FR2508468A1 - NOVEL COMPOSITION OF PLASTIC MATERIAL, THREAD CARRIED OUT WITH THIS PLASTIC MATERIAL AND USE THEREOF IN THE PACKAGING OF LOADS ON PALLET - Google Patents

Abstract

THIS COMPOSITION IS CHARACTERIZED BY THE FACT THAT IT CONTAINS E.V.A. IN A PROPORTION NOT EXCEEDING ABOUT 10 BY WEIGHT, THE REST CONSISTING OF A MIXTURE OF POLYPROPYLENE AND LOW DENSITY POLYETHYLENE. APPLICATION IN PARTICULAR TO THE REALIZATION OF A STRETCH NET FOR THE PACKAGING OF PALLETIZED LOADS.

Description

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  The present invention relates to a novel

  position of plastic material, and a net made using

said plastic material.

  Such a net can be used in particular for packing loads on pallets. It is known that the transport or handling of a large number of goods is currently being carried out, by distributing

  or stacking these goods as pallet loads.

  In order to stabilize the palletised loads, it is necessary to provide them with a package, and various solutions have been proposed to this effect, including the plastic film packaging or the packaging.

under plastic net.

  A particularly interesting package can be made in the form of a stretch net longitudinally, stretching being performed at the same time as the laying of the package

on the palletised load.

  The development of plastic compositions allowing the realization of stretch nets for packaging

  palletized loads raise many difficulties.

  It is indeed necessary that the stretch net remains relatively

  It is important that the net once stretched retains both properties of sufficient strength and elasticity to allow the transport to be carried out lightly while having a good breaking strength and being extensible by at least 100% cold. and the safe handling of palletized loads. Finally, it is necessary that the composition of plastic material

  an acceptable cost price.

  Stretchable nets have already been proposed for various compositions of plastic material, especially compositions containing a high proportion of ethylene-vinyl acetate copolymer (E V A), for example compositions

  containing 90% by weight of E V A and about 10% by weight of poly-

  propylene, or even E V A alone.

  However, the high cost of the E V A strikes the cost price of such compositions.

  Polypropylene is a raw material

  interesting because of its good mechanical resistance properties and its acceptable cost price. However, stretched polypropylene nets do not have sufficient elasticity to allow use in the form of nets.

  stretchable for packaging palletized loads.

  It has now been discovered that it is possible to

  stretchable nets for packing pallet loads

  with a new low V E plastic composition.

  This new plastic composition contains

  A mixture of E V A and polyolefins is characterized in that it contains E V A in a proportion not exceeding about 10% by weight, the balance being

  a blend of polypropylene and low density polyethylene.

  Generally, in the composition of the invention, the

  proportion by weight of E V A is greater than about 4%.

  According to a particular embodiment, the composition

  of the invention contains from about 40 to 80% by weight of poly-

  propylene, and preferably from 45 to 75% by weight.

  A particularly preferred composition contains about 60 to 70% by weight of polypropylene, 30 to 40% by weight of low density polyethylene and 4 to 10% of E V A. In this application the expression EVA designates except contrary indications, an ethylene-acetate copolymer

  vinyl containing from 15 to 20% by weight of vinyl acetate.

  Of course the content of E V A of the composition of the invention may vary depending on the content of acetate of

E V vinyl used.

  The expression "low density polyethylene" refers to a

  polyethylene having a density ranging from 0.918 to 0.930.

  It should be noted that, in the compositions of the invention, the polypropylene may be added in the form of a polypropylene polyethylene copolymer having a low polyethylene content, for example a content of less than or equal to 10% by weight. The plastic composition of the invention finds a particularly advantageous application in the field of stretch-nets used for the packaging of

  Palletized loads These nets form part of the invention.

  Such nets, whose meshes are preferably square or rectangular, may be manufactured according to the known methods, in particular using a machine comprising two extrusion dies movable relative to each other. such

  than that described in the French patent N 01 303 014.

  For the realization of these nets can also be used the methods and machines described in French Patents 71 45140 and its addition 72 39700, 1 601 465, 1 600 202, 71.40270, or in French Patent No. 1 310 478 and its

first addition 80,076.

  To produce the net of the invention, the polymers used as raw material are mixed and homogenized, and then the homogeneous mixture, in the form of a softened composition, is subjected to extrusion according to the processes just mentioned. Preferably the stretch packing nets for

  palletised loads of the invention have the characteristics

  following ticks: a) mesh size: longitudinal strand spacing: 1.5 3 cm transverse strand spacing: 5 6 cm b) longitudinal strand section: 0.3 0.6 mm 2 c) transverse strand section: 0 , 2 0.4 mm 2 d) width of the net: 45 55 cm e) weight per m 2: 20 30 g / m 2 -f) extensibility of the longitudinal strands: upper

100 %

  g) extensibility of transverse strands: superior

at 400%

  h) breaking strength of the net (meaning

  longitudinal: greater than 20 kgf.

