JP4820140B2 - Buffer material for fruits and method for producing the same - Google Patents

Description

  The present invention relates to a cushioning material useful for protecting fruits, particularly fruits whose skin is soft and easily damaged, and a method for producing the same.

  In order to prevent the fruit from being damaged during the transportation process, storage process, exhibition work, etc., various cushioning materials made of foam are used. For example, fruits with soft epidermis (such as 20th century pears) are stored in a polystyrene foam tray, and a laminate of foam and substrate (olefin resin foam net and polyethylene bonded together) Laminates, laminates of polyethylene resin foam sheets and corrugated cardboard) are placed with the foam facing the fruit side, and the fruit and foam are brought into contact with each other for packing or wrapping and shipping. . However, it is necessary to prepare a laminate by laminating the foam and the base material, and the laminating operation is complicated. In the separation process, it is difficult to separate the foam and the base material.

  In the utility model registration No. 3067233 (Patent Document 1), when fruits are stacked, the fruit made of a synthetic resin foam is interposed between each stage so that the lower surface is in contact with the upper surface of the lower fruit. A packaging partition material for fruit packaging in which an indentation viewing recess recessed upward is formed at a location corresponding to the substantially central region of the fruit of the flower bed on the mask is disclosed. . This document also describes a partition material in which the deciduous dent recess is formed in a groove shape extending linearly along the lower surface, and a partition material in which the lower surface is formed in a corrugated cross section. This document also describes forming a foam with polyethylene.

In Japanese Utility Model Publication No. 7-25343 (Patent Document 2), a foamed plastic sheet mainly composed of low-density polyethylene has low rigidity against bending, so that it is difficult to handle in a packaging operation, and the surface is too smooth, so that an article tends to slip laterally. It is described. Therefore, in Patent Document 2, a sheet-like cushioning material having a density of 0.01 to 0.05 g / cm ^{2 made} of a mixed resin foam of high-density polyethylene, low-density polyethylene, and polystyrene-based resin, The upper or lower side of the cross section is corrugated, the apparent maximum compressive elastic modulus is 10 to 200 kgf / cm ² and the apparent bending elastic modulus is 1 to 300 kgf / cm ² when the full thickness is compressed 25% in the vertical direction. A sheet-like cushioning material showing cm ² is disclosed. This document also describes a sheet-like cushioning material having a total thickness of 5 to 20 mm and a wave height of 2 to 20% of the total thickness.

However, if fruits or fruits (especially fruits with soft epidermis) are wrapped using cushioning materials composed of such foams, the fruits or fruits are easily damaged, and the commercial value of the fruits or fruits is greatly increased. Reduce.
Utility Model Registration No. 3067233 (Scope of Claim for Utility Model Registration, Paragraph Number [0013]) Japanese Utility Model Publication No. 7-25343 (Scope of request for registration of utility model, [Prior art and its problems] column)

  Accordingly, an object of the present invention is to provide a cushioning material that can smoothly wrap or pack fruits without damaging the fruits and a method for producing the same.

  Another object of the present invention is to provide a cushioning material that is easy to handle, packs or packs, and does not damage even if the skin is soft, and a method for producing the same.

  Still another object of the present invention is to provide a cushioning material that can effectively protect fruits during transportation or storage, and a method for producing the same, which do not require a bonding operation and a separation process.

  As a result of intensive studies to achieve the above-mentioned problems, the present inventors have found that (1) a polyethylene resin, (2) a polystyrene resin, and (3) a copolymer of ethylene and a non-olefin copolymerizable monomer. By foaming a resin composition composed of a polymer and forming convex portions that can come into contact with fruits, it is possible to effectively prevent the fruits from being damaged even when stacked or packed with fruits that are soft and easily damaged. And the present invention was completed.

  That is, it is comprised with the sheet-like resin foam which has the convex part which can contact the buffer material for fruits of this invention (or buffer material for fruit packaging) fruit. In this cushioning material, the resin foam is selected from (1) polyethylene resin, (2) polystyrene resin, (3) ethylene, aliphatic organic acid vinyl ester, and (meth) acrylic monomer. And a copolymer with at least one monomer (for example, ethylene-vinyl acetate copolymer, etc .; hereinafter, it may be simply referred to as a soft ethylene copolymer). The foam is, for example, 30 to 80 parts by weight (for example, 40 to 75 parts by weight) of polystyrene resin and 10 to 50 parts by weight of a copolymer (soft ethylene copolymer) with respect to 100 parts by weight of polyethylene resin. You may comprise by the resin composition containing a part (for example, 15-45 weight part). Further, the expansion ratio of the foam may be, for example, about 30 to 85 times (for example, 40 to 80 times). Further, the structure of the sheet-like resin foam is not particularly limited. For example, the foam is formed of a sheet main body and a convex portion that is formed on the surface of the sheet main body at a predetermined interval and can come into contact with the fruit. You may comprise. Further, the foam may be composed of a sheet main body and a rib portion (for example, a protruding rib portion) that is formed in parallel to each other at a predetermined interval on the surface of the sheet main body and can come into contact with the fruit. Good. The rib portions may protrude from the surface of the sheet main body, and may be scattered or continuously extended along directions parallel to each other. Further, the foam may be formed in a corrugated plate shape. The thickness A of the sheet main body, the height B of the rib part from the surface of the sheet main body, the pitch C of the rib part, and the width D of the rib part can be designed according to the kind of fruit, for example, B / A = 0 0.1 to 1.3 (for example, 0.1 to 0.5), C / (A + B) = 0.6 to 3 (for example, 1.1 to 3), D / A = about 0.8 to 3 There may be. Further, the cushioning material composed of the sheet-like resin foam can be used for stacking fruits in a form that can contact the upper surface of the fruits.

