EP0130602B1

EP0130602B1 - Interlocking closure device having controlled separation and improved ease of occlusion

Info

Publication number: EP0130602B1
Application number: EP84107591A
Authority: EP
Inventors: Gerald Harry Scheibner
Original assignee: First Brands Corp
Current assignee: Glad Products Co
Priority date: 1983-06-30
Filing date: 1984-06-29
Publication date: 1988-06-29
Also published as: ES287449U; FI850830L; IE841664L; IE55422B1; AU3101484A; FI78437B; NZ208748A; ES289498U; ES289498Y; FI850830A0; CA1267116A; WO1985000343A1; ES287448U; ES287449Y; DK160699C; JPS60501705A; EP0130602A1; PT78832B; DE3472387D1; ATE35404T1

Abstract

A female closure element comprising a U-shaped channel element including a profile portion (24) comprising a base portion (26) having a pair of spaced-apart, parallelly disposed webs (27) extending from the base portion (26) and terminating in hooks (28) extending nonlinearly from the webs and facing each other. The hooks (28) each include a projection (30) extending nonlinearly in a direction facing away from each other. The female closure element may be employed with a male closure element having a U-shaped channel element including a profile portion (18) comprising a base portion (20) having a pair of spaced-apart, parallelly disposed webs (21) attached to the base portion (20) and extending therefrom, the webs (21) terminating in hooks comprising hook portions (22) facing away from each other and hook projections (31) facing toward each other. The closure elements may be employed with containers (10) to provide thereto improved ease of occlusion and deocclusion.

