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WO2002085619A1 - Boyau multicouche a base de nylon 6 - Google Patents

Boyau multicouche a base de nylon 6 Download PDF

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Publication number
WO2002085619A1
WO2002085619A1 PCT/JP2002/003766 JP0203766W WO02085619A1 WO 2002085619 A1 WO2002085619 A1 WO 2002085619A1 JP 0203766 W JP0203766 W JP 0203766W WO 02085619 A1 WO02085619 A1 WO 02085619A1
Authority
WO
WIPO (PCT)
Prior art keywords
layer
polyamide layer
casing film
nylon
multilayer casing
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/JP2002/003766
Other languages
English (en)
Inventor
Junji Nakajima
Hisanori Tobita
Kosuke Abe
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Kureha Corp
Original Assignee
Kureha Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Kureha Corp filed Critical Kureha Corp
Publication of WO2002085619A1 publication Critical patent/WO2002085619A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/06—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material
    • B32B27/08—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material of synthetic resin
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C55/00—Shaping by stretching, e.g. drawing through a die; Apparatus therefor
    • B29C55/28—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of blown tubular films, e.g. by inflation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B1/00—Layered products having a non-planar shape
    • B32B1/08—Tubular products
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/30—Layered products comprising a layer of synthetic resin comprising vinyl (co)polymers; comprising acrylic (co)polymers
    • B32B27/306—Layered products comprising a layer of synthetic resin comprising vinyl (co)polymers; comprising acrylic (co)polymers comprising vinyl acetate or vinyl alcohol (co)polymers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/32—Layered products comprising a layer of synthetic resin comprising polyolefins
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/34—Layered products comprising a layer of synthetic resin comprising polyamides
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B37/00—Methods or apparatus for laminating, e.g. by curing or by ultrasonic bonding
    • B32B37/14—Methods or apparatus for laminating, e.g. by curing or by ultrasonic bonding characterised by the properties of the layers
    • B32B37/15—Methods or apparatus for laminating, e.g. by curing or by ultrasonic bonding characterised by the properties of the layers with at least one layer being manufactured and immediately laminated before reaching its stable state, e.g. in which a layer is extruded and laminated while in semi-molten state
    • B32B37/153—Methods or apparatus for laminating, e.g. by curing or by ultrasonic bonding characterised by the properties of the layers with at least one layer being manufactured and immediately laminated before reaching its stable state, e.g. in which a layer is extruded and laminated while in semi-molten state at least one layer is extruded and immediately laminated while in semi-molten state
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B7/00—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
    • B32B7/04—Interconnection of layers
    • B32B7/12—Interconnection of layers using interposed adhesives or interposed materials with bonding properties
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2023/00—Use of polyalkenes or derivatives thereof as moulding material
    • B29K2023/04—Polymers of ethylene
    • B29K2023/06—PE, i.e. polyethylene
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2023/00—Use of polyalkenes or derivatives thereof as moulding material
    • B29K2023/04—Polymers of ethylene
    • B29K2023/08—Copolymers of ethylene
    • B29K2023/083—EVA, i.e. ethylene vinyl acetate copolymer
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2023/00—Use of polyalkenes or derivatives thereof as moulding material
    • B29K2023/04—Polymers of ethylene
    • B29K2023/08—Copolymers of ethylene
    • B29K2023/086—EVOH, i.e. ethylene vinyl alcohol copolymer
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2077/00—Use of PA, i.e. polyamides, e.g. polyesteramides or derivatives thereof, as moulding material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29L—INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES
    • B29L2009/00—Layered products
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29L—INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES
    • B29L2023/00—Tubular articles
    • B29L2023/001—Tubular films, sleeves
    • B29L2023/002—Sausage casings
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B38/00—Ancillary operations in connection with laminating processes
    • B32B38/0012—Mechanical treatment, e.g. roughening, deforming, stretching
    • B32B2038/0028—Stretching, elongating
