JP2021053826A - Composite resin foam board and resin pallet - Google Patents

Abstract

To provide a composite resin foam board and a resin pallet that can reduce an environmental load and are superior in strength.SOLUTION: A composite resin foam board 1 includes: a long-sized resin foam 10; and a tabular metal material 20 that is inherent in the resin foam 10 and extends in a longitudinal direction of the resin foam 10. An open cell ratio of the resin foam 10 is 20% or less, and a foaming ratio of the resin foam 10 is 1.5 times or more and 2.5 times or less.SELECTED DRAWING: Figure 1

Description

The present invention relates to a composite resin foam plate and a resin pallet.

The resin foam can be extruded in any shape. In addition, recycled raw materials can be used for the resin foam, and it is possible to reduce the environmental load. For this reason, long resin foams are widely used as materials for building materials such as edges and roof tiles as an alternative material to wood.
For example, Patent Document 1 proposes a cargo handling pallet formed by assembling a long plate material made by extruding a foamed synthetic resin into a pallet shape instead of wood. In the cargo handling pallet of Patent Document 1, a metal material is embedded inside the plate-shaped resin foam to improve the strength.

Japanese Unexamined Patent Publication No. 2007-223619

However, the plate-shaped resin foam of Patent Document 1 did not have sufficient strength.

Therefore, an object of the present invention is a composite resin foam plate and a resin pallet that can reduce the environmental load and are superior in strength.

In order to solve the above problems, the present invention has the following aspects.
[1] In a composite resin foam plate having a long resin foam and a plate-shaped metal material inherent in the resin foam and extending in the longitudinal direction of the resin foam, the open cell ratio of the resin foam. Is 20% or less, and the foaming ratio of the resin foam is 1.5 times or more and 2.5 times or less.
[2] The composite resin foam plate according to [1], wherein the resin foam has a skin layer on the surface.
[3] The composite resin foam plate according to [1] or [2], wherein the melt mass flow rate (MFR) of the resin constituting the resin foam is 1.5 g / 10 min or more and 6.0 g / 10 min or less.
[4] The composite resin foam plate according to any one of [1] to [3], wherein the resin constituting the resin foam is a polystyrene resin.
[5] The composite resin foam plate according to [4], wherein the polystyrene-based resin is a recycled resin.
[6] A plurality of deck plates arranged with their longitudinal lengths parallel to each other and a plurality of digit plates for fixing the deck plates are provided, and the deck plate and the digit plates are any of [1] to [5]. A resin pallet, which is the composite resin foam plate according to item 1.
[7] The resin pallet according to [6], wherein the distance between adjacent digit plates is wider toward the end in the longitudinal direction than toward the center in the longitudinal direction of the deck plate.

According to the composite resin foam plate of the present invention, the environmental load can be reduced and the strength is superior.

It is a perspective view of the composite resin foam plate which concerns on one Embodiment of this invention. It is a front view of the composite resin foam plate of FIG. It is a schematic diagram which shows an example of the manufacturing apparatus of the composite resin foam board which concerns on this invention. It is a perspective view of the resin pallet which concerns on one Embodiment of this invention. It is a front view of the resin pallet of FIG.

[Composite resin foam board]
The composite resin foam plate of the present invention has a long resin foam and a plate-shaped metal material that is inherent in the resin foam and extends in the longitudinal direction of the resin foam.
Hereinafter, an example of the composite resin foam plate of the present invention will be described with reference to the drawings.

FIG. 1 is a perspective view of a composite resin foam plate according to an embodiment of the present invention. The composite resin foam plate 1 of FIG. 1 includes a long resin foam 10 and a plate-shaped metal material 20 inherent in the resin foam 10 and extending in the longitudinal direction (± Y direction in the figure) of the resin foam 10. Has.
As shown in FIG. 1, the composite resin foam plate 1 is a rectangular parallelepiped having a width in the ± X direction, a length in the ± Y direction, and a thickness in the ± Z direction.

The thickness of the composite resin foam plate 1 is preferably 15 to 50 mm. When the thickness of the composite resin foam plate 1 is at least the above lower limit value, the strength is more excellent. When the thickness of the composite resin foam plate 1 is not more than the above upper limit value, it is easy to control the open cell ratio and the foaming ratio of the resin foam 10.
The width and length of the composite resin foam plate 1 are not particularly limited, and can be appropriately adjusted according to the use of the composite resin foam plate 1.

The bending strength of the composite resin foam plate 1 is preferably 20 MPa or more, more preferably 22 MPa or more, and even more preferably 24 MPa or more. The larger the value of the bending strength, the more rigid the composite resin foam plate 1 is, and the more excellent the strength is. When the bending strength of the composite resin foam plate 1 is equal to or higher than the above lower limit value, the composite resin foam plate 1 is less likely to be broken by an external force in the ± Z direction. The upper limit of the bending strength of the composite resin foam plate 1 is not particularly limited, but is, for example, 50 MPa.
The bending strength of the composite resin foam plate 1 can be measured by the following measuring method.

(Measuring method of bending strength)
From the composite resin foam plate 1, a test piece having a width of 55 mm, a length of 300 mm, and a thickness of 18 mm is obtained. The obtained test piece is stored in a JIS K 7100: 1999 symbol 23/50 (temperature 23 ° C., relative humidity 50%) for 16 hours in a second-class environment, and then measured in the same environment. The bending strength is measured under the following test conditions.
"Test condition"
-Measuring device: Tensilon (registered trademark) universal testing machine (RTG-1310, manufactured by A & D Co., Ltd.).
-Number of test pieces: 3.
-Test speed: 20 mm / min.
-Distance between fulcrums: 220 mm.
・ Tip jig: Pressurized wedge 15R.
-Support stand: 15R.

The bending strength of the composite resin foam plate 1 is the type of resin constituting the resin foam 10, the thickness of the resin foam 10, the open cell ratio of the resin foam 10, the foaming ratio of the resin foam 10, and the metal material 20. It can be adjusted by the arrangement and the combination thereof.