Description

This application is related to copending European Patent Applications Nos. 84 107 590.6 and 84107589.8 (Publication Nos. 0130601 and 0130600).
This invention relates to closure fastening devices, and more particularly, to interlocking closure fastening devices having improved occlusion and deocclusion characteristics.
An interlocking closure fastening device comprising a female closure element and a male closure element formed such that the male closure element and the female closure element engage in interlocking relationship, the female closure element comprising a U-shaped channel element including a profile portion comprising a base portion having a pair of spaced-apart, parallelly disposed webs extending from the base portion, the webs terminating in hooks extending nonlinearly from the webs and facing toward each other, the male closure element comprising a U-shaped channel element including a profile portion comprising a base portion having a pair of spaced-apart, parallelly disposed webs extending from the base portion, the webs terminating in hooks comprising hook portions facing away from each other, is known from GB-A-2 017 813.
Closure fastening devices for use with plastic bags should be relatively easy to open and close, and also provide a satisfactory seal. However, it has been found that some prior art interlocking closure fastening devices suffer from a tendency of the male and female closure elements to straddle each other and to not occlude during attempted occlusion as opposed to a normaly occluded position. Such a non-occluded, and also straddled condition of the male and female closure elements on a plastic bag precludes occlusion of the closure elements and results in the bag contents not being securely contained within the bag. Therefore a need exists to provide more positive guidance of the opposing closure elements such that the elements engage more repeatedly into the normally occluded condition, and that the elements be inhibited from engaging into a non-occluded and straddled condition.
In addition, prior art interlocking closure fastening devices suffer from lack of significant controlled separation, i.e., deocclusion characteristics. The controlled separation characteristic of a closure device may be described as the ability to resist opening any further than the initial gap induced by the original opening force of the user. This deficiency in controlled opening manifests itself during opening of a plastic container or bag and is especially troublesome to a user during the closing or sealing operation of the container. More specifically, when plastic bags having closure fastening devices are partially opened, they can continue to open completely with little or no external separating force applied to the fastening device. Such a characteristic is desirable for opening the plastic bag but presents a disadvantage on closure since the user often desires to expel the preponderance of air from the bag prior to sealing. This is most desirably accomplished if the major portion of the fastening device is interlocked, and only a small aperture remains for expelling most of the residual air from the bag before accomplishing the final closure and sealing. Thus, there is a need to provide closure fastening devices which have controlled opening characteristics, so that a partially occluded bag will not deocclude, except to the extent that the user may further apply an opening force.
In conformity with the present invention an interlocking closure fastening device comprising . a female closure element and a male closure element formed such that the male closure element and the female closure element engage in interlocking relationship, the female closure element comprising a U-shaped channel element including a profile portion comprising a base portion having a pair of spaced-apart, parallelly disposed webs extending from the base portion, the webs terminating in hooks extending nonlinearly from the webs and facing toward each other, the male closure element comprising a U-shaped channel element including a profile portion comprising a base portion having a pair of spaced-apart, parallelly disposed webs extending from said base portion, the webs terminating in hooks comprising hook portions facing away from each other, is characterized in that the hooks of the female profile portion each include a projection extending nonlinearly in a direction facing away from each other.
The pair of projections extending from the hooks of the female profile portion in the form of a wing or ear increase the width of the transverse opening between the webs in the area of the hooks and provide a funneling action to guide occlusion of the female closure element with a complementary male closure element. The projections included on the female closure element inhibit the tendency for just one of the webs of the male closure element to enter the opening between the webs of the female closure element. The female closure element of this invention thus reduces the potential for straddling when occluding an interlocking closure fastening device comprising a female closure element and a male closure element, thereby resulting in greater ease of occlusion and the obtainment of secure occlusion therebetween. The projections on the female closure element reduce the necessity for precise alignment with the profile portions of a male closure element to attain occlusion therewith. Thus, the closing operation of an interlocking closure fastening device is facilitated for the user since occlusion is less dependent on precise transverse alignment of the interlocking profile elements.
In addition, the projections on the female closure element cause the 'interlocked profile elements to resist continued separation after partial deocclusion, thereby providing controlled separation of the interlocked profile elements. The controlled separation of the profile elements is due in part to contact interference between the female closure element projections and the male flange portions immediately adjacent the male profile portion during the process of deocclusion. The interlocking closure fastening device preferably has an occluded height of between about 1.52 mm (60 mils) and about 2.16 mm (85 mils), most preferably about 1.78 mm (70 mils), and a corresponding occluded width of between about 2.41 mm (95 mils) and about 3.18 mm (125 mils), most preferably about 2.79 mm (110 mils). The projections extending from the hooks of the female closure element preferably each have a length, on a proportionate scale to the occluded height and occluded width of the interlocking closure fastening device, of between about 0.20 mm (8.mils) and about 0.46 mm (18 mils), and the hooks of the female closure element preferably have a length, on a proportionate scale to the occluded height and occluded width of the interlocking closure fastening device, of between about 0.13 mm (5 mils) and about 0.25 mm (10 mils), and most preferably 0.25 mm (10 mils).
In a preferred embodiment of this invention, the female closure element of this invention is preferably employed with a male closure element as described in European Patent Application No. 84 107 590.6 (EP-A-0 130 601 Said male closure element comprises a U-shaped channel elemeht including a profile portion comprising a base portion having a pair of spaced-apart, parallelly disposed webs attached to the base portion and extending therefrom, said webs terminating in hooks facing away from each other. The hooks on each web of the male closure element comprise a hook projection wherein the two hook projections face toward each other. The two hook projections facing toward each other reduce the width of the transverse opening between the webs of the male closure element in the area of the hooks, thereby inhibiting the tendency for either of the webs of the female closure element to enter the opening between the webs of the male closure element. This male closure element reduces the potential for straddling when occluding an interlocking closure fastening device comprising a male closure element and a female closure element, thereby resulting in greater ease of occlusion and the obtainment of secure occlusion. The hook projections of the male closure element have lengths, on a proportionate scale to the occluded height and occluded width of the interlocking closure fastening device of between about 0.13 mm (5 mils) and about 0.51 mm (20 mils), and the hooks of the male closure element have lengths, on a proportionate scale to the occluded height and occluded width of the interlocking closure fastening device, of between about 0.13 mm (5 mils) and about 0.25 mm (10 mils) and preferably about 0.25 mm (10 mils).
As employed herein, the term "proportionate" is to indicate the relative proportions of the closure elements of the interlocking closure fastening device when the male and female closure elements are occluded. Thus, when the interlocking closure fastening device of this invention has an occluded height of between about 1.52 mm (60 mils) and about 2.16 mm (85 mils), and an occluded width of between about 2.41 mm (95 mils) and about 3.18 mm (125 mils), the lengths of the hooks of the female closure element are between about 0.13 mm (5 mils) and about 0.25 mm (10 mils), and the lengths of the hook projections of the female closure element are between about 0.20 mm (8 mils) and about 0.46 mm (18 mils) on a proportionate scale to the occluded height and occluded width of the interlocking closure fastening device. Likewise, the lengths of the hooks of the male closure element should be between about 0.13 mm (5 mils) and about 0.25 mm (10 mils), and the lengths of the hook projections of the male closure element should be between about 0.13 mm (5 mils) and about 0.51 mm (20 mils) on a proportionate scale to the occluded height and occluded width of the interlocking closure fastening device. Accordingly, when the occluded height and occluded width of the interlocking closure fastening device of this invention are either increased or decreased, then the lengths of the hooks and hook projections of the female closure element and those of the male closure element should be proportionately increased or decreased to maintain the relative proportions of the closure elements. Preferably the aforedescribed male and female closure elements have a base portion which is resiliently bendable.

