JPS6067151A - Film laminate food packaging material and pouch for said food - 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 The present invention relates to flexible boil-resistant film laminates and packaging materials, such as retort food pouches, made therefrom.

Certain packaging applications, such as retort food packaging materials, require that the packaging material constitute a tractable barrier to the passage of oxygen and moisture vapor. Additionally, packaging for certain foods requires minimal oxygen permeation to the contents.

Cheese is one food product that should be packaged to exclude oxygen.

Oriented polyacrylonitrile (PAN) films have excellent oxygen barrier properties. Its moisture barrier properties, however, are worse than desirable properties for some packaging purposes. -1-1 It is not 7-rule per se.

Both of these deficiencies could be overcome by applying a layer of thermoplastic material with good moisture barrier properties to one side of the PAN. For some purposes, it is desirable to bond the PAN film to itself. therefore,
It is necessary to consider inserting an adhesive or bonding system either between two layers of PAN or between one layer of PAN and one thermoplastic moisture barrier film.

By providing an effective adhesive bond between such films, the result meets a growing need in the food packaging industry. In recent years, in this industry, ξ
There is strong interest in the home-packed food concept, which, among other benefits, does not require storage refrigeration and therefore eliminates the need for costly and energy-intensive refrigerated transportation and storage equipment. can. Using materials that are toxicologically safe as well as providing a variety of properties sufficient to withstand the rigors of sterilization and subsequent reheating, such as microwave heating, and adequately protect the contents during storage; Significant efforts have been made to develop flexible food pouches.

According to U.S. Pat. No. 6,453,173, a polyolefin-polyacrylonitrile laminate, which is said to have excellent heat-sealability and excellent barrier properties against gas permeation, is made by bonding a polyolefin surface and a polyacrylonitrile surface together through an adhesive. It is made by gluing them together. Either or both surfaces may be treated with gaseous mixtures of boron trifluoride, such as those described in British Patent No. 834,196, U.S. Pat.
They can be prepared in some way to make them more adhesive, by treatment with corona discharge as described in US Pat. No. 632,921. Among the adhesives used in the manufacture of laminates are the ethylene vinyl acetate copolymers described in U.S. Pat. No. 2,200,429. Interlayer adhesion in boiling water is not expected to be strong since the preparation conditions and adhesive used do not contribute to the formation of primary valence bonds. PAN to use a metal layer as one effective surface to achieve adhesion to a water vapor barrier film.
If you have to rely on metal plating on the film, f, C,
won.

One object of the present invention is to provide a polyacrylonitrile film laminate or composite of two or more than two PAN layers bonded with a unique and effective bonding system.

One object of the present invention is to provide a polyacrylonitrile film laminate straddle composite that has a PAN and a thermoplastic moisture barrier layer bonded together in a unique and effective bonding system.

Another object of the present invention is to provide a tube for food or products made from the above laminate.

Another object of the present invention is to provide a method for improving the bonding strength between the above-mentioned quiz films.

According to the present invention, there is provided a flexible film laminate suitable for use in the packaging of everyday items, especially food products, which laminate has the following formula: =Id, GH3-ch, fl is an integer from 2 to 4); (b) in contact with the polyacrylonitrile film, (111=5
a styrene-butadiene block copolymer with a monomer weight part ratio of from A combination of alpha methyl styrene with one random terpolymer,
one adhesive layer, the combination consisting essentially of 1 to 6 parts by weight of a block copolymer and 1 to 1 part by weight of a terpolymer; (C) the heterogenized copolymer in contact with the adhesive layer; Consisting of: one second oriented polyacrylonitrile or one heat sealable polyolefin.