The punching strength of the composite resin foam plate 1 is preferably 2500 N or more, more preferably 3000 N or more, and even more preferably 3300 N or more. The larger the value of the punching strength, the lower the open cell ratio of the resin foam 10. When the punching strength of the composite resin foam plate 1 is at least the above lower limit value, the metal material 20 is less likely to be punched from the composite resin foam plate 1, and the strength of the composite resin foam plate 1 can be easily maintained. That is, it is not necessary to bond the composite resin foam plate 1 and the metal material 20 via an adhesive. Therefore, it is easy to reduce the environmental load. The upper limit of the punching strength of the composite resin foam plate 1 is not particularly limited, but is, for example, 6000 N.
The punching strength of the composite resin foam plate 1 can be measured by the following method.

(Measuring method of punching strength)
Only the resin foam 10 is scraped so that the metal material 20 protrudes 3 mm from the composite resin foam plate 1 to obtain a test piece. The obtained test piece is fixed in a vise, a load is applied to the protruding metal material 20, and the load when the metal material 20 moves is used as the punching strength. The punching strength is measured under the following test conditions.
"Test condition"
-Measurement environment: temperature 23 ° C, relative humidity 50%.
-Measuring device: Tensilon (registered trademark) universal measuring device (UCT-5T, manufactured by A & D Co., Ltd.).
-Number of test pieces: 3.
-Test speed: 2 mm / min.
-Load cell rating: 50,000N.

The punching strength of the composite resin foam plate 1 depends on the type of resin constituting the resin foam 10, the open cell ratio of the resin foam 10, the foaming ratio of the resin foam 10, the type of the metal material 20, and a combination thereof. Can be adjusted.

<Resin foam>
The resin foam 10 is formed by foaming a resin composition containing a resin and a foaming agent. Examples of the resin constituting the resin foam 10 include polyethylene-based resin, polypropylene-based resin, polystyrene-based resin, polyurethane-based resin, polyester-based resin, and the like. As the resin constituting the resin foam 10, polypropylene-based resin and polystyrene-based resin, which are easy to mold and have excellent strength after foaming, are preferable, and polystyrene-based resin is more preferable.

Examples of the polypropylene-based resin include block polypropylene (block PP), homopolypropylene (homoPP), high melt tension polypropylene (HMS-PP), and the like.
Block PP is a resin in which polyethylene is dispersed in homo PP. The block PP preferably has an EPR phase (ethylene-propylene-rubber phase) around polyethylene. Such a block PP is produced by obtaining a homo-PP by polymerizing propylene gas in the first stage and then polymerizing EPR in the coexistence of ethylene gas in the second stage.

HMS-PP is polypropylene having a melt tension of 6 cN or more at 230 ° C.
Examples of HMS-PP include Waymax (registered trademark, manufactured by Japan Polypropylene Corporation), Daploy (trade name, manufactured by Borealis) and the like. The melt tension at 230 ° C. can be measured using, for example, a twin-bore capillary rheometer Rheological 5000T (manufactured by Chiast, Italy).

Examples of the polystyrene-based resin include homopolymers of styrene-based monomers such as styrene, α-methylstyrene, vinyltoluene, chlorostyrene, ethylstyrene, i-propylstyrene, dimethylstyrene, and bromostyrene, or copolymers thereof; A copolymer of a styrene-based monomer as a main component (50% by mass or more) and a styrene-based monomer and a vinyl monomer polymerizable on the styrene-based monomer: a copolymer of a styrene-based monomer and a rubber component such as butadiene, or a styrene-based monomer. So-called high-impact polystyrene resin (HIPS); etc., which is a homopolymer of the above, a copolymer thereof, a copolymer of a styrene-based monomer and a vinyl monomer, and a mixture or a polymer of a diene-based rubbery polymer. Can be mentioned.

Examples of the vinyl monomer that can be polymerized with the styrene-based monomer include alkyl (meth) acrylates such as methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, and cetyl (meth) acrylate, and (meth) acrylonitrile. Examples thereof include bifunctional monomers such as dimethyl maleate, dimethyl fumarate, diethyl fumarate, ethyl fumarate, divinylbenzene, and alkylene glycol dimethacrylate. These vinyl monomers may be used alone or in combination of two or more.
Here, "(meth) acrylate" represents one or both of "acrylate" and "methacrylate", and "(meth) acrylonitrile" represents one or both of "acrylonitrile" and "methacrylonitrile".

Examples of the diene-based rubber-like polymer include polybutadiene, styrene-butadiene copolymer, ethylene-propylene-non-conjugated diene three-dimensional copolymer, and acrylonitrile-butadiene-styrene copolymer.
These polystyrene-based resins may be used alone or in combination of two or more.

Polystyrene-based resins include polystyrenes that are not recycled raw materials, such as general-purpose polystyrene resins (GPPS), high-impact polystyrene resins (HIPS), commercially available polystyrene-based resins, and polystyrene-based resins newly prepared by methods such as suspension polymerization. It may be a polystyrene-based resin or a polystyrene-based resin (recycled resin) as a recycled raw material. As the polystyrene-based resin, a recycled resin is preferable from the viewpoint of further reducing the environmental load.
The recycled resin is a used polystyrene-based resin foam molded product. Recycled resin is obtained by collecting trays for food packaging, fish boxes, cushioning materials for home appliances, etc., and regenerating them by a limonene melting method or a heating volume reduction method. In addition, the recycled resin that can be used is non-foamed polystyrene resin molding that is separately collected from home appliances (for example, TVs, refrigerators, washing machines, air conditioners, etc.) and office equipment (for example, copiers, facsimiles, printers, etc.). The body may be crushed, melt-kneaded and repelletized.

