GB2178694A

GB2178694A - Packaging material

Info

Publication number: GB2178694A
Application number: GB08600569A
Authority: GB
Inventors: Hiroshi Yamashiro; Ko Suzuki
Original assignee: Individual
Current assignee: Individual
Priority date: 1985-06-06
Filing date: 1986-01-10
Publication date: 1987-02-18
Anticipated expiration: 2006-01-10
Also published as: IT1190127B; IT8620705A0; CH672474A5; GR861482B; NZ216439A; ES8707699A1; ES555827A0; TNSN86084A1; AU5847786A; IL79057A0; IT8620705A1; ZA864171B; GB2178694B; GB8600569D0; BE904886A

Abstract

A dunnage shock absorber and a method and apparatus for making the same is disclosed. The shock absorber is constructed from plastics material e.g. a laminate of polyethylene and polyester or nylon, which forms a series of trigonal-shaped, gas-filled units which maintain adequate shock absorbing characteristics over a broad range of temperature conditions. This disclosed method includes the steps of forming a plastic tubular body, introducing a cooled gas into the body and forming individual trigonal- shaped united having cooled gas entrapped through angularly heat sealing the edges of such units. The disclosed apparatus forms plastic film into a series of gas-filled trigonal units through the use of fin seal rollers to seal the film into a tubular body. Sponge-like rollers downline of the fin seal rollers grip the tubular body and a conduit injects cooled gas into the tubular body. Horizontal and vertical sealers are provided downline of the sponge-like rollers to heat seal the tubular body with gas entrapped therein.

Description

SPECIFICATION Dunnage shock absorber and method and apparatus for making the same The present invention relates to plastic shock absorbing packing materials or dunnage and to a method and apparatus for making such shock absorbing packing materials from plastic film.

More specifically, the invention relates to packing materials having bulbous, expanded, hollow units in which gas is entrapped and to a method and apparatus for forming such materials.

BACKGROUND OF THE INVENTION In the prior art, various forms of plastic shock absorbing materials are known, including nonhollow bodies having a spherical or spaghetti shape that are made from foamed plastics. Such packing materials do not provide integrated shock absorbing action and often act hydrodynamically, thus permitting the packed object to be subjected to undesirable movement and vibration as the packing materials itself deforms. In addition, such materials often provide unsatifactory shock absorbing characteristics, are difficult to handle and are expensive due to the additional plastic material that is necessary because of the non-hollow nature of the packing material.

Alternatively, those prior art packing materials that attempt to use a hollow, rather than a foamed body, have shapes that do not easily permit the complete and efficient filling of voids around the object to be packed and do not maintain fully adequate shock absorbing capabilities over a wide range of shipping temperatures. As a consequence, more working units are required, and decreased shock absorbing compression and deformation characteristics result.

SUMMARY OF THE INVENTION: In accordance with the present invention, a shock absorber packing material is provided that is constructed from a plastic film material and includes a series of essentially trigonal shaped, gasfilled units that are heat sealed and are used to fill the areas around the object to be packed and of also maintaining adequate shock absorbing characteristics over a broad range of temperature conditions. A desirable method of making such packing materials involves the formation of a plastic tubular body, the introduction of a cooled gas into the tubular body and the formation of essentially trigonal shaped individual units containing entrapped gas by angularly heat sealing the tubular body at spaced intervals.An apparatus also is provided for forming a plastic film into a series of gas-filled essentially trigonal-shaped units through the use of fin seal rollers for sealing the overlapping side edges of the film to form a tubular body, deformable rollers forward or down line of the fin seal rollers for gripping the side portions and advancing of the tubular body downline, a conduit for injecting cool gas into the tubular body, and lateral or horizontal and vertical sealers located in series, downline of the sponge-like rollers to heat seal the tubular body into a preferred shape for packing and shock absorbing efficiency.

It is, therefore, an object of the present invention to provide shock absorber packing materials that provide a superior shock absorbing and packing action achieved in one body by a plurality of linked units containing a gas.

It is another object of the present invention to provide shock absorber material that can be mass-produced at low cost by simplified equipment.

It is still a further object of the present invention to provide packing material of high bulk and capable of efficiently filling the void area around the object that is packed, thereby reducing the unprotected areas around the packed object.

It is still a further object of the invention to provide packing material that is capable of maintaining its highly desirable shock absorbing characteristics over a wide range of operating temperatures.

Moreoverm the method and apparatus for making the subject packing materials are economical, operate at improved manufacturing speeds and are capable of efficiently manufacturing highly desirable packing materials that provide improved packing and shock absorbing characteristics.

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 below.

BRIEF DESCRIPTON OF THE DRAWINGS: Embodiments of the present invention are illustrated in the drawings as described generally below.

