JP2601241Y2 - Laminated sheets and packaging containers - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated sheet used as a packaging sheet for a cushioning packaging material, a packaging container and the like, and a container for protecting and packaging fruits and the like.

[0002]

2. Description of the Related Art As one of conventional packaging containers, a container having sufficient cushioning and shape retention (rigidity) for packaging soft materials (eg, fruits, etc.) and precision machinery as contents. Is widely used. As this kind of packaging container, for example, one having the following configuration is known.

[0003] As disclosed in Japanese Utility Model Application Laid-Open No. 60-182384 and Japanese Utility Model Application Laid-open No. 60-182385,
A styrene resin foam sheet laminated on one side with a crosslinked polyethylene resin foam sheet. 58-9
As disclosed in Japanese Patent Publication No. 2040, a wrapping material formed by laminating a crosslinked olefin resin foam on both sides of a stiff synthetic resin sheet that can be formed and processed. 5-281
No. 82, a three-layer tray in which a soft foam sheet and a highly rigid synthetic resin sheet are sequentially laminated on the lower surface of a nonwoven fabric sheet.

[0004] In any of the above-mentioned containers, each sheet is previously bonded together using an adhesive such as hot melt to produce a laminated sheet, and the laminated sheet is formed into various containers by means such as vacuum forming. It is obtained by molding into a shape. Further, if necessary, portions other than the molded container portion (so-called ear portions) are cut to obtain a container having a desired shape. And the above ears were discarded.

[0005]

[Problems to be Solved by the Invention] In recent years, from the viewpoint of environmental problems, there is a strong demand for resource saving by reusing used containers and reducing waste of raw materials. From this point of view,
The above-mentioned conventional laminated sheets and containers have the following disadvantages.

[0006] 1) When collecting and recycling unnecessary containers and the like, since different types of resins such as styrene-based resins and olefin-based resins cannot be processed at the same time, it is necessary to separate and melt both of them. Is being done. Therefore, when resin sheets of different types are laminated as in the above-described conventional container, it is necessary to separate both resin layers.
However, since the conventional container uses a laminated sheet that is firmly bonded by hot melt bonding or the like,
It was very difficult to separate the two resin layers and recycling was not easy.

[0007] 2) Further, it is also difficult to sort and collect the laminated sheet in the same manner as described above when collecting ears generated when the laminated sheet is formed into a predetermined shape or defective products generated due to defective molding. Met.

The present invention is intended to solve the above-mentioned drawbacks of the prior art, and it is possible to mold a container having both cushioning and rigidity, and furthermore, a sheet lost at the time of molding or the like, a container after use, and the like. It is an object of the present invention to provide a laminated sheet which can be easily separated and separated by easily peeling off each of the laminated sheets at the time of recycling, and a packaging container which is easy to manufacture and easily recyclable. I do.

[0009]

SUMMARY OF THE INVENTION The laminated sheet of the present invention comprises:
A laminated sheet in which a foamed polypropylene resin sheet is releasably laminated on one side of a foamed polyethylene resin sheet, and the peel strength between the foamed sheets (JISK
180-degree peel test according to 6854) is 3-35.
0 g.

[0010] The packaging container of the present invention is a packaging container in which a polypropylene resin foam sheet is laminated on one side of a crosslinked polyethylene resin foam sheet, and a holding portion for holding an article to be packaged is formed by molding. A container, wherein the cross-linked polyethylene resin foam sheet is located on the holding portion side, and the cross-linked polyethylene resin foam sheet and the polypropylene resin foam sheet are releasably integrated.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a sectional view showing an example of the laminated sheet of the present invention.

As shown in FIG. 1, a laminated sheet 1 of the present invention has a polypropylene resin foam sheet (hereinafter abbreviated as a PP foam sheet) on one side of a polyethylene resin foam sheet (hereinafter abbreviated as a PE foam sheet) 2. 3) are laminated and integrated, and the PE foam sheet 2 and the PP foam sheet 3 are laminated with a peelable adhesive strength.