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2250/00—Layers arrangement
    • B32B2250/24—All layers being polymeric
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/70—Other properties
    • B32B2307/724—Permeability to gases, adsorption
    • B32B2307/7242—Non-permeable
    • B32B2307/7246—Water vapor barrier
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2323/00—Polyalkenes
    • B32B2323/04—Polyethylene
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2323/00—Polyalkenes
    • B32B2323/04—Polyethylene
    • B32B2323/046—LDPE, i.e. low density polyethylene
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2323/00—Polyalkenes
    • B32B2323/10—Polypropylene
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2331/00—Polyvinylesters
    • B32B2331/04—Polymers of vinyl acetate, e.g. PVA
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2377/00—Polyamides
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2439/00—Containers; Receptacles
    • B32B2439/70—Food packaging

Definitions

  • the present invention relates to a multilayer casing film for packaging foods comprising a filling and solidified pasty meat product, such as sausage and ham. More specifically, the present invention relates to a polyamide/polyolefin-based multilayer casing film satisfying various properties of a multilayer casing film for packaging such foods by a simple layer structure including a nylon 6-layer as a principal component in combination with a layer of polyolefin that is also a general-purpose resin. [BACKGROUND ART]
  • Foods such as sausage and ham, are generally prepared by filling a film casing with a pasty meat material, and the thus-packaged meat material is heated for sterilization and cooking, before provision to the market.
  • the casing (film) for packaging these foods is required to satisfy the following properties in the course of production and circulation of the foods.
  • Strength and rigidity required as basic properties for preventing a puncture due to an internal pressure increase during the filling and heating of the pasty meat material, and preventing the breakage in resistance to an external stress applied during the handling of the food products.
  • Meat adhesion This is a property for a casing to adhere to the content meat at its inside film boundary and required to suppress the occurrence of gravy or meat juice at the boundary and prevent the spreading of rotting.
  • a multilayer casing film having a plurality of component layers is ordinarily used.
  • a polyamide-based multilayer casing film having an outer and an inner layer comprising principally a polyamide resin excellent in the above-mentioned (a) strength and rigidity, (b) thermal creep resistance, (c) gas-barrier property and (d) meat adhesion, and an intermediate non-polar polyolefin layer for improving the water vapor-barrier characteristic (International Publications WO 95/13707 and WO 00/59724).
  • the above-mentioned multilayer casing films do not necessarily have a good balance among the properties of the inner and outer polyamide layers or are not satisfactory with respect to the above-mentioned properties, of e.g., (a) strength and rigidity and (b) thermal creep resistance required of a multilayer casing film due to the use of a partially aromatic polyamide (represented by a polyamide comprising component units of metaxylylene-adipamide (generally called "nylon MXD6" incorporated for the purpose of improving the stretchability of a polyamide layer (WO 95/13707), or the use of a copolymer nylon 6-66 layer (WO 00/59724).
  • a partially aromatic polyamide represented by a polyamide comprising component units of metaxylylene-adipamide (generally called "nylon MXD6"
  • nylon MXD6 a partially aromatic polyamide
  • WO 95/13707 a polyamide comprising component units of metaxylylene-adipamide
  • a principal object of the present invention is to provide a polyamide/polyolefin-based multilayer casing film satisfying the above-mentioned properties required of a multilayer casing film by utilizing nylon 6 that is the most frequently used polyamide resin to the highest degree.
  • the nylon 6-based multilayer casing film according to the present invention has been developed so as to achieve the above-mentioned object, and comprises two polyamide layers of (a) an outer polyamide layer and (b) an inner polyamide layer, and (c) a non-polar polyolefin layer sandwiched between a pair of adhesive polyolefin layers disposed between the outer polyamide layer (a) and the inner polyamide layer (b), wherein
  • the outer polyamide layer (a) comprises nylon 6
  • the inner polyamide layer comprises a (co- )polyamide
  • the outer polyamide layer (a) has a thickness which is 1 to 4.5 times that of the inner polyamide layer (b)
  • the non-polar polyolefin layer (c) has a thickness which is equal to or smaller than that of the outer polyamide layer (a).