Two or more polyacrylonitrile films, or one polyacrylonitrile film and one heat-sealable polyolefin (,zl) into the above polyacrylonitrile film (wherein R is H or CH3 and n is an integer from 2 to 4); (hl between the above films, fl) styrene-getadiene glock with a monomer weight part ratio of 1:3 to 3:1; copolymer and +2130 to 4 parts by weight of 1.3--?ntagene, 50 to 4
0 parts by weight of monocyclic chlorine, and 25 to 65 parts by weight of alpha methylstyrene random ter, d+47-
This combination consists of a combination of 1 to 6M parts of Glockco F1? Inserting one layer of an adhesive composition consisting essentially of 6 to 1 part by weight of 1 part by weight of 1 part by weight of 1 part by weight of 3 part by weight of 1 part by weight of 1 part by weight of 1 part by weight of 1 part by weight of 1 part by weight of 1 part by weight of 1 part by weight of 1 part by weight of 1 part by weight of 1 part by weight of 3 part by weight of 1 part by weight of 1 part by weight of 1 part by weight of 1 part by weight of 1 part by weight of 1 part by weight of 1 part by weight of 1 part by weight of 1 part by weight of 1 part by weight of 1 part by weight of 1 part by weight of 1 part by weight of 1 part by weight of 1 part by weight of 1 part by weight of 1 part by weight of 1 part by weight of 1 part by weight of 1 part by weight of 1 part by weight of 1 part by weight of 1 part by weight of 1 part by weight of ter 4 part by weight of the adhesive composition.
and (applying pressure and/or heat to the C1 film surface;

The polyacrylonitrile film of the present invention has a polyacrylonitrile film of at least 80%
% of acriconyl repeating units. Flat PAN films may be solution cast by the method of U.S. Pat. No. 4,066,731, incorporated herein by reference.
In this case, the acrylonitrile homopolymer or copolymer is cast from a C-I extrusion die onto a rotating drum and solidified as a self-supporting film. The organic solvent in the film, such as dimethyl sulfoxide, is then exchanged by a water bath, typically resulting in 40 to 60 molecules of water, either integrally bound in the molecular pores or dispersed in the orientable polymer matrix. It is possible to obtain an aqueous film containing. The tubular PAN film can be extruded and coagulated with water if necessary, and the unoriented film can be cut lengthwise to provide flat strips to processing and orientation equipment.

Aqueous PAN films can also be made by melt extrusion of high temperature polymer hydrates in known manner.

Preferred PAN feedstocks are addition polymer materials containing sufficient water that are drawn at low temperatures. Acrylonitrile polymer containing at least 5 H2O, preferably 40 to 6
Aquagel containing 1 H2O is an excellent film substrate for use in the present invention. The system of the present invention is particularly valuable for processing PAN homopolymers such as DuPont's Tyzo A resin. Homopolymer PAN, copolymers and copolymers with hydrophilic ethylenically unsaturated monomers such as acrylic acid and esters can be adapted to this new process. Typical high nitrile 4+1
No. 2, US Pat.
No. 585.444, No. 3,873,508.

3.896.204, 3,984,601 and 4
．． No. 053,442.

Preferred adhesion promoting plasticizers for impregnation into the PAN films of the present invention are within the general formulas set forth above.

These are low molecular weight glycol ether compounds that are migratory in polymer matrices and range from 106 to 25
n width between 4+-7-band or more-m rumored to be non-volatile and at least 150tZ' preferably 245-3oo
It is an adhesion promoter with a boiling point of c. Specific substances include diethylene glycol, triethylene glycol, and tetraethylene glycol, alone or in combination.

Glycol ethers are present in the film in plasticizing and adhesion promoting proportions. This amount should be at least 1 part of PAN polymer. More specifically,
Glycol ethers are present from 5 to 65% by weight of the PAN polymer.

The method for forming a PAN film with liquid glycol ether incorporated therein is to maintain a predetermined concentration of the liquid glycol ether as an aqueous solution, and to maintain a predetermined concentration of the above liquid glycol ether as an aqueous solution.Ib) yt? A continuous film of lyacrylonitrile aquagel is contacted with this solution, thereby incorporating the glycol ethyl into the aquagel, (cl sequentially or simultaneously) the glycol ether-aquagel PAN (7) film system is stretched to The method comprises the steps of orienting an acrylonitrile film and drying the oriented film with fd to at least substantially remove water (fd) to yield a glycol ether absorbent film.