Figure 1 and Figure 2 are schematic drawings illustrating an embodiment of a production process for making a shock absorber packing material of the present invention from plastic sheet material; Figure 3 is a perspective view of an embodiment of the shock absorber packing material of the present invention; Figure 4 is a perspective view of an embodiment of the shock absorber packing material having a cut or score in a heat sealed portion thereof; Figure 5 is a schematic illustration of the manner in which the shock absorber packing material of the present invention can be used to efficiently pack an object; Figure 6 is a diagrammatic perspective view illustrating an apparatus for processing and utilizing flat film to produce a shock absorber according to the present invention;; Figure 7 is an elevational view of Fig. 6 showing further details of the apparatus for making the subject packing materials; Figure 8 is a top view of the apparatus of Fig. 7; Figure 9 is an end view of the apparatus of Fig. 7 Figure 10 illustrates an embodiment of the desired packing material processed by the apparatus illustrated in Figs. 6 through 9; Figure 11 illustrates the timing sequence for the horizontal and vertical sealers of the illustration apparatus such that a gas may be injected and held in the formed bulbous, hollow shock absorber units of the packing material;; Figure 12 graphically illustrates the deformation levels of a shock absorber packing material of the present invention in which the gas filled units contain gas injected at ambient temperature versus a more desirable temperature 220C below ambient conditions.

Figure 13 graphically illustrates the compressed energy levels for shock absorber packing materials containing gas injected at ambient versus 220C below ambient conditions.

DETAILED DESCRIPTION OF THE INVENTION: Although any number of plastic films may be useful in the practice of the present invention, a laminated film made up of two kinds of plastics which have different melting points is preferred.

Plastic films are selected on the basis of strength, elasticity and melting point considerations.

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 can 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 . Most desirably, however, it has been found that films in the thickness range of 9 to 30 microns is adequate to provide structural integrety at minimal cost. When a polyethlene-polythylene terephthalate film is used a combined thickness in the range of 12 to 30 microns is used. When a three layer film of low density polyethylene, high density polyethylene and polyethylene and terephthalate is used at 10-10-12 micron film thicknesses respectively, a total thickness of 32 microns is used.

As an example a co-extrusion plastic film manufactured by Dai Nippon Printing Company, and formed from linear low density polyethylene having a melting point between about 1 600C and 1 800C and a polyethylene terephthalate having a melting point between about 2300C and 240 C, bound together with a low density polyethylene glue has been found desirable as a film material useful in the practice of the present invention. The lower melting point polyethylene assists in forming the seal in the resultant product while the polyethylene terephthalate assists in maintaining a web. The use of composite films made up of seperate films having different melting points assists in providing proper sealing and forming characteristics for the resultant packing material.

The diameter of the cylindrical body used in forming the packing material structure of the present invention is not specifically limited and is normally selected from a range of about several centimeters to several tens of centimeters, more preferably 4 to 10 centimeters. Moreover, heat-pressing is preferably made at intervals ranging from several centimeters and several tens of centimeters, more preferably 4 to 10 centimeters.

Although any number of inert gases may be desirably used in the practice of the present invention, air is most preferably used because it is so readily available and inexpensive. Alternatively, nitrogen may be used because it is obtainable in liquid form, is inexpensive and in liquid form is in a cooled condition ready for injection without additional cooling. A gas controlled to be cooler than the ambient air temperature, more preferably cooled by about 1 00C to 200C or more from the ambient air temperature, gives the desired satisfactory shock absorbing results.

That is, in cases where the temperature of the gas sealed in a cylindrical body is equal to that of the open air, e.g. ambient conditions, the gas somewhat expands with heat at the time of heat-pressing. Therefore, when the temperature inside the hollow units formed by vertical and horizontal heat-sealing becomes equal to that of the open ambient air, the hollow units can somewhat deflate. In contrast, when a gas controlled to be cooler than the open air is contained, in time the temperature inside the hollow units is elevated to that of the surroundings to thus allow the gas to expand. As a result, the hollow units swell to be roundish, enhancing shock absorbing effects.

More specifically, it has been determined that the temperature differential between the ambient conditions at which processing normally takes place and the temperature at which the gas is inhected to form the hollow, gas-filled units can affect the properties of the resultant plastic shock absorbing packing material. Most desirably, the temperature differential should be sufficient to provide a fully swelled, rigid unit structure with resultant high shock absorbing characteristics over a wide operating range of packing conditions. At 10 C temperature differentials the gasfilled units typically achieve a roundish shape with adequate shock absorbtion. At 1 50C temperature differentials unit swelling is improved still further as is shock absorption.And, at temperature differentials of 200C the shape of the gas-filled units is rigid and desirable shock absorption characteristics are achieved. Temperatures differences even greater than 200C produce highly satisfactory results, but are typically not desired because of the added expense associated with the need to further cool the injected gas.

Naturally, because it is difficult to create a pressurized condition in the individual gas-filled units through injection of gas at temperatures above atmospheric conditions, the injection of a chilled gas (such as air) at or slightly above atmospheric conditions, which is then allowed to increase in temperature to individually pressurize the gas-filled units, has been found particularly desirable.

