Injection-molded end stop for a slider-operated fastener

ES 2 320 195 T3

DESCRIPTION

Injection molded end stop for slide operated closure.

Field of the invention

The present invention relates generally to reclosable plastic bags and, more specifically, to an injection molded end stop for a slide operated closure.

Background of the invention

A closure arrangement for reclosable plastic bags typically includes a closure, a slide, and a pair of end stops. The closure includes first and second rails. The first rail includes a first profile, and the second rail includes a second profile for engaging the first profile. The slide is slidably mounted on the closure to move between opposite ends of the closure. End stops are located at opposite ends of the closure.

The end stops perform three functions: (1) preventing the slide from exceeding the ends of the closure, (2) keeping the profiles together to resist the stresses applied to the profiles during normal use of the plastic bag, and (3 ) minimization of leakage from inside the plastic bag through the ends of the closure. In US Patent No. 5,067,208, each end stop is shaped like a moderately rigid strap / fastener that wraps around the top of the closure. One end of the strip is provided with a rivet-like member that penetrates through the flaps of the closure and into a cooperating opening at the other end of the strip. In US patents. numbers 5,924,173 and / or 5,833,791 and / or 5,482,375 and / or 5,448,807 and / or 5,442,837 and / or 5,405,478 and / or 5,161,286 and / or 5,131,121 and / or 5,088,971 other types of end stops are disclosed; and documents EP0240991 A2 and US 4 842 799 disclose other types of end stops.

For example, US Patent No. 5,833,791 proposes an injection molded end stop disposed along only one exterior of the closure outside of a pair of profiles hooked together. The narrow end stop is spaced from a cutting edge at the end of the closure and extends along the length of the closure only a very short distance. On the other hand, the process of manufacturing the softened plastic material for its injection around the closure and the molding of the plastic material inside the end stop is fast, efficient and economical. On the other hand, because the end stop is so limited in size as it is not firmly anchored, the end stop is more brittle than some other types of end stops such as the riveted strip mentioned above. As a consequence, the end stop may not be able to withstand some of the misuse and stress that can be caused by the slide during normal use of the plastic bag.

Accordingly, there is a need for an injection molded end stop that overcomes the drawbacks associated with prior injection molded end stops.

Summary of the invention

A closure arrangement according to the invention is defined in claim 1 including a closure, a slide and an injection molded end stop. The closure includes first and second rails. The first rail includes a first profile, and the second rail includes a second profile for engaging the first profile. The closure extends between the first and second ends. The slide is slidably mounted on the closure to move between the first and second ends. The injection molded end stop is located at at least one of the first and second ends. The end stop causes the slide travel to end at one of the first and second ends. The end stop includes an interior plastic material disposed in an interior of the closure between the first and second profiles. The one of the first and second ends includes a cutting edge that forms an angle with an axis of the closure extending between the first and second ends. The end stop may include exterior plastic material along an exterior of the closure outside of the first and second profiles and covering the cutting edge. A method of forming the end stop is also disclosed.

Brief description of the drawings

Other objects and advantages of the invention will become apparent upon reading the following detailed description, with reference to the drawings, in which:

Figure 1 is an isometric view of a reclosable plastic bag, the bag including a closure arrangement along its mouth, the closure arrangement including a slide closure and a pair of end stops at opposite ends of the closure;

Figure 2 is an enlarged isometric view of one end of the closure prior to formation of an end stop;

Figure 3 is an enlarged isometric view of the closure showing a pair of reciprocating molds in an open position;

ES 2 320 195 T3

Figure 4 is a side view of one of the molds;

Figure 5 is an enlarged isometric view of the end of the closure showing the pair of molds in a closed position while forming the end stop;

Figure 6 is an enlarged isometric view of the end of the closure showing the pair of molds returned to the open position after formation of the end stop;

Figure 7 is an enlarged isometric view of the end of the closure after formation of the end stop;

Figure 8 is a sectional view taken generally along line 8-8 of Figure 7;

Figure 9 is a sectional view taken generally along line 9-9 of Figure 7;

Figure 10 is a side view of the end of the closure prior to formation of the end stop, in accordance with one embodiment of the present invention;

Figure 11 is a sectional view taken generally along line 11-11 of Figure 10; Y

Figure 12 is a sectional view similar to that of Figure 11 after formation of the end stop.

Although the invention is susceptible to various modifications and alternative forms, a specific embodiment thereof has been shown in the drawings, by way of example, which will be described in detail below. However, it should be understood that the scope of the invention is defined by the appended claims.