This method can be particularly adapted to absorb the subject water-soluble glycol ethers into PAN by maintaining a predetermined concentration of the glycol ether in an aqueous bath under steady state process conditions.

The polymeric aquagel continuous film is passed through a bath at a substantially constant water content. A glycol ether impregnant is thereby applied onto the film. The impregnating agent may be added to the aqueous bath as a steady stream consisting essentially of polyether. The glycol ether can be metered into the bath substantially without dilution, and additional water can be injected into the process as needed. It should be understood that the glycol ether, alone or as an aqueous solution, may be applied to the PAN film by any method, such as spray, roller, brush, etc. application methods! 0. reactor.

As mentioned above, the adhesive system of the present invention separates the polyacrylonitrile film from +? It can be used to bond a thermoplastic heat-sealable 2-remer film to a single thermoplastic heat-sealable reamer film. Particularly suitable are polyolefins. Polyolefins useful here are -
One or more alpha olefins, such as ethylene, globylene, phthene-1. ninoten 1.
Hexene-1゜-, butene-1, octene-1, etc.
A film-forming homopolymer formed by the polymerization of ~oxhyco, g+1 mer. Useful polyolefins also include one or more monomers copolymerized with preferably up to 20% in total and up to 5% by weight in total of one or more monomers that can be copolymerized with the alpha olefin. Contains film-forming copolymers of many alpha olefins. Examples of such monomers are carbon monoxide: sulfur dioxide; acrylic acid and/or acrylic acid esters such as methyl acrylate, amyl acrylate, hexyl acrylate, cyclohexyl acrylate, etc.; methacrylic acid or methacrylic acid. Esters such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, amyl methacrylate, etc.; vinyl acetic acid or vinyl esters such as vinyl formate, vinyl acetate, vinyl gropio, +-), vinyl gutilate, vinyl benzoate, ingropinol. Contains acetate, etc.

Methods of polymerizing alpha olefins and copolymerizing alpha olefins with other monomers such as those listed herein are well known and are not part of this invention. Polyolefins useful herein may be atactic, isotactic, syndiotactic, crystalline or amorphous;
Or it can be any combination of these. Preferred polyolefin films are homopolymers and copolymers of ethylene and propylene. Particularly good 7j? Lyolefin film is a random copolymer of propylene and a small amount of ethylene (commercially known as EX-
(available from Exxon Corporation as 24)
It is. Good adhesion can be obtained without surface treatment of the films of the invention, but better adhesion can be obtained by subjecting the polyolefin film to corona discharge and/or other equivalent means before applying the adhesive. can get.

Not only must the adhesive system of the present invention be an effective adhesive for PAN films, but under the conditions of the present invention it must be an effective bonding system for thermoplastic moisture barrier films.

Although the reason is not fully understood, the presence of heterogenized glycol ethers in PAN films = PAN
Significantly stronger bonding occurs at the interface between the PAN and the adhesive system than would be possible in the absence of this heterogenized glycol ether.

This adhesive is a combination of a commercial product sold as the Kraton 1000 Series product (Shell Chemical Company, Polymer Division) and a second component.

One material in this series, Kraton 1102, is a styrene-butadiene block co-H solimer with the following properties measured at 23C on films cast from a toluene solution: tensile strength, 4600 psi (3+
20kl? /=J); 300% modulus, 40 D
psi (28kg/cTA): elongation rate %, 800;
Hardness, Shore A62; Right angle tear strength - Die C11
90pJ, i (3,4klil/mi'): specific gravity,
0.94; Solution viscosity -25% by weight, toluene solution, 12
00 centipoise.