Fig. 1 is a perspective view of a flexible container including a closure fastening device in accordance with the invention;
Fig. 2 is a sectional view of a female closure element in accordance with this invention;
Fig. 3 is a sectional view of a female closure element in accordance with this invention and a prior art male closure element in a misaligned position;
Fig. 4 is a sectional view of a female closure element in accordance with this invention and a prior art male closure element in a properly aligned position just prior to occlusion;
Fig. 5 is a sectional view of a female closure element in accordance with this invention and a prior art male closure element in an occluded position;
Fig. 6 is a sectional view of a male closure element in accordance with that shown in EP-A-0 130 601;
Fig. 7 is a sectional view of the female closure element shown in Fig. 2 and the male closure element shown in Fig. 6 in a misaligned position;
Fig. 8 is a sectional view of the female closure element shown in Fig. 2 and the male closure element shown in Fig. 6 in a properly aligned position;
Fig. 9 is a sectional view of the female closure element shown in Fig. 2 and the male closure element shown in Fig. 6 in an occluded position;
Fig. 10 is a sectional view of a female closure element in accordance with this invention and a prior art male closure element in a partially deoccluded position.
Fig. 11 is a sectional view of part of a female closure element in accordance with this invention and part of the male closure element shown in Fig. 10 wherein one pair of hooks is in an engaged condition, as in the occluded position.
Fig. 12 is a sectional view of part of a female closure element in accordance with this invention and part of the male closure element shown in Fig. 10 in a partially rotated position, such as during deocclusion; and
Fig. 13 is a sectional view of a female closure element in accordance with this invention and the male closure element shown in Fig. 6, in a partially deoccluded position.
Fig. 1 shows a typical flexible container 10 formed from a plastic film which is folded at bottom portion 11 and is heat sealed along the side edges 12 to form a pouch or bag. The sidewalls 13 may extend beyond a closure fastening device 14 to provide grasping sections 16 and 17 to simplify the opening of closure fastening device 14.