  • the present invention also provides a process for producing a nylon 6-based multilayer casing film, comprising the steps of: providing a co-extruded and cooled tabular product having a laminar structure including (a) another polyamide layer comprising nylon 6, (b) an inner polyamide layer comprising a (co- )polyamide, and (c) a non-polar polyolefin layer sandwiched between a pair of adhesive polyolefin layers and having a thickness equal to or smaller than that of the outer polyamide layer (a), the outer polyamide layer (a) having a thickness which is 1 to 4.5 times that of the inner polyamide layer (b), re-heating the tubular product through a warm water bath within at most 5 seconds, inflating the tubular product while externally heating the tubular product to biaxially stretch the tubular product, and heat-treating the inflated tubular product from its outer polyamide layer (a) to anneal the inflated tubular product.
  • Nylon 6 is a representative of general- purpose aliphatic polyamides, and it is well known that a film thereof is excellent in (a) strength and rigidity, (b) thermal creep-resistance and (f) meat adhesion and also has (c) good gas-barrier characteristic.
  • a film thereof is excellent in (a) strength and rigidity, (b) thermal creep-resistance and (f) meat adhesion and also has (c) good gas-barrier characteristic.
  • a non-polar polyolefin layer for also imparting (e) the water-vapor barrier characteristic
  • nylon 6 has a considerably high melting point (e.g., 225 °C) compared with polyolefins (typically having melting points of ca. 110 - 170 °C) and a noticeable crystallizability.
  • the above- mentioned WO 95/13707 has proposed to solve the problem by incorporating a partially aromatic polyamide (polyamide or nylon MXD6).
  • the partially aromatic polyamide has a better gas-barrier property than nylon 6 and therefore well functions also for providing an improvement in (c) gas-barrier property.
  • the partially aromatic polyamide is a special polyamide resin, and the inclusion thereof not only is uneconomical but also is liable to impair (a) the strength and rigidity that is the greatest characteristic of nylon 6.
  • the partially aromatic polyamide is liable to be affected by the moisture, and can fail to well exhibit its characteristic gas-barrier property if it is used in a large amount in the inner polyamide layer contacting the pasty content material.
  • WO 95/13707 has adopted a large thickness ratio of 4.6:1 (in Examples), but this is not necessarily desirable particularly in view of a balance of mechanical properties which is principally governed by the outer polyamide layer and the inner polyamide layer.
  • the film is liable to be curled, so that the operation of filling with the pasty content material becomes difficult. More specifically, for example, the clipping for tight sealing of the casing film ends after the filling becomes difficult.
  • WO 00/59724 has solved the difficulty of co-stretching of a nylon 6/polyolefin laminate film by a combination of one layer of nylon 6 and a thicker layer of another polyamide.
  • This can solve several of the above-mentioned problems accompanying the use of a partially aromatic polyamide, but this modification functions to lower (a) the strength and rigidity and (b) the thermal property which are characteristic of nylon 6 and also inevitably results in an inferior performance in respect of (c) the gas-barrier property compared with a structure principally comprising a nylon 6 layer.
  • the multilayer casing film of the present invention comprises two polyamide layers of (a) an outer polyamide layer and (b) an inner polyamide layer, and (c) a non-polar polyolefin layer sandwiched between a pair of adhesive polyolefin layers disposed between the two polyamide layers (a) and (b).
  • the outer polyamide layer (a) comprises nylon 6 which is particularly excellent in strength, rigidity, thermal creep resistance and meat adhesion, and also retains a good gas-barrier characteristic.
  • the melting point thereof is generally on the order of 220 - 230 °C.