  The present invention provides a copolymer of (1) a polyethylene resin, (2) a polystyrene resin, (3) a monomer selected from ethylene, an aliphatic organic acid vinyl ester, and a (meth) acrylic monomer. Also included is a method for producing a fruit cushioning material by foaming a resin composition containing a polymer to form a sheet-like resin foam having convex portions that can come into contact with fruits. Further, the present invention includes a method of wrapping or packing fruits by disposing a sheet-like resin foam with the convex portion of the cushioning material facing the upper surface of the fruits.

  In the present invention, a sheet-shaped resin foam having convex portions that can come into contact with fruits is formed with a predetermined resin composition. Therefore, even if vibrations act on the transportation process, the fruits can be smoothly removed without damaging the fruits. Can be packaged or packed. In particular, even fruits with soft epidermis (such as pears such as 20th century pears) are not damaged, and the fruits can be effectively protected during transportation or storage. Moreover, since it has moderate rigidity, handling property, packaging, or packing workability | operativity can be improved. Furthermore, since it is not necessary to form a laminated structure of the foam and other members, a bonding operation and a separation process are unnecessary, which is advantageous in terms of cost and economy.

  Hereinafter, the present invention will be described in detail with reference to the accompanying drawings as necessary.

  FIG. 1 is a schematic perspective view showing an example of the cushioning material (or sheet-like resin foam) of the present invention, and FIG. 2 is a sectional view taken along the line II-II of the cushioning material of FIG.

  In the above example, a cushioning material for packaging pears (such as 20th century pears) whose skin is soft and easily damaged is shown. The sheet-like resin foam 1 constituting the cushioning material includes a foam sheet main body 2 and projecting rib portions (foam rib portions or bowl-shaped ribs) formed to extend in parallel to each other on the surface of the sheet main body at a predetermined interval. Part) 3. That is, one surface of the sheet-like resin foam 1 is formed in a corrugated plate shape. Moreover, the said protruding rib part 3 is formed in the cross-sectional trapezoid shape which has a gentle both-sides part, and can contact a pear in a packing or a packaging state. The sheet-like resin foam 1 is composed of a resin composition of about 60 to 70 parts by weight of polystyrene and 25 to 35 parts by weight of an ethylene-vinyl acetate copolymer with respect to 100 parts by weight of linear low density polyethylene. The expansion ratio is about 55 to 65 times.

  Further, when the thickness of the sheet body 2 is A, the height of the rib part 3 from the surface of the sheet body 2 is B, the pitch of the rib part 3 is C, and the width of the rib part 3 is D, B / A = 0. .22 to 0.28, C / (A + B) = 1.5 to 1.9, and D / A = 1.3 to 1.7.

  Such a sheet-like resin foam 1 can be used as a cushioning material for transporting and storing pears. For example, in a predetermined container (such as corrugated cardboard), as shown in FIG. 2, the pear is accommodated in an accommodating recess formed in a foamed resin tray (such as a polystyrene foam tray) 4 and the accommodated pear is Thus, the first-stage packing or packaging can be performed by arranging the sheet-like resin foam 1 so as to face the rib portion 3. In this example, a second-stage foamed resin tray 4 is disposed on the first-stage sheet-shaped resin foam 1 and pears are accommodated in the accommodation recesses, and the second-stage sheet-shaped resin foam 1 is It arrange | positions and forms the package or package of a two-step pile. That is, the sheet-like resin foam 1 is used as an intermediate member or a partition member that partitions each step in a stacked package or package.