Description of illustrative embodiments

Returning to the drawings, Figure 1 depicts a reclosable plastic bag 10. Bag 10 includes a pair of facing panels 12 and 14 joined along a pair of sides 16 and a bottom portion 18 connecting the pair of sides. The bag 10 also includes a closure arrangement 19 along its mouth opposite the bottom 18. The closure arrangement 19 includes a closure 20, a slide 22, and a pair of injection molded end stops 24. Referring to Figure 2, the closure 20 includes first and second rails 26 and 28 facing each other. The first rail 26 includes a first profile 30, and the second rail 28 includes a second profile 32 for engagement with the first profile. Preferably, the first profile 30 forms a groove and, preferably, the second profile 32 forms a rib for insertion into the groove of the first profile. Referring again to Figure 1, injection molded stops 24 are located at opposite ends of closure 20. Slider 22 is slidably mounted on closure 20 to move to said opposite ends. The end stops 24 terminate the movement of the slider 22 at the respective ends of the closure 20. In one embodiment, slider 22 disengages profiles 30 and 32 as slider 22 moves in an opening direction toward one of end stops 24, and engages profiles 30 and 32 as slider 22 moves in a closing direction towards the other of the end stops 24.

Figure 2 is an enlarged view of one end of closure 20 prior to formation of end stop 24. The end of the closure 20 includes an edge 34 angled to an axis of the closure 20 that extends between opposite ends of the closure. Preferably, this angle is 90 degrees such that the cutting edge 34 is perpendicular to the axis of the closure 20.

Figures 3 to 6 depict an end stop that forms an application stop of each end stop 24 to the closure 20. Each end stop 26 is made of a predetermined quantity of flowable plastic material that migrates or is injected from a supply tube 36 to through one of the molds 38 and 40 of a reciprocating pair. At the stop shown the supply tube 36 injects the plastic material into an interior surface or cavity of the mold 38.

End stop 24 is comprised of one or more flowable plastic materials that can solidify and anchor to closure 20. Flowable materials can be thermoplastic or thermoset materials. Typical base materials for making the end stop may include polyolefins such as polymethylpentene, cyclic olefin copolymer, and blends of these polymers with PE or PP; thermoplastics such as ethylene-vinyl acetate, polyethylene, polyvinyl acetates, polypropylene, polyesters (PET, PPT, PBT, PEN, etc.), polyamides (nylon 6, nylon 6,6, etc.), polycarbonate, polyarylates, polysulfones (PSU, PESU, etc.), polyimides (PEI, PAI, etc.), liquid crystal polymers, acrylics (PMMA, etc.), sterenic (PS, HIPS), polyphenylene oxide / sulfide (PPO / PPS), polyacetals, polyvinyl butyrate, cellulosics (cellulose acetate, triacetate, etc.), polyketones (peek, etc.), polyurethanes, fluorohydrocarbons (PTFE, ECTFE, PVDF, etc.) and others; and thermosets such as phenolic resins, amino resins, unsaturated polyester resins, epoxy resins, urethanes, silicone resins, allyl resins, etc. Other modifying components may include some of the following combinations of the following: 1) adhesives to promote hydration, flexibility and adhesion, such as rosin, sticky polymers, terpenes, hydrocarbons, and chlorinated hydrocarbons, 2) plasticizers to promote flexibility and hydration, such as phthalates, glycolates, polybutenes, and mineral oil, 3) wax to dilute, not clog, stiffen, and promote hydration and vary hardening speed, such as paraffin, microcrystalline, vegetable and synthetic wax, 4) expander to reduce costs and control

ES 2 320 195 T3 the melt or color flow, such as talc, barites or clay, 5) antioxidant to maintain and stabilize viscosity, color and odor, such as inhibited phenols, and 6) colorants.

The inner surface of each mold (eg, mold 38 of FIG. 4) defines a funnel-shaped receiving channel 42 that receives the flowable plastic material from the supply tube and a guide channel 44 that guides the received plastic material into the end of the closure 20.

The guide channel 44 includes a deep section 44a and a shallow section 44b. The deep section 44a is directly coupled to a lower end of the receiving channel 44 and supports the cutting edge 34 of the closure and the immediately adjoining section when the molds 38 and 40 are closed around the end of the closure 20. The deep section 44a is deep enough that there is a small gap between the outer surface of the associated closure profile and the wall of the deep section 44a when the molds 38 and 40 are closed around the end of the closure 20. The shallow section 44b it extends from the deep section 44a and supports a portion of the closure proximate the cutting edge 34 when the molds 38 and 40 are closed around the end of the closure 20 (see FIG. 5). Shallow section 44b is shaped to fit snugly around the outer surface of the associated closure profile when molds 38 and 40 are closed around the end of the closure.

20.

In the stop-forming end stop, the reciprocating molds 38 and 40 are initially in an open position shown in Figure 3. In response to the transport of the end of the closure 20 between the separated molds 38 and 40, the molds 38 and 40 move to a closed position depicted in Figure 5. As the molds 38 and 40 are closed around the end of the closure 20, a predetermined amount of flowable plastic material is forced to flow around and between the profiles of the closure by a conventional reverse pressure device (not shown) coupled to the tube. supply.