Typically the contained gas is injected at a pressure slightly higher than atmospheric pressure, between about 1 Omm of water to 100mm of water and most preferably between about 20 and 35mm of water. At pressures above 100mm of water it becomes more difficult to properly seal the individual units, while at pressures below 1 Omm of water is sometimes becomes more difficult to properly expand the individual units into their properly inflated bulbous condition.

An additional benefit of the use of cooler gas is that it tends to increase the productivity of the packing material manufacturing process since the chilled gas tends to permit more rapid cooling of the heat seals, e.g. the melted seam portions forming the boundaries for each sealed gas-filled unit, and thus accelerates adherence of the seam. As a consequence, it has been determined that at ambient operating conditions of 320C (as a base condition) increases in production of 9 percent have been achieved at 1 20C temperature differentials, 15 percent at 1 70C temperature differentials, 23 percent at 220C temperature differentials and 54 percent at 320C temperature differentials.

Although heat-sealing can take place at varying angular configurations, heat-sealing is desirably effected substantially vertically and horizontally. More preferably, the heat-sealing should be made alternatively vertically and horizontally. The hollow units thus obtained are of trigonal shape and generally swollen and roundish in cross-section when containing a gas cooler than the ambient air. The trigonal shape is superior in bulkiness which leads to an increase in desired packing characteristics which includes reducing andf attenuating motion of the surrounded objects.

Heat sealing of the individual units is desirably carried out at temperature and pressure conditions that provide an acceptable seal capable of containing the injected gas. When a laminated, composite film is used, the sealing temperature is at least higher than the melting point of the lower melting temperature plastic component, but below the melting point of the higher melting temperature component. Thus, only partial melting of the two or three component plastic film takes place, e.g. only one component melts. In the case of a polyethylene-polyethy- lene terephthalate composite film, for example, a range of about 1300C to about 1800C is an acceptable sealing temperature, while a range of about 1 600C to about 1 800C is preferable.At temperatures above about 1 800C the polyethylene terephthalate component would be damaged, while at temperatures above about 230 C the polyethylene component would be damaged. Heat sealing pressures are typically set as low as possible to achieve quality sealing. If an increased dwell period is used, pressures can be set substantially lower, e.g., below about 4kg/cm2. At pressures above about 10kg/cm2 the edge portion of the seals can be damaged.

The essentially trigonal shape shown in Figs. 3, 4 and 10 provides a highly efficient packing and shock absorbing product. The linked units, in series for example, provide a high degree of shock absorbency and aid in filling the corners of the packing container. In addition, the essentially trigonal shape helps to completely surround the packed object, reduces voids in the packing container and fits easily into corner areas through increased positionability as shown, for example, in Fig. 5. By disposing the hollow, gas-filled, bulbous units end-to-end, voids and corners are more easily filled, In addition, the linking of individual units in series tends to make the resultant structure less movable, which enhances working efficiency and improves overall shock absorbing characteristics.

The desirable shape, therefore, for the gas-filled bulbous units of the present invention is one which efficiently fills the void and corner areas in the packing container, completely and effciently surrounds and packed objects and at the same time provides highly efficient shock absorbing characteristics.

Although the trigonal shaped units illustrated in Figs. 3, 4 and 10 are preferred because it provides increased bulk and shock absorptions while preventing the surrounded objects from moving, it should be understood that other shapes capable of achieving the efficient filling and shock absorbing characteristics of the trigonal shape are also useful in the practice of the present invention. Where a smaller diameter cylindrical body is used, for example, a pillowshaped unit can also prove effective. In such cases heat pressing can be horizontal and horizontal to form the pillow-shaped units or alternatively vertical and vertical, although vertical-vertical arrangements sometimes tend to form irregular seals. Alternatively, the seals may be made at angular variations from horizontal or vertical.

When pre-arranged scores or cuts are made on the heat sealed portions of the hollow units as shown in Fig. 4, detaching an optional length is possible without using knives or scissors and hence working efficiency is markedly enhanced. The cuts may include, for example, a sewing stitch-like cut, a slit-like cut, a score line and the like, excepting both ends. The perforations, cuts or score lines may be located ay any heat sealed portion of the resultant packing material, sometimes most desirably at every heat sealed portion and at other times at every other or every fourth sealed portion.

An example of a process useful for producing a shock absorber packing material of the present invention will be explained by referring to Figs. 1 and 2.

As shown generally in Fig. 1, a laminated film is, at first, prepared in an ordinary manner, then the edges of the laminated film are heat-sealed to form a continuous cylindrical body (1). As shown in Fig. 2, the so obtained cylindrical body (1) is then heat sealed 1(a) and 1(b) at suitable intervals, as shown for example 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-shaped hollow units connected in series. Fig. 3 is a perspective view of an embodiment of the so obtained shock absorber of the present invention. Preferably, the heatpressing is conducted at a temperature between about 130 C and about 1 800C under a pressure between about 4 Kg/cm2 and about 10 Kg/cm2 for about 0.3 to about 0.7 seconds.