The peel strength of both foamed sheets in the laminated sheet 1 of the present invention is defined as a peel strength in a range of 3 to 350 g, preferably 4 to 300 g, more preferably 5 to 180 g according to a 180 ° peel test according to JIS K 6854. ~ 20
It only needs to be 0 g. By setting the peel strength between the PE-based foam sheet 2 and the PP-based foam sheet 3 within the above range, the sheet is not peeled in the normal handling of the laminated sheet, but when the two sheets are peeled by hand, both sheets ( In particular, a highly flexible PE-based foam sheet) can be cleanly peeled off without being torn off, and it has become possible to separate and collect it and easily reuse it. When the above-mentioned peel strength is less than 3 g, the integration of the foamed sheets is insufficient, and peeling occurs during normal handling such as a distribution process. Also, the peel strength is 3
Even if it exceeds 50 g, if the peel strength is sufficient until the material breakage of the foamed sheet occurs, it is possible to obtain a material that can be peeled cleanly by hand. The increase leads to a sharp increase in peel strength, and the peel strength exceeds a value at which material destruction occurs. Therefore, from the viewpoint of temperature control of the bonding process, it is very difficult to laminate and bond in the range of the peel strength immediately before the material destruction occurs from 350 g. The same effect can be expected for the adhesive having a peel strength of 3 to 350 g even if the adhesive is partially adhered to the laminated surface, but it is preferable that the adhesive is adhered to the entire surface of the laminated surface from the viewpoint of workability during handling.

In the present invention, a 180 ° C. peel test method performed according to JIS K 6854 “Test method for peel strength of adhesive” will be described below. According to the present invention, JIS K685 is obtained from a laminated sheet or a packaging container.
5 specimens each having a width of 25 mm and a length of 300 mm similar to those of Example No. 4 were prepared, and 180 specimens were obtained at a gripping speed of 200 mm / min.
° Peeling tensile test was conducted, and the average value of the peeling strength of the bonded portion was taken as the peeling strength. The peel test is performed by keeping the PP-based foam sheet straight and turning the PE-based foam sheet 180 °. The obtained data is a wavy curve showing the abscissa: peel amount, and the ordinate: peel strength, and from the wavy curve, an abnormal value is eliminated by using a statistical means based on a bar X-R control chart, and the average value of the peel strength is obtained. And determine the peel strength.

As a specific means for laminating and integrating the laminated sheet 1 so as to have the above-mentioned peel strength, it is preferable to use a hot-air laminate. The hot-air lamination uses, for example, a hot-air laminating device 4 as shown in FIG. 2 and a dryer 7 on a laminated surface of the PE-based foam sheet 2 sent from the sending device 5 and the PP-based foam sheet 3 sent from the sending device 6. Hot air is supplied to heat both sheets, and the two sheets are laminated and integrated while being pressed by a pressure roll 8 and then wound by a winding device 9 to form a PE foam sheet 2 and P
The laminated sheet 1 in which the P-based foamed sheets 3 are laminated and integrated can be continuously obtained.

The processing conditions of the hot-air laminate are such that the thickness, density and density of both foamed sheets are set so that the peel strength is within the above range.
The temperature of hot air, the line speed, and the like are appropriately adjusted according to the cell structure, the type of the base resin, and the like. The temperature of the hot air can also be adjusted by adjusting the distance between the hot air outlet and the pressure roll. Processing conditions hot lamination is generally density 0.02~0.045g / cm ³ of PE-based foamed sheet and density 0.023~0.045g / cm ³ of PP
When laminating with a foamed sheet, the hot air temperature is 130 to 2
30 ° C., preferably 140 ° C. to 200 ° C., and a line speed of about 10 to 20 m / min are employed.

The use of hot air lamination for lamination of both sheets enables lamination of two sheets without using an adhesive, and there is no need to consider an adhesive resin when recycled. In addition, the hot air lamination has an advantage that a laminated sheet in which both sheets are weakly adhered and the foamed sheets are laminated and integrated so that they can be peeled off from each other can be easily manufactured. Further, since no adhesive is used, there is no possibility that the flexibility of the foam sheet is impaired by the adhesive.

As a production example of the laminated sheet of the present invention, the results of experiments on the relationship between the temperature of hot air of the hot air laminate and the state of adhesion between the foamed sheets are shown below. The experiment was performed using a hot air laminating apparatus shown in FIG. 2, using a crosslinked PE foam sheet having a foaming ratio of 40 times and a sheet thickness of 1 mm and a PP foam sheet having a foaming ratio of 30 times and a sheet thickness of 2 mm. The temperature was from 120 ° C. to 2 as shown in Table 1.
The temperature was changed to 50 ° C., and both sheets were laminated and integrated. The peel strength of the obtained laminated sheet was measured, and the bonded state of both foamed sheets was observed. The line speed of the hot air laminator was 15 m / min, and the distance between the hot air outlet and the pressure roll was 15 cm. Further, Experimental Examples 2 and 4
Measured the tensile elongation (%) according to JIS K6767.

