Stock material or miscellaneous articles – Hollow or container type article – Nonself-supporting tubular film or bag
Reexamination Certificate
2001-02-23
2003-02-11
Bell, Mark L. (Department: 1755)
Stock material or miscellaneous articles
Hollow or container type article
Nonself-supporting tubular film or bag
C428S036100, C428S364000, C264S210800, C264S211170, C524S292000, C524S293000, C524S284000
Reexamination Certificate
active
06517917
ABSTRACT:
The invention relates to shaped bodies and methods for their production, the shaped bodies being used for transporting, packaging, storing, and handling food products, the shaped bodies made of monofilaments based on polyesters, and the monofilaments required for this, as well as methods for their production.
Monofilaments based on polyesters have been known for some time and are used in very different fields of technology, for example, in the form of industrial textile materials, such as woven materials used in the pressing section of paper machines.
Such monofilaments are described, for example, in EP 0 342 563 A2.
In these fields of application, hydrolysis resistance and mechanical properties such as bending strength and splitting resistance are particularly important.
When used in the food industry, i.e., for objects that come into contact with food products, for example during transport, packaging, and storage or also during the handling of food products, such as in sieves or on drying belts, it is very important that the abrasion is very low, because even the most minuscule particles enter the food and may then result in a health hazard when these food products that carry the abraded particles are consumed.
It is also important that the materials that come into contact with food do not contain any substances that diffuse out of the object or can be dissolved from them and then enter the food. It is also important that these materials are not only hydrolysis-resistant but also are substantially resistant to chemical substances that may be released from food products themselves when these are contacted. This in particular includes, among others, organic acids, but also fats, esters, and similar substances.
Even though numerous materials are known that come into direct contact with food products during the transport, packaging, storage, and also handling of food products, there is still a need for analogous materials that are improved and can be easily produced.
It is therefore the objective of the invention to provide food-compatible materials which can be in direct contact with foods during transport, packaging, storage, and also handling, which are characterized by improved abrasion characteristics, in particular also by improved abrasion resistance, and which during the contact do not give off any abraded particles and harmful substances into the food, which are easily, economically and safely produced, and which meet today's requirements and demands for materials that come into contact with foods.
This objective is realized by food-compatible, flat-shaped bodies or shaped bodies made from flat shaped bodies, such as woven and non-woven materials, knits, multiaxial layers, flat structures, such as grids, net-shaped flat structures, etc., or shaped bodies made from these flat shaped bodies, such as sacks, bags, nets, sieves, filters, transport belts, etc., containing monofilaments based on polyester that contain 0.5 to 3.5% by weight of a polycarbonate. The shaped bodies according to the invention preferably contain monofilaments having a knife abrasion resistance of 55,000 to 170,000 abrasion cycles. It is preferred that the polyester that makes up the monofilaments is free from terminating agents, such as mono- or polycarbodiimide.
Especially advantageous embodiments of the food-compatible, flat-shaped bodies according to the invention are described in claims 3 to 10.
Another embodiment of the invention relates to food-compatible monofilaments based on polyester that contain 0.5 to 3.5% by weight of a polycarbonate. These food-compatible monofilaments preferably have a knife abrasion resistance of 55,000 to 170,000 abrasion cycles.
Another embodiment of the invention is a procedure for producing flat-shaped bodies or shaped bodies made from flat-shaped bodies, such as woven and non-woven materials, knits, multiaxial layers, spiral cloths or spiral sieves, pin wires, flat structures such as grids or net-shaped flat structures etc., or shaped bodies made from these flat shaped bodies, such as nets, sacks, bags, nets, sieves, filters etc. for transport, packaging, storage, and handling of foods by spinning polyester with an additive of 0.5 to 3.5% by weight of a polycarbonate in the molten mass by extrusion into monofilaments, and the monofilaments are processed into flat shaped bodies, such as woven materials, looped materials, nets, etc., and the flat shaped bodies are, if required, made into sacks, bags, filters, transport belts, etc.
It is preferred that polyethylene terephthalate is used as the polyester. The intrinsic viscosity, measured in dichloroacetic acid at 25° C., is preferably between 0.5 to 1.5 dl/g, in particular 0.68 to 0.915 dl/g. But other polyesters, such as polybutylene terephthalate can also be used. Very useful are also copolyesters, in which the acid component, for example the terephthalic acid, is partially substituted with another acid component, in particular isophthalic acid. Modifications by partial substitution of the glycol components, for example the ethylene glycol, with 1,4-dihydroxymethylcyclohexane are also possible.
For the polycarbonate, commercially available products, for example the one marketed by Bayer AG under the trademark MAKROLON, can be used.
In a particularly advantageous embodiment of the method according to the invention, the polyesters do not contain any terminating agents, such as mono- or polycarbodiimide.
The flat-shaped bodies produced from monofilaments based on polyesters with an additive of 0.5 to 3.5% by weight of a polycarbonate, such as woven and non-woven materials, knits and other looped materials, spiral cloths or spiral sieves, pin wires, nets and grid-shaped fat structures can be used to produce ready-made articles, such as bags, sacks, sieves, filters, transport belts, etc.
The food-compatible monofilaments according to the invention can be used to produce the flat-shaped bodies or the shaped bodies composed of the flat-shaped bodies. These food-compatible monofilaments are based on polyesters that contain 0.5 to 3.5% by weight of a polycarbonate; they preferably have a knife abrasion resistance of 55,000 to 170,000 abrasion cycles with the knife abrasion resistance is determined according to the procedure described hereafter. The polycarbonate is preferably distributed homogeneously in the polyester.
The monofilaments preferably are produced according to a method in which a mixture of a polyester and 0.5 to 3.5% by weight of a polycarbonate is spun from a molten mass, the resulting monofilaments are cooled in a spinning bath, are stretched, and, if necessary, are wound.
The extrusion speed of the molten mass, the drawing during spinning and the stretching are hereby adapted to each other so that the monofilaments have a diameter of at least 0.07, preferably 0.1 to 1.5 mm.
To produce the shaped bodies according to the invention, monofilaments are produced by extrusion through nozzles of polyester, especially of polyethylene terephthalate to which have been added 0.5 to 3.5% polycarbonate by weight.
Preferably, polyethylene terephthalate is used as the polyester. Also advantageous are polybutylene terephthalate or copolyesters, such as, in particular, polyethylene terephthalate in which the terephthalic acid component has been partially substituted with isophthalic acid.
The raw materials, i.e. the polyester and the polycarbonate, are mixed well with each other and then melted in an extruder, filtered in a spinning pack, and spun through a spinning nozzle.
On leaving the spinning nozzle, the exiting molten mass monofilaments are quenched with cooling in a spinning bath that preferably is a water bath. The spinning bath generally has a temperature of 30 to 90° C., in particular 70° C. The threads are then wound or pulled off at a speed that is greater than the extrusion speed of the molten mass. The drawing during spinning generally is 1:1.5 to 1:6.0, preferably 1:3 to 1:5, and the spinning pull-off or draw speed is 5 to about 40 m per minute.
The spun monofilament produced in this manner is again str
Brüning Hans-Joachim
Lichtblau Andreas
Striegl Peter
Bell Mark L.
Burns Doane , Swecker, Mathis LLP
Manlove Shalie A.
Teijin Monofilament Germany GmbH
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