Ideally, of course, the bulbous, gas-filled units maintain their firm shape and efficient shock absorbing characteristics over a wide range of temperatures to which the packed object is exposed. After air, nitrogen or any other suitable gas is injected and then sealed into the individual units of the shock absorbing packing material, the return to ambient temperatures tends to increase the pressure within the gas-filled units because unit volume is relatively constant, given the relative inelasticity of the plastic film. Thus, as the gas temperature rises so does the pressure. Each hollow gas-filled unit, in the preferred bulbous form, will retain its original expanded shape until the ambient, surrounding temperature is reduced such that the pressure within each unit is reduced below one atmosphere of pressure, e.g. 14.7 psi.Thereafter, the units will lose approximately 10 percent of their volume for each 300C reduction in temperature. At the upper limit of temperature, it has been determined that the temperatures above about 70 C are undesirable and set the practical limit on the temperature to which the plastic packing material should be exposed in actual use. Obviously, the units will retain their expanded, fully pressurized condition at temperatures exceeding the ambient temperature at time of manufacture, and as set forth above will decrease in volume at a rate of approximately 10 percent for each 300C reduction in temperature below ambient temperature at the time of manufacture.If the volume of the units is reduced below 80 percent of their maximum, expanded volume, the resultant packing material rapidly loses its desired shock absorbing characteristics. This condition is achieved, for example, when the temperature to which the gas-filled units are exposed is about 600C or more below the temperature at which the cooled air was injected.

For purposes of illustration only various aspects of embodiments of the present invention will be explained in more detail by way of examples that follow, to which examples the invention itself is in no way limited.

EXAMPLE 1 A laminated film comprising a polyethylene layer "SUMIKASEN (correct spelling is not known)" produced by SUMMITOMO CHEMICAL CO., LTD., having the thickness of 20 microns and a polyester layer "LUMILAR (correct spelling is not known)" produced by TORAY INDUSTRIES, INC. (also known as TOYORO), having the thickness of 12 microns was obtained in an ordinary process. Next, as was shown in Fig. 1, the opposite edges of the laminated film were heatpressed so as to keep the polyethylene layer inside at the temperature of 1 500C under the pressure of 5Kg/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. This process forms a shock absorber comprising a plurality of substantially trigonal-shaped units (2) linked in series, each unit having a side of about 9 cm in length as depicted in Fig. 2 and Fig. 3.

EXAMPLE 2 A laminated film was prepared which comprises a polyethylene film 'SUMIKASEN" having a thickness of 20 microns and a polyamide film "AMILAN (correct spelling is not known)" produced by TORAY INDUSTRIES, INC., having a thickness of 15 microns. Using the laminated film, a shock absorber was obtained in a similar fashion to the procedure of Example 1, except for the fact that the temperature of air was varied. The results obtained are given in Table I. The above procedure was carried out at about 100C under atmospheric pressure.

TABLE I Temperature of Injected State of the hollow, gas-filled Air (cc) unit when the temperature inside reached the open ambient air temperature (1UOC) 10 Elasticity is poor and shock absorption is not sufficient.

5 Substantially trigonal shape is maintained but shock absorption is not satisfactory.

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 Slit-like cuts or scores (3) were made on the heat-pressed portions (V) and (H) of the shock absorber, prepared in Example 2, in which air cooled to 10 C below ambient temperature was contained. Fig. 4 shows a perspective view of the shock absorber having contained cooled air therein.

EXAMPLE 4 As set forth above, the shock absorber packing materials of the present invention exhibit the most desirable shock absorbing characteristics when gas-filled at temperature at least 10 C and preferably 200C below ambient temperature conditions at the time of manufacture. As a further example, the following data indicates the state of the individual gas-filled units at varying temperatures of the filled gas: TABLE fi Difference in temperature State of the hollow unit between ambient air and packed air ( C) 0 Elasticity is poor and shock absorption is not sufficient.

10 It becomes close to expected roundish shape, considerably, but sufficient shock absorption is not yet obtained.

15 It swells to be somewhat hard and shock absorption is virtually satisfactory.

20 It swells to be hard with good shock absorption.

Fig. 5 illustrates the use of the shock absorber packing materials (2) of the present invention.

The numeral (4) is an object to be packed, and (5) is a package container in which object (4) is packed. The shock absorber packing material of the present invention has been found to have improved static and dynamic shock absorbing characteristics. For instance, falling test were performed in which an apparatus weighing 10Kg, packed in a polycarbonate container with the packing materials of the present invention, was allowed to fall from the height of 60 cm every 90 seconds for 8 hours. Neither deformation nor damage of the packing material was observed with the shock absorbing characteristics unchanged.

As shown in Figs. 13 and 14 differences in shock absorbing characteristics also result as the temperature of the contained gas is varied during the filling operation. For example, when the packing materials of the present invention are gas-filled at temperatures about 220C below ambient temperature (at the time of manufacture) versus 00C , a difference in the degree of compression of the resultant material takes place when subjected to a 7.5 Kg load, e.g.

compression to 15 cm (at a 220C differential) versus an increased compression to 12 cm (at a 0 C differential). In short, the resultant packing material is not capable of withstanding loads (it compresses to a far greater extent) as the gas-fill temperature differential approaches 0 C.

