JPS61279533A - Protective piece for shrinkable bag - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION 11 Animals L This invention relates to a bone-in meat bandage. More particularly, the present invention relates to a guard strip that prevents or reduces the possibility that bone will puncture and rupture the thermoplastic vacuum bag and guard strip combination.

BACKGROUND OF THE INVENTION The use of heat-shrinkable thermoplastics as flexible packaging materials for vacuum packaging various food products, including meat, is well known. However, while such materials are generally convenient for packaging meat, they have difficulties in conveniently packaging products with sharp bones. For example: - Attempts to package bone-in meat usually result in a large number of unsatisfactory breakages of the bag due to holes in the bones. The use of cushioning materials such as paper, paper laminates, wax impregnated fabrics and various plastic inserts has proven unsatisfactory in solving this problem.

Attempts have been made to produce specific cuts of meat or to cut near the bone with removal of interfering bones. However, this provides only a limited solution to this problem as it does not provide the aggressive protection needed for a wide range of commercial bone-in meats. Additionally, bone removal is a relatively expensive and time consuming process.

It is an object of the present invention to provide a protective strip material and a method for manufacturing such a protective strip, which minimizes and eliminates the occurrence of such damage.

An example of a conventional method for protecting thermoplastic bags from punctures is 1.
Mey S., Serpy, June 23, 959.
US Pat. No. 2,891,870, issued to et al.

In this Selby patent, the exposed bones of bone-in meat are wrapped in wax-impregnated cloth and the meat thus protected is placed within a heat-shrinkable plastic bag.

It is therefore another object of the present invention to eliminate the need for a separate packaging material, such as a wax-impregnated cloth, which must be carefully positioned over the bone and is not sensitive to or dependent on the position of the bone within the vacuum bag. The purpose is to provide a protective piece that will not damage the product.

Another object of the invention is to provide a protective strip for thermoplastic vacuum bags that is relatively strong and easily adheres to the outer surface of the thermoplastic empty bag.

It will be easier to understand from the explanation.

SUMMARY OF THE INVENTION In one aspect, the present invention is a method of making a multilayer protective strip for a heat-shrinkable thermoplastic bag, the inner wall comprising a first ethylene vinyl acetate copolymer and the outer wall comprising a large proportion of linear low density material. A multilayer thermoplastic tube consisting of a blend of polyethylene and a small amount of a second ethylene vinyl acetate copolymer is coextruded; on the inside of the tubular extrudate is a sufficient amount so that the tube does not adhere to itself when collapsed. Applying powdered cornstarch or the like; crushing the tube; irradiating the collapsed tube to crosslink the material; opening, heating and stretching the tube to biaxially orient the tube material. oriented tube: - crushing and flattening the tube, thereby adhering the tube to itself; and cutting the tube into at least one protective piece.

In another aspect, the invention provides a multilayer protective strip for a heat-shrinkable vacuum bag, the protective strip comprising linear low density polyethylene from 80% to 100%, vinyl acetate content ranging from 7% to 12%. 20% ethylene vinyl acetate copolymer with
an outer layer consisting of a blend of ~0% and 5% to 0% pigments and additives; an inner layer consisting of an ethylene vinyl acetate copolymer with a vinyl acetate content of 20% to 35% and biaxially heat-shrinkable. It is possible. In particularly preferred embodiments, the guard strip material is crosslinked to the extent that radiation dose levels range from 4.5 to 13 MR.

Large-U Referring to Figures 1-6, a bone-in meat 2, such as a leg of lamb with an exposed bone portion 6, is shown. Also shown is a protective strip 8 on the bag 12 covering a substantial portion of the visible side of the package.

Having a protective strip on the outside of the bag facilitates the step of filling the bag since there is no need to worry about shifting the hand-placed cloth protective strip or the protective strip glued to the inside of the bag. Therefore, filling can be performed more easily. After filling the bag with bone meat, the air is removed from the package and the neck 10 of the bag is assembled to have the appearance shown in FIG. 1, after which clips 4 are applied to securely seal the bag. The bag is then immersed in warm water and contracted tightly against the meat, thus providing a meat product for macerating and preserving in a vacuum atmosphere. The protective strip 8 contracts with the bag, thus reducing the tendency for the laminate to peel off when it does not contract in the same way as the bag.

FIG. 2 shows a prior art bag 12 and covering cloth 8, which requires careful positioning of the cloth 8 over the bone 6;
Also, care must be taken in positioning the bones within the bag so that the fabric 8 is not pushed or moved out of position.

Figure 3 shows the exposed bone portion 6 wrapped in a bag 12, with a preferred protective piece 8 adhered to the outside of the bag over the bony prominence.

In FIG. 4, a protective piece 8 is preferably provided on the wall of the bag 12. In many applications it is desirable to adhere protective strips to both sides of the bag.

FIG. 5 is a cross-sectional view of FIG. 4, showing that the protective strip 8 is adhered to one wall of the bag 12.