The content of the polystyrene-based resin is preferably 60% by mass or more, more preferably 70% by mass or more, further preferably 80% by mass or more, and further preferably 90% by mass or more, based on the total mass of the resin constituting the resin foam 10. Is particularly preferable, and may be 100% by mass. When the content of the polystyrene-based resin is at least the above lower limit value, the resin foam 10 can be easily molded.

The melt mass flow rate (MFR) of the resin constituting the resin foam 10 is preferably 1.5 g / 10 min or more and 6.0 g / 10 min or less, more preferably 1.7 g / 10 min or more and 5.8 g / 10 min or less. More preferably, it is 9 g / 10 min or more and 5.6 g / 10 min or less. When the MFR of the resin constituting the resin foam 10 is within the above numerical range, the open cell ratio is likely to be lowered and the strength of the resin foam 10 is likely to be increased.
MFR is determined by measuring in accordance with JIS K 7210: 1999 "Plastics-Test Method for Melt Mass Flow Rate (MFR) and Melt Volume Flow Rate (MVR) of Thermoplastics".
In the present specification, MFR is a value at 230 ° C. and 0.23 MPa.

The resin composition contains a foaming agent.
Examples of the effervescent agent include hydrocarbons such as propane, normal butane, isobutane, normal pentane, isopentane, neopentane, cyclopentane, cyclopentadiene and hexane, ketones such as acetone and methyl ethyl ketone, and alcohols such as methanol, ethanol and isopropyl alcohol. Examples include ethers such as dimethyl ether, diethyl ether, dipropyl ether, methyl ethyl ether and petroleum ether, carbon dioxide, nitrogen, ammonia, water and the like.
Further, as the foaming agent, a degradable foaming agent such as an organic acid such as azodicarbonamide, dinitrosopentamethylenetetramine, sodium hydrogencarbonate, citric acid or a mixture thereof and sodium hydrogencarbonate (baking soda) is used. You may.
These foaming agents may be used alone or in combination of two or more.
As the foaming agent, carbon dioxide is preferable because it is easy to foam uniformly even at low magnification.
The content of the foaming agent is not particularly limited, but is preferably 0.1 to 10 parts by mass with respect to 100 parts by mass of the resin.

The resin foam 10 may contain other components (arbitrary components) in addition to the resin and the foaming agent.
Optional components include bubble modifiers, stabilizers, UV absorbers, colorants (pigments), crystallization accelerators, lubricants, cross-linking agents, surfactants, shrinkage inhibitors, flame retardants, deterioration inhibitors and the like. ..
The total of the resin, the foaming agent and the optional component does not exceed 100% by mass.

The open cell ratio of the resin foam 10 is 20% or less, preferably 15% or less, more preferably 10% or less, still more preferably 8% or less. When the open cell ratio of the resin foam 10 is not more than the above upper limit value, the strength of the resin foam 10 can be further increased. The lower limit of the open cell ratio of the resin foam 10 is not particularly limited, but is, for example, 1.0%.

The open cell ratio is based on ASTM D-2856-87 and can be measured by the 1-1 / 2-1 atm method.
Specifically, it is measured by the following method.
From the resin foam 10, a test piece having a length of 25 mm, a width of 25 mm, and a thickness of 18 mm is obtained. The outer dimensions of the obtained test piece are measured to 1/100 mm using a "Digimatic Caliper" manufactured by Mitutoyo Co., Ltd., and the apparent volume (cm ³ ) is determined.
^{Next, the volume (cm 3} ) of the test piece is determined by the 1-1 / 2-1 atm method using a dry automatic densitometer Accubic II 1340 (manufactured by Micromeritics, USA).
The open cell ratio (%) is calculated by the following formula (1).
Open cell ratio (%) = {apparent volume (cm ³ ) -test piece volume (cm ³ )} / apparent volume (cm ³ ) x 100 ... (1)
Obtain the average value of the open cell ratios of the five test pieces. The test piece is stored for 16 hours in the environment of JIS K7100: 1999 symbol 23/50, class 2, and then the measurement is performed in the environment of JIS K7100: 1999 symbol 23/50, class 2.

The open cell ratio of the resin foam 10 includes the type of resin constituting the resin foam 10, the type and amount of foaming agent, the temperature at which the resin foam 10 is molded, the temperature at which the resin foam 10 is cooled, and the like. And their combination can be controlled.

The foaming ratio of the resin foam 10 is 1.5 times or more and 2.5 times or less, preferably 1.6 times or more and 2.4 times or less, and more preferably 1.7 times or more and 2.3 times or less. When the foaming ratio of the resin foam 10 is at least the above lower limit value, the impact resistance is likely to be excellent. When the foaming ratio of the resin foam 10 is not more than the above upper limit value, the strength of the resin foam 10 can be more easily increased.
The expansion ratio of the resin foam 10 is a value obtained by dividing "1" by the apparent density of the resin foam 10.
The apparent density of the resin foam 10 is determined by measuring in accordance with JIS K 7222: 2005 "Foam plastics and rubber-How to determine the apparent density".

The expansion ratio of the resin foam 10 includes the type of resin constituting the resin foam 10, the type and amount of foaming agent, the temperature at which the resin foam 10 is molded, the temperature at which the resin foam 10 is cooled, and the temperature at which the resin foam 10 is cooled. It can be controlled by their combination.

The density of the resin foam 10 is preferably 0.43 g / cm ³ or more 0.70 g / cm ³ or less, 0.48 g / cm ³ or more 0.65 g / cm ³ or less is more preferable. When the density of the resin foam 10 is at least the above lower limit value, the strength is more excellent. When the density of the resin foam 10 is not more than the above upper limit value, it is lightweight and easy to handle.
The density of the resin foam 10 is determined by measuring the volume and mass of the test piece obtained by cutting out the resin foam 10.

