Pattern Laminated Double Wall Hot Formable Plastic Web With Enhanced Puncture Resistance
The present disclosure is concerned with thermoformable webs with improved puncture resistance suitable for use in semi-automatic horizontal form fill and seal (HFFS) packaging machines and a process for packaging hard food items with sharp angular surfaces using such webs in such machines. The webs have a double wall partially laminated structure. The structure is conveniently formed by adhesively laminating two component films in a face to face configuration using a pattern of adhesive which leaves a substantial portion of the two facing surfaces unlaminated. The lamination just needs to be sufficient that the two component films will hot form together when they are vacuum drawn into a die to form a cavity for packaging the food items. The lamination pattern can vary from just edge strips to the edge strips and a honey comb pattern or a pattern of dots over the facing surfaces between the edge strips.
1 . A double wall partially laminated hot formable web with enhanced puncture resistance comprising two independently manufactured thermoplastic films, each capable of forming a product containing cavity upon being heated and drawn into a mold, said films being partially laminated to each other such that
a. a substantial portion of the surfaces of the two films facing each other are unlaminated;
b. the laminate is capable of forming a product containing cavity upon being heated and drawn into a mold; and
c. the unlaminated surface of one of said films is heat sealable.
2 . The web of claim 1 wherein the web can be deep drawn.
3 . The web of claim 1 wherein the two films are adhesively laminated.
4 . The web of claim 1 wherein less than 50% of said surfaces are laminated to each other.
5 . The web of claim 3 wherein the adhesive is present in a repeating pattern.
6 . The web of claim 5 wherein said pattern is a honeycomb or spaced apart circles.
7 . The web of claim 1 wherein at least one of said films includes an oxygen barrier.
8 . The web of claim 1 wherein the structures of the two films are identical.
9 . The web of claim 7 wherein both of said films includes an oxygen barrier.
10 . The web of claim 1 wherein the surfaces of said films which face each other are heat sealable.
11 . The web of claim 1 wherein each of said independently formed films is between about 2 and 24 mil thick.
12 . The web of claim 10 wherein each of said independently formed films is between about 4 and 20 mil thick.
13 . The web of claim 1 wherein the adhesive joining said independently formed films is between about 2 and 5 microns thick.
14 . A process for packaging hard food items with sharp angular surfaces in hot drawn pouches comprising:
a. Providing a double wall partially laminated hot formable web with enhanced puncture resistance comprising two independently manufactured thermoplastic films, each capable of forming a product containing cavity upon being heated and drawn into a mold, said films being partially laminated to each other such that
i. a substantial portion of the surfaces of the two films facing each other are unlaminated;
ii. the laminate is capable of forming a product containing cavity upon being heated and drawn into a mold; and
iii. the unlaminated surface of one of said films is heat sealable;
b. heating a portion of said double wall web to a forming temperature;
c. forming said portion of said double wall web into an open mouth cavity to accommodate the hard food items to be packaged;
d. placing said hard food items into said cavity;
e. covering the mouth of said cavity with a web of thermoplastic film;
f. evacuating the interior of said cavity;
g. heat sealing a portion of said covering web of thermoplastic film to said portion of said double wall web which forms said cavity to seal said open mouth; and
h. isolating said sealed package from the remainder of said double wall web and from the remainder of said covering web of thermoplastic film.
15 . The process of claim 14 wherein the cavity forming step is a deep drawing step.
16 . The process of claim 14 wherein said films are adhesively laminated to each other.
17 . The process of claim 14 wherein said hard food items are bones or meat products containing exposed bone.
18 . The process of claim 14 wherein the packaged food items also contain liquid.
19 . The process of claim 14 wherein one of the films forming said double wall web includes an oxygen barrier.
20 . The process of claim 19 wherein both of the films forming said double wall web includes an oxygen barrier.
21 . The process of claim 14 wherein the surfaces of the films forming said double wall web which face each other are heat sealable.
22 . The process of claim 14 wherein said covering web of thermoplastic film is also a partially laminated double wall web.