JPS6016340B2 - Laminated film for packaging - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a laminated film used for packaging processed meat products such as hams and sausages.

In the manufacturing process of processed meat products such as hams and sausages, seasoned and aged meat (hereinafter referred to as "processed meat") is used.

) is inserted into a cylindrical packaging film made of vinylidene chloride or other material with excellent oxygen barrier properties, boiled at a temperature of 8,000 to 9,000 degrees Celsius for several minutes to several hours, and then cooled to form a product. It must have excellent oxygen barrier properties and maintain the internal processed meat sufficiently tight even after the boiling and cooling process (hereinafter this property is referred to as ``tension suitability'').
That's what it means. ). Various films for packaging these processed meats have been developed in the past, but a film that combines both the above-mentioned oxygen barrier properties and stress suitability has not yet been released on the market, and its development is awaited. This is the current situation.

The present invention is a laminated film having both of the above-mentioned properties, and its gist is a laminated film made of a thermoplastic resin with excellent oxygen barrier properties and another thermoplastic resin. The shrinkage rate at 85°C is 5% or more in both the vertical and horizontal directions, and the shrinkage rate is 8500, 20k.
9/ The expansion/contraction rate under tensile stress is within ±15% in both the vertical and horizontal directions, and the shrinkage return rate when the stress is removed at a temperature of 2000°C is 1 in both the vertical and horizontal directions.
% or more.

In the present invention, the thermoplastic resin with excellent oxygen barrier properties is defined as having a gas permeability coefficient (measured using the industrial test formula) of 1 x 10-11 cc.
- A resin smaller than arc/base/sec/skin Hg, such as polyamide, polyethylene terephthalate, saponified ethylene-pinyl acetate copolymer, polyvinyl alcohol, etc. If the gas permeability coefficient is larger than the above value, the amount of oxygen permeation will be large, making it unsuitable for preserving processed meat.
Atm or less, measured by ASTM D1434), the thickness of the film used must be increased, which adversely affects other physical properties.

Other thermoplastic resins to be combined with the above thermoplastic resins include ethylene-vinyl acetate copolymer, polybutene-1, crosslinked polyethylene, and the like.

Further, in the present invention, the shrinkage rate, expansion/contraction rate, and shrinkage return rate are defined as follows.

Let L be the distance between the two points of the reference attached to the laminated film at room temperature, and let L be the distance between the two points of the above reference after heating it for about 5 minutes at a temperature of 85 qo without load,
5 at a temperature of 85oo under 20kg/c tiger tensile stress.
Let L2 be the distance between the two reference points after heating for about a minute, and let the distance between the two reference points after removing the tensile stress at a temperature of 2000℃ and leaving it at this temperature for about 5 minutes be -
Then, shrinkage rate = 3≠3×,.

〇, expansion/contraction rate = Shi3LX,. 〇Shrinkage return rate = 333 x, o
o. Processed meat is inserted into the cylindrical laminated film made of the above combination, but in order to improve work efficiency during insertion, the inner diameter of the laminated cylindrical packaging film is made larger than the outer diameter of the processed meat. The subsequent boiling causes the laminated packaging film to shrink and hold the processed meat.

Therefore, the heat shrinkage rate of the laminated packaging film is required to be 5% or more in both the vertical and horizontal directions when heated at a temperature of 85° C. for about 5 minutes.

If the heat shrinkage rate is less than 5%, the inner diameter of the laminated packaging film cannot have a large allowance for the outer diameter of the processed meat.
As a result, the work efficiency when inserting processed meat deteriorates, and the amount of shrinkage of the film during boiling in the subsequent process is insufficient, making it impossible to hold the processed meat tight and sagging at the binding part. It is undesirable that flesh marks etc. tend to accumulate in some areas. In order to keep this processed meat tight, the expansion/contraction rate and the shrinkage return rate are important factors in addition to the contraction rate. In order to hold the processed meat tightly, the expansion/contraction rate is within ±15% in both the vertical and horizontal directions, preferably 0 to 10%, and the shrinkage return rate is 1% or more in both the vertical and horizontal directions. It is a factor. If the film has an expansion/contraction ratio of more than -15%, the stress during boiling shrinkage of the film will be too strong and breakage will easily occur from the binding portion or from a weak portion of the film.

Moreover, a film with a value exceeding 115% has a weak stress during boiling shrinkage and is easily stretched or deformed locally, impairing its commercial value. In addition, if the shrinkage return rate is less than 1%, it will not be able to follow the shrinkage caused by cooling the processed meat that occurs in the cooling process after boiling, resulting in a decrease in commercial value.

In order to achieve a shrinkage return rate of 1% or more, the combination of resins used, the thickness of the resin film, the thickness composition ratio, etc. should be appropriately selected and determined. In order to obtain packaging films with excellent oxygen barrier properties and suitability for processing processed meat, the above-mentioned resins are coextruded, or each unstretched sheet is made into a laminated sheet by a known method, and the resulting laminated sheet is The sheet is stretched at a temperature range of 6,000 to 11,000℃, and the product of the stretching ratio is 2.
．． The film may be stretched two times at the same time or two times sequentially with a stretching ratio of 0.5 to 2.0.

Claims (1)

[Claims] 1 A laminated film made of a thermoplastic resin with excellent oxygen barrier properties and another thermoplastic resin, wherein the shrinkage rate of the laminated film at 85°C is 5% or more in both the longitudinal and lateral directions, and the shrinkage rate at 85°C , the expansion/contraction rate under a tensile stress of 20 kg/cm^2 is within ±15% in both the vertical and horizontal directions, and the contraction return rate in the vertical direction when the stress is removed at a temperature of 200°C, A laminated film for packaging, characterized in that it is 1% or more in both the lateral direction.