As shown in Fig. 3, the closure fastening device 14 comprises a male profile portion 18 which is connected to a flange portion 19 and includes a base portion 20, a pair of spaced-apart parallelly disposed webs 21 extending in a generally normal direction from the base portion 20, and male hooks 22 extending from webs 21 and facing away from each other. The male hooks each have a rounded crown surface 23, and 23' which generally serve to guide the hook for occlusion with the female hooks of a mating closure element. A female profile portion 24 is connected to flange portion 25 and includes a base portion 26, a pair of spaced-apart, parallelly disposed webs 27 extending in a generally normal direction from the base portion 26, and female hooks 28 extending from webs 27 and facing towards each other. Profile portions 18 and 24, as shown in Fig. 3, may be separately formed and thereafter connected to a film which forms sidewalls 13, or they may be integrally formed with sidewalls 13 as shown in Fig. 1.
In Fig. 2, the female closure element in accordance with this invention is shown in detail, wherein a pair of extensions or projections 30 on hooks 28 can be seen extending from the broken lines 29" shown therein to form an enlarged opening between the hooks 28. The projections 30 extend nonlinearly from the hooks 28 and in a direction away from each other, thereby increasing the width of the transverse opening in the area between the hooks to provide a guiding action for engagement with a male closure element. One effect of the projections 30 is to physically guide the hooks of the male closure element into alignment with the hooks of the female closure element and thereby inhibit the interlocking closure elements from slipping into an undesired straddling position. Such guidance of the hook of the male closure element by the projections on the female closure element assists the engagement of the closure elements into their proper occluded position.
In accordance with this invention, projections 30 may be any suitable length and configuration to provide the desired degree of guiding effect to the hooks of the male closure element. However, satisfactory results have been obtained when projections 30 have lengths, on a proportionate scale to the occluded height and occluded width of the interlocking closure fastening device, of between about 0.20 mm (8 mils) and about 0.46 mm (18 mils) as measured between the dotted lines 37 shown in Fig. 2. Further, when projections 30 of the female hooks 28 are contoured as shown in Fig. 2 it has been found that such a construction is more forgiving to misalignment and provides more positive guidance of the mating closure elements, and the elements engage more easily and accurately into the desired occluded position compared to prior art interlocking closure fastening devices.
Fig. 3 shows a female closure element in accordance with this invention in a misaligned position with respect to a prior art male closure element just prior to occlusion therewith. It can be seen that even though the female closure element and the male closure element are misaligned they will be guided into the desired occluding alignment by hook projections 30 nonlinearly extending away from each other and from female .hooks 28 for ultimate interlocking occlusion.
In Fig. 4 it can be seen that when the female closure element in accordance with this invention is properly aligned with a prior art male closure element just prior to occlusion, such will not only lead to greater ease of occlusion therebetween, but will also inhibit the movement of the female closure element and the male closure element into a straddle position.
In Fig. 5, the female closure element of this invention is shown in the normally occluded position with a prior art male closure element.
In Fig. 6, a male closure element is shown in accordance with that disclosed in EP-A-0 130 601, wherein hook projections 31 on hooks 22 can be seen extending from the broken lines 23", shown therein, to form a reduced gap between hooks, to thereby physically hinder the straddling of a male closure element and a female closure element. Thus, the desired hindrance of the straddle position that could occur between a male closure element and a female closure element is obtained, and likewise, the other desired characteristic of ease of occlusion is enabled by providing a guiding action for the hook surfaces of the female closure element to slide along the outside surfaces 32 of hooks 22 of the male closure element. Such guidance helps direct the male and female closure elements into their proper occluded position. As disclosed in EP-A-0 130 601, hook projections 31 may be any suitable length so as to virtually close the gap or void between them and preclude entrance therein of the hooks and webs of the female closure element, thereby virtually insuring occlusion and eliminating straddling between the male and female closure elements.