As shown in Table 1, when the hot air temperature was in the range of 140 to 200 ° C., the hot air laminate was capable of easily laminating two foam sheets. On the other hand, when the hot air temperature was 120 ° C., the temperature was too low, so that the crosslinked PE foam sheet and the PP foam sheet were not sufficiently softened, and both foam sheets did not adhere at all. On the other hand, when the hot air temperature is 250 ° C., the temperature is too high. In particular, the crosslinked PE-based foamed sheet shrinks due to heat, and a good laminated sheet cannot be obtained. Could not.

[0020]

[Table 1]

The PE foam sheet 2 of the laminated sheet 1 of the present invention has a buffering function in a packaging container or the like formed from the laminated sheet by utilizing its flexibility. As the PE foam sheet 2, a crosslinked polyethylene foam sheet (hereinafter abbreviated as a crosslinked PE foam sheet) is particularly preferably used. The thickness of the PE foam sheet 2 is 0.5 to 5 m.
m, more preferably 1-3 mm, density 0.3-0.0
18 g / cm ³ , more preferably 0.045 to 0.02
It is preferably about g / cm ³ because it has a good balance of flexibility, buffering property, hot-air laminating property and the like.
The hot-air laminating property is the adhesiveness of the resin when the foamed sheets are laminated with each other by using the hot air as described above, and takes into consideration the releasability.

The crosslinked PE foam sheet is usually obtained by the following method. A method in which a mixture of a polyethylene resin and a foaming material is irradiated with ionizing radiation to cause a crosslinking reaction, and then heated under normal pressure to foam.
A mixture of an organic peroxide, a thermal decomposition foaming agent, and a polyethylene resin is heated to a temperature lower than the decomposition temperature of the foaming agent and higher than the decomposition temperature of the organic peroxide to cause a cross-linking reaction. A method of foaming by heating above the temperature. A method using an ethylene resin (crosslinkable polyethylene resin) having a hydrolyzable silyl side group introduced into the molecule. For example, a composition comprising a polyethylene resin containing a crosslinkable polyethylene resin, a pyrolytic foaming agent, and a crosslinking catalyst is kneaded to form a sheet, and the sheet is brought into contact with moisture to cause a crosslinking reaction. After that, foaming is carried out by heating to above the decomposition temperature of the foaming agent used under normal pressure, or a foaming agent and additives are mixed in polyethylene resin containing silylated ethylene resin and kneaded under pressure This is extruded into a low-pressure region to form a foam, and a known method such as a method of causing a cross-linking reaction by bringing the foam into contact with moisture in the presence of a silanol condensation catalyst is used.

As a preferred method for producing a crosslinked PE foamed sheet, for example, a crosslinkable polyethylene resin such as a silylated ethylene resin and a foaming agent are melt-kneaded by an extruder, and the kneaded product is attached to the tip of the extruder. Extrusion from a circular die having an annular lip into a low-pressure region to obtain a tubular foam, and then cutting the tube into a sheet and contacting it with moisture in the presence of a silanol condensation catalyst to obtain a foam. In the above case, the silanol condensation catalyst may be already blended at the time of extrusion foaming, or may be applied after extrusion.

Examples of the base resin for the crosslinked PE foam sheet include low-density polyethylene, high-density polyethylene, and linear low-density polyethylene. From the viewpoint of flexibility, low-density polyethylene and linear low-density polyethylene are preferred. In addition, these resins, styrene-butadiene copolymer, butadiene rubber, ethylene-propylene rubber,
By copolymerizing or mixing about 0.3 to 30% by weight of a rubber component such as isoprene rubber, the molding adhesiveness and flexibility are further improved.

The PP-based foam sheet 3 of the laminated sheet 1 of the present invention is used to give a shape maintaining function in a packaging container or the like formed from the laminated sheet by utilizing its rigidity. PP foam sheet 3 has a thickness of 0.5 to 5 m
m, more preferably 1-3 mm, density 0.3-0.0
2 g / cm ³ , more preferably 0.045 to 0.023
Those having about g / cm ³ are particularly preferable because of good shape retention, buffering properties and thermoformability.