  Since such a sheet-like resin foam is composed of the resin composition, it has high rigidity and is easy to handle. In particular, since the reinforcing rib portion 3 is provided, it is possible to improve rigidity, handleability, packaging or packing workability. Moreover, since the specific rib part 3 which can contact with a pear is provided, it can protect effectively, without injuring a pear. In particular, since the rib portion 3 is formed at a predetermined height and interval with respect to the sheet main body 2, even if the load of the upper pear acts on the lower pear in the stacked package, the rib portion for the pear 3 can be prevented from being damaged, and the pear and the rib portion 3 are in contact with each other. Therefore, even if vibration during transportation acts, the rib portion 3 can absorb the vibration, and the foam 3 and the pear are rubbed. It is possible to prevent scratches caused by Therefore, it can prevent effectively that a pear is damaged and a wound part turns black. In particular, the sheet-like resin foam requires fruits to be exported overseas (for example, the pear having a thin epidermis), for example, long-term refrigerated storage and long-term transportation period (for example, about 2 months at the longest) after harvesting. Useful for transport and storage of exported fruits.

  The resin foam is not limited to the protruding rib portion, and may have various convex portions or rib portions that can come into contact with the fruit. The convex portions or the rib portions may be regularly or irregularly scattered, may extend continuously (or extend) in a predetermined direction, and may extend in a lattice shape or a cross shape. In many cases, the convex portions or rib portions are formed in parallel to each other at a predetermined interval on the surface of the sheet main body. The convex part (or rib part) may be formed on at least one surface of the sheet-like resin foam, and the position and / or shape (pattern) may be the same or different on both surfaces. Good. The shape of the convex part (or rib part) is not particularly limited, and may be the above-mentioned trapezoidal cross-sectional shape, cross-sectional square shape (square shape, rectangular shape, etc.), cross-sectionally curved trapezoidal shape, and the like. FIG. 3 is a schematic perspective view showing another example of the cushioning material (or sheet-like resin foam) of the present invention.

  In this example, the sheet-like resin foam 11 includes a foam sheet main body 12 and projecting rib portions (foam rib portions or bowl-shaped rib portions) formed on the surface of the sheet main body so as to extend in parallel with each other at a predetermined interval. ) 13 and the cross section of the protruding rib portion 13 is formed in a semicircular arc shape or semicircular cross section. The sheet-like resin foam 11 is produced by foaming a resin composition similar to the above to an expansion ratio of about 60 to 65 times.

  Similarly to the above, when the thickness of the sheet body is A, the height of the rib part from the surface of the sheet body is B, the pitch of the rib part is C, and the width of the rib part is D, B / A = 0. .25 to 0.30, C / (A + B) = 1.6 to 2, and D / A = 1.2 to 1.6. Even if the cushioning material is formed of such a sheet-like resin foam, it is possible to effectively prevent damage to fruits such as pears.

The resin foam is at least one selected from (1) polyethylene resin, (2) polystyrene resin, (3) ethylene, aliphatic organic acid vinyl ester, and (meth) acrylic monomer. And a copolymer (soft ethylene copolymer) with the above monomer. (1) As a polyethylene-type resin, the copolymer (ethylene-type copolymer) of ethylene and another copolymerizable olefin monomer other than an ethylene homopolymer can be used. Examples of the ethylene homopolymer include low density polyethylene resin, medium density polyethylene resin or high density polyethylene resin, and linear low density polyethylene resin. Examples of the copolymerizable olefin monomer include propylene, 1-butylene, isobutylene, 1-pentene, 3-methyl-1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1 Α-C _3-20 olefins (preferably α-C _3-10 olefins, more preferably α-C _3-4 olefins, especially propylene) such as -decene, 1-undecene and 1-dodecene, cyclic olefins (norbornene) , Ethylidene norbornene, cyclopentene, cyclopentadiene, cyclohexene, etc.) and dienes (butadiene, isoprene, 1,4-pentadiene, etc.). These olefinic monomers may be used alone or in combination of two or more. Examples of the polyethylene copolymer include an ethylene-propylene copolymer, an ethylene-butene-1 copolymer, an ethylene-propylene-butene-1 copolymer, and an ethylene- (4-methylpentene-1) copolymer. Etc. can be exemplified.

  The ratio (weight ratio) between ethylene and the copolymerizable olefin monomer can be selected in the range of the former / the latter = 100/0 to 50/50, for example, about 95/5 to 60/40, preferably It may be about 90/10 to 65/35, more preferably about 85/15 to 70/30. The polyethylene copolymer (resin) may be a random copolymer or a block copolymer.

  These polyethylene resins can be used alone or in combination of two or more. A preferred polyethylene resin is polyethylene (particularly linear low density polyethylene). Further, a preferred polyethylene resin is a resin polymerized with a metallocene catalyst. Polyethylene resins using metallocene catalysts have a sharp molecular weight distribution and high crystallinity. Therefore, the foaming efficiency can be improved and the mechanical properties (rigidity and strength) can be improved.