Manufacturing considerations may limit the extent to which hook projections 31 are brought close together thereby reducing the guidance effect between the male closure element and the interlocking female closure element of the instant invention. Satisfactory results have been obtained when the hook projections 31 on said male closure element have lengths, on a proportionate scale to the occluded height and occluded width of the interlocking closure fastening device, of between about 0.13 mm (5 mils) and about 0.20 mm (8 mils) as measured between the dotted lines 33 shown in Fig. 6. However, it is preferred that said hook projections 31 have lengths, on a proportionate scale to the occluded height and occluded width of the interlocking closure fastening device, of between about 0.13 mm (5 mils) and about 0.51 mm (20 mils), as such lengths provide the aforementioned desired characteristics to interlocking closure fastening devices. Further, the hooks 22 of the male closure element have lengths, on a proportionate scale to the occluded height and occluded width of the interlocking closure fastening device, of between about 0.13 mm (5 mils) and about 0.25 mm (10 mils) as measured between the dotted lines 34 shown in Fig. 6.
Fig. 7 shows a female closure element in accordance with this invention in a misaligned position with respect to the male closure element shown in Fig. 6 just prior to occlusion therewith. It can be seen that even though the female closure element and the male closure element are misaligned, they will be guided into the desired occluding alignment by female hook projections 30 extending away from each other from female hooks 28, and by male hook projections 31 extending toward each other from male hooks 22, for ultimate interlocking occlusion.
In Fig. 8, it can be seen that when the female closure element in accordance with this invention is properly aligned with respect to the male closure element of Fig. 6 just prior to occlusion, such will not only lead to greater ease of occlusion therebetween, but will inhibit the transverse movement of the female closure element and the male closure element into a non-occluded straddle position.
Fig. 9 shows the novel female closure element of this invention in the occluded position with a male closure element as shown in Fig. 6. In Fig. 9 the female closure element includes projections 30 each having a length, on a proportionate scale to the occluded height and occluded width of the interlocking closure. fastening device, of about 0.36 mm (14 mils) and the inside hook has a length, on a proportionate scale to the occluded height and occluded width of the interlocking closure fastening device, of about 0.25 mm (10 mils). The male closure element has inside hooks 22 having a length, on a proportionate scale to the occluded height and occluded width of the interlocking closure fastening device, of about 0.25 mm (10 mils), and hook projections 31 each having a length, on a proportionate scale to the occluded height and occluded width of the interlocking closure fastening device, of about 0.18 mm (7 mils).
Fig. 10 shows the female closure element of this invention and a male closure element in accordance with Fig. 3 in a partially deoccluded position. In Fig. 10, the inside male hook 22, and the inside female hook 28, have lengths, on a proportionate scale to the occluded height and occluded width of the interlocking closure fastening device, of 0.23 mm (9 mils), and 0.25 mm (10 mils), respectively. Projections 30 on the female closure element have a length, on a proportionate scale to the occluded height and occluded width of the interlocking closure fastening device of 0.30 mm (12 mils).
It can be seen from Fig. 11 and Fig. 12, during deocclusion of the female closure element of this invention and a male closure element that significant entrapment occurs between the inside female hook 28 and the inside male hook 22. That is, it can be seen that the hooks are spatially hindered from further rotation, thereby resisting further deocclusion. Entrapment also occurs as shown in Fig. 10 between projection 30 on the inside female hook 28 and the flange portion 36 adjacent the inside male web portion 21' of the male closure element. These portions of the closure fastening device require substantial bending and/or distortion thereof for complete deocclusion therebetween. Such required bending and/or distortion of the aforementioned closure elements results in controlled separation during deocclusion of the interlocked closure fastening device.
Fig. 13 shows the female closure element of this invention and the male closure element pursuant to Fig. 6 in a partially deoccluded position. In Fig. 13, the inside male hook 22 and the inside female hook 28, have lengths, on a proportionate scale to the occluded height and occluded width of the interlocking closure fastening device, of 0.25 mm (10 mils) and 0.25 mm (10 mils), respectively. Projections 30 on the female closure element each have a length, on a proportionate scale to the occluded height and occluded width of the interlocking closure fastening device of 0.36 mm (14 mils). Hook projections 31 on the male closure element each have a length, on a proportionate scale to the occluded height and occluded width of the interlocking closure fastening device, of 0.18 mm (7 mils).
It can also be seen in Fig. 13 that during deocclusion of this closure fastening device, substantial entrapment occurs between the inside female hook 28 and the inside male hook 22. Entrapment also occurs between projection 30 on the inside female hook 28 and the male flange portion 36 adjacent the inside web portion 21' of the male closure element. These portions of the closure fastening device require significant bending and/or distortion for complete deocclusion of the closure fastening device. Such required bending and/or distortion of the closure elements provides controlled separation during deocclusion of the interlocked closure fastening device.