The method for producing the PP-based foam sheet 3 is as follows: a propylene-based resin and a foaming agent are melt-kneaded by an extruder;
The kneaded product is extruded under a low pressure range from a circular die having an annular lip attached to the extruder tip to obtain a tubular foam, and then the tube is cut open to form a sheet.

The base resin of the PP foam sheet 3 is as follows.
Homopolypropylene, propylene and ethylene, carbon number 4
A block or random copolymer with the above-mentioned α-olefin, or a mixture of two or more of the above resins, or a high-density polyethylene, a low-density polyethylene, a linear low-density polyethylene, a polystyrene resin, etc. Mixtures of more than one species. In addition, mixing a plurality of resins as the base resin is not preferable in terms of recycling when recycling the resin. From the viewpoint of recycling, it is preferable to use only the same kind of resin as much as possible.

The proportion of the above mixed resin must be limited to 40% by weight so as not to impair the basic physical properties of the polypropylene resin. Further, a rubber component can be added to these resins similarly to the crosslinked polyethylene resin.

As the PP foamed sheet 3, for example, as disclosed in JP-A-4-363227,
It is particularly preferable to use a non-crosslinked polypropylene resin having a melt tension at 30 ° C. of 7 gf or more and a half-crystallization time of 800 seconds or more at a crystallization temperature of + 15 ° C. as the base resin. This non-crosslinked polypropylene-based resin is obtained by mixing a linear propylene-based resin having an overall isotactic structure containing low molecular weight polypropylene with a low-temperature decomposition type (decomposition temperature: about room temperature to about 120 ° C.) peroxide. C. or higher, and the linear polypropylene-based resin is formed by recombining the low-molecular-weight polypropylene as a branched chain into the linear polypropylene-based resin. The linear polypropylene-based resin may have a branched structure having a long-chain branch at an end mainly. . Examples of such a polypropylene resin include “PF-815” and “PF-81” manufactured by Highmont Corporation of the United States.
4 "," X10005 "," SD-632 ", and the like.

In the production of the crosslinked PE foam sheet and PP foam sheet, as the foaming agent, an inorganic foaming agent, a volatile foaming agent, a decomposition type foaming agent, or the like can be used. Examples of the above-mentioned inorganic foaming agent include carbon dioxide, air, and nitrogen. Examples of the volatile blowing agent include propane, n-butane, i-butane, a mixture of n-butane and i-butane, pentane, aliphatic hydrocarbons such as hexane, trichlorofluoromethane, dichlorodifluoromethane, and 1,1-dichloromethane.
-1,1,1,2-tetrafluoroethane, 1,1-difluoro-1-
Examples thereof include halogenated hydrocarbons such as chloroethane, 1,1,1,2-tetrafluoroethane, methyl chloride, ethyl chloride, and methylene chloride. Examples of the decomposable blowing agent include azodicarbonamide, dinitrosopentamethylenetetramine, azobisisobutyronitrile, sodium bicarbonate and the like. These foaming agents can be used alone or in a suitable mixture. The amount of foaming agent used is
The amount of the foaming agent used to obtain a foamed sheet having a density of 0.3 to 0.02 g / cm ³ depends on the type of the foaming agent, the desired expansion ratio (density), and the like. About 0.5 to 15 parts by weight (in terms of butane) of a volatile blowing agent, about 0.2 to 7.0 parts by weight (in terms of carbon dioxide) of an inorganic blowing agent, and 0.1 to 25 parts by weight of a decomposable blowing agent Parts.

If necessary, an air conditioner may be added to the melt-kneaded product of the resin and the foaming agent when producing the above-mentioned crosslinked PE foamed sheet or PP foamed sheet.
As a foam regulator, talc, inorganic powders such as silica,
Examples thereof include acid salts such as polycarboxylic acids, and reaction mixtures of polycarboxylic acids with sodium carbonate or sodium bicarbonate. It is preferable to add about 13 parts by weight or less of the cell adjuster per 100 parts by weight of the resin (however, this is not the case when a large amount of inorganic filler is contained in the resin). Further, if necessary, additives such as a heat stabilizer, an ultraviolet absorber, an antioxidant, and a coloring agent can be added to the melt-kneaded product. Further, an inorganic filler may be contained in the resin in advance up to about 40% by weight of the total weight. As the inorganic filler, for example, talc, silica, calcium carbonate, clay,
Examples thereof include zeolite, alumina, barium sulfate, and magnesium hydroxide. The average particle size is preferably from 1 to 70 μm. When a large amount of an inorganic filler is added, the obtained foamed sheet has improved heat resistance and incineration treatment. If you do, reduce the calories burned.