  Polyethylene resins include crosslinkable groups [thermally crosslinkable groups (polymerizable unsaturated groups such as vinyl groups, (meth) acryloyl groups), photocrosslinkable groups, hydrolytic condensable groups [for example, hydrolyzable to silicon atoms. A crosslinkable polyethylene having a group (for example, an alkoxysilyl group, a halosilyl group, or the like) directly bonded to a group (for example, an alkoxy group such as a methoxy group or an ethoxy group) or a halogen atom (such as a chlorine atom)] Although it may be a resin, it is usually a non-crosslinkable resin having no crosslinkable group.

Under the conditions of a temperature of 190 ° C. and a load of 21.6 N (2.16 kgf), the melt flow rate of the polyethylene resin can be selected, for example, from a range of about 0.1 to 100 g / 10 minutes. 20 g / 10 min (for example, 0.15 to 15 g / 10 min), preferably 0.2 to 12 g / 10 min (for example, 0.2 to 10 g / 10 min), more preferably 0.25 to 8 g / 10 Minutes (for example, 0.3-7 g / 10 minutes) may be sufficient. The density of the polyethylene resin, for example, 0.90~0.970g / cm ^3, preferably 0.91~0.96g / cm ^3, more preferably be about 0.915~0.95g / cm ³ Also good.

  The melting point of the polyethylene resin can be selected, for example, from a range of 150 ° C. or lower (for example, about 80 to 140 ° C.), 130 ° C. or lower (for example, about 90 to 125 ° C.), preferably 125 ° C. or lower (for example, 95 ˜120 ° C.), more preferably 120 ° C. or less (eg, about 100-115 ° C.).

  Further, the molecular weight distribution of the polyethylene resin using the metallocene catalyst is, for example, 1.01 to 3.0, preferably 1.02 to 2.0 (for example, 1.05 to 1.8), and more preferably 1. It may be about 1 to 1.5 (for example, 1.15 to 1.4).

(2) Polystyrene resins include, for example, styrene monomers such as styrene, vinyl toluene, α-methyl styrene, or copolymers (polystyrene GPPS, styrene-vinyl toluene copolymer, etc.), styrene monomers. Styrene copolymer of monomer and copolymerizable monomer, rubber reinforced styrene resin (medium impact polystyrene MIPS, high impact polystyrene HIPS), acrylonitrile-styrene resin AS, acrylonitrile-butadiene-styrene resin ABS, etc. ) Etc. are included. Examples of copolymerizable monomers include (meth) acrylic acid, (meth) acrylic acid alkyl esters (methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate) and the like. a C _1-6 alkyl ester), (meth) acrylic acid glycidyl ester, etc. can be exemplified (meth) acrylic acid hydroxyalkyl ester, (meth) acrylonitrile, maleic anhydride. These copolymerizable monomers can be used alone or in combination of two or more. Examples of styrene copolymers include copolymers of styrene and (meth) acrylic monomers (such as styrene-methyl methacrylate copolymer (MS resin)), styrene- (meth) acrylonitrile copolymers, and styrene. -Maleic anhydride copolymer etc. can be illustrated. These polystyrene resins can be used alone or in combination of two or more. The polystyrene resin is preferably polystyrene or MS resin.

(3) Examples of the soft ethylene copolymer include a copolymer of ethylene and a non-olefin copolymerizable monomer, and examples of the non-olefin copolymerizable monomer include aliphatic organic acid vinyl. Esters (for example, vinyl esters such as vinyl acetate and vinyl propionate), (meth) acrylic monomers [(meth) acrylic acid or salts thereof, (meth) acrylic acid esters (for example, ethyl acrylate, acrylic acid (Meth) acrylic acid C _1-4 alkyl ester such as butyl)]. These copolymerizable monomers can be used alone or in combination of two or more. The weight ratio of ethylene and copolymerizable monomer can be selected, for example, within the range of the former / the latter = 99/1 to 60/40, for example, about 98/2 to 70/30, preferably 97/3. It may be about ˜80 / 20 (for example, 96/4 to 85/15), more preferably about 95/5 to 90/10.

Examples of the soft ethylene copolymer include ethylene-vinyl acetate copolymer, ethylene- (meth) acrylic acid copolymer or metal salt thereof, ethylene- (meth) acrylic acid C _1-4 alkyl ester copolymer (ethylene -Ethyl acrylate copolymer, ethylene-butyl acrylate copolymer, ethylene-methyl methacrylate copolymer, etc.). As the soft ethylene copolymer, an ethylene-vinyl acetate copolymer, an ethylene-ethyl acrylate copolymer, an ethylene-butyl acrylate copolymer, etc. are preferable, and an ethylene-vinyl acetate copolymer is often used. .