Likewise, under the same load conditions, load deformation of packing materials gas-filled at a 220C temperature differential (curve A) are smaller than that experienced for packing materials that are gas-filled at a 0 C temperature differential (curve B). Under identical deformation conditions, moreover, the packing materials that are gas-filled at a 220C temperature differential absorb more compressed energy and thus have greater shock absorbing characteristics (Fig. 13).

The resultant shock absorbing packing material, therefore, has the advantages of being an economic filler which is capable of providing high bulk at low cost. It can be made at a working site because of the relative simplicity of the equipment needed for manufacture. In addition, the resultant packing material reduces the problems of static electricity associated with other packing materials, e.g. it does not fly to the ceiling or stick to a person when the package is opened. It can be used repeatedly. And it is easily disposed of simply by piercing the hollow units and allowing the entrapped gas to escape. Moreover, the packing material of the present invention provides all of the highly desirable packing, filling and shock absorbing characteristics described in greater detail above.

As is shown in even greater detail in Table Ill below the difference in temperature between the ambient air and the packed or injected air (at the time of injection) influeneces both the volume of the hollow gas filled unit and the pressure inside each such unit.

TABLE m Temperature Volume Temperature Theoretical Volume Pressure Inside Difference of Injected of Ambient Air Volume of Hollow Unit From Ambient Air (ml) Air (OC) At Each Hollow (atm) ( C) Temperature Unit (ml) Level (ml) 8 157.1 148 1.061 10 158.2 149 1.062 15 161 15 1.073 -10 147 20 163.8 151.5 1.081 25 166.6 152 1.096 30 169.4 153 1.107 35 172.2 153.5 1.122 8 154.1 148 1.041 10 155.2 149 1.042 15 158 150 1.053 -5 147 20 160.7 151.5 1.061 25 163.5 152 1.076 30 166.2 153 1.086 35 168.9 154 1.100 8 151.3 148 1.022 10 152.4 149 1.U23 15 155.1 150 1.034 o 147 20 157.8 151.5 1.042 35 160.5 152 1.056 30 163.2 153 1.067 35 165.8 154 1.080 8 148.6 148 1.004 10 149.6 149 1.004 15 152.3 150 1.015 +5 147 20 154.9 151.5 1.022 25 157.6 152 1.039 30 160.2 153 1.047 35 162.9 153.5 1.061 Turning now, more specifically, to the desired for processing film apparatus used to make the shock absorbing packing materials of the present invention, Figs. 6, 7, 8 and 9, illustrate one embodiment of a machine which performs a line of successive steps to form the shock absorbing packing materials of the present invention. The illustrated machine includes stations at which a film (6) is fed over a guide roller (7) and between a pair of feed rollers (8), (9) toward a second guide roller (10). Film (6) is thereafter guided forward or downline to the next station, a former (11) which forms the film into a tubular member.

Former (11) includes a vertical plate (12) for guiding the film upwardly as well as a table plate at its upper end. Former (11) also includes triangular folding plates (13), (13) extending downline from the upper end of vertical plate (12) for folding the side edges of the film upwardly, and a lower plate (14) for pressing the upper surfaces of the film (6) which extends downline between folding plates (13), (13).

As shown in Fig. 7, a cutter (15) and an electrically actuated solenoid (16) are provided behind vertical plate (12). Cutter (15) is reciprocated by a solenoid (16) allowing the film (6) to be slit as the film is fed a predetermined length. Cutter (15) is biased away from film (6) by a spring (17) and is moved forwardly only when an electric current flows through the solenoid.

The solenoid (16) is controlled by an accumulation counter not shown.

A draw roller assembly including draw rollers (18), (18), a heating assembly including preheat bars (19), (19) and a sealing roller assembly including fin seal rollers (20), (20) are postioned in succession and downline respectively, in front and above former (11). Draw rollers (18), (19) draw film (6) downline by gripping the side edges of the film, preheat bars (19), (19) heat seal the film substantially entirely along its length, while fin seal rollers (20), (20) tightly seal the film substantially entirely along its length.

A tubular body advancing assembly including sponge-like rollers (21), (21), is provided to advnce film (6). Sponge like rollers (21), (21) are positioned in front of fin seal rollers (20), (20), which are mounted on vertical shafts (22). Rollers (21), (21) grip the side edges of film 6 and advance the film downline in a generally continuous manner. A conduit (23) in communication with a compressor (not shown) is connected to an injection assembly including an injection pipe (24) through an ultra-low temperature generator (25) for cooling air or gas. This generator (25) serves to chill the air preferably to a temperature about 200C below the atmospheric temperature when the air or gas is injected into the film. Pipe (24) extends downline above the upper plate (14) and between the sponge-like rollers (21), (21), opening in front of the sponge-like rollers.A pressure detector (26) and a temperature detector (27) are located adjacent to the outlet of the pipe (24) to control the entry of cool air.

