Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
  • B65D—CONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
  • B65D85/00—Containers, packaging elements or packages, specially adapted for particular articles or materials
  • B65D85/07—Containers, packaging elements or packages, specially adapted for particular articles or materials for compressible or flexible articles

Definitions

• This invention relates to the compression-packaging of mineral wool products with polyethylene film.
• the packaged product is usually in the form of a rectangular slab and may be composed of a single batt or a pile of batts. It can also however be in the form of a roll.
• Low density polyethylene (LDPE) film has been conventionally used to compression pack mineral wool products.
• the normal degree of compression is about 18%, based on the original volume.
• a mineral wool product compression-packaged in a film of polyethylene comprising high density polyethylene.
• the plastic film can be applied and sealed after compression but is usually applied prior to compression and then sealed tight after compression.
• the polyethylene film is generally applied to the upper and lower surface of the batt or pile of batts before compression. After compression the lower and upper polyethylene films may be laminated together for intance with the aid of hot and cold air followed by end sealing and cutting. It is most usual to use a set of converging conveyor belts which convey the lower polyethylene film, the batt or pile of batts and the upper polyethylene film forward while being compressed.
• the method and equipment described in EP-551,228 can be used.
• the mineral wool product usually has a normal density of 8 to 80 kg/m 3 . It can be unbonded but is usually a bonded web of mineral fibres for instance having an organic content of 0.5 to 10% by weight.
• the mineral wool fibres may be ceramic fibres or glass fibers, but are preferably fibres generally known as stone, rock or slag fibres, in which the analysis of the fibre shows an alkali metal content (measured as alkali metal oxide based on total oxides) usually of less than 10% and an alkali earth metal content of usually above 10, 15 or 20%, by weight.
• the present invention involves the use of a film containing high density polyethylene. It preferably has high strength, high modulus of elasticity and low creep. Low and compact rectangular or other packages can thus be made and maintained during transport and storage with reduced risk of tear or significant creep.
• the film preferably has substantially the same strength and elasticity in both directions (so called machine direction and a direction perpendicular thereto). This makes the film more versatile in relation to different packaging machines.
• the polyethylene film may be a laminate but is preferably a single-ply film.
• the preferred film is formed of a blend of low density polyethylene and high density polyethylene generally in a ratio of 6:4 to 9:1 most preferably 7:3 to 9:2.
• the preferred film is a single-ply film formed of 70 to 80% low density polyethylene and 20 to 30% high density polyethylene.
• the polyethylene blend generally has a density in the range of about 0.93 to 0.94, preferably in the range 0.932 to 0.935.
• the polyethylene blend preferably has a melt temperature in the range of about 120 to 125°C, preferably about 123°C.
• the film has an enthalpy of about 120 to 135, most preferably 124 to 130 joules/g.
• the polyethylene blend has a crystallisation temperature of around 102 to 110°C preferably about 107°C.
• the polyethylene blend preferably has a crystallinity of 20 to 45%, most preferably around 25 to 35%.
• the pressure to which the mineral wool product is compressed during packaging is preferably in the range 0.15 to 0.50, usually below 0.35, preferably 0.2 to 0.25 N/mm 2 . These are values which are suitable for providing 40% compression.
• the batt or pile of batts is preferably compressed during the packaging step by greater than 10 or 15% in volume (generally height), more preferably by greater than 20%. Some products may be compressed by up to about 95% in volume. However most products are generally compressed by more than 40 or 50% in volume. Preferably, substantially the entire compression is released when the plastic film is removed.
• the film is formulated from 75% low density polyethylene and 25% high density polyethylene having the following properties: Density: 0.932 kg/dm 3 Melt temperature: 126°C Enthalpy: 124 to 130 joules/g Crystallisation temperature: 107°C Crystallinity: 42%

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Cited By (3)

Citations (8)

• 1997
  • 1997-10-13 EP EP97308103A patent/EP0908400A1/de not_active Withdrawn

Patent Citations (8)

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