When so contoured, the controlled separation characteristics of interlocking closure fastening devices, as provided by the female closure element of this invention, are the result of the following mechanism during the deocclusion. Separation of interlocking closure fastening devices involves disengagement of entrapped fitted sections of the closure profiles. Controlled separation results when one or more fitted sections of an occluded closure profile cannot easily separate from its or their corresponding matched sections via minor bending or distortion of either of their sections. This minor bending or distortion is restricted by the presence of projections 30 on the female closure element.
If desired, different materials can be used to form either or both of the matched sections of the closure devices so as to yield greater stiffness in the sections to be bent or distorted during deocclusion. Further, the size of matched sections can be increased or decreased to also correspondingly influence stiffness. In addition, the length of any engaging hooks of the closure devices can be increased or decreased to correspondingly cause greater or less entrapment of the fitted hook sections of the closure devices.
It should be noted that during the occlusion operation of a female profile portion and a male profile portion, at least one of the base portions flexes, or the webs flex, or the hooks flex, or a combination of these parts flex to achieve occlusion.
In accordance with this invention, separation of the resulting closure fastening device sections from an occluded condition becomes more controlled. This controlled separation is due to greater spatial hindrance of the inside female hook and hook projection during the process of deocclusion with the inside hook portion of the male closure element. Hindrance results from the inside male closure hook rotating, with respect to the inside female closure hook, and engaging therewith more completely as the outside hooks begin to separate, or are separating. Further separation is prevented by the entrapment of the inside female hook and projection in the cavity defined by the inside male hook and flange adjacent the inside male web. Separation then becomes possible only through bending and/or distortion of the hooks and/or adjacent areas, a process which requires greater force than that of the simple ftexing of bases, webs and hooks during deocclusion of a conventional closure fastening device.
Generally, the closure fastening devices of this invention may be formed from thermoplastic materials such as polyethylene, polypropylene, nylon, or the like, or from a combination thereof. Thus, resins or mixtures of resins such as high density polyethylene, medium density polyethylene and low density polyethylene may be employed to prepare the novel closure device of this invention.
The closure fastening device of the invention may be manufactured by extrusion, or other known methods of producing such devices. The closure fastening device can be manufactured as individual closure elements for later attachment to a film, or the closure elements can be manufactured integral with a film. In addition, the closure fastening device can be manufactured with or without flange portions on one or both of the closure elements depending upon intended use or expected additional manufacturing operations.
In the practice of the instant invention, the closure fastening device may be integrally formed with sidewalls of a container, or connected to a container, or to a film to be formed into a container, by the use of any of many known methods. A thermoelectric device can be applied to a film in contact with the flange portion of a closure element, or the thermoelectric device can be applied to a film in contact with the base portion of a closure element having no flange portion, to cause a transfer of heat through the film to produce melting at the interface of the film and the flange portion or base portion of the closure element. On cooling, the interface. region joins the film and the closure element. The thermoelectric device can be heated rotary discs; or resistance heated slide wires, or traveling heater bands, or the like. The connection between the film and the closure element can also be established by the use of hot melt adhesives, or hot jets of air to the interface, or ultrasonic heating, or other known methods. Generally, the closure fastening device and films can be made from a heat sealable material so that a container can be formed economically by heat sealing the aforementioned components to form the container.
The closure fastening device of this invention provides many advantages for use in containers to be used by consumers. For example, the closure device is easy to occlude and does not tend to twist and distort during attempted occlusion as in the case of some prior art devices such as the arrowhead-shaped device employed with a container available under the tradename ZIPLOC^O from Dow Chemical Company of Midland Michigan. This provides convenience in the occluding operation.