A horizontal heat sealing assembly including horizontal sealers (28), (28) having a notching or scoring device, is positioned in front of rollers (21), (21). Each sealer is mounted to a rotatable horizontal shaft (29). A vertical heat sealing assembly including vertical sealers (30), (30) is positioned in front or upline of the horizontal heat sealing assembly. Vertical sealers (30), (30) are mounted to rotatable shafts (31) in a vetically crossing relationship with repsect to horizontal sealers (28), (28). A discharge conveyor (32) and a chute (33) are located in front of sealers (30), (30).

In operation, film (6) is unwound by feed rollers (8), (9) and formed into a tubular configuration by former (11). The overlapping edge portions of the tube are heated by the preheat bars (19), (19) to be pressed and tightly sealed by fin seal rollers (20, (20). Thus, pipe (24) is positioned within film (6) in its tubular configuration. While spongy rollers (21), (21) primarily serve to prevent the supplied air from leaking out of tubular film (6), they also grip the sides of the film, advancing the film down line. Rollers (21), (21) rotate at a speed which is faster than the feeding speed of film (6) in order to feed the film without sagging.

Pipe (24) which is surrounded by tubular film (6) supplies compressed air which causes the film to bulge and which is sufficiently cooler than the atmosphere within the portion of the tubular film extending beyond sponge-like rollers (21), (21). The leading end of the sufficiently bulged tubular film (6) is completely sealed by vertical sealers (30), (30), thereafter the film is sealed by horizontal sealers (28), (28).

Horizontal sealers (28), (28), simultaneously notch the heat sealed portion (lea), indicated by score line (1b), as illustrated in Fig. 10. By providing the vertical seals (V) and horizontal seals (H) alternately on the film in this manner, a series of trigonal hollow body sections A can be produced, and such bodies are discharged from the device through discharge conveyor (32) and chute (33).

Each time a predetermined quantity of film (6) is fed, an electric current is supplied to solenoid (16) activating cutter (15) thereby scoring and/or slitting the predetermined film section A.

Accordingly, counting of the hollow bulges being formed (Section A) is facilitated by the complete hollow body sections being sealed and scored ar predetermined intervals.

As can be seen in Fig. 11, operation of this invention is enhanced by the inclusion of a predetermined timing sequence which provides controlled operation of the describe components.

As illustrated, time interval t3 is the period of time during which one complete section A is formed and sealed at both ends. Time interval t2 depicts the sealing of one section A of tubular film (6) by vertical sealers (30), (30). Time interval t depicts the sealing of the same section A by horizontal sealers (28), (28) which occurs preferably a short period of time after it is sealed by vertical sealers (30), (30). This type of timing sequence allows gas to be entrapped within each section A after it is formed and completely sealed. While a timing sequence which first provides for filling of the tubular film and the subsequent sealing of each section A is described above, it should be understood that a variety of operable specific time intervals (i.e. t2 and t3) are contemplated by the method and machine of this invention.

According to the present invention, a series of shock absorbers in the form of sealed hollow trigonal bodies can be automatically produced. Further, chilled and compressed gas is encapsulated in each of the hollow bodies. This provides the desired increased shock absorbing quality since the encapsulated gas tends to expand at room temperature providing well-swollen shock absorber segment as illustrated by Section A of Fig. 10.

Although horizontal sealers (28), (28) and vertical sealers (30), (30) are illustrated as rotary sealers, a variety of sealers are contemplated. These sealers may include, but are not limited to, sealers having dual cam means and the like which can provide high speed operation of the machine described herein.

It should be understood, of course, that the apparatus, methods and packing materials described above are intended to illustrate embodiments of the invention and do not limit the scope of the invention, which is defined by the claims set forth below. It should also be understood that alternatives to and equivalents of the specific embodiments described can be made and indeed are contemplated without departing from the scope of the invention as defined in the claims set forth below.

Claims

1. A plastic shock absorber for packing comprising a series of hollow plastic bodies having heat pressed end portions connecting one body to another, said end portions located at alternating horizontal and vertical intervals, such that each body forms a generally trigonal-shaped hollow unit, each unit being filled with a gas cooler than than of the ambient air when injected into said plastic body.

2. The plastic shock absorber of claim 1, wherein said plastic body is made of a laminated film comprising at least one material selected from the group consisting of polyethylene, polyester and polyamide.

3. The plastic shock absorber of claim 1, wherein said gas is air.

4. The plastic shock absorber of claim 1, wherein said gas is cooler than ambient air when injected into said hollow plastic bodies by at least 10 C.

5. The plastic shock absorber of claim 4, wherein said gas is cooler than the ambient air by at least 20 C.

6. The plastic shock absorber of claim 1, wherein each heat-pressed end portion has at least one of a cut and score line.

7. A process for producing a plastic shock absorber for packing comprising the steps of: heat sealing a plastic film to form a hollow cylindrical body; and heat sealing said cylindrical body at alternating horizontal and vertical strips at suitable intervals to create generally trigonalshaped hollow units while blowing a gas into said cylindrical body, said gas being cooler than the ambient air when injected into said cylindrical body.