  • the outer polyamide layer consists essentially of nylon 6 alone (i.e., except for optional additives, such as a lubricating agent and a nucleating agent), but another resin can be co-used within an extent of not exerting adverse effects thereby, more specifically in an amount of at most ca. 10 wt. % , preferably up to ca. 5 wt. %.
  • Representative examples of such another resin may include other polyamide resins constituting the inner polyamide layer (b) described below.
  • the inner polyamide layer (b) comprises a (co- )polyamide, i.e., a polyamide homopolymer or copolymer, and most preferably comprises nylon 6 similarly as the outer polyamide layer (a) , but it is also possible to use nylon 6-66, nylon 6-69, nylon 61 (polyhexamethylene isophthalamide) , etc., in addition to nylon 6. It is preferred that the melting point is at least 180 °C, more preferably at least 200 °C. In addition to the (co- )polyamide, it is possible to mix at most 30 wt . %, preferably up to 10 wt. % , of another resin.
  • Such another resins are other polyamides, examples of which may include: nylon 66, nylon 69, nylon 612, nylon MXD6, nylon 61 (polyhexamethylene isophthalamide) , nylon 6T (polyhexamethylene terephthalamide) , nylon 66-61, nylon 6-69, nylon 66-610-MXD6, and nylon 6I-6T.
  • the outer polyamide layer (a) has a thickness which is 1 - 4.5 times, preferably more than 1 and at most 4.0 times, further preferably 1.2 - 3.0 times, that of the inner polyamide layer (b). That is, the outer polyamide layer (a) requiring utmost degrees of mechanical strength, rigidity and thermal creep resistance, has a thickness which is equal to or larger than that of the inner polyamide layer (b).
  • the product multilayer casing film is liable to curl at the time of filling with a pasty content material, thus causing difficulties, such as difficulty in clipping for tight sealing of casing ends.
  • the crystallization of the outer polyamide layer (a) is promoted by moisture absorption, whereby the stretching is obstructed due to an excessively large expansion force at the time of heat stretching.
  • a non-polar polyolefin layer (c) sandwiched between a pair of adhesive polyolefin layers is disposed between the above-mentioned two polyamide layers (a) and (b).
  • the non-polar polyolefin layer (c) is disposed to ensure a water vapor-barrier characteristic of the product multilayer casing film, but the thickness thereof is suppressed to at most the thickness of the outer polyamide layer (a).
  • the lower limit of the thickness may preferably be at least 30 % , particularly at least 50 % , of the outer polyamide layer (a), from the viewpoint of a required water vapor-barrier characteristic.
  • the non-polar polyolefin resin constituting the non-polar polyolefin layer (c) may be a polyolefin homopolymer or copolymer.
  • the melting point may be at least 80 °C, preferably 110 °C or higher.
  • Specific examples thereof may include: ethylene- ⁇ -olefin copolymers, such as VLDPE (very low-density polyethylene), and LLDPE (linear low-density polyethylene); and polypropylene resins, such as PP (polypropylene), PP-Et (propylene-ethylene copolymer), and PP-Et-But (propylene-ethylene-butene copolymer) .
  • the product multilayer casing film tends to have an improved thermal creep resistance. It is possible to color (c) the non-polar polyolefin layer (c) by blending a colorant to the non-polar polyolefin resin. This embodiment is preferred in order to alleviate thermal deterioration of the colorant than the embodiment of coloring the polyamide layer (a) or (b), and is preferred in order to alleviate the lowering in extrudability than the embodiment of coloring the adjacent adhesive polyolefin layers.
  • the non-polar polyolefin layer (c) is sandwiched between a pair of adhesive polyolefin layers and then disposed between the above-mentioned polyamide layers (a) and (b).
  • the adhesive polyolefin layers are effective in ensuring the intimate adhesion of the non-polar polyolefin layer (c) which is inherently poor in adhesiveness, to the adjacent layers, particularly the polyamide layer (a) or (b) , thereby preventing the inter-layer peeling during the stretching step or the shirring step, and also in improving the pin-hole resistance of the product multilayer casing film.
