A PLASTIC SHOCK ABSORBER FOR PACKING AND PROCESS FOR PRODUCING THE SAME

Abstract: A plastic shock absorber for packing which is prepared by sealing a gas such as air in a hollow cylindrical plastic body (1) which is heat-pressed substantially vertically (V) and horizontally (H) at suitable intervals.

Description: A PLASTIC SHOCK ABSORBER FOR PACKING AND PROCESS FOR PRODUCING THE SAME BACKGROUND OF THE INVENTION: The present invention relates to a plastic shock absorber for packing comprising a plurality of hollow units made of a plastic material and to a process for producing it. In the prior art, as a shock absorber for an'object packed in a packing container, non-hollow bodies having a spherical or spaghetti shape and being made of foamed plastics and the like are normally packed in individual and separate pieces. Accordingly, shock absorption is achieved by the individual, separate bodies. Integrated shock absorbing action can never be expected. The packings, therefore, act hydrodynamically permitting the surrounded object to move and vibrate in accordance with the movement and deformation of the packings, and thus, less satisfactory shock absorption is provided. Moreover, those are used in separate drops and thus difficult to handle. In addition, a great amount of material is necessary owing to non-hollow bodies, necessarily leading to high cost. Furthermore, environental pollution can be a problem in disposal by burning. SUMMARY OF THE INVENTION: It is an object of the present invention to provide a shock absorber producing a superior shock absorbing action achieved in one body by a plurality of units containing a gas. It is another object of the present invention to provide a shock absorber which can be mass-produced at low cost by a simplified equipment. These and other objects of the present invention together with the advantages thereof will become apparent to those skilled in the art from the detailed disclosure of the present invention as set forth hereinbelow. The present invention has been completed on the discovery that the foregoing objects can be accomplished by a shock absorber prepared by sealing a gas in a cylindrical plastic body and heat-pressing it substantially vertically and horizontally at suitable intervals. BRIEF DESCRIPTION OF THE DRAWINGS: Figure 1 and Figure 2 are schematic illustrations showing an embodiment of a production process of a shock absorber of the present invention; Figure 3 is a perspective view of a shock absorber of the present invention; Figure 4 is a perspective view of a shock absorber, having a cut in a heat-pressed portion thereof; and Figure 5 is a schematic illustration showing how to use a shock absorber of the present invention. DETAILED DESCRIPTION OF THE INVENTION: As a plastic film used in the present invention, a laminated film is preferred. Most preferably, a laminated film composed of polyethylene and polyester or polyamide (nylon) is employed. The thickness of the film is not limited, in particular, and normally had best be selected from a range of from about 10 to about 50 microns for polyethylene, about 10 to about 20 microns for polyester and about 10 to about 20 microns for polyamide-. The diameter of a cylindrical body is not specifically limited and normally selected from a range of from about several centimeters and several tens af centimeters, more preferrably 4 to 10 centimeters. Vertical and horizontal heat-pressing had best be made at intervals ranging from several centimeters and several tens of centimeters, more preferrably 4 to 10 centimeters. As a gas used in the present invention, air is most preferrable in respects of cheapness and easy obtaining, but other inert gases are also usable. A gas controlled to be cooler than the open air, more preferrably, cooler by about 10 C or more than the open air gives more satisfactory results. That is, in cases where the temperature of the gas sealed in a cylindrical body is equal to that of the open air, the gas somewhat expands with heat at the time of heat-pressing. Therefore, when the temperature inside hollow units formed by vertical and horizontal heat-pressing becomes equal to that of the open air, the hollow units somewhat deflate. In contrast, when a gas controlled to be cooler than the open air is contained, the temperature inside the hollow units go up to that of the surroundings to thus allow the gas to expand. As a result, the hollow units swell to be roundish, giving by far superior shock absorbing effects. Heat-pressing is effected substantially vertically and horizontally. More preferrably, the heat-pressing should be made alternatively vertically and horizontally. The hollow units thus obtained are of trigonal shapes and swollen roundish trigonal shapes when contained a gas cooler than the open air, as aforesaid. The trigonal shape is superior in bulkiness as well as an effect of preventing surrounded objects from moving. When cuts are made on the heat-pressed portions of the hollow units, cutting to an optional length is possible without using knives or scissors and hence working efficiency is markedly enhanced. The cuts may include a sewing stitch-like cut, a slit-like cut excepting both ends and the like. A process for producing a shock absorber of the present invention will be explained by referring to Figure 1 and Figure 2. As shown in Figure 1, a laminated film is, at first, prepared by an ordinary manner, then the both edges of the laminated film are heat-pressed to thus form a continuous cylindrical body (1). Then, the so obtained cylindrical body (1) is heatpressed at suitable intervals substantially in vertical (V) and horizontal (H) directions to thereby obtain a shock absorber of the present invention which comprises a plurality of substantially trigonal hollow units connected in series. Figure 3 is a perspective view of the obtained shock absorber of the present invention. The heat-pressing is conducted at the temperature between about 1300C and about 1800C under the pressure between about 4 Eg/cm2 and about 10 Kg/Cm2 for about 0.3 to about 0.7 seconds. Hereinafter, the present invention will be explained in more detail by way of examples that follow, to which examples the invention is in no way limited. EXAMPLE I A laminated film comprising a polyethylene film "SUEIRASEN (correct spelling is not known)" produced by StmiITOMO CHEMICAL-CQ., LTD., having the thickness of 20 microns and a polyester film "LUMILAR (correct spelling is not known)" produced by TORAY INDUSTRIES, INC., having the thickness of 12 microns was obtained in an ordinary process. Next, as was shown in Figure 1, the opposite both edges of the laminated film were heat-pressed so as to keep the polyethylene film inside at the temperature of 1500C under the pressure of 5 Kg/cm2 to thereby provide a continuous cylindrical body (1), about 6 cm in diameter. The resulting cylindrical body (1) was heat-pressed vertically (V) and horizontally (H), alternately, at an interval of about 7 cm, while blowing air in the cylindrical body and a shock absorber comprising a plurality of substantially tragonalshaped units (2) linked in series, each unit having a side of about 9 cm was obtained as depicted in Figure 2 and Figure 3. EXAMPLE 2 A laminated film was prepared which comprises a poly- ethylene film "SUMIKASEN" having the thickness of 20 microns and a polyamide film "AMILAN (correct spelling is not known)" produced by TORAY INDUSTRIES, INC., having the thickness of 15 microns. Using the laminated film, a shock absorber was obtained in a similar fashion to the procedure of Example 1, excepting that the temperature of air was varied. The resulte obtained are given in Table I. The above procedure was carried out at about LOOC under atmospheric pressure, TABLE I Temperature of State of the hollow unit when the Air ( C) inside reached the open air (10 C) 10 Elasticity is poor and shock absorption is not sufficient. 5 Substantially trigonal shape is main tainted but shock absorption is not satisfactory. TABLE I Temperature of State of the hollow unit when the Air (OC) Inside reached the open air ("C) O It becomes close to expected roundish shape, considerably, but sufficient shock absorption is not yet obtained. - - 5 It swells to be somewhat hard and shock absorption is virtually satisfactory. -10 It swells to be hard considerably with good shock absorption. EXAMPLE 3 A A slit-like cuts (3) were made on the heat-pressed por- tions (V) and (H), excepting both ends thereof, of the shock absorber, prepared in Example 2, in which air cooled to lO0C was contained. Figure 4 shows a perspective view of the shock absorber contained. In Figure 5, there is shown a schematic representation illustrating how a shock absorber of the present invention is used. The numeral (4) is an object and (5) is a package contain er. A shock absorber of the present invention is superior in static and dynamic shock absorbing characteristics. For instance, falling test was performed in which an apparatus weighing 10 Kg packed in a polycarbonate container with a shock absorber of the present invention was allowed to fall down from the height of 60 cm every 90 seconds for 8 hours but neither deformation nor damages of the shock absorber was observed with the shock absorb ing characteristics unchanged. As apparent from the foregoing, shock absorbers of the present invention are exceedingly useful in the industry, having 1numerous advantages as set forth below: (1) Since hollow units are connected in series by horizontal heat-pressed portions (H) and vertical heat-pressed portions (V), the units are enfolded while being pulled one another to thus produce a shock absorbing effect in one body. Accordingly, the load imposed on each of the units is dispersed uniformly and superior pressure resistance and shock absorption are provided. (2) (2) Air is preferrably used to serve as a gas contained so that the amount of materials can be drastically reduced. Hence, a shock absorber is produced very economically and contributes to the saving of the resources. (3) Continuous production is possible by a simplified equipment and thus, it can be mass-produced. (4) It is much easier to handle, as compared with independent, separate bodies which have been used heretofore. Moreover, cuts made on the heat-pressed portions enhance working efficiently surprisingly.