8. The process of claim 7, wherein said plastic film is a laminated film comprising at least one material selected from the group consisting of polyethylene, polyester and polyamide.

9. The process of claim 7, wherein said gas is air.

10. The process of claim 7, wherein said gas is controlled to be sufficiently cooler than the ambient air when injected into said plastic cylindrical body to create bulbous trigonal-shaped bodies upon being warmed to ambient conditions.

11. The process of claim 10, wherein said gas in controlled to be cooler than the ambient air by at least 10 C.

12. The process of claim 7, including making a cut on certain of said heat pressed strips.

13. A shock absorbing material made from plastic film material in an elongated tubular configuration and adapted for use as dunnage comprising: a plurality of hollow units maintained in a generally bulbous configuration by gas contained therein; a plurality of heat-sealed end portions defining and connecting successive hollow units; successive heat-sealed end portions being disposed in spaced, generally perpendicular relationship wherein said spaced hollow units are disposed in alternating complimentary positions to facilitate use of said shock absorber as dunnage.

14. The packing material of claim 13 wherein said hollow units are essentially trigonal in shaped.

15. The packing material of claim 13 wherein said contained gas is injected into said hollow units at temperatures sufficiently below ambient temperatures to provide a firm, bulbous, shock absorbing structure upon elevation of the temperatures of said contained gas to ambient conditions.

16. The packing material of claim 15 wherein said contained gas is injected into said hollow units at temperatures of about 10 C or more below ambient temperatures.

17. The packing material of claim 15 wherein said contained gas is injected into said hollow units at temperatures of about 200C or more below ambient temperatures.

18. A continuous plastic shock absorbing packing material comprising: a plurality of spaced gas-filled units maintained in a generally bulbous, inflated configuration by entrapped gas contained therein; and a plurality of heat-sealed end portions separating said spaced units and located at alternating intervals; wherein each unit is filled with gas at a temperature sufficiently below ambient temperatures during injection such that said bulbous, inflated condition is maintained at temperatures at least 600C below the temperature at which said gas is injected.

19. The plastic shock absorbing packing material of claim 18 wherein said gas-filled units are formed in a generally trigonal shaped.

20. The plastic shock absorbing material of claim 19 wherein said gas is injected into said gas-filled unit at temperature of at least 10 C below ambient temperature.

21. The plastic shock absorber of claim 20 wherein gas is air and the temperature at which said gas is injected into said gas-filled unit is at least 200C below ambient temperature.

22. The plastic shock absorber of claim 18 wherein said gas is injected into said gas-filled unit at pressures between about 1 0mm and 100mm of water

23. The plastic whock abosrber of claim 22 wherein said pressure is between about 20mm and 35mm of water.

24. A method of producing a dunnage shock absorber manufactured from plastic film material having a plurality of bulbous units in which a gas is contained, comprising forming plastic film material into a tubular body, forming a first tranverse end heat seal proximate the leading edge of said tubular body thereby closing said end, introducing a gas into said portion of said tubular body rearwardly of said first transverse end seal, forming a second transverse end heat seal in said tubular body rearwardly of and spaced from said first transverse heat seal at an angle relative to said second end seal thereby forming a hollow unit between said end seals having gas entrapped therein, introducing a gas into the portion of said tubular body rearwardly of said second end transverse heat seal and forming a third end transverse heat seal in said tubular body rearwardly of said second end tranverse heat seal and forming a third end transverse heat seal in said tubular body rearwardly and spaced from said second end transverse seal at an acute angle relative to said second end heat seal corresponding to the acute angle between said first and second end heat seals thereby forming a complimentary shaped hollow unit between said second and third end heat seals having gas entrapped therein.

25. The method of claim 24 wherein said first tranverse heat seal is horizontal, said second end heat seal is vertical and said third end heat seal is horizontal, and said first transverse heat seal is at an acute angle relative to said second end heat seal.

26. The method of claim 24 wherein said gas is air and is introduced into said portion of said tubular body at temperatures at least between about 1 00C to 200C below ambient temperatures.

27. A method for making a plastic packing material having a series of hollow interconnected plastic units that contain a gas comprising forming a generally tubular body from a plastic film, heat sealing said tubular body at preselected spaced intervals to form a series of successive units, and injecting a gas cooled to temperatures below the ambient temperature into said units before they are sealed to thus form a series of gas-filled bulbous shock absorbing units.

28. The method of claim 27 wherein heat sealing is carried out at alternating intervals that are in an angular relationship with respect to one another.

29. The method of claim 27 wherein the heat sealing of each end portion of each plastic unit is carried out at an angle of abut 90 C from each opposing end portion to form a series of generally trigonal-shaped units.

30. The method of claim 29 wherein the heat sealing is carried out at pressures between about 4 and 10Kg/cm2 for 0.3 to 0.7 seconds at spaced intervals of about 4 to 10 cm.

