped groove 11 and becomes the inner side of the folded box, and the V-groove end surfaces of the foam base material sheet 2 formed by the V-shaped groove 11 are connected to each other. Are in contact with each other to form a bent portion 13 of 90 degrees. By using a biodegradable resin film having a tensile strength of 100 MPa or more and an elongation at break of 50% or more as the biodegradable resin film 3 b of the bent portion 13, When the side frame member 10 is bent, it is not broken even if it is bent at 90 degrees or more, and a small box is not generated, and a folded box 20 having a good appearance can be produced.

  This folding box 20 exemplifies the case of using the folding box peripheral side frame material 10 provided with the bottom plate fitting groove 12, while fitting the peripheral edge of a rectangular bottom plate (not shown) to the groove 12, The folded box peripheral frame material 10 is bent into a peripheral side part, and both ends of the folded box peripheral frame material 10 are joined by a method such as heat fusion to form a bottomed box shaped folded box 20.

  In addition, the groove | channel 12 is not provided in the folding box 20, and the V-groove 11 of the peripheral frame material 10 for folding boxes is bent without using a bottom plate, the both ends are joined to make a folding box, and this is used as an outer container. It is also possible to make a folded box of a type in which an inner container produced by thermoforming is stored in an outer container.

  When this folded box 20 is used as a circumferential side part of a folded box using the printed circumferential frame 10 for folded boxes, the folded box 20 has various textures and gloss such as lacquer, lacquer, paulownia, etc. A high-quality folded box with a pattern or the like can be obtained.

  Hereinafter, the effects of the present invention will be demonstrated by examples, but the following examples are merely illustrative of the present invention, and the scope of the present invention is not limited to the description of the following examples.

[Example 1]
(Manufacture of primary sheet)
As the extruder, a tandem extruder in which an inner diameter 90 mm extruder and a 115 mm extruder were connected was used. 100 parts by mass of HRM-26 (trade name) manufactured by Toyo Styrene Co. as a polystyrene resin, and 4.5 parts by mass of MAX401-2HP (trade name) manufactured by Takehara Chemical Co., Ltd. as a foam nucleating agent with respect to 100 parts by mass of the resin, A blended raw material to which 6.8 parts by mass of 6TSM4MA-188 (trade name) manufactured by Toyo Ink Manufacturing Co., Ltd. was added as a pigment was supplied to the extruder, melted and kneaded at a maximum temperature of 243 ° C. in the extruder, and then used as a foaming agent. 3.8 parts by mass of butane (iso / normal = 30/70% by mass) was added to 100 parts by mass of the resin and kneaded. Then, it cooled to the resin temperature of 150 degreeC suitable for foaming.
Further, a foaming agent-containing resin was extruded from a circular die having a diameter of 128 mmφ attached to the tip of the extruder and set to a slit clearance of 0.942 mm, foamed, and then cooled to obtain a cylindrical foamed sheet.
Subsequently, the cylindrical foamed sheet was cut by a cutter provided on the left and right sides to obtain two primary sheets. Each primary sheet was wound around a winding roll while stretching between multiple rolls. At the time of winding, the drawing speed was set to 10 m / min in order to apply stretching in the MD direction of the primary sheet. The obtained primary sheet has a thickness of 2.3 mm, a density of 0.074 g / cm ³ , a short direction bubble diameter (L1) of 0.21 μm, and a long direction bubble diameter (L2) of 0.20 μm, bubbles. The diameter ratio (L1 / L2) was 1.08.

(Biodegradable resin film)
As a biodegradable resin film, a biodegradable resin film containing polylactic acid (PLA) as a main component (trade name: Palgreen LC, manufactured by Tosero Corporation, thickness 25 μm, tear strength: 125 Mpa, elongation at break: 65% , Density 1.27 g / cm ³ ).
One side of this biodegradable resin film was coated with an adhesive (adhesive ink) so as to have a thickness of about 0.1 μm.

