Plastic and nonmetallic article shaping or treating: processes – Mechanical shaping or molding to form or reform shaped article – To produce composite – plural part or multilayered article
Reexamination Certificate
2001-05-29
2004-02-24
Ortiz, Angela (Department: 1732)
Plastic and nonmetallic article shaping or treating: processes
Mechanical shaping or molding to form or reform shaped article
To produce composite, plural part or multilayered article
C264S328800
Reexamination Certificate
active
06696003
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to beltings and more particularly to a modular conveyor belt comprising interconnected modules of a similar integral construction. The modules comprising the conveyor belt preferably include an antimicrobial material associated therewith to inhibit bacterial growth and which is safe for human contact. More particularly, the modules are formed of an injection molding process as a sandwich layer construction.
2. Prior Art
Modular conveyor belts are well known. For quality control purposes in the food industry it is desirable that the conveyor be readily inspected to assure cleanliness. Government and industry regulations also specify standards of inspection and cleanliness for equipment used in processing products for human consumption. There is, therefore, a need for a conveyor belt having associated therewith an antimicrobial material that inhibits bacterial growth and promotes improved hygiene conditions on the belting through extended wear, and that is safe for human contact. The antimicrobial material must also conform to the regulatory requirements of the country in which it is used. As will be explained in detail presently, the conveyor belt of the present invention built from modules comprising a central core of a first polymeric material completely encased by a polymeric skin of a second material and having an antimicrobial material associated with at least the skin material meets these criteria. This module configuration is referred to as a sandwich layer construction.
SUMMARY OF THE INVENTION
The sandwich layer construction provides a module whose cross-section has a three-layer configuration. The outer or “skin” surface is of a polymeric material containing the antimicrobial material or compound, and the inner or “core” structure consists of another material, preferably a polymeric material. Antimicrobial materials are relatively expensive. In order to inhibit bacterial growth on a module, they only need to be present in the outer regions of the polymeric module. Also, in today's environmentally conscious society, there is an increased emphasis on recycling, which has prompted many molders to look for ways to use reground material.
The sandwich layer module configuration effectively uses reground material as the core since it still has adequate physical properties. This construction takes advantage of the fact that the outer (skin) material is relatively thin, thereby helping reduce the cost of the molded article by minimizing the amount of virgin material and the amount of polymeric material containing an antimicrobial material. According to the present invention, the core of the sandwich module can also be a relatively inexpensive polymeric material, such as polyethylene, in comparison to the skin material which is of a higher grade.
In one preferred molding technique referred to herein as the sandwich molding method, the sandwich configuration is achieved when two polymeric materials are conveyed one after the other into the mold cavity. When the polymeric materials are injected under laminar flow conditions, the injection melt begins to solidify immediately as it contacts the mold wall so that the melt at the center of the flow advances faster than the melt in the vicinity of the mold wall. Accordingly, polymeric material injected later displaces material injected earlier, particularly in the middle of the cross-section of the flow stream, while the melt that contacts the cold mold walls solidifies to form and maintain the outer or skin layer of the module. In this manner, the second polymeric material devoid of the antimicrobial material serves as the core structure and provides the module of the present invention having a sandwich or three-layer configuration.
To ensure that the polymeric material intended to be the core of the module does not mix with the skin polymeric material in the sandwich molding method, the skin material having the antimicrobial material provided therein is always injected first. The core material then follows at a short timed overlap. The overlap in injection of the two materials is necessary to prevent the melt flow front from momentarily stopping which would result in surface blemishes called “knit lines”. With this type of timed sequence, the second (core) material must be a subsequent melt stream that flows through the flow cross-section of the first injected antimicrobial-containing polymeric material in order to form the sandwich configuration.
Another preferred method for manufacturing a module having a sandwich layer configuration is termed an over molding method and comprises providing the core of the module in a first mold. The core is then centered in a second mold of a somewhat larger shaped cavity to provide an annulus about the entire surface of the core. A second polymeric material containing the antimicrobial material is then injected into the second mold to fill the annulus and bond to the core as the skin polymeric material.
In that respect, the present invention relates to a modular conveyor belt having antimicrobial characteristics that inhibit bacterial growth and which is safe for human contact, the belting comprising: a plurality of like modules of a polymeric material, each module comprised of a polymeric material and including a first plurality of link ends, a second plurality of link ends and an intermediate section integrally formed with and joining the first and second plurality of link ends, wherein the link ends of each of the modules are releasably engaged between link ends of an adjacent module except for individual link ends disposed at the extreme sides of the module; a pivot rod for pivotally connecting the modules at engaged link ends; and an antimicrobial material incorporated into the polymeric material thereof, wherein the antimicrobial material is selected from the group consisting of antimicrobial compounds based on Mg
+2
, Ca
+2
, Zn
+2
, Ag
+2
, Cu
+2
, Al
+3
, their oxides and hydroxides, zinc pyrithione, imidazole, mixtures thereof, and wherein when the antimicrobial agent is incorporated into the polymeric material comprising the modules, the antimicrobial agent continuously inhibits bacterial growth on the belting and is safe for human contact. Further, the polymeric material comprising the module is in a sandwich layer construction having a first skin polymeric material supported on a second core polymeric material, and wherein the antimicrobial material is incorporated into the skin polymeric material at a greater concentration than that in the core.
It is also contemplated by the present invention that the pivot rod can be of a sandwich molded configuration having the antimicrobial compound concentrated in the skin material.
These and other aspects of the present invention will become more apparent to those of ordinary skill in the art by reference to the following description and to the appended drawings.
REFERENCES:
patent: 3269526 (1966-08-01), Imse et al.
patent: 3870141 (1975-03-01), Lapeyre et al.
patent: 4459257 (1984-07-01), Baciu
patent: 4715802 (1987-12-01), Arai
patent: 5101966 (1992-04-01), Lapeyre
patent: 5125504 (1992-06-01), Corlett et al.
patent: 5156264 (1992-10-01), Lapeyre
patent: 5361893 (1994-11-01), Lapeyre et al.
patent: 5433910 (1995-07-01), Mukai et al.
patent: 5443378 (1995-08-01), Jaroschek et al.
patent: 5469956 (1995-11-01), Greve et al.
patent: 5558204 (1996-09-01), Daringer
patent: 5586643 (1996-12-01), Zabron et al.
patent: 5634550 (1997-06-01), Ensch et al.
patent: 5645786 (1997-07-01), Okada et al.
patent: 5816389 (1998-10-01), van Zijderveld
patent: 6030567 (2000-02-01), Takeuchi
patent: 6039964 (2000-03-01), Sanduja et al.
patent: 6103167 (2000-08-01), Mukai et al.
patent: 6180042 (2001-01-01), Takeuchi et al.
patent: 6474464 (2002-11-01), Horton et al.
patent: 6499587 (2002-12-01), Greve
patent: WO 97/44172 (1997-11-01), None
patent: WO 00/37337 (2000-06-01), None
Cediel Luis
Honold Claudia Susanne
Habasit AG
Hodgson & Russ LLP
Ortiz Angela
LandOfFree
Methods for manufacturing a module for a modular conveyor... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Methods for manufacturing a module for a modular conveyor..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Methods for manufacturing a module for a modular conveyor... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3329839