The average cell diameter of the resin foam 10 is preferably, for example, 200 μm or more and 400 μm or less. When the average cell diameter of the resin foam 10 is at least the above lower limit value, the impact resistance is likely to be excellent. When the average cell diameter of the resin foam 10 is not more than the above upper limit value, the open cell ratio tends to be lowered. The average cell diameter of the resin foam 10 is determined by measuring according to the method described in ASTM D2842-69.

As shown in FIG. 2, the resin foam 10 has an inner layer 12 and a skin layer 14.
The inner layer 12 is a foamed layer formed by foaming the resin composition.
The skin layer 14 is a layer formed on the surface when the resin foam 10 is manufactured, and refers to a thin skin portion that does not contain air bubbles.
The thickness of the skin layer 14 is preferably 100 μm or more, more preferably 200 μm or more, and even more preferably 300 μm or more. When the thickness of the skin layer 14 is at least the above lower limit value, the strength of the resin foam 10 can be further increased. The upper limit of the thickness of the skin layer 14 is not particularly limited, but is, for example, 500 μm.
In the present specification, the thickness of the skin layer refers to the average value of the thickness measured by the following measuring methods.

(Measuring method of skin layer thickness)
The resin foam 10 is cut in a direction perpendicular to the surface (thickness direction), and the vicinity of the surface of the cut surface is magnified 30 to 100 times using a microscope (VHX-1000, manufactured by KEYENCE CORPORATION). And observe. The thickness of the skin layer 14 is the length from the surface of the resin foam 10 to the surface of the bubbles on the outermost layer side, and eight randomly selected bubbles on the outermost layer side are measured at three points for each bubble. The average value of the measured values at 24 points is defined as the skin layer thickness (μm).

The thickness of the skin layer 14 includes the type of resin constituting the resin foam 10, the type and amount of foaming agent, the temperature at which the resin foam 10 is molded, the temperature at which the resin foam 10 is cooled, and the like. It can be controlled by the combination of.

<Metallic material>
The metal material 20 is a metal member processed into a plate shape extending in the longitudinal direction of the resin foam 10. The metal material 20 is a member whose longitudinal direction is the ± Y direction.
From the viewpoint of increasing the bending strength of the composite resin foam plate 1, as shown in FIG. 2, the metal material 20 is preferably contained in the resin foam 10 with the width direction (± Z direction) vertical.
The metal material 20 may be inherent in the resin foam 10 with the width direction horizontal.
The length in the width direction and the length in the thickness direction (± X direction) of the metal material 20 may be the same.

Examples of the metal forming the metal material 20 include aluminum, iron, copper, silver, chromium, nickel, and alloys of these metals.
As the metal forming the metal material 20, aluminum and iron are preferable because they have sufficient strength and are easy to process, and aluminum is more preferable because they are lightweight and easy to handle. Among the aluminums, a grade aluminum 5052 (containing 2.5% by mass of magnesium) in which magnesium, silicon and the like are contained in a small amount (for example, 2 to 4% by mass) to improve the tensile strength is more preferable.

[Manufacturing method of composite resin foam plate]
In the composite resin foam plate, when a resin composition containing a resin and a foaming agent is extruded while being foamed to form a resin foam, a metal material is supplied from the rear of a mold (insert die) in the extrusion direction. , Obtained by extruding a resin foam and a metal material at the same time.
An example of a method for manufacturing a composite resin foam plate will be described with reference to FIG.

The composite resin foam plate manufacturing apparatus 200 shown in FIG. 3 includes an extruder 210, an insert die 214, a sizing die 220, a cooling water tank 230, a take-up machine 240, and a cutting machine 250. The direction of the arrow A is the resin extrusion direction.
The extruder 210 includes a hopper 212.
The sizing die 220 includes an air-cooled section 222 that cools with air and a water-cooled section 224 that cools with water. The zone of the sizing die 220 near the insert die 214 is the air-cooled portion 222.
The cooling water tank 230 includes a pump 232.
The pick-up machine 240 includes a pair of upper and lower belt rollers 242.
The cutting machine 250 includes an upper cutter 252 and a lower cutter 254.

First, the raw material of the resin composition is charged into the extruder 210 from the hopper 212. The raw materials input from the hopper 212 are a resin, a foaming agent, and an optional component to be blended as needed.

In the extruder 210, the raw materials are mixed while being heated to an arbitrary temperature to obtain a resin melt.
The heating temperature is appropriately determined within a range in which the resin is melted and the additive is not denatured in consideration of the type of resin and the like.

After the resin melt is sufficiently kneaded, the temperature of the resin melt is adjusted. At this time, the temperature of the resin melt (hereinafter, also referred to as resin temperature) is preferably 150 to 180 ° C., more preferably 160 to 170 ° C. in the case of polystyrene, for example. When the resin temperature is within the above numerical range, a resin foam having a desired expansion ratio can be easily obtained.

Next, the plate-shaped metal material 20 is inserted into the insert die 214 in front of the extruder 210. The number of metal materials 20 to be inserted into the insert die 214 is adjusted according to the use of the composite resin foam plate 1. Along with the insertion of the metal material 20, the resin melt is supplied to the insert die 214. In the insert die 214, the resin melt and the metal material 20 are integrally extruded into the sizing die 220.

The resin melt integrated with the metal material 20 is cooled while being foamed by the sizing die 220, and is formed into a desired size and a desired shape.
The resin melt extruded to the sizing die 220 is supplied to the water cooling unit 224 via the air cooling unit 222. By providing the water-cooled portion 224 after the air-cooled portion 222, the resin melt can be efficiently and rapidly cooled while foaming the resin melt to a desired foaming ratio, and the foaming ratio of the resin foam can be suppressed to a low level. In addition, a resin foam having a skin layer on the surface can be easily obtained. Therefore, it is easy to obtain a resin foam having a small open cell ratio, and it is easy to increase the strength of the composite resin foam plate 1.
As described above, for the cooling of the sizing die 220, it is preferable to use both air cooling with air and water cooling with water.
The sizing die may be only the air-cooled part or only the water-cooled part. Further, the sizing die may be provided with an air-cooled portion after the water-cooled portion.