(Biodegradable resin laminated foam sheet)
A biodegradable resin film was disposed on both sides of the obtained primary sheet, and the film was sandwiched between the hot roll and the nip roll, and was thermocompression bonded. Then, after about 1 second, a biodegradable resin laminated foam sheet in which a biodegradable film was laminated on both sides of the primary sheet was manufactured by passing through a cooling roll at 21 ° C. and cooling. The temperature of the hot roll was 165 ° C., the feed speed of the primary sheet and the biodegradable resin film was 23.0 m / min, and the nip pressure (linear pressure) of the nip roll was 5.0 kg / m. The mass ratio of the biodegradable resin film to the mass of the obtained biodegradable resin laminated foam sheet was 27% by mass.
The mass ratio was calculated by the following formula.
Mass ratio (%) = (mass of biodegradable resin film / mass of biodegradable resin laminated foam sheet) × 100

(Secondary foam sheet laminate)
Thereafter, the obtained biodegradable resin laminated foam sheet was passed through a tunnel-type electric heating furnace, and electrically heated under conditions of a heating temperature: 149 ° C., a length of 3.5 m, and a moving speed: 18.0 m / min. Foaming was performed to obtain a secondary foam sheet laminate (biodegradable resin laminate foam sheet) having a thickness of 3.8 mm. In the obtained secondary foamed sheet laminate, the density of only the foamed layer was 0.045 g / cm ³ . The mass ratio of the biodegradable resin film to the mass of the obtained secondary foamed sheet laminate (biodegradable resin laminate foam sheet) was 27% by mass.
The mass ratio was calculated by the following formula.
Mass ratio (%) = (mass of biodegradable resin film / mass of biodegradable resin laminated foam sheet) × 100
This secondary foamed sheet laminate was subjected to <Puncture test>, <Surface hardness measurement>, and <Falling ball test> by the following measurement methods. The results are shown in Table 1.

<Puncture test>
The obtained secondary foamed sheet laminate was cut into a width of 50 mm and a length of 150 mm, and set in a cylindrical jig having a diameter of 50 mm. This was set on a jig base so that the needle stuck into the film surface.
The maximum point load (N) and the maximum point displacement (mm) were measured using a Tensilon universal testing machine (manufactured by A & D, RTG-1310).
The measurement conditions were as follows (number of measurement samples N = 15).
・ Jig dimensions: 50 mmφ, 50 mm high cylindrical shape ・ Needle: 7 mm length, 1 mm diameter needle ・ Compression speed: 50 mm / min
・ Puncture distance: 5mm
・ Distance between needle and sample: 3mm
Maximum point load (N), maximum point displacement (mm), and automatically input the sample thickness, width and length into the program of the general-purpose testing machine data processing system (MAND0002RTF / RTG manufactured by A & D) Obtained as calculated data.
The obtained maximum point load (N) was defined as the puncture strength (N).
(Criteria)
A: Extremely good: The puncture strength is 10.0 N or more, and the puncture resistance is very good.
○: Good: Puncture strength is 7.0 N or more, and has good puncture resistance.
X: Defect: The puncture strength is less than 7.0 N, and it is easily puncture defect.

<Surface hardness measurement>
The obtained secondary foamed sheet laminate was cut into strips having a width of 50 mm and a length of 550 mm, and measured every 10 mm from both ends (N = 5). The measurement measured the film surface.
The measurement was performed using a low-pressure loader for rubber hardness tester (CL-150, manufactured by Asker).

<Falling ball test>
The obtained secondary foamed sheet laminate was cut into a strip having a width of 50 mm and a length of 540 mm, and a total of three points, a point 90 mm inside from both ends in the longitudinal direction and a position just in the center in the length direction, were measured points. did.
The measurement was performed using a falling ball tester (Kanetec Co., Ltd., KANETEC). The jig base was set so that the length direction was the horizontal direction. At this time, it set so that the measurement position of the laminated body cut in strip shape may come to the center point between jigs. In addition, the film surface was set on the surface where the ball fell.
The measurement conditions were as follows.
・ Height: 1000mm
・ Ball mass: 500g
・ Distance between jigs: 100 mm
(Criteria)
A ball drop test was carried out at three locations for each strip-shaped laminate, and “crack” occurred even at one location was regarded as defective (×), and no crack occurred at one location as good (◯). did.

[Example 2]
Except for the thickness of the biodegradable resin film being 15 μm (trade name: Pal Green LC, manufactured by Tosero Corporation, thickness 15 μm, tear strength: 97 Mpa, elongation at break: 49%, density 1.27 g / cm ³ ) Then, a secondary foam sheet laminate (biodegradable resin laminate foam sheet) was produced in the same manner as in Example 1. The mass ratio of the biodegradable resin film to the mass of the obtained secondary foamed sheet laminate (biodegradable resin laminated foam sheet) was 18% by mass. The results are shown in Table 1.