FIG. 6 shows outer M14 and 16 and inner M118 and 20.
FIG. 2 is an exaggerated cross-sectional view of a protective piece 8 provided with . In a preferred embodiment, the composition of outer surfaces 14 and 16 consists of 87% by weight linear low density polyethylene, 10% by weight ethylene vinyl acetate copolymer with 9% vinyl acetate, and 3% v additive to aid in pigment and extrusion. A preferred linear low density polyethylene is Dowlex 2045F, available from Dow Chemical Co., Midland, Mich., and a preferred ethylene vinyl acetate copolymer is ELVA 2045F, available from DuPont Co., Wilmington, Plateau.
X) 3128.

Inner layers 1B and 20 were manufactured by National Distillers of New York.
) U, S, I. Consisting of ethylene vinyl acetate copolymer with 28% vinyl acetate from Sector. All layers are crosslinked by irradiation to a radiation dose level equivalent to 7MR.

17°5 inches (44 cm) wide on one side for one test
, 5 cm), with a protective strip of the invention 18 inches (45,7 cm) long and 17.5 inches (44,5 cm) wide on the other side.
5cm>, and a bag with a protective strip 10 inches long (25°4c+a) was reported. The flattened dimensions of these bags were 18 inches (45,7 ca+) wide and 30 inches (76,2 (!11) long).
Larger bag (22” x 34”) for es)
<55.9cm x 86.4c+a) 21 on one side
．． 5” x 24” (54.6cm x 60.9cm)
protective strip, 21.5″X8″ (54,6CI) on the other side
A protective piece measuring 20.3 cm) was used. Various bone-in beef products were packaged both in bags using the above-mentioned protective piece of the present invention and in bags using bone-wrapping cloth. The product ranged from the ribs to the shoulder blades and arms. A total of 11 pieces of cloth were used to wrap the protruding bones.
A total of 55 out of 73 packages had holes, but only 18 out of 2097 packages using the protective strip of Rikiki's invention had holes in the middle length.

While the embodiments described above are preferred, a satisfactory protective piece is one in which the inner and outer layers 14.16 contain 15% ethylene vinyl acetate copolymer with 9% vinyl acetate, 83.3% linear low density polyethylene and 1 pigment. It can be made if it consists of .7%.

A more satisfactory protective piece is 90% linear low-density polyethylene.
and an outer layer of 10% vinyl acetate copolymer. According to the red test.

The desired composition range for the outer layer is believed to be 80% to 100% linear low density polyethylene and 20% to 10% ethylene vinyl acetate copolymer with 7% to 12% vinyl acetate. Preferably, the inner layer consists of an ethylene vinyl acetate copolymer having 20-35% vinyl acetate.

Surprisingly, it has been found that the strength and tenacity of the protective strip according to the invention are significantly improved by the use of linear low density polyethylene. Preferred copolymers for linear low density polyethylene are generally 0.900-0.935
These linear low density polyethylenes are not homopolymers but are generally polyethylenes.
It is called. In fact, these are ethylene and carbon number 18
It is a copolymer with the following alpha olefins, such as butene-1, pentene-1, hexene-1, octene-1, etc. The Dowlex brand linear low density polyethylene used in the preferred embodiment described above was found to have an octene-1 alpha olefin. Examples of patents showing the use of such polymers include Barry A. Cooper
No. 4,425,268, issued January 8, 1984 to Nishimo
U.S. Pat. No. 4,456.646, issued June 26, 1984, to William F.
No. 4, issued August 16, 1983. ．． 3
99.180, and David L. Newsome (D
avid L.

No. 4,457,960, issued July 3, 1984 to Newsome.

The flat vacuum bags and the vacuum bags used in the tests and examples described above are described by Barry J.
J, 3rax) et al. June 26, 1973
Manufactured according to the method set forth in U.S. Pat. No. 3,741,253 issued on D.A. The method of Blanks et al. is included by reference in Suimei II and provides the background for the method of manufacturing the protective strips of the present invention.

To produce the protective strips of the invention, a first ethylene vinyl acetate copolymer having a vinyl acetate content of about 28% by weight is fed to a first extruder. This material is layer 18 and 20
(Fig. 6) is formed. A blend having a large proportion of linear low density polyethylene and a small proportion of a second ethylene vinyl acetate copolymer (which has a vinyl acetate content in the range of 7-12%) is also fed to a second extruder. This material forms layers 14 and 16. Both extruders feed a common coextrusion die of a type well known to those skilled in the art. The extruded product exiting the die has an inner wall of the first ethylene vinyl acetate copolymer and an outer wall of the blend. This type of coextrusion essentially extrudes two concentric tubes, one on top of the other, and in this case the first vinyl acetate copolymer is the inner tube.

As the tube is extruded in the F direction, it is closed and flattened by the pinch rolls, but the inside of the tube is covered with an inert dust or powder to keep the first vinyl acetate copolymer from adhering to itself. , preferably cornstarch, at a surface concentration sufficient to prevent self-adhesion.