The temperature of the air cooling in the air cooling unit 222 is preferably 20 to 50 ° C.
Water cooling in the water cooling unit 224 is performed by allowing water to flow through the inside of a cylinder (not shown) provided on the outer circumference of the sizing die 220.
The temperature of the water to be passed through the water cooling unit 224 (hereinafter, also referred to as the first water temperature) is preferably 5 to 20 ° C, more preferably 10 to 20 ° C. When the first water temperature is equal to or higher than the above lower limit value, the resin melt tends to foam appropriately. When the first water temperature is not more than the above upper limit value, it is easy to keep the foaming ratio of the resin foam low.
The flow rate of water to be passed through the water cooling unit 224 (hereinafter, also referred to as the first flow rate) is preferably 20 to 40 L / min, more preferably 25 to 35 L / min. When the first flow rate is at least the above lower limit value, it is easy to keep the foaming ratio of the resin foam low. When the first flow rate is not more than the above upper limit value, the resin melt tends to foam appropriately.

The resin melt molded by the sizing die 220 is extruded into the cooling water tank 230 as an appropriately foamed molded product.

In the cooling water tank 230, the molded product is cooled and cured, and a composite resin foam plate in which the metal material 20 is contained in the resin foam is obtained.
In the cooling water tank 230, water is sprayed for a predetermined time to cool the molded product. From the viewpoint of excellent heat removal efficiency, the cooling water tank is preferably a cooling water tank having a spraying facility rather than a storage water tank that can store a certain amount of water.
The time for spraying water in the cooling water tank 230 (hereinafter, also referred to as spraying time) is preferably 5 to 20 minutes, more preferably 5 to 15 minutes. When the spraying time is equal to or more than the above lower limit, the inside of the molded product is cooled, and the molded product is easily sufficiently cured. When the spraying time is not more than the above upper limit value, the production efficiency of the composite resin foam plate is enhanced.
The temperature of the water to be sprayed in the cooling water tank 230 (hereinafter, also referred to as the second water temperature) is preferably 5 to 20 ° C, more preferably 10 to 20 ° C. When the second water temperature is at least the above lower limit value, it is easy to maintain the strength of the molded product. When the second water temperature is not more than the above upper limit value, the inside of the molded body is cooled, and the molded body is easily sufficiently cured.
The flow rate of the water to be sprayed in the cooling water tank 230 (hereinafter, also referred to as a second flow rate) is preferably 50 to 150 L / min, more preferably 80 to 120 L / min. When the second flow rate is not more than the above lower limit value, the inside of the molded body is cooled, and the molded body is easily sufficiently cured. When the second flow rate is not more than the above upper limit value, it is easy to save the amount of water used.
The second flow rate can be adjusted by the pump 232 connected to the cooling water tank 230.

The composite resin foam plate that has left the cooling water tank 230 is continuously extruded by a pair of upper and lower belt rollers 242 of the take-up machine 240.

The composite resin foam plate that has left the take-up machine 240 is cut by the upper cutter 252 and the lower cutter 254 of the cutting machine 250 to obtain the composite resin foam plate 1 having a desired length.

In the composite resin foam plate 1 of the present embodiment, the metal material 20 is contained in the resin foam 10. Therefore, it is easy to increase the bending strength, and the strength is superior.
The resin foam 10 has an open cell ratio of 20% or less. Therefore, the resin foam 10 is excellent in strength, and the strength of the composite resin foam plate 1 can be further increased.
The resin foam 10 has a foaming ratio of 1.5 times or more and 2.5 times or less. Therefore, the resin foam 10 is excellent in impact resistance and strength, and the strength of the composite resin foam plate 1 can be further increased.

Although the composite resin foam plate of the present invention has been described above, the present invention is not limited to the above-described embodiment, and can be appropriately changed without departing from the spirit of the present invention.
The composite resin foam plate 1 has two metal materials 20, but the number of metal materials contained in the composite resin foam plate may be one or three or more.
The composite resin foam plate may have the same length in the width direction (± X direction) and the length in the thickness direction (± Z direction).

[Resin pallet]
The resin pallet of the present invention has a plurality of deck plates arranged in parallel with each other and a plurality of digit plates for fixing the deck plates, and the deck plate and the digit plates are formed of the composite resin foam plate of the present invention. Will be done. That is, the resin pallet of the present invention is formed by assembling the above-mentioned composite resin foam plate of the present invention into a pallet shape.
A resin pallet according to an embodiment of the present invention will be described with reference to the drawings.

As shown in FIG. 4, the resin pallet 100 is a pallet having a rectangular shape in a plan view. The resin pallet 100 is used when carrying an article (luggage) by a forklift or the like.
The resin pallet 100 has an upper surface deck 30, a lower surface deck 40, and a plurality of digit plates 50.
The upper surface deck 30 is formed by arranging a plurality of upper surface deck plates 32 having the ± X direction as the longitudinal direction in the ± Y direction.
The lower surface deck 40 is formed by arranging a plurality of lower surface deck plates 42 having the ± X direction as the longitudinal direction in the ± Y direction.
The digit plate 50 has a length in the ± Y direction, and fixes the upper deck plate 32 and the lower deck plate 42. A plurality of digit plates 50 are arranged in the ± X direction, and each digit plate 50 connects the upper deck plate 32 and the lower deck plate 42. A hole 60 that opens in the ± Y direction is formed between the adjacent digit plates 50.

The upper deck plate 32 and the lower deck plate 42 are formed of a composite resin foam plate 1.
In the digit plate 50, one metal material 22 is embedded in the center of the resin foam of the present invention. The digit plate 50 is narrower in width and thicker than the upper deck plate 32 and the lower deck plate 42.
In the digit plate 50, the metal material 22 is inherent in the vertical direction (± Z direction). Therefore, the resin pallet 100 is superior in strength against an external force in the ± Z direction.