Due to the small gap between the wall of the deep section 44a of the guide channel 44 and the associated seal profile, the deep section 44a allows a portion of the injected plastic material to flow along an exterior of the seal 20 out of the way. profiles 30 and 32. The outer plastic material essentially forms a thin sheet covering the outer surface of profiles 30 and 32 of the closure at the end of closure 20. Because there is no gap between the wall of the shallow section 44b of the guide channel 44 and the associated seal profile, the outer plastic material stops migrating along the outside of the seal 20 at the junction between the sections 44a. , 44b deep and shallow of the guide channel 44. The injected plastic material, in addition to flowing along an exterior of the closure 20, covers the cutting edge 34. As the plastic material covers the cutting edge 34, a portion of the injected plastic material is introduced into an interior of the closure 20 via the cutting edge 34 and flows inwardly between the profiles 30 and 32, starting from the edge 34 cutting. The cooled molds 38 and 40 shape and solidify the plastic material.

Once the injected plastic material is molded around and between the profiles 30 and 32 and solidified, the reciprocating molds 38 and 40 are returned to the open position shown in Figure 6. The resulting closure pattern, which includes the stop 24 injection molded terminal is shown in Figure 7. As indicated above, the plastic material includes both an outer part and an inner part. The outer plastic material covers the orthogonal cutting edge 34 at the end of the closure 20 and, starting from this cutting edge 34, the outer plastic material extends along the outside of the closure 20 by a Lext length equal to or greater than zero. and, more preferably, at least 0.762 mm (0.030 inches), and most preferably about 1.270 mm to 1.575 mm (0.050 to 0.062 inches) (see Figure 9). In addition, the outer plastic material has a thickness equal to or greater than zero, and most preferably about 0.254 mm (0.010 inches). In other words, the thickness represents the distance that the outer plastic material extends outward from the outer surface of the closure 20. The inner plastic material extends along the interior of the closure 20 in a Lint length of at least about 0.381 mm (0.015 inches), starting from the cutting edge 34 (see FIG. 9).

Referring again to Figures 1 and 2, the slide 22 includes a spreader finger 23 that extends downwardly from the top wall of the slide and between the profiles 30 and 32. As its name indicates, the spreader finger 23 assists in separating or disengaging profiles 30 and 32 as slider 22 travels along the closure in the "open" direction. As the slider 22 moves along the closure 20 in either "open" or "closed" direction and approaches one end of the closure 20, the separating finger 23 contacts the interior plastic material of the end stop 24 to terminate the slide movement 22. To assist in terminating the movement of slide 22, end stop 24 and / or slide 22 may be designed so that the forward end of the slide simultaneously contacts the outer plastic material of end stop 24. More information regarding the slide 22 and the manner in which the closure 20 operates can be obtained from US Pat. 5,007,143.

In Figures 1-9, the injection molding process causes some plastic material to flow into the closure 20 between the profiles 30 and 32 via the cutting edge 34. This inner plastic material increases the resistance of the end of the closure provided by the end stop 24. To further increase end strength, closure 20 may include an opening 46 proximate each of its opposite ends as depicted in Figures 10 and 11. As shown in Figure 12, opening 46 allows more plastic material to flow between profiles 30 and 32 during the injection molding process. Specifically, the injection molding process causes the plastic material to flow into the closure 20 between the profiles 30 and 32 through both

ES 2 320 195 T3 of the cutting edge 34 as of the opening 46. The opening 46 extends from the outside of the closure 20 out of the profiles 30 and 32 into the closure 20 between the profiles 30 and 32. Preferably, the aperture has a minimum diameter of approximately 0.762mm (0.030 inch). At smaller diameters, the opening can be created with a piercing needle; at larger diameters, the opening can be created with a piercing mechanism.

Preferably, the end stop is designed to exert a minimum slide retention force of approximately 3 to 4.5 pounds (1.4 kg to 2.0 kg), which should retain the slide on the clasp during normal use of the bag. To achieve this retention force, different parameters can be varied with respect to each other, such as (1) the length Lext, the thickness, and the length Lint, of the end stop, (2) the diameter of the opening, and ( 3) the composition of the end stop. The increments of one dimension can allow the decrement of another dimension. For example, it is possible to make a functional end stop by injecting plastic material into closure 20 only, without any exterior plastic material.

Although the present invention has been described with reference to one or more specific embodiments, those skilled in the art will recognize that many changes can be made thereto, without departing from the scope of the present invention. For example, the molds can be modified to allow the simultaneous formation of a pair of injection molded end stops on contiguous bags in a line of interconnected bags. In this case, an end stop is formed at a rear end of a closure segment of one bag and another end stop is formed at a leading end of a closure segment of the next adjoining bag. To achieve the simultaneous formation of a pair of end stops, each mold can be designed with two sets of identical channels symmetrically around a vertical plane in which each set of channels is used to receive and guide flowable plastic material for the formation of a respective end stop. Each of these embodiments and their obvious variants are contemplated, whereby the scope of the invention is set forth in the following claims.