  The ratio of these resin components can be appropriately selected according to the type of fruit, for example, 30 to 80 parts by weight of polystyrene resin (preferably 40 to 75 parts by weight, more preferably 100 parts by weight of polyethylene resin) Preferably, it is about 50 to 70 parts by weight), and 5 to 50 parts by weight (preferably 10 to 40 parts by weight, more preferably 13 to 35 parts by weight, particularly 15 to 30 parts by weight) of a soft ethylene copolymer.

  The resin composition may contain other thermoplastic resin as necessary. Examples of the thermoplastic resin include polypropylene-based resins (eg, polypropylene; propylene-containing 80 mol% or more such as propylene-ethylene copolymer, propylene-butene-1 copolymer, propylene-ethylene-butene-1 copolymer). Propylene-α-olefin copolymers, etc.), polyamide resins (polyamides 6, 11, 12, etc.), aromatic polyester resins (polyalkylene arylate resins such as polyethylene terephthalate resins, polybutylene terephthalate resins, poly Examples thereof include aromatic polyester resins such as arylate resins, aliphatic polyester resins, etc., acrylic resins (polymethyl methacrylate PMMA, etc.), polyvinyl alcohol resins (ethylene-vinyl alcohol copolymer, etc.), and the like. These thermoplastic resins can be used alone or in combination of two or more. Of these thermoplastic resins, polypropylene resins are preferred. The polypropylene resin may be a resin polymerized using a metallocene catalyst.

  The ratio (weight ratio) between the polyethylene resin and the other thermoplastic resin is the former / the latter = 100/0 to 75/25, preferably 99/1 to 80/20, more preferably 95/5 to 85/15. It may be a degree.

  The resin composition only needs to be foamable by a foaming agent, and the foaming agent may be a volatile foaming agent or a decomposable foaming agent. Among the foaming agents, volatile foaming agents include volatile gas and / or foaming agents that generate volatile gas (for example, hydrocarbons such as propane, butane, pentane, hexane, HCFC22, HFC-142b, HFC-134a). Examples thereof include halogenated hydrocarbons such as, organic gases such as chlorinated hydrocarbons such as methylene chloride and methyl chloride, inorganic gases such as air, carbon dioxide gas, and nitrogen gas), water, and the like. Examples of the decomposable foaming agent include citric acid, azo compounds (such as azodicarboxylic amide), hydrazide compounds (such as p-toluenesulfonyl hydrazide), azide compounds, carbonates (such as sodium bicarbonate), and the like. These foaming agents can be used alone or in combination of two or more. The usage-amount of these foaming agents is not specifically limited, According to the kind of foaming agent and desired expansion ratio, it can select suitably. For example, the amount of the volatile foaming agent used (the amount of press-in of the foaming agent) can be appropriately selected according to the expansion ratio. The amount of the foaming agent used is, for example, 0.1 to 40 parts by weight (for example, 1 to 30 parts by weight), preferably about 5 to 25 parts by weight with respect to 100 parts by weight of the resin composition, depending on the expansion ratio. It is. The foaming agent may be used by mixing with the resin composition, or may be used by impregnating the resin or the resin composition. Moreover, you may use a foaming agent as a masterbatch melt-kneaded with resin or a resin composition. Further, a foaming agent (such as a volatile foaming agent) may be added or pressed into the melt-kneaded resin. Further, water can be used as the foaming agent, and water may be given directly to the extruder using a pump or the like.

  The foamable resin composition of the present invention may contain an anti-shrinkage agent or a bubble regulator as necessary in addition to the above components. These components can be used alone or in combination of two or more.

  Examples of the shrinkage inhibitor include surfactants such as nonionic surfactants (polyoxyethylene alkylphenyl ether, polyoxyethylene glycerin fatty acid ester, polyoxyethylene sucrose fatty acid ester, glycerin fatty acid ester, etc.). The proportion of the shrinkage inhibitor may be, for example, about 0 to 10 parts by weight, preferably about 0.1 to 10 parts by weight (for example, 1 to 5 parts by weight) with respect to 100 parts by weight of the resin composition.

  Examples of the air conditioner include non-foaming components such as silicates such as talc, silica and kaolin, metal carbonates such as calcium carbonate, metal oxides such as zinc oxide and aluminum oxide, calcium stearate, magnesium stearate, stearin. Examples thereof include higher fatty acid salts such as aluminum oxide and calcium montanate. Even if the ratio of a bubble regulator is 0.1-5 weight part (for example, 0.5-4 weight part) with respect to 100 weight part of resin compositions, Preferably it is about 1-3 weight part. Good. The decomposable foaming agent can also be used as a bubble regulator. More specifically, with respect to 100 parts by weight of the resin composition, 0 to 5 parts by weight, preferably 0.1 to 1 part, of a foaming agent such as citric acid and / or baking soda as a foam regulator (foaming aid). A part by weight may be added.