  The subject of the invention is also the application of

  stretchable nets of the invention to the packaging of the

  lettisées. In order to carry out the packing of palletized loads by means of the net of the invention, the well-known methods and machines used for packaging using nets or stretch films are used. cases, either by arranging at different heights strips of

  net, or by winding the net spiral around the load.

  The invention also relates to stretched nets

  set up on palletized loads.

  The following examples illustrate the invention without

however, limit it.

  In these examples, the starting material used is the polypropylene-polyethylene copolymer with 9% polyethylene sold under the commercial name Propathene by the company I C.

  the low density polyethylene sold under the name

  CARLONA by the SHELL Company.

  E V A in the form of an ethylene-vinyl-copolymer

  acetate at 18% by weight of vinyl acetate.

  In the example compositions, the percentages

are expressed in weight.

EXAMPLE 1

  A mixture having the following composition is produced: Prbpathene 71.4% Carlona 23.8%

E V A 4.8%

  After homogenization, it is manufactured according to the process of

  French Patent 1 303 014 a net presenting the characteristics

  following ticks: width: 50 cm spacing of longitudinal strands: 2.7 cm spacing of transverse strands: 5.5 cm Section of longitudinal strands: 0.5 mm 2 Section of transverse strands: 0.3 mm 2 weight per m 2: 29 g / m 2 elongation at 15 kg load: 75% residual elongation after loosening

constraint: 55%.

breaking strength: 23.5 kgf

EXAMPLE 2

  We made a net with the same characteristics

  dimensions than that of Example 1 with the material mixture

  Plastic resins with the following composition (in%): Propathene 67,6 Carlona 27

E V A 5.4

  Characteristics: weight / m 2: 27 g -5- elongation of the net at 15 kg load: 90% residual elongation after loosening of the

stress: 65%.

breaking strength: 26.5 kgf

EXAMPLE 3

  A net similar to that of Example 1 was made with a mixture of plastics having the following composition (in%): Propathene 62.5 Carlona 31.25

E V A 6.25

  Characteristics: weight per m 2: 24 g elongation at 15 kg load: 85% residual elongation after loosening of the

constraint: 60%.

breaking strength: 23 kgf.

EXAMPLE 4

  A net similar to that of Example 1 was made with the following mixture (composition in%): Propathene 69.7% Carlona 23.3%

E V A 7%

  Characteristics: weight per m 2: 28 g elongation at 15 kg load: 90% residual elongation after release of the stress: 70%

breaking strength: 25 kgf.

EXAMPLE 5

  A net similar to that of Example 1 was made with the mixture having the following composition (in%): Propathene 45.5 Carlona 45.5

E V A 9

  Characteristics: weight per m 2: 29 g elongation at 15 kg load 73.5% residual elongation after loosening

stress: 43.5%.

  breaking strength: 22.5 kgf.

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EXAMPLE 6

  A net similar to that of Example 1 was made with the mixture having the following composition (in%): Propathene 62.5 Carlona 31.25

E V A 6.25

  Characteristics: weight per m 2: 28 g elongation at 15 kg load: 77% residual elongation: 52%

Breaking strength: 24 kgf.

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Claims (7)

  1 Plastic composition containing a mixture of EV A and polyolefins, characterized in that it contains E V A in a proportion not exceeding about 10% by weight, the remainder consisting of a mixture of   polypropylene and low density polyethylene.   Composition according to Claim 1, characterized   in that the proportion of E V A is greater than 4% in viron.   3 Composition according to any one of the claims   1 and 2, characterized in that the E V A contains 15 at 20% vinyl acetate.   4 Composition according to any one of the claims   tions, characterized by the fact that it contains   from 40 to 80% by weight of polypropylene.   Composition according to Claim 4, characterized   in that it contains from 45 to 75% by weight of polypro- pylene.   6 Composition according to any one of the   preceding cation, characterized in that it contains from 70 to 70% by weight of polypropylene, from 30 to 40% by weight of low density polyethylene and from 4 to 10% of E V A. 7 Stretchable net, characterized by the makes it is   realized in a composition as defined in any one   conque of the preceding claims.   8 Application of the nets of claim 7 to   packaging palletized loads.   9 stretched net, set up on a palletised load,   characterized by the fact that it is realized by means of a com-   position as defined in any of the claims cations 1 to 6.