As shown in FIG. 5, the resin pallet 100 has 6 digit plates 50 and 5 holes 60.
The distances (widths of the holes 60) between the adjacent digit plates 50 are a, b, c, d, and e in order from the holes 60 located in the −X direction.

In the resin pallet, the distance between adjacent digit plates is closer to the center in the longitudinal direction (± X direction) of the deck plates (hereinafter, the upper deck plate and the lower deck plate are collectively referred to as “deck plates”). However, it is preferable that the deck plate is wider toward the end in the longitudinal direction. That is, in the resin pallet 100, it is preferable that the width a of the hole 60 (or the width e of the hole 60) is wider than the width c of the hole 60.
When the width a or the width e is larger than the width c, the strength of the central portion of the upper deck 30 of the resin pallet 100 is further increased. Therefore, a heavy load can be placed in the central portion of the upper deck 30, and the load can be easily stabilized when the load is placed on the resin pallet 100 and transported. In addition, when the width a or the width e is larger than the width c, it is easy to insert the claws of the forklift into the hole 60, and it is easy to improve the workability when transporting the load.

As for the width of the hole 60, it is preferable that the width a and the width e are equal and the width b and the width d are equal. When the width a and the width e are equal and the width b and the width d are equal, the luggage is likely to be stable when the luggage is placed on the resin pallet 100 and transported.
The width of the hole 60 is preferably width a> width b> width c and width e> width d> width c. When the width of the hole 60 is width a> width b> width c and width e> width d> width c, it is easier to carry the load more stably.

[Manufacturing method of resin pallet]
The method for producing the resin pallet is not particularly limited, and the resin pallet can be produced by a conventional method.
For example, in the case of the resin pallet 100, the upper deck plate 32 is placed so as to be orthogonal to the plurality of digit plates 50 arranged, and the upper deck plates 32 are joined by screws, nails, or the like. As the nail, a screw nail that is hard to come off is preferable. After joining a predetermined number of upper deck plates 32 to the digit plate 50, the digit plate 50 and the lower deck plate 42 are joined with screws, nails, or the like on the surface facing the joint surface between the upper deck plate 32 and the digit plate 50. To do. A resin pallet 100 is obtained by joining a predetermined number of lower deck plates 42 to the digit plate 50.

When obtaining the resin pallet 100, as described above, it is preferable to join the digit plates 50 so that the width of the holes 60 is a> c (e> c), and the width of the holes 60 is a> b>. It is more preferable to join the digit plates 50 so that c (e> d> c).

The method of joining the upper deck plate 32 and the digit plate 50 is not limited to the above-described embodiment, and may be joined using an adhesive.
Further, it is not necessary to join the upper deck plate 32 and the digit plate 50 first, and the lower deck plate 42 and the digit plate 50 may be joined first, or these may be joined at the same time.

Since the resin pallet of the present invention is formed by using the composite resin foam plate of the present invention, it is more excellent in strength.
Resin pallets are more durable than wood pallets because they do not rot.
By using recycled resin as the raw material for the resin pallet, it is excellent for the global environment.
Even if the resin pallet is damaged, the resin can be melted and repeatedly manufactured, and waste can be reduced.

Although the resin pallet of the present invention has been described above, the present invention is not limited to the above-described embodiment, and can be appropriately changed without departing from the spirit of the present invention.
In the resin pallet 100, the upper deck 30 is used as a loading surface for luggage, but the lower deck 40 may be used as a loading surface for luggage.
In the resin pallet 100, the upper deck plate 32 and the lower deck plate 42 have the same shape, but the upper deck plate and the lower deck plate may have different shapes.
In the resin pallet 100, the thickness of the deck plate and the digit plate 50 is different, but the thickness of the deck plate and the digit plate may be the same.
The resin pallet 100 has five holes 60 formed between the digit plates 50, and the number of holes can be appropriately set according to the load of the load. The number of holes formed between the digit plates may be, for example, 2 or more and 4 or less, or 6 or more.

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited to the following description.
The raw materials used in this example are as follows.

<Resin>
-Main raw material A: Polystyrene resin, HRM-52 (product name), manufactured by Toyo Styrene Co., Ltd., MFR = 2.1 g / 10 min.
-Main raw material B: Recovered pellets using used HRM-52 (product name) as the main raw material, MFR = 4.0 g / 10 min, number average molecular weight 90,000.
-Main raw material C: polystyrene resin, HRM-12N (product name), manufactured by Toyo Styrene Co., Ltd., MFR = 5.4 g / 10 min.
<foaming agent>
-Chemical foaming agent: Cellmic (registered trademark) 6067, manufactured by Sankyo Kasei Co., Ltd.
<Arbitrary ingredient>
-Rubber component: Toughprene (registered trademark) A, manufactured by Asahi Kasei Corporation.
-Colorant: Pigment, manufactured by Dainichiseika Kogyo Co., Ltd.

[Example 1]
As a resin, 1.1 parts by mass of the foaming agent, 1.0 part by mass of the rubber component, and 3.0 parts by mass of the colorant are mixed with 100 parts by mass of the main raw material A, and the diameter is 65 mm and the L / D ratio is 32. It was supplied to a shaft extruder, melted at 200 ° C., and kneaded to obtain a resin melt. After that, the resin temperature was set to 165 ° C., and the resin melt was extruded from an insert die having an opening shape of 7.5 mm (metal material passing portion: 13 mm) × 92 mm together with two aluminum plates having a width of 10 mm and a thickness of 1.0 mm. .. Table 1 shows the resin temperature immediately before the insert die. The resin melt was extruded and foamed at a discharge rate of 55 kg / h, and an aluminum plate was supplied to a sizing die of 18 mm × 110 mm × 600 mm at the same speed. In the sizing die, air cooling (28 ° C.) is performed from the inlet to 50 mm, and water having a water temperature of 15 ° C. and a water volume (flow rate) of 30 L / min is passed through a cylinder provided on the outer circumference of the sizing die from 50 mm to 600 mm. , The resin melt and the aluminum plate were water-cooled to obtain a molded product. This molded product was supplied to a cooling water tank having a length of 6 m, and water having a water temperature of 15 ° C. and a water volume of 100 L / min was sprayed for 7 minutes to cool the molded product. The cooled molded product was pulled by a pair of upper and lower belt rollers and cut into a predetermined length by a cutting machine to obtain a composite resin foam plate having a thickness of 18 mm, a width of 110 mm and a length of 2205 mm. By observing the cross section of the obtained composite resin foam plate, it was confirmed that two aluminum plates were vertically inserted at positions 9 mm from both ends in the width direction without using an adhesive.

