Textiles: knitting – Fabrics or articles – Articles
Patent
1997-03-26
1998-12-29
Stryjewski, William
Textiles: knitting
Fabrics or articles
Articles
66202, 28166, D04B 3900
Patent
active
058529411
DESCRIPTION:
BRIEF SUMMARY
This application is the national phase of international application PCT/EP96/01550 filed Apr. 11, 1996 which designated the U.S.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a method for producing woven or knit webs or mesh hoses, in particular double-knit webs or mesh hoses, from which biodegradable, in particular decomposable (compostable), high-strength sacks and bags are to be made.
2. Background Information
Various methods for producing biodegradable foils made of raw vegetable materials are known. In this respect reference is made to DE-C-4 228 016, which also refers to numerous other references.
Foils of this type are easily suitable for producing bags, carrier bags, and the like; however, it has been found that such bags in the closed form are not suitable for packaging bags for many products, since they encourage decomposition processes. Perforating such bags also does not bring any significant improvement and reduces tensile strength to such a degree, that they can also not be used.
There is a particular demand for packaging potatoes, onions or other agricultural products. The custom here is to package them in mesh or bags, but not in foil bags. Mesh and bags are considered to be more product-relevant, in particular with fresh and/or moist goods.
A mesh strip for enclosing bodies pressed from straw material is known from DE-A-4 130 508. The mesh strip is made of double-knit small foil strips. The small strips are cut from a foil made of a plastic material. An additive, which undergoes a change under long-term light effects or under the effects of air and/or humidity, is added to the plastic material. A starch preparation which can be plasticized is added to the web strip for forming the web.
Cutting and stretching of small polyolefin flat foil strips is described in unstretched foil of a maximum width of 600 mm and a thickness of 50 to 100 .mu.m is cut into strips in one process step, is mono-axially stretched and wound up. Stretching takes place at a ratio of 1:4 to 1:10. A setting of 1:6, for example, results in an elongation value of 30% to 35%.
Cutting and stretching of small flat polyolefin strips cannot be transferred to plasticized starch preparations for producing mesh strips, because starch is a brittle material to use, which causes processing problems the higher its proportion in the entire volume is.
SUMMARY OF THE INVENTION
It is therefore the object of the invention to recite a method, by means of which it is possible to produce a high-strength sack or bag or a high-strength mesh from a foil-like basic material, known per se, which is produced on the basis of modified starch, along with the employment of weaving and knitting techniques, known per se. It should be possible to ventilate the product and it should be suitable for transporting, storing and selling potatoes, onions and other field vegetables, but still be biodegradable in accordance with the properties of the basic foil material.
DESCRIPTION OF THE INVENTION
This object is attained by a method for producing mesh hoses, woven or knit webs, in particular double-knit webs or mesh hoses, from which biodegradable, in particular decomposable high-strength sacks and bags are to be made, wherein the basic material has a thickness of between 10 .mu.m and 350 .mu.m, which is produced on the basis of modified starch and has a softening point between 60.degree. and 80.degree. C., in accordance with the following process steps:
A) Slitting the foil into small foil strips which can be woven or knitted, preferably into strips of 1 to 10 mm width,
B) Pre-stretching and stretching the small foil strips while heating them simultaneously or at a later time to a temperature between 30.degree. C. to 70.degree. C., preferably in the range of 35.degree..+-.3.degree. C. at a stretching ratio between 1:3 to 1:10. preferably in the range between 1:4.5 to 1:6.5,
C) Letting them cool to room temperature,
D) Processing of small foil strips of suitable titer and suitable width into a woven or knit web or a mes
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patent: 5415827 (1995-05-01), Tomka
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Natura Verpackungs GmbH
Stryjewski William
Worrell Jr. Larry D.
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