  Furthermore, the resin composition may contain an antistatic agent. Antistatic agents include nonionic surfactants (esters of polyhydric alcohols such as glycerin, sorbitan, and sucrose and higher fatty acids, for example, polyhydric alcohol higher fatty acid esters such as glycerin monostearate; polyoxyethylene Polyhydric alcohol higher fatty acid ester, polyoxyethylene higher alkyl ether, polyoxyethylene alkylphenyl ether, polyoxyethylene alkylamine, ethylene oxide-propylene oxide block copolymer, etc.), anionic antistatic agent (carboxylate, sulfone) Acid salts, phosphates, etc.), cationic antistatic agents (quaternary ammonium salts, etc.), amphoteric antistatic agents (betaine type antistatic agents, etc.), and low molecular weight antistatic agents. It can be a polymer antistatic agent. . The proportion of the antistatic agent may be, for example, about 0 to 10 parts by weight, preferably about 0.1 to 10 parts by weight (for example, 1 to 5 parts by weight) with respect to 100 parts by weight of the resin composition. For example, 0 to 2 parts by weight, preferably about 0.1 to 1.6 parts by weight of glycerin monostearate may be added as an antistatic agent.

  In order to increase the frictional resistance, the resin composition has a thermoplastic elastomer, for example, a polystyrene-based elastomer (an elastomer containing a block unit of a polydiene such as polybutadiene or polyisobrene or a hydrogenated product thereof as a component other than a soft ethylene copolymer. Etc.), polyolefin elastomers (EPDM, elastomers containing block units such as butyl rubber, etc.), polyurethane elastomers, polyester elastomers, polyamide elastomers and the like.

  The resin composition includes various additives such as stabilizers [antioxidants (hindered phenol-based antioxidants, etc.), ultraviolet absorbers, heat stabilizers, weathering stabilizers, etc.], organic or inorganic fillers ( (Including powdered or fibrous reinforcing agents), lubricants, mold release agents, lubricants, impact modifiers, colorants (dyes and pigments, etc.), plasticizers, crystallization accelerators, crystal nucleating agents, flame retardants, antibacterial agents And may contain preservatives and the like. The additives may be used alone or in combination of two or more.

  The foamable resin composition of the present invention may be a mixture of components or may be in the form of pellets.

  In the foam of the present invention composed of the resin composition, the cell structure is not particularly limited, and may be a closed cell structure or an open cell structure, or both cell structures may be mixed. . A preferred cell structure has at least a closed cell structure.

  The expansion ratio of the foam (sheet-like resin foam) can be selected within a range not damaging the fruit, and is, for example, 30 to 85 times, preferably 40 to 80 times, more preferably 50 to 75 times (for example, 55 to 70). Times).

  The average cell diameter of the foam is, for example, about 0.3 to 1.5 mm, preferably about 0.4 to 1.5 mm, and more preferably about 0.5 to 1.3 mm (for example, 0.6 to 1.2 mm). It may be about 0.7 to 1.1 mm. The cross-sectional shape of the bubbles is not limited to a circular shape, and may be an elliptical shape or an indefinite shape. Note that the foam of the present invention has a large average cell diameter, unlike a general foam. The cell diameter of such a foam can be adjusted by the amount of the cell regulator used.

  In the foam having a closed cell structure, the closed cell ratio can be selected from the range of, for example, about 50 to 100%, and is usually 70 to 100% (for example, 75 to 98%), preferably 80 to 100%, Preferably, it may be about 90 to 100%.

  In addition, the shape of the resin foam may be a sheet shape (two-dimensional shape) as a whole, and may be a board shape, a plate shape, a sheet shape, a film shape, or the like. The thickness of the sheet-like resin foam is not particularly limited. For example, the thickness D of the foam sheet main body is 1 to 10 mm, preferably 2 to 8 mm (for example, 2.5 to 7.5 mm), and more preferably 3 to 7 mm. It may be a degree.

  As described above, when the thickness of the sheet body is A, the height of the rib part from the surface of the sheet body is B, the pitch of the rib part is C, and the width of the rib part is D, the rib with respect to the thickness A of the sheet body The ratio B / A of the height B of the part can be selected from a range of about 0.1 to 1.3 (for example, 0.15 to 1.0), and is usually 0.1 to 0.7 (for example, 0 0.2 to 0.6), preferably 0.1 to 0.6 (for example, 0.15 to 0.5), and more preferably about 0.2 to 0.45. If the height of the rib portion is too high, the rib portion that comes into contact with the fruit is pressure-bonded and easily damaged by the load of the upper fruit. On the other hand, if the height of the rib is small, the load on the upper fruit makes contact with the fruit and the sheet surface becomes depressed, and the fruit and the sheet are rubbed by vibration during transportation, and the fruit is easily scratched.