The laminated sheet 1 of the present invention can be used not only as a buffer sheet for packaging but also as a packaging container by thermoforming. FIG. 3 is a perspective view showing the appearance of an example of a packaging container for fruits and the like formed by molding the laminated sheet of the present invention. As shown in FIG. 3, the packaging container 10 for fruits and the like has a concave portion for holding the contents as a holding portion 14, the PE foam sheet 2 is located on the holding portion 14 side, and the PP foam sheet 3 is located on the opposite side. The packaging sheet 10 for fruits and the like is formed with a peripheral portion 12 at the same time as the holding portion 14 is formed. The packaging container obtained by molding such a laminated sheet of the present invention has excellent buffering properties and shape retention properties of the container itself, and includes peach, apple, strawberry,
It can be optimally used as a food packaging container for pears and the like or a packaging container for machine parts and the like.

As a molding means for producing the packaging container by molding the laminated sheet 1 of the present invention, various known molding methods such as vacuum molding, pressure molding, matched molding, plug assist molding and the like can be used. it can.

Although the laminated sheet of the present invention is formed so as to be peelable by hand, the molded article such as a packaging container after molding has an improved adhesive strength between the two sheets due to heat and pressure during molding. In particular, when a molding means using a plug or the like is used, the pressure is locally applied, so that the adhesion of the portion is improved, and the peel strength of the other portions where no pressure is applied does not change much. Further, when the sheet is pressed uniformly as in the case of vacuum forming, the change in the adhesive force between the two sheets is relatively small. Further, in the laminated sheet at the time of molding, for example, in the case of performing infrared heating, the adhesive force between the two sheets is also changed by a heating adjusting means such as adjusting the wavelength, and appropriate adjustment is required depending on the application.

Hereinafter, embodiments of the packaging container of the present invention will be described in detail with reference to the drawings. FIG. 4 shows one of the packaging containers of the present invention.
FIG. 5 is an external perspective view showing an example, and FIG. 5 is a vertical sectional view taken along line AA of FIG.

As shown in FIGS. 4 and 5, the packaging container 11 of the present invention is made of, for example, a crosslinked polyethylene resin foam sheet 1.
2, a polypropylene resin foam sheet 13 is laminated on one side, and a concave portion corresponding to the shape of the packaged object is provided as a holding section 14 by molding to hold the packaged article such as fruit, and the holding section 14 side. Each of the resin foam sheets 12 and 13 is positioned so that the crosslinked polyethylene resin foam sheet 12 is located.
They are stacked. The above-mentioned crosslinked polyethylene resin foam sheet 12 and polypropylene resin foam sheet 1
For example, 3 is not laminated and integrated with an adhesive or the like before molding, but is integrated at the time of molding, and the crosslinked polyethylene resin foam sheet 12 and the polypropylene resin foam sheet 13 are formed so as to be peelable. Have been.

The shape of the packaging container 11 of the present invention may be at least provided with the holding portion 14 by molding.
The shape and the number of the holding portions 14 and the like are not particularly limited to the embodiment of FIG. The holding portion 14 may have any shape as long as it can hold an object to be packaged such as fruit, and is provided as a recess having a size approximately half that of the fruit to be packed.
The number of the holding portions 14 may be appropriately provided according to the use of the packaging container.

In the packaging container of the present invention, the adhesive force between the cross-linked polyethylene resin foam sheet 12 and the polypropylene resin foam sheet 13 does not peel off when used as a packaging container, and when it becomes unnecessary, it becomes a hand. It is sufficient that both sheets (particularly, a highly flexible crosslinked polyethylene resin foam sheet) are adhered to such an extent that they can be peeled cleanly without tearing.