In addition, the closure fastening device is more difficult to deocclude from the inside of the containers than from the outside of the containers, thereby providing more secure containment of goods such as food products. The profile portions of the closure device have approximately uniform cross-sections. This not only simplifies the manufacturing of the device but it also contributes to the physical flexibility of the device, which is a desirable property.
In the examples, the following procedure was employed to evaluate the degree of controlled separation provided by various occluded closure fastening devices. An occluded closure fastening device sample was cut into three 305 mm (12 inch) long samples. The closure fastening device samples were each partially deoccluded or peeled apart at one end only. Each sample was tested independently as described herein. The partially deoccluded male portion of the closure fastening device was mounted in the upper jaw, and the female portion of the closure fastening device was mounted in the lower jaw of an Instron^@ tensile tester. The peel tension from the occluded closure fastening device is recorded on a strip chart recorder during deocclusion of 203 to 254 mm (8 to 10 inches) of the closure fastening device sample. The average value is taken visually from the near linear portion of the recording and is recorded as average zipper strength. The jaw separation (deocclusion) rate is 508 mm (20 inches) per minute and the full scale load is 100 grams. Each sample was reoccluded and retested for a total of 3 tests. The average value is reported for the three tests for all three samples.
The Instron instrument is a tensile tester Model No. 1130, using a "B" load cell with a zero to 100 gram range. The Instron tester is initially calibrated in the following manner. The pen and chart recorder are turned on. The zero button is pressed and held, and the zero adjust knob is positioned for a 0.00 reading on the recorder. The zero button is then released. The range switch is then turned to the setting of 1 on its 1, 2, 5, 10, 20 scale. The coarse balance control is turned so that if the pen is all ths way over to the left, it starts coming towards zero on the right. The coarse balance control is left at this position. Then the fine balance control is turned so that the pen is at a setting of 0.00. A 100 gram weight is placed in the upper jaw of the Instron instrument and the calibration control is adjusted for a full-scale recorder reading. After removing the 100 gram weight, the recorder should again read 0.00. The zero button is pressed and held, and the recorder should again read 0.00.
The test results are given in Table 1.
The Control represents a channel closure fastening device whose general configuration is depicted in Fig. 3 of GB-A-2 017 813. It is employed commercially as the closure fastening device for a container sold under the tradename SNAP LOCK@ by Union Carbide Corporation, Danbury, CT. The Control closure fastening device was made with low density polyethylene, that is, having a density of about 0.923 grams per cubic centimeter, wherein the lengths of the inside hooks of the male and female closure elements were about 0.15 mm (6 mils).
Example 1 was the same as the Control except that the female closure element was made with projections 30 as depicted in Fig. each having a length of about 0.30 mm (12 mils).
The closure fastening device of Example 2 was the same as the Control, except that the inside male and female hooks were lengthened from 0.15 mm (6 mils) to 0.25 mm (10 mils).
The closure fastening device of Example 3 was the same as that of Example 1, except that the polyethylene material employed to prepare the female closure element contained about 20 percent by weight of high density polyethylene, having a density of about 0.960 g/cm³, based on the weight of the closure element.
From the above results in Table 1, the average zipper strength values represent the amount of resistance encountered to further opening of the partially deoccluded closure fastening devices. This value is measured in grams when peeling or zippering the male and female portions apart in the lengthwise direction. It can be seen from the above values that the presence of projections 30 on the female closure element structure of this invention substantially increases the zipper strength of an interlocking closure fastening device.
Further improvement in controlled separation characteristics of interlocking closure fastening devices are obtained by lengthening the inside male and female hooks, i.e., the pair of hooks which is closer to the inside of the container. Further zipper strength improvement is provided to closure fastening devices by employing resin having greater stiffness.
A closure fastening device in accordance with this invention can also be used as a flexible straw because a good seal at the engaged surfaces is possible and a compartment defined by the occluded closure elements provides a passageway which does not collapse when the closure fastening device is bent moderately.
Generally, the closure fastening device of this invention can be manufactured in a variety of forms to suit the intended use. In addition, the male and female closure elements can be positioned on opposite sides of a film. Such an embodiment would be suited for enwrapping an object or a collection of objects such as wires. Generally, the male and female closure elements on a film should be parallel to each other, but this would depend on the intended use.