  Furthermore, the ratio C / (A + B) of the pitch C of the rib portion to the entire thickness A of the sheet main body and the height B of the rib portion is in the range of about 0.6 to 3 (for example, 0.7 to 2.5). Usually, 1 to 3 (for example, 1.1 to 3), preferably 1.2 to 2.8 (for example, 1.3 to 2.5), more preferably about 1.4 to 2 is there. If the pitch of the rib portions is too large, the function of the ribs cannot be expressed effectively, and the fruits are easily damaged. Furthermore, the ratio D / A of the width of the rib portion to the thickness A of the sheet body is 0.8 to 3 (for example, 0.9 to 2.5), preferably 1 to 2.3 (for example, 1-2). More preferably, it is about 1 to 1.7 (for example, 1 to 1.5). If the interval D between the rib portions is too large, the function of the ribs cannot be expressed effectively, and the fruits are easily damaged.

  Since the sheet-like resin foam having convex portions or rib portions of such a dimensional size can effectively protect the fruits, it can be applied to one-stage packing or packaging in which the fruits are arranged in one row in the vertical and horizontal directions, It is useful for stacking fruits in a form that can contact the top surface of the fruits. In stacked packaging or packaging, the number of stages is not particularly limited, and may be about 2 to 10 stages, but is usually about 2 to 5 stages in many cases.

  The sheet-like resin foam may be laminated with a non-slip sheet on the contact surface with the fruit in order to increase the contact friction resistance with the fruit and prevent the fruit from rubbing.

  In addition, what is necessary is just to use the said sheet-like resin foam as a buffering material with respect to a fruit, and may distribute | arrange to the upper part side (top part) of the said fruit, and may distribute | arrange between a bottom part side, a side part side, and fruits. Moreover, you may distribute a sheet-like resin foam between the side wall and fruit of a package or a package. Containers for storing fruits are not limited to foamed resin trays (such as foamed polystyrene trays) having the housing recesses, but various containers, for example, synthetic resin foams such as polyethylene and polypropylene, paper cushioning materials, etc. Available. Further, the container may be an individual package capable of individually packing or storing fruits, and may be a tray capable of storing fruits vertically and / or horizontally as described above.

  The foam can be produced by a conventional foam molding method. For example, a sheet-shaped resin foam can be obtained by melt-kneading a foamable resin composition under pressure and injecting the foamed resin composition into a mold at atmospheric pressure or by extruding the sheet from a die into a sheet. In foam molding, the foaming agent may be preliminarily contained in the resin composition, or may be injected or added to the melt-kneading system in the extruder.

  In this invention, a fruit can be effectively protected by arrange | positioning a sheet-like resin foam for the convex part or rib part among buffer materials toward the upper surface of a fruit. Therefore, the present invention also includes a method of packaging or packing fruits by disposing a sheet-like resin foam with the convex portions or rib portions facing the upper surface of the fruits. The cushioning material composed of the sheet-like resin foam of the present invention can be used for packaging or packing various fruits or fruits, such as apples, pears (20th century pears, etc.), peaches, strawberries, figs, watermelons, melons, etc. Available. In particular, it can be used for packaging or packing fruits or fruits that are thin and easily damaged. In addition, since the fruit or fruit can be effectively protected, the partition member of the package or the package used in the transportation process in which vibration acts, particularly between the stages in the package or package for stacking fruits or fruits. It is useful as a partition member.

  Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples.

Examples 1-2 and Comparative Examples 1-2
Resin composition consisting of tandem type extruder (first stage screw diameter 100mm, second stage screw diameter 120mm) with polyethylene resin, polystyrene resin, soft ethylene copolymer, antistatic agent, bubble regulator About 22 parts by weight of hydrocarbon gas (mixed gas of butane and pentane) was injected from the middle part of the first stage extruder. Cool in the second stage extruder, lower the resin temperature to the foaming temperature, continuously extrude the cylindrical foam sheet from the circular die attached to the tip of the extruder, center cut, then sheet resin foam Was cut into predetermined dimensions (width 320 mm × length 460 mm) to obtain a predetermined sheet-like resin foam.

[Example 1]
A closed cell sheet-like resin foam in which 24 protruding rib portions extend in parallel [Example 2]
Closed cell sheet-like resin foam with 46 protruding ribs extending in parallel [Comparative Example 1]
Closed cell sheet-shaped resin foam with no protruding ribs and a flat surface In Examples 1 and 2 and Comparative Example 1, a resin composition composed of the following components was used, and a sheet shape of a closed cell structure A resin foam was obtained.