FIG. 6 is a sectional view showing another embodiment of the packaging container of the present invention. As shown in FIG. 6, the packaging container of the present invention can be provided with a gap 16 by laminating and integrating the resin foam sheets of the holding portion 14 so as not to contact each other. When formed in this manner, the cushioning effect of the void portion 16 is obtained, so that a packaging container having more excellent buffering properties can be obtained. Further, the packaging container of the present invention can have a plurality of holding portions 14 and an edge portion 12 at an upper portion of the periphery as shown in FIG.

In the present invention, the crosslinked polyethylene resin foam sheet 12 and the polypropylene resin foam sheet 13
Is adhered to the extent that it can be peeled off, which means that when using a packaging container, it does not peel off during normal use such as storage or distribution process of the packaged object, but it tried to treat the container that became unnecessary In this case, when two resin foam sheets laminated and integrated are separated by hand, the two sheets are adhered to the extent that they can be easily separated without tearing. Such an adhesive state differs depending on the strength and the adhesive area of the resin foam sheet, the shape of the molded concave portion, and the like. In the part, the peel strength between the crosslinked polyethylene resin foam sheet 12 and the polypropylene resin foam sheet 13 is (JIS K
(A 180 ° peel test according to 6854, according to the test method described above)) If the amount is from 3 to 350 g, the object of the present invention is sufficiently achieved, more preferably from 4 to 300 g, and still more preferably from 5 to 200 g.

The reason for the above-mentioned releasable integration is not so clear, but is considered to be due to the following reasons. Generally, the thermal adhesiveness when a polypropylene resin and a polyethylene resin are simply heated and pressed is not very good. However, compared to the case where a styrene resin and an olefin resin are bonded, they are the same olefin resin, and are not resin sheets but resin foam sheets having fine irregularities on the surface. -It is thought that the point of pressure and the point of strong pressing locally at the step formed by the processing for forming work act synergistically to obtain an appropriate physical adhesive force. Can be

In the present invention, the crosslinked polyethylene resin foam sheet 12 and the polypropylene resin foam sheet 13
In order to integrate the two, the resin foam sheets 12 and 13 that are not laminated and integrated are preferably overlapped and formed into a desired shape when performing the molding process. According to this method, the holding portion and the entire shape are molded, and the two resin foam sheets are weakly adhered to each other by heat and pressure during molding without being completely adhered to each other so as to be peelable. Be transformed into In addition, the laminated sheet which has been peelably weakly adhered,
The packaging container of the present invention can be obtained by molding under heat molding conditions of a low temperature and a short time as possible.

In the packaging container of the present invention, the crosslinked polyethylene resin foam sheet 12 is used so as to be positioned on the holding portion 4 side in order to protect the packaged object by utilizing its flexibility. The crosslinked polyethylene resin foam sheet 12 has a thickness of 0.5 to 5 mm, more preferably 1 to 3 mm, and a density of 0.3 to 0.018 g / cm ³ , more preferably 0.0
45 to 0.02 g / cm ³ is desirable, and within the above range, the foam sheet has a good balance of flexibility, cushioning property, adhesiveness, and the like. On the other hand, the polypropylene resin foam sheet 1
3 has a thickness of 0.5 to 5 mm, more preferably 1 to 3 m
m, the density is preferably from 0.3 to 0.02 g / cm ³ , more preferably from 0.045 to 0.023 g / cm ³ , and within the above range, shape retention, buffering properties, thermoformability and adhesiveness Etc. are good.

The adhesiveness refers to the adhesiveness relating to the integration of the resin foamed sheets when the resin foamed sheets are bonded to each other using heat, and also takes into account the peelability and the laminating integration. And a degree of adhesion that can be easily peeled off.

The crosslinked polyethylene resin foam sheet 1
2 and the base resin, additives and manufacturing method of the polypropylene-based resin foam sheet 13 are the cross-linked PE, particularly cross-linked, of the PE-based resin foam sheet 2 of the aforementioned laminated sheet.
The same resin foam sheet 2 and PP resin foam sheet 3 are used. The heating conditions when forming the foamed sheet into a packaging container may be appropriately selected from the conditions for the peelable integration according to the density, thickness, type of the base resin, and the like of the foamed sheet. When the two resin foam sheets having the preferable thickness and density are integrated, the heating time is 170
It is 6 to 20 seconds at ~ 240 ° C, and the molding time is usually about 7 to 15 seconds.