[Comparative Example 1]
Instead of the biodegradable resin film, a polystyrene resin film having a thickness of 25 μm (trade name: OPS film GM, manufactured by Asahi Kasei Co., Ltd., thickness 25 μm, tear strength: 72 Mpa, elongation at break: 5%, density 1.05 g / cm ³ ) Was used in the same manner as in Example 1 to produce a secondary foamed sheet laminate. The mass ratio of the polystyrene resin film to the mass of the obtained secondary foamed sheet laminate was 24% by mass. The results are shown in Table 1.

[Comparative Example 2]
Instead of a biodegradable resin film, a polystyrene resin film having a thickness of 15 μm (trade name: OPS film GM, manufactured by Asahi Kasei Co., Ltd., thickness 15 μm, tear strength: 65 Mpa, elongation at break: 4%, density 1.05 g / cm ³ ) Was used in the same manner as in Example 1 to produce a secondary foamed sheet laminate. The mass ratio of the polystyrene resin film to the mass of the obtained secondary foamed sheet laminate was 16% by mass. The results are shown in Table 1.

  From the results of Table 1, Examples 1 and 2 according to the present invention have higher puncture strength than Comparative Examples 1 and 2 in which a polystyrene resin film is laminated on a polystyrene resin foam sheet, and the results of a falling ball test are also shown. It was good.

[Example 3]
(Manufacture of water-absorbent foam sheet)
For water-absorbent first foam, 78.9% by mass of polystyrene resin ("XC-515" manufactured by Dainippon Ink & Chemicals, Inc., melt mass flow rate 1.3 g / 10 min), copolymer of styrene and conjugated diene 15.8% by mass of hydrogenated product (“SS9000” manufactured by Asahi Kasei Co., Ltd.), high density polyethylene resin (“HJ565W” manufactured by Nippon Polyethylene Co., Ltd., density 0.968 g / cm ³ , melt mass flow rate 5.0 g / 10 min) 5 The product name "Erestmaster S-520" (made by Kao Co., Ltd., a polystyrene resin masterbatch containing 20% by mass of alkylsulfonic acid-based surfactant, with respect to 100 parts by mass of the mixed resin composition containing 3% by mass. ) 10 parts by mass and a mixed raw material mixed with 0.6 parts by mass of talc as a bubble regulator, a first extruder having an inner diameter of 115 mm, and an inner diameter of 150 mm Two extruders was fed into the hopper of the first extruder of the tandem extruder connected. The maximum cylinder temperature of the extruder is 220 ° C., and 3.5 parts by weight of butane (isobutane / normal butane = 70/30) is press-fitted and kneaded as a blowing agent, and the foamable molten mixture is cooled in a second extruder. The resin temperature was adjusted to 161 ° C. and flowed into the confluence mold at an extrusion rate of 150 kg / hr.
On the other hand, for the second foam, 100 parts by mass of polystyrene resin (“HRM-12” manufactured by Toyo Styrene Co., Ltd., melt mass flow rate 5.5 g / 10 min) is used as a bubble adjusting agent. The mixture obtained by mixing 7 parts by mass was supplied to a hopper of a single-screw extruder having an inner diameter of 115 mm, the cylinder temperature of the extruder was 230 ° C. at maximum, and butane (isobutane / normal butane = 70/30) 4.0 as a blowing agent. The mass part was press-fitted, kneaded and cooled, the resin temperature of the foamable molten mixture was adjusted to 154 ° C., and flowed into the confluence mold at an extrusion rate of 100 kg / hr.
The resin merged in the merge mold is poured into an annular mold having a diameter of 175 mm, extruded into a cylindrical shape from a slit having a thickness of 0.45 mm, taken along a cooling mandrel having a diameter of 670 mm, and attached to the rear part of the mandrel. The cylindrical foam was cut with two cutters to obtain two upper and lower laminated foam sheets. Air was blown into and out of the foam immediately after exiting the slit to cool the foam surface. The resulting water-absorbent foam sheet had a thickness of 2.8 mm and a density of 0.063 g / cm ³ . The open cell ratio of the water absorbent foam sheet was 52%. Here, the open cell ratio is a value measured by the following measurement method.

<Continuous bubble ratio measurement method>
The closed cell ratio (%) and the open cell ratio (%) of the obtained water-absorbent foam sheet are calculated as follows.
Closed cell ratio = 100 × {Measurement volume of foam with air comparison type hydrometer− (Mass of foam / density of resin)} / apparent volume of foam Open cell ratio = 100 × (apparent volume of foam− (Measurement volume of the foam with an air comparison type hydrometer) / apparent volume of the foam Note that the closed cell ratio = 100− (open cell ratio + ratio occupied by the resin).