[Example 2]
A composite resin foam plate was obtained in the same manner as in Example 1 except that the main raw material C was used as the resin. The resin temperature is shown in Table 1.

[Example 3]
A composite resin foam plate was obtained in the same manner as in Example 1 except that the main raw material B was used as the resin. The resin temperature is shown in Table 1.

[Example 4]
A composite resin foam plate was obtained in the same manner as in Example 3 except that the resin temperature was adjusted to the values shown in Table 1 based on the conditions of Example 3.

[Comparative Examples 1 to 4]
Based on the conditions of Example 3, the resin temperature, the water temperature of the sizing die, and the amount of water of the sizing die were adjusted to the values shown in Table 1, and a composite resin foam plate was obtained in the same manner as in Example 1.

The following evaluations were made on the composite resin foam plates of each example. The results are shown in Table 1. In Table 1, "○" indicates that the surface of the composite resin foam plate has a skin layer having a thickness of 100 μm or more, and “×” indicates that there is no skin layer having a thickness of 100 μm or more on the surface of the composite resin foam plate. Show that.

[Measurement of skin layer thickness]
The resin foam of the composite resin foam plate is cut in the direction perpendicular to the surface (thickness direction), and the vicinity of the surface of the cut surface is 30 to 30 using a microscope (VHX-1000, manufactured by KEYENCE CORPORATION). It was observed at a magnification of 100 times. The thickness of the skin layer was the length from the surface of the resin foam to the surface of the bubbles on the outermost layer side, and eight randomly selected bubbles on the outermost layer side were measured at three points for each bubble. The average value of the measured values at 24 points was taken as the thickness of the skin layer (μm).

[Measurement of open cell ratio]
A test piece having a length of 25 mm, a width of 50 mm, and a thickness of 18 mm was cut out from the resin foam of the composite resin foam plate. The outer dimensions of the obtained test piece were measured to 1/100 mm using a "Digimatic Caliper" manufactured by Mitutoyo Co., Ltd., and the apparent volume (cm ³ ) was determined.
^{Next, the volume (cm 3} ) of the test piece was determined by the 1-1 / 2-1 atm method using a dry automatic densitometer Accubic II 1340 (manufactured by Micromeritics, USA).
The open cell ratio (%) was calculated by the following formula (1).
Open cell ratio (%) = {apparent volume (cm ³ ) -test piece volume (cm ³ )} / apparent volume (cm ³ ) x 100 ... (1)
The average value of the open cell ratios of the five test pieces was calculated. When calculating the open cell ratio, the test piece is stored in a JIS K7100: 1999 symbol 23/50, class 2 environment for 16 hours, and then in a JIS K7100: 1999 symbol 23/50, class 2 environment. Measurements were made.

[Measurement of foaming ratio]
The apparent density of the resin foam of the composite resin foam plate was determined by measuring in accordance with JIS K 7222: 2005 "Foam plastics and rubber-How to determine the apparent density". The foaming ratio was calculated by dividing "1" by the apparent density of the resin foam.

[Measurement of density]
A test piece having a length of 25 mm, a width of 50 mm, and a thickness of 18 mm was cut out from the resin foam of the composite resin foam plate. ^{The volume (cm 3} ) of the test piece was determined by the 1-1 / 2-1 atmospheric pressure method using a dry automatic densitometer Accubic II 1340 (manufactured by Micromeritics, USA). Next, the mass (g) of the test piece was measured, and the mass (g) of the test piece ^{was divided by the volume (cm 3} ) of the test piece to calculate the density. The density was the average value of the five test pieces.

[Measurement of bending strength]
A test piece having a width of 55 mm, a length of 300 mm, and a thickness of 18 mm was obtained from the composite resin foam plate. The obtained test piece was stored in a JIS K 7100: 1999 symbol 23/50 (temperature 23 ° C., relative humidity 50%) for 16 hours in a second-class environment, and then the bending strength was measured in the same environment. .. The test conditions were as follows.
"Test condition"
-Measuring device: Tensilon (registered trademark) universal testing machine (RTG-1310, manufactured by A & D Co., Ltd.).
-Number of test pieces: 3.
-Test speed: 20 mm / min.
-Distance between fulcrums: 220 mm.
・ Tip jig: Pressurized wedge 15R.
-Support stand: 15R.

[Measurement of punch strength]
Only the resin foam was scraped so that the aluminum plate protruded 3 mm from the composite resin foam plate to obtain a test piece. The obtained test piece was fixed in a vise, a load was applied in the longitudinal direction of the protruding aluminum plate, and the load when the aluminum plate moved was measured and used as the punching strength. The test conditions were as follows.
"Test condition"
-Measurement environment: temperature 23 ° C, relative humidity 50%.
-Measuring device: Tensilon (registered trademark) universal measuring device (UCT-5T, manufactured by A & D Co., Ltd.).
-Number of test pieces: 3.
-Test speed: 2 mm / min.
-Load cell rating: 50,000N.