Claims

1. An interlocking closure fastening device comprising a female closure element and a male closure element formed such that said male closure element and said female closure element engage in interlocking relationship, said female closure element comprising a U-shaped channel element including a profile portion (24) comprising a base portion (26) having a pair of spaced-apart, parallelly disposed webs (27) extending from said base portion, said webs terminating in hooks (28) extending nonlinearly from said webs and facing toward each other, said male closure element comprising a U-shaped channel element including a profile portion (18) comprising a base portion (20) having a pair of spaced-apart, parallelly disposed webs (21) extending from said base portion, said webs terminating in hooks (22) comprising hook portions facing away from each other, characterized in that the hooks (28) of said female profile portion (24) each include a projection (30) 'extending nonlinearly in a direction facing away from each other.

2. An interlocking closure fastening device in accordance with claim 1 wherein the hooks (22) of said male profile portion (18) include hook projections (31) facing toward each other.

3. An interlocking closure fastening device in accordance with claim 1 or 2 having an occluded height of between about 1.52 mm (60 mils) and about 2.16 mm (85 mils), and a corresponding occluded width of between about 2.41 mm (95 mils) and about 3.18 mm (125 mils).

4. An interlocking closure fastening device in accordance with any one of claims 1 to 3 wherein said base portion (26) of said female closure element is resiliently bendable.

5. An interlocking closure fastening device in accordance with any one of claims 1 to 4 wherein said base portion (20) of said male closure element is resiliently bendable.

6. An interlocking closure fastening device in accordance with any one of claims 1 to 5 wherein at least one of said webs (27) of said female closure element is resiliently bendable.

7. An interlocking closure fastening device in accordance with any one of claims 1 to 6 wherein at least one of said webs (21) of said male closure element is resiliently bendable.

8. An interlocking closure fastening device in accordance with any one of claims 1 to 7 wherein at least one of said hooks (28) of said female closure element is resiliently bendable.

9. An interlocking closure fastening device in accordance with any one of claims 1 to 8 wherein at least one of said hooks (22) of said male closure element is resiliently bendable.

10. An interlocking closure fastening device in accordance with any one of claims 1 to 9 wherein said base portion (26) of said female closure element includes a flange portion (25).

11. An interlocking closure fastening device in accordance with any one of claims 1 to 10 wherein said base portion (20) of said male closure element includes a flange portion.

12. An interlocking closure fastening device in accordance with any one of claims 1 to 11 wherein each of said projections (30) extending from said hooks (28) of said female closure element has a length, on a proportionate scale to the occluded height and occluded width of said interlocking closure fastening device (14), of between about 0.20 mm (8 mils) and about 0.46 mm (18 mils).

13. An interlocking closure fastening device in accordance with any one of claims 1 to 12 wherein said hooks (28) on said female closure element have a length, on a proportionate scale to the occluded height and occluded width of said interlocking closure fastening device (14), of between about 0.13 mm (5 mils) and about 0.25 mm (10 mils).

14. An interlocking closure fastening device in accordance with any one of claims 2 to 13 wherein said hook projections (31) on said hooks (22) of said male closure element have lengths, on a proportionate scale to the occluded height and occluded width of said interlocking closure fastening device (14), of between about 0.13 mm (5 mils) and about 0.51 mm (20 mils).

15. An interlocking closure fastening device in accordance with any one of claims 1 to 14 wherein said hook portions of said male closure element have lengths, on a proportionate scale to the occluded height and occluded width of said interlocking closure fastening device (14), of between about 0.13 mm (5 mils) and about 0.25 mm (10 mils).

16. An interlocking closure fastening device in accordance with any one of claims 1 to 15 wherein said female closure element is connected to one of two sidewalls (13) of a container (10), and said male closure element is connected to the other of said two sidewalls.

17. An interlocking closure fastening device in accordance with any one of claims 1 to 15 wherein said female closure element forms an integral part of one of two sidewalls (13) of a container (10), and said male closure element forms an integral part of the other of said two sidewalls.