The method of forming the foamed sheet for obtaining the packaging container 11 of the present invention includes plug and ridge molding, ridge molding, matched mold molding, plug assist molding and the like by clamping around the molded portion. Used.
In the present invention, a method having a pressing means such as a plug is particularly preferable.

When forming the void 16 in the packaging container as shown in FIG. 6, the polypropylene resin foam sheet 13 side is evacuated, and the crosslinked polyethylene resin foam sheet 12 side is placed in the mold recess 2. It can be obtained by pushing with a plug to about / 3. In this case, the crosslinked polyethylene resin foam sheet 12 and the polypropylene resin foam sheet 1
3 is secured by the flat portion 15. The flat portion 15 for securing the adhesion may be partially present, for example, scattered on the packaging container lamination surface, but it is preferable to secure the adhesion portion on the entire lamination surface. The adhesive stability at the time is excellent.

The packaging container of the present invention can be optimally used as a packaging container for foods such as peaches, apples, strawberries, and pears, or a packaging container for machine parts and the like.

[0049]

As described above, the laminated sheet of the present invention is formed by laminating and unifying a polypropylene resin foam sheet on one side of a polyethylene resin foam sheet with a peel strength of 3 to 350 g. Since the foamed sheets can be separated by hand by separating the foamed sheets from each other, it is possible to easily separate and collect a lossy material such as a slit portion generated at the time of manufacturing the laminated sheet.

Furthermore, by forming the laminated sheet of the present invention such that the polyethylene resin foam sheet is on the inner side (the side in contact with the contents), a packaging container excellent in cushioning and shape retention can be obtained. Recycling of defective molded products and ears after molding that occur during the production of containers can be easily performed by separating and collecting two laminated sheets of the laminated sheet by hand. Thus, the laminated sheet of the present invention greatly contributes to the effective use of resources in terms of environmental problems.

On the other hand, in the packaging container of the present invention, by adopting the above-described configuration, two resin foam sheets are integrated, and the package is securely held with good buffering property and the overall shape is reduced. Despite being able to be maintained well, compared to conventional packaging containers of this type, there is no need to previously bond each sheet with a hot melt adhesive or the like to laminate and integrate, making the manufacturing process streamlined and easy. It can be manufactured.

Further, in the packaging container of the present invention, when processing a packaging container that is no longer needed, the two laminated resin foam sheets can be easily peeled off by hand and easily separated from each other. The sheets can be separated and collected for easy recycling, greatly contributing to the effective use of resources in terms of environmental issues.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an example of a laminated sheet of the present invention.

FIG. 2 is an explanatory diagram of a case where a laminated sheet is manufactured by hot-air lamination.

FIG. 3 is a perspective view showing the appearance of an example of a packaging container for fruits or the like formed by molding the laminated sheet of the present invention or a packaging container of the present invention.

FIG. 4 is an external perspective view showing an example of the packaging container of the present invention.

FIG. 5 is a vertical sectional view taken along line AA of FIG. 1;

FIG. 6 is a vertical sectional view of a main part showing another example of the packaging container of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Laminated sheet 2 Polyethylene resin foam sheet (PE foam sheet) 3 Polypropylene resin foam sheet (PP foam sheet) 11 Packaging container 12 Crosslinked polyethylene resin foam sheet 13 Polypropylene resin foam sheet 14 Holding part

Continuation of the front page (72) Inventor Akinori Taira 1078-4 Komaocho, Utsunomiya City, Tochigi Prefecture Casa Eye 202 (58) Field surveyed (Int. Cl. ⁶ , DB name) B32B 1/00-35/00 B65D 65/40 B65D 85/30-85/48

Claims (2)

(57) [Scope of request for utility model registration] 1. A laminated sheet in which a polypropylene resin foam sheet is releasably laminated on one side of a polyethylene resin foam sheet, and a peel strength between the foam sheets (by a 180 ° peel test according to JIS K 6854). ) Is 3 to 350 g. 2. A packaging container in which a polypropylene-based resin foam sheet is laminated on one side of a cross-linked polyethylene-based resin foam sheet, and a holding portion for holding an article to be packaged is provided by molding. A packaging container, wherein a polyethylene-based resin foam sheet is located on a holding portion side, and a cross-linked polyethylene-based resin foam sheet and a polypropylene-based resin foam sheet are integrated so as to be peelable.