  • an adhesive polyolefin layer has a rather low cohesion strength, and a thick layer thereof makes it difficult to increase the strength because of cohesion breakage of the adhesive polyolefin layer per se. It may be possibly conceived of to provide a single adhesive polyolefin layer having a water vapor-barrier characteristic by mixing an adhesive polyolefin resin and a non-polar polyolefin resin and disposing the adhesive polyolefin layer between the polyamide layers (a) and (b). In this case, however, the adhesive effect intended by the adhesive polyolefin layer is lowered, so that it is difficult to attain the desired properties.
  • the adhesive polyolefin resin constituting the adhesive polyolefin layers may comprise at lea,st one species of adhesive polyolefin resin, selected from acid-modified ethylene- ⁇ -olefin copolymers and acid-modified polypropylene-based resins, inclusive of, e.g., acid-graft-modification products of VLDPE, LLDPE, PP, PP-Et and PP-Et-But.
  • the multilayer casing film of the present invention is caused to have a 5-layered structure comprising the above-mentioned outer polyamide layer (a) and inner polyamide layer (b), and the non-polar polyolefin layer (c) sandwiched with a pair of the adhesive polyolefin layers disposed between the polyamide layers (a) and (b).
  • a multilayer casing film having a good harmony among the above-mentioned properties (a) - (f) required of a multilayer casing film for a pasty content material. It is however possible to insert an additional layer, as desired, in order to strengthen a part of the above-mentioned properties, or for another purpose.
  • EVOH ethylene-vinyl acetate copolymer saponification product
  • nylon MXD6 nylon MXD6, etc.
  • the outer polyamide layer (a) constitutes the outermost layer of the multilayer casing film, but the outer polyamide layer (a) can be subjected to a printing treatment or provided with a matte-finish layer as the outermost layer.
  • a matte-finish layer may also be preferably formed as a polyamide resin-based layer.
  • the matte-finish layer comprises nylon 6, the thickness thereof is included as a part of the outer polyamide layer (a) thickness.
  • an inorganic material or organic material in the form of fine particles of at most 20 ⁇ m in diameter may be added, and specific examples thereof may include fine particles of silicon oxide compounds, such as silica, talc and mica, and volcanic expanded particles (so-called "shirasu balloon” in Japanese) as inorganic materials.
  • organic materials may include fine particles of thermoplastic resins, such as VLDPE, LLDPE, LDPE, EVA, EEA, EAA, EMA, EMAA, MMA, and MAA.
  • the multilayer casing film of the present invention may preferably be formed as a multilayer casing film having a total thickness (as a single sheet) of 15 - 120 ⁇ m, more preferably 25 - 80 ⁇ m.
  • the layer (a) may have a thickness of 7 - 80 ⁇ m, preferably 10 - 40 ⁇ m; and the layer (b) may have a thickness of 2 - 18 ⁇ m, preferably 3 - 12 ⁇ m.
  • the non-polar polyolefin layer (c) may have a thickness of 7 - 25 ⁇ m, preferably 12 - 20 ⁇ m.
  • Each adhesive polyolefin layer may have a thickness of ca. 0.5 - 5 ⁇ m.
  • the gas-barrier layer may be disposed as desired depending on the desired level of gas-barrier property in a thickness for satisfying the desire as a lower limit. The upper limit may be determined depending on the stretchability. In view of these factors, the gas-barrier layer may generally have a thickness of ca. 1 - 20 ⁇ m, preferably ca. 2 - 10 ⁇ m.
  • the multilayer casing film may preferably be formed to have a lay-flat width of 50 - 600 mm, particularly 100 mm or larger so as to be suitable for providing a sausage casing subjected to hung-down heating.