A secondary foamed sheet laminate was produced in the same manner as in Example 1 except that the water absorbent foamed sheet produced as described above was used as the foamed base sheet.
The resulting secondary foamed sheet laminate was subjected to <Puncture test>, <Surface hardness measurement>, and <Falling ball test> in the same manner as in Example 1. The results are shown in Table 2.

[Example 4]
Laminated secondary foam sheet in the same manner as in Example 1 except that one side of the biodegradable resin film was coated with an adhesive (adhesive ink) containing an isocyanate curing agent so as to have a thickness of about 0.1 μm. The body was made. The mass ratio of the biodegradable resin film to the mass of the obtained secondary foamed sheet laminate was 27% by mass.
The resulting secondary foamed sheet laminate was subjected to <Puncture test>, <Surface hardness measurement>, and <Falling ball test> in the same manner as in Example 1. The results are shown in Table 2.

[Example 5]
A resin mixture of 75% by mass of HRM-26 (trade name) manufactured by Toyo Styrene Co., Ltd. as polystyrene resin and 25% by mass of “Terramac” (trade name) manufactured by Unitika Co., Ltd. as a polylactic acid resin is used as a resin raw material for the foam base sheet. A secondary foamed sheet laminate was produced in the same manner as in Example 2 except that.
The resulting secondary foamed sheet laminate was subjected to <Puncture test>, <Surface hardness measurement>, and <Falling ball test> in the same manner as in Example 1. The results are shown in Table 2.

  From the results in Table 2, the puncture strength is higher for Examples 3 to 5 as compared to Comparative Examples 1 and 2 in which a polystyrene resin film is laminated on a polystyrene resin foam sheet, as in Examples 1 and 2. The result of the falling ball test was also good.

  The present invention relates to a biodegradable resin laminated foam sheet obtained by laminating a biodegradable resin film on a polystyrene resin foam sheet, a peripheral frame material for a folded box produced by using the laminated foam sheet, and a peripheral side for the folded box The present invention relates to a folded box made using a frame material.

  DESCRIPTION OF SYMBOLS 1 ... Biodegradable resin laminated foam sheet, 2 ... Polystyrene resin foam sheet, 3a, 3b ... Biodegradable resin film, 10 ... Peripheral frame material for folding boxes, 11 ... V groove, 12 ... Groove, 13 ... Bending Part, 20 ... folded box.

Claims (12)

  A biodegradable resin laminate foam, characterized in that a biodegradable resin film is laminated on one or both sides of a foam base sheet made of a polystyrene resin foam sheet, and the puncture strength is 7.0 N or more. Sheet. The biodegradable resin laminated foam sheet according to claim 1, wherein the foam base material sheet has a density in a range of 0.035 to 0.105 g / cm ³ .   The biodegradable resin laminated foam sheet according to claim 1 or 2, wherein a mass ratio of the biodegradable resin film to a mass of the biodegradable resin laminated foam sheet is 25% by mass or more.   The biodegradable resin laminated foam sheet according to any one of claims 1 to 3, wherein the biodegradable resin film is made of a polylactic acid resin.   The biodegradable resin laminated foam sheet according to any one of claims 1 to 4, wherein the foam base sheet is a water absorbent foam sheet having an open cell ratio of 40% or more.   The water-absorbent foam sheet is formed by laminating a first foam layer having an open cell ratio of 40% or more and a second foam layer having an open cell ratio of 30% or less. The biodegradable resin laminated foam sheet as described.   The biodegradable resin laminate according to any one of claims 1 to 6, wherein the foamed base sheet and the biodegradable resin film are bonded with an adhesive containing an isocyanate curing agent. Foam sheet.   The biodegradable resin laminated foam sheet according to any one of claims 1 to 7, wherein the foam base material sheet contains less than 50% by mass of a biodegradable resin.   The biodegradable resin laminated foam sheet according to any one of claims 1 to 8 is cut into a long rectangular shape to form a plurality of folding V-grooves, and the V-grooves can be folded to constitute a folded box. A peripheral frame material for a folded box, characterized in that   The peripheral frame material for folded boxes according to claim 9, wherein a groove for fitting a bottom plate is provided along the longitudinal direction.   A folding box formed by bending the peripheral frame material for a folding box according to claim 9 or 10, and joining both ends thereof.   A folding box formed by bending the peripheral frame material for a folding box according to claim 9 or 10, fitting a bottom plate, and joining both end portions of the peripheral frame material for the folding box.

Images