Claims: Claims: 1. Plastic shock absorber for packing, characterized in that it comprises a cylindrical hollow plastic body (1) filled with a gas, which body (l) is heat pressed along substantially vertical (V) and horizontal (H) lines, respectively, at suitable intervals to form a series of hollow units (2) containing the gas. 2. Shock absorber as claimed in claim 1, characterized in that said plastic body (1) is made of a Ipninated film comprising at least one material selected from the group consisting of polyethylene, polyester, and polyamide 3. Shock absorber as claimed in claim 15 characterized in that said gas is air. 4. Shock absorber as claimed in claim I or 3, characterized in that said gas is controlled to be cooler than the open or ambient air. 5. Shock absorber as claimed in claim 4, characterized in that said gas is controlled to be cooler by 10 0C or more than the open or ambient air. 6. Shock absorber as claimed in anyone of claims I to 5, characterized in that a cut (3) is provided in each heat-pressed portion (V and H). 7. Process for producing a plastic shock absorber for packing as claimed in anyone of claims 1 to 6, characterized in that a plastic film is heat-pressed to form a hollow cyclindrical body (1) and heat pressing it substantially vertically and horizontally at suitable intervals, while blowing a gas in the cylindrical body. 8. Process as claimed in claim 7, characterized in that a cut (3) is made in the heat-pressed portions (V and H).

Inventors: YAMASHIRO, HIROSHI
Applicants: KABUSHIKI KAISHA E.P.E.
Application year: 1983
Main classification: B65D81
IPC codes: B31D5, B65D81