The second component of this adhesive combination is 60 to 40% by weight of 1
．． It is a resinous random terpolymer containing ro-pentadiene, 60 to 40 parts by weight of monocyclic styrene, and 25 to 35 weight percent alpha methyl styrene. Although the preferred monocyclic compound for use in the combinations of the present invention is terphelandin, other monocyclic compounds or mixtures thereof may also be used. These are diinten.

Alpha-terpinene, beta-terpinene, alpha-phelandrene, gamma-terpinene.

Contains terpyrune, syl-4-strene, origanene, pyronenes, etc.

This terpolymer additive has the following properties: melting point range (
Ring and ball type) 75-125tll' specific gravity 1.08-0.
90 Bromine number 6-14 Iodine number 79 Acid number 1 or less Saponification number 1 or less Decomposition temperature (in air) 300C Color (in 50.4 toluene solution) Gardner 6 viscosity (
70% in toluene) A particularly preferred random terpolymer is a feed stream containing 67,575% by weight of 6-antadiene, 57,575% by weight of terphelandrene, and 25% by weight of alpha-methylstyrene in toluene diluent with aluminum chloride. Produced by polymerization in the presence of a catalyst. The resulting terpolymer contained 64.0% by weight of 1.3--
! 'ntadiene, 36.5 parts by weight of terphelandrene and 295 parts by weight of alpha methylstyrene. This substance has a molecular weight (weight average) of 1880
.

Bromine number of 14, iodine number of 79, glass transition temperature of 68C, viscosity in toluene of 70 inches, ftog, and 300C
It had a decomposition temperature (in air) of

The individual films that make up the laminates described herein can vary in thickness over a wide range, such as from 0.1 mil (0.0025 mm) to 10 mil (0.25 mm), preferably 0.5 mil (0.00 mm),
0.125 mm) to 5 mils (0.125 mm). The thickness of the adhesive layer should, of course, be no thicker than is necessary for the intended application. In some cases, the thickness is in the micron range; for other purposes, the thickness may range from a few fractions of a mil to more than a mil.

The layers that make up the laminate of the present invention can be assembled in a variety of ways. For example, a combination adhesive, a styrene-getadiene block copolymer mixed with a random terpolymer, can be prepared from a suitable solution such as a toluene solution.
can be deposited onto a N film. The second PAN film is then laminated with an adhesive film, and the bond is compressible. Indeed, the two PAN films can be covered or applied with adhesive separately and then brought together by the application of pressure and/or heat. When the second layer to be laminated is a thermoplastic film of the type described above, the combination adhesive can be applied to this layer from a solvent solution and the PAN film is subjected to pressure and / or “can be brought into intimate interfacial contact with the thermoplastic film by application of heat.

Once the layers of the present invention have been laminated together, they can be formed into a suitable container. For example, they can be formed into retort pouches using known methods. According to one method, the laminate could be folded with the heat-sealable olefin sides facing each other and the sides edge-sealed between hot plates.

Such pouches can be filled with food or other materials and heat sealed at the top to provide an effective retort pouch. The lamination of two sheets 1) Butaronitrile 21% bonding can be achieved by using the adhesive of the present invention. This is because the soriacrylonitrile surfaces cannot be heat sealed together.

Examples Random copolymers of propylene and a small amount of ethylene (
EX-'? 6 parts by weight of styrene were added to a strip of corona discharge treated thickness filter mill (0,075 mm) commercially available from Exxon Corporation as 7:1).
A combination of butadiene block copolymer and 16 parts by weight, 64 parts by weight of 1.3-'l-ntadiene, 665 parts by weight of beta-phellandrene and 295 parts by weight of alpha-methylstyrene, I? 2 combination adhesives containing rimmer and
A 5% by weight diluted toluene solution is applied. This layer is 2
Dry at 00F for 20 seconds. Approximately 065 mils (0,021
A corresponding strip of biaxially oriented polyacrylonitrile homo-d-solimer film 11#l) thick is prepared containing about 20% by weight triethylene glycol.