31. An apparatus for producing a dunnage shock absorber manufactured from plastic material and having a plurality of bulbous hollow units in which an entrapped gas is contained comprising: means for forming said plastic material into a tubular body; means for forming a first transverse end heat seal proximate the leading end of said tubular body to close said end; means for introducing a gas into the portion of said tubular body rearwardly of said first tranverse end seal; and means for forming a second transverse end heat seal in said tubular body rearwardly of and spaced from said first transverse heat seal and at an acute angle relative to said first end heat seal to form a hollow units between said end seals having entrapped gas contianed therein.

32. The apparatus of claim 31 wherein said means for forming said plastic material into a tubular body includes means for drawing said plastic material down line.

33. The apparatus of claim 31 wherein said means for forming said plastic material into a tubular body includes means for heat sealing said plastic material along the substantial entirely of its longitudinal dimension.

34. The apparatus of claim 31 wherein said means for forming said plastic material into a tubular body includes means for maintaining pressure on said plastic material thereby tightly sealing said plastic material along the substantial entirely of its longitudinal dimensions.

35. The apparatus of claim 31 wherein said means for forming said first tranverse end heat seal comprises a first heat sealer.

36. The apparatus of claim 35 wherein said first heat sealer is a vertical heat sealer.

37. The apparatus of claim 31 wherein said means for introducing said gas includes a low temperature generator.

38. The apparatus of claim 31 wherein said means for introducing said gas includes an injection pipe.

39. The apparatus of claim 31 wherein said means for introducing said gas includes a pressure detector and a temperature detector.

40. The apparatus of claim 31 wherein said means for forming said second tranverse end heat seal comprises a second heat sealer.

41. The apparatus of claim 40 wherein said second heat sealer is a horizontal heat sealer.

42. The apparatus of claim 40 wherein said second heat sealer includes means for at least one of scoring and cutting said plastic film.

43. The apparatus of claim 31 including tubular body advancing means for moving said tubular body downline in a generally continuous manner.

44. The apparatus of claim 43 wherein said tubular body advancing means includes a sponge-like roller.

45. A multi-station apparatus for producing a shock absorber manufactured from plastic film material and having a plurality of connected trigonal-shaped bulbous hollow units in which an entrapped gas is contained comprising: means for drawing said plastic film material downline; means for heat sealing said plastic film material along substantially its entire length thereby forming said plastic film material into a tubular body; means for maintaining pressure along said longitudinal heat seal of said tubular body; means for selectively transversely heat sealing the leading edge of said tubular body to close said end; means for introducing gas into the portion of said tubular body rearwardly of said leading edge heat seal; means for sensing the pressure and temperature of said gas as it is introduced into said tubular body; and means for selectively tranversely heat sealing said tubular body rearwardly of and spaced from said leading edge heat seal and at an acute angle relative to said leading edge heat seal to form a series of trigonal-shaped hollow units between each of said heat seals having entrapped gas contained therein.

46. The apparatus of claim 45 including tubular body advancing means for moving said tubular body downline in a generally continuous manner.

47. The apparatus of claim 46 wherein said tubular body advancing means comprises at least one sponge-like roller.

48. The apparatus of claim 46 wherein said tubular body advancing means comprises a pair of sponge-like rollers.

49. The apparatus of claim 45 wherein said means for selectively transversely heat sealing the leading edge of said tubular body comprises a vertical heat sealer.

50. The apparatus of claim 45 wherein means for selectively transversely heat sealing said tubular body rearwardly of and spaced from said leading edge comprises a horizontal heat sealer.

51. A multi-station apparatus for producing a shock absorber manufactured from plastic film and having a plurality of bulbous hollow units in which an entrapped gas is contained comprising: a draw roller assembly for drawing said plastic film downline; a heating assembly for heating sealing said plastic film along substantially its entire length thereby forming said plastic film into a tubular body; a sealing roller assembly for maintaining pressure along and tightly sealing said longitudinal heat seal of said tubular body; a tubular body advancing roller assembly for moving said tubular body downline; a first heat sealing assembly for selectively transversely heat sealing the leading edge of said tubular body thereby closing said leading edge end; an injection assembly for introducing gas into the portion of said tubular body rearwardly of said leading edge heat seal; and a second heat sealing assembly for selectively transversely heat sealing the trialing edge of said tubular body rearwardly of and spaced from said leading edge heat seal, thereby entrapping gas between said heat seals forming a series of bulbous hollow units.

52. The multi-station apparatus of claim 51 wherein said first heat sealing assembly includes a vertical heat sealer and said second heat sealing assembly includes a horizontal heat sealer whereby said trailing edge heat seal is formed at an acute angle relative to said leading edge heat seal to form a series of trigonal shaped bulbous hollow units.

53. The multi-station apparatus of claim 52 wherein said draw roller assembly includes a pair of draw rollers; said sealing roller assembly includes a pair of sealing rollers and said tubular body advancing roller assembly includes a pair of sponge-like rollers.