Polyethylene-based resin: 55 parts by weight of low-density polyethylene (“F101” manufactured by Sumitomo Chemical Co., Ltd.) Polystyrene-based resin: 30 parts by weight of polystyrene (Idemitsu Petroleum Corporation “HH102”) Soft ethylene-based copolymer: ethylene-vinyl acetate Copolymer (Toso Co., Ltd. “631”, vinyl acetate content 20% by weight) 15 parts by weight Antistatic agent: Boehringer Ingelheim Chemicals Co., Ltd. “HYD325” 1.5 parts by weight Bubble regulator: Eiwa Kasei Co., Ltd. “EE275” manufactured by 0.6 part by weight [Comparative Example 2]
Closed-cell sheet-shaped resin foam with 24 protruding rib portions extending in parallel. In Comparative Example 2, a closed-cell sheet-shaped resin foam was obtained using a resin composition composed of the following components. It was.

Polyethylene resin: 70 parts by weight of low density polyethylene (“F101” manufactured by Sumitomo Chemical Co., Ltd.) Polystyrene resin: 30 parts by weight of polystyrene (Idemitsu Oil Co., Ltd. “HH102”) Antistatic agent: Boehringer Ingelheim Chemicals Co., Ltd. "HYD325" 1.5 parts by weight Bubble regulator: "EE275" 0.6 parts by weight manufactured by Eiwa Kasei Co., Ltd. And, for the obtained sheet, the thickness A of the sheet body, the height of the rib part from the surface of the sheet body B, pitch C of the rib portion, and width D of the rib portion were measured, and B / A, C / (A + B), and D / A were calculated. In addition, the expansion ratio was obtained by an equation (V / W) × resin density (where V represents the volume of the foam sheet and W represents the weight of the foam sheet) using an electronic hydrometer (Mirage Trading Co., Ltd.). .

  In the accommodation recess of the polystyrene tray placed in the cardboard, 12 twentieth century pears were accommodated in the vertical and horizontal directions in one row, and the resulting sheets were stacked to produce a two-tiered package shown in FIG. . Then, after transporting back and forth between Tottori and Tokyo by truck, the degree of damage of the 20th century pear was evaluated according to the following criteria.

1: No scratch 2: Slight scratch 3: Large scratch The results are shown in Table 1.

  As is clear from Table 1, in Comparative Example 2, the height of the rib was high, and the pear was scratched with the rib portion being crimped. In Comparative Example 1, the surface of the pear was rubbed and scratched. In contrast, the pears were not damaged in the examples.

FIG. 1 is a schematic perspective view showing an example of the cushioning material (or sheet-like resin foam) of the present invention. 2 is a cross-sectional view of the cushioning material of FIG. 1 taken along the line II-II. FIG. 3 is a schematic perspective view showing another example of the cushioning material (or sheet-like resin foam) of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,11 ... Sheet-like resin foam 2,12 ... Foam sheet main body 3,13 ... Projection rib part

Claims (6)

A cushioning material comprising a sheet body and a sheet-like resin foam formed on the surface of the sheet body in parallel with each other at a predetermined interval and having a trapezoidal rib portion having a trapezoidal cross section that can come into contact with the fruit Because
The resin foam is composed of (1) a polyethylene resin composed of linear low density polyethylene using a metallocene catalyst , (2) a polystyrene resin, (3) ethylene, an aliphatic organic acid vinyl ester, and (meta And) a copolymer with at least one monomer selected from acrylic monomers ,
The foaming ratio of the resin foam is 50 to 75 times,
The closed cell ratio of the resin foam is 90 to 100%, and
B / A = 0.1 to 1.3, where A is the thickness of the sheet body, B is the height of the rib part from the surface of the sheet body, C is the pitch of the rib part, and D is the width of the rib part. C / (A + B) = 0.6~3, D / A = 0.8~3 der Ru fruit cushions. The buffer material according to claim 1, wherein the resin foam is composed of a resin composition containing 30 to 80 parts by weight of a polystyrene resin and 10 to 50 parts by weight of a copolymer with respect to 100 parts by weight of a polyethylene resin. In contactable forms with the upper surface of the fruit, a resin foam for staked fruit, resin foam, relative to 100 parts by weight Po Riechiren resin, polystyrene resin 40 to 75 parts by weight, ethylene - cushioning material according to claim 1, wherein is a resin composition comprising a vinyl copolymer 15 to 45 parts by weight of acetic acid. The cushioning material according to claim 1, wherein the fruit is a fruit having a soft epidermis. Foaming a resin composition comprising a polyethylene resin, a polystyrene resin, and a copolymer of ethylene and a monomer selected from an aliphatic organic acid vinyl ester and a (meth) acrylic monomer; The manufacturing method of the buffer material for fruits of Claim 1 which forms the sheet-like resin foam which has a convex part which can contact with a fruit. The method of packaging fruits disposing the sheet-shaped resin foam toward the protruding rib on the upper surface of the fruit of the cushioning material of claim 1, wherein.

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