This strip is applied to an adhesive coated copolymer of propylene and ethylene, and the Toru et al. film is placed together under gentle pressure sufficient to cause substantial interfacial contact between them. This laminate is then heated at 250F for 15 seconds. This creates a laminate that cannot be removed without the application of great force. Even after exposure to boiling water,
This laminated bond is still perfect.

The glycol ether-free polyacrylonitrile film of the present invention does not bond as strongly to another PAN film or zll olefin film with the adhesive of the present invention.

% Applicant Mobil Oil Corporation (
(4 people outside)

Claims (1)

[Claims] A polyalkylene glycol having the formula % (%) (wherein R is H or CH3, and n is an integer from 2 to 4) in an adhesion-promoting ratio. a polyacrylonitrile film; (b) an adhesive layer in contact with the polyacrylonitrile film, comprising: (1111 to 6:1 parts by weight monomer ratio of styrene-gtadiene zlock copolymer and 12+30 to 40 parts by weight of 1.3 --!'-ntadiene, 60 to 40 parts by weight of monocyclic styrene, and 25 to 35 parts by weight of alpha methyl styrene, a combination of 1 to 6 parts by weight of Glock copolymer and 6 to 1 part by weight of terpolymer. a flexible film laminate consisting essentially of an adhesive layer; and (C) a second oriented polyacrylonitrile containing the glycol ether or a heat-sealable polyolefin in contact with the adhesive layer; 2. The laminate of claim 1, wherein the polyacrylonitrile contains at least 80 repeating units of acrylonitrile. 3. The polyacrylonitrile is a homopolymer.
A laminate according to claim 1. 4. A laminate according to claim 1, wherein the adhesive layer comprises 6 parts by weight of the styrene-getadiene glock copolymer and 16 parts by weight of the terimer. A laminate according to claim 4. 6. The laminate according to claim 1, wherein the glycol ether is a member selected from the group consisting of diethylene glycol, triethylene glycol, tetraethylene glycol, and mixtures thereof. 7. A laminate according to claim 1, wherein the glycol ether is present in at least 1% by weight of the polyacrylonitrile. 8. A laminate according to claim 7, wherein the glycol ether is present in an amount of 5 to 65% by weight of the polyacrylonitrile film. 9 The above heat-sealable polyolefin is C2-08
Alpha olefin Bomo 71? The laminate according to claim 1, which is a remer or a copolymer. 10. 2 of the one or more monomers with which the polyolefin film can be copolymerized with the alpha olefin.
The laminate according to claim 9, comprising 0% by weight -i. Claim 1, wherein the polyolefin film contains not more than 5 parts by weight of one or more other monomers copolymerizable with the alpha olefin.
The laminate according to item 0. 12. A laminate according to claims 1-0, wherein the 12-holyolefin film is a homopolymer of ethylene or propylene, but is a copolymer of ethylene and propylene. 13(α) Incorporating an adhesion-promoting percentage of a polyalkylene glycol ether with the formula % (wherein R is H or CH3 and n is an integer from 2 to 4) into the polyacrylonitrile film; Between the bl films, a styrene-gutadiene zlock copolymer with a monomer parts by weight ratio of (111:3 to 6=1) and (2+30 to 40 parts by weight of 1.3--'?
a random copolymer of alpha methyl styrene, 60 to 40 parts by weight of monocyclic tyrene, and 25 to 65 parts by weight of alpha methyl styrene;
a layer of an adhesive composition consisting essentially of from 3 to 1 part by weight of a block copolymer to 3 to 1 part by weight of a terpolymer;
bonding two or more polyacrylonitrile films or one polyacrylonitrile and one heat-sealable polyolefin film, comprising: inserting; and (C) applying pressure or pressure and heat to the film surface; How to combine them. 14 The above adhesive composition is applied to one or both films from a solvent solution or dispersion thereof, the solvent is evaporated to maintain interfacial adhesion, and the laminate is heated to aid bonding. The method according to item 16. 15. For products made from the patented end-opening case 1-top rust-protruding film laminate, or tube.