This flattened tube is then fed into an irradiation chamber where it is preferably subjected to a radiation dose of approximately 7 MR to crosslink the polymeric material comprising the tube. The preferred range is 4.5MR to 13MR, and the most suitable range is 6 to 13MR.
It is 8MR. Although chemical crosslinking using organic peroxides is considered an alternative crosslinking method, entirely satisfactory results have been obtained with the use of radiation crosslinking, and radiation crosslinking is preferred.

After receiving the crosslinking radiation dose, the tube is opened, inflated, heated, and stretched by the well-known bubble process described in the Blanks et al. patents mentioned above. This biaxial stretching orients the tube material.

After the material has been drawn to the desired diameter and wall thickness, it is rapidly cooled and crushed. This method results in a biaxially oriented protective strip material that is shrinkable at temperatures that are oriented. Because the stretching reduces the concentration of corn starch on the bubbles or inner surface of the stretched tube, the tube tends to stick to itself when crushed and flattened. This concentration is now low enough to allow self-adhesion. The amount of vinyl acetate in the inner wall is about 28% by weight.

This is an ethylene vinyl acetate copolymer that is within the scope of acting as an adhesive. Thus, a multi-layered tubing material is produced, in this example a four-layered material as shown in FIG. This material can be cut into protective strips and adhered to one or both sides of a heat-shrinkable bag to produce a protective material that greatly reduces bone perforation.

Many suitable adhesives for adhering the protective strip to the bag are available and can be easily selected by those skilled in the art. Since the protective strip, like the bag, contracts biaxially, the tendency for the layers to peel off is greatly reduced.

[Brief explanation of drawings]

FIG. 1 is a schematic representation of meat wrapped in a heat-shrinkable bag with the protective strip of the invention on the outside, and FIG. 2 is similar to FIG. 1, but with a conventional protective strip in place. FIG. 3 is a cross-sectional view taken along line 3-3 of FIG. 1, and FIG. 4 is a plan view showing a protective piece of the present invention adhered to a thermoplastic vacuum bag. 5 is a cross-sectional view taken along line 5--5 of FIG. 4, and FIG. 6 is an exaggerated cross-sectional view showing the preferred layer arrangement of the protective material of the present invention. 2: Meat with bones, 6: Bone,

Claims (1)

[Claims] A method for manufacturing a multilayer protective strip for an axially heat-shrinkable thermoplastic bag, comprising: (a) an inner wall comprising a first ethylene vinyl acetate copolymer and an outer wall comprising a large proportion of A multilayer thermoplastic tube consisting of a blend of linear low density polyethylene and a small amount of a second ethylene vinyl acetate copolymer is coextruded, and (b) a sufficient amount of the tube does not adhere to itself when crushed. (c) crushing the tube; (d) irradiating the crushed tube to crosslink the material; (e) opening, inflating, heating, and stretching the tube. (f) cooling, collapsing and flattening the tube, thereby causing the tube to adhere to itself; and (g) cutting the tube into at least one protective piece. A method characterized by comprising: 2. The method of claim 1, comprising the additional step of adhering a protective strip to the surface of the shrinkable thermoplastic bag, thereby protecting the bag from punctures. 3. The vinyl acetate content of the second copolymer is 7% to 12
%, the vinyl acetate content of the first copolymer is in the range of 20-35%, and the blend of linear low density polyethylene and the second ethylene vinyl acetate copolymer has a vinyl acetate content of 8%.
0%~100% linear low density polyethylene, 20%~0
% ethylene vinyl acetate copomer and up to 5% pigments and additives. 4. The method of claim 3, wherein the tube is irradiated with a radiation dose in the range of 4.5 to 13.0 MR. 5, (I) (a) Linear low density polyethylene 80% to 10
(b) an outer layer consisting of a blend of 20% to 0% ethylene vinyl acetate with a vinyl acetate content of 7% to 12%, and (c) 5% to 0% of pigments and additives; (II) 20% For a biaxially heat-shrinkable bag comprising an inner layer consisting of an ethylene-vinyl acetate copolymer having a vinyl acetate content of ~35%, and (III) being biaxially heat-shrinkable. Multi-layer protection piece. 6. A protective strip according to claim 5, wherein the protective strip material is crosslinked to a radiation dose level in the range of 4.5 to 13 MR. 7. The protective piece according to claim 6, wherein the protective piece material is crosslinked by being irradiated with a radiation dose in the range of 6 to 8 MR. Claim 7 consisting of four layers, the outer layer consisting of the material of layer (I) and the inner layer consisting of the material of layer (II)
Protective piece as described in section. 9. The material of layer (I) is 87% linear low density polyethylene.
, a blend of 10% ethylene vinyl acetate copolymer having a vinyl acetate content of 9% and 3% pigments and additives, wherein layer (II) consists of an ethylene vinyl acetate copolymer having a vinyl acetate content of 28%. 8th
Protective piece as described in section. 10. The protective piece according to claim 9, which is bonded to a biaxially shrinkable thermoplastic vacuum bag.