<Manufacturing of digit board>
A resin composition having the same composition as in Example 1 was supplied to the same extruder as in Example 1 and melted at 200 ° C. and kneaded to obtain a resin melt. Then, the resin temperature was set to 165 ° C., and the resin melt was extruded from an insert die having an opening shape of 20 mm (16 mm at the center) and 79.5 mm together with one aluminum plate having a width of 30 mm and a thickness of 1.0 mm. The resin melt was extruded and foamed at a discharge rate of 55 kg / h, and an aluminum plate was supplied to a sizing die of 40 mm × 80 mm × 600 mm at the same speed. The sizing die was cooled in the same manner as in Example 1 to obtain a molded product. This molded product was supplied to the same cooling water tank as in Example 1, and water at a water temperature of 15 ° C. and a water volume of 100 L / min was sprayed for 11 minutes to cool the molded product. The cooled molded product was pulled by a pair of upper and lower belt rollers and cut into a predetermined length by a cutting machine to obtain a composite resin foam plate (digit plate) having a thickness of 40 mm, a width of 80 mm, and a length of 2195 mm. .. By observing the cross section of the obtained digit plate, it was confirmed that one aluminum plate was inserted sideways in the central portion without using an adhesive.

<Manufacturing of resin pallets>
As shown in Table 2, the six obtained digit plates were arranged at intervals of a, b, c, d, and e, and 19 composite resin foam plates (upper deck) obtained in Example 1 were placed on the upper part. The plates) were arranged at equal intervals, and 17 composite resin foam plates (bottom deck plates) obtained in Example 1 were arranged at equal intervals at the bottom. Three plastic sheet screws (manufactured by Max Co., Ltd.) were screwed to the places where the digit plates at both ends and the upper deck plate contact. Similarly, three plastic sheet screws (manufactured by Max Co., Ltd.) were used to fasten the contact points between the digit plates at both ends and the lower deck plate. The remaining four digit plates and the upper deck plate were nailed with two plated nails (length under the neck 65 mm, body diameter φ2.9 mm, manufactured by Max Co., Ltd.) at each location. Similarly, the remaining four digit plates and the lower deck plate were nailed with two of the plated nails at each location to produce a resin pallet having a length of 2200 mm, a width of 2200 mm, and a height of 116 mm. ..

[Experimental Examples 1 to 6]
Ten roll-shaped polystyrene resin foam sheets (mass 50 kg) were loaded on the obtained resin pallets of each example, and the resin pallets were lifted by a forklift with a distance between the two claws of 1800 mm and a claw length of 1850 mm. The degree of bending of the resin pallet was visually confirmed. The degree of bending of the resin pallet and the ease of inserting the claws of the forklift were evaluated according to the following evaluation criteria. The results are shown in Table 2. The resin pallet of Experimental Example 2 has five digit plates.
"Evaluation criteria"
⊚: The resin pallet does not bend and the forklift claws can be easily inserted.
◯: The resin pallet does not bend, but the forklift claws are slightly difficult to insert.
Δ: The resin pallet bends slightly, or the forklift claws are difficult to insert.
X: The resin pallet bends.

It was found that Examples 1 to 4 to which the present invention was applied had a bending strength of 20 MPa or more and a punching strength of 2500 N or more, and were superior in strength.
On the other hand, in Comparative Examples 1 to 4 in which the open cell ratio and the foaming ratio were outside the range of the present invention, the bending strength was less than 20 MPa and the punching strength was less than 2500 N.
According to Experimental Examples 1 to 6 in which the spacing (hole width) between the digit plates of the resin pallet was changed, when the width (a and e) of the holes near the end in the longitudinal direction of the deck plate was wide, the resin pallet was used. It was found that the pallet did not bend and it was easy to insert the claws of the forklift. In Experimental Example 2, the number of digit plates was small and the widths of all the holes were wide, so that the entire resin pallet was bent. If the resin pallet bends, the loaded load may move and interrupt the work, which is not preferable.

From these results, it was found that the composite resin foam plate and the resin pallet of the present invention can reduce the environmental load and are superior in strength.

1 ... Composite resin foam plate, 10 ... Resin foam, 12 ... Inner layer, 14 ... Skin layer, 20, 22 ... Metal material, 30 ... Top deck, 32 ... Top deck board, 40 ... Bottom deck, 42 ... Bottom deck board , 50 ... digit plate, 60 ... hole, 100 ... resin pallet, 200 ... composite resin foam plate manufacturing equipment, 210 ... extruder, 212 ... hopper, 214 ... insert die, 220 ... sizing die, 222 ... air cooling part, 224 ... Water cooling part, 230 ... Cooling water tank, 232 ... Pump, 240 ... Pickup machine, 242 ... Belt roller, 250 ... Cutting machine, 252 ... Upper cutter, 254 ... Lower cutter

Claims (7)

In a composite resin foam plate having a long resin foam and a plate-shaped metal material inherent in the resin foam and extending in the longitudinal direction of the resin foam.
The open cell ratio of the resin foam is 20% or less, and the resin foam has an open cell ratio of 20% or less.
A composite resin foam plate having a foaming ratio of 1.5 times or more and 2.5 times or less of the resin foam. The composite resin foam plate according to claim 1, wherein the resin foam has a skin layer on the surface. The composite resin foam plate according to claim 1 or 2, wherein the melt mass flow rate (MFR) of the resin constituting the resin foam is 1.5 g / 10 min or more and 6.0 g / 10 min or less. The composite resin foam plate according to any one of claims 1 to 3, wherein the resin constituting the resin foam is a polystyrene resin. The composite resin foam plate according to claim 4, wherein the polystyrene-based resin is a recycled resin. Multiple deck boards lined up with their lengths parallel to each other,
It has a plurality of digit plates for fixing the deck plate, and has
A resin pallet in which the deck plate and the digit plate are composite resin foam plates according to any one of claims 1 to 5. The resin pallet according to claim 6, wherein the distance between the adjacent digit plates is wider toward the end in the longitudinal direction than toward the center in the longitudinal direction of the deck plate.

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