  • the multilayer casing film of the present invention may preferably be formed through a process wherein a plurality of extruders are provided corresponding to a necessary number of starting resin species (equal to or less than a number of laminated layers since some layers can be formed of a common starting resin (mixture)) and the respective resins from the extruder are co-extruded through an annular die to form a tubular sheet before stretching (called a "parison"), which is then biaxially stretched by inflation into a casing film.
  • the stretching ratio may preferably be ca.
  • the parison co-extruded through the annular die is cooled down to a temperature which is below the melting points of the respective layer resins by applying water onto the outer surface of the parison, and then moved to an orientation region where the parison is re-heated to a temperature allowing the stretching.
  • the re-heating is performed quickly (e.g., passing the parison through a warm water bath at 70 - 80 °C within 5 sec, preferably ca. 2 - 3 sec.) so as not to promote the crystallization of nylon 6.
  • the pre-heated parison is pulled vertically (e.g., upwards) to form a bubble of tubular film with fluid air introduced into the bubble between pinch rollers, whereby the tubular film is biaxially stretched simultaneously at a ratio of 2 - 4 times in each of the machine direction (MD) and the transverse direction (TD) , while subjecting the tubular film to auxiliary heating with warm air at 80 - 100 °C blown through an air ring toward the circumference of the tubular film.
  • MD machine direction
  • TD transverse direction
  • the thus-biaxially stretched tubular film is then subjected to an annealing treatment at a temperature of 60 - 100 °C so as to cause a relaxation of 0 - 10 % in each of MD and TD, thereby proving a tubular biaxially stretched multilayer casing film according to the present invention.
  • a good thermal creep resistance e.g., a hot water creep of at most 25 %, preferably at most 20 % , in MD and a smaller hot water creep than in MD of at most 20 % , preferably at most 15 % , in TD according to a hot water creep test described hereinafter
  • Such an annealing condition has been difficult to adopt for a polyamide- based multilayer casing film comprising copolymer nylon as a principal layer component, because it causes a size change of the multilayer casing film after the production and before the filling with a content material.
  • the above-mentioned casing film production process may be performed by using an inflation apparatus system similar to the one disclosed in WO 01/98081 except for temperature conditions around the inflation step mentioned above.
  • the heating methods for the stretching and annealing are not limited to those described above.
  • the heating may be effected by infrared ray heater, or with hot air or steam.
  • the present invention will be described more specifically based on Examples and Comparative Examples. The following measurements were applied to resins used and resultant multilayer casing films in Examples and Comparative Examples, and the above- mentioned properties of the multilayer casing film of the present invention are also based on the results of the measurement .
  • Five sample films from each product film are subjected to the above measurement, and the average value of percentage decrease is indicated in each of the MD and TD in a style of, e.g., 12/15 (MD/TD) ( ).
  • An oxygen gas transmission rate through a sample film is measured by using an oxygen gas transmission meter ( "MOCON OXTRAN Model-100", made by Modern Controls Co.) in an atmosphere of 30 °C/100 % 2
  • a water vapor-transmission rate (WVTR) through a sample film is measured by using a water vapor transmission meter ( "MOCON PERMATRAN Model-
  • a sample casing is filled with 2.3 kg of pasty sausage meat in a length of ca. 43 - 44 cm between clips so as to achieve an overfilling of 110 %, and after being clipped at upper and lower ends, the filled casing is heat-treated for 120 min. in a smoke chamber at 80 °C, immediately followed by cooling with water for 10 min. and standing for 1 day in a form of being hung in a refrigerator at 5 °C.
  • the thus-treated sausage-filled casing is evaluated with respect to the following items.
  • a deformation ( % ) [(a circumferential length at a point 5 cm above the lower clip) - (a circumferential length at a point 5 cm below the upper clip)] x 100/(the circumferential length at the point 5 cm above the lower clip) .
  • a deformation (%) of at most 7 % is a level of deformation which cannot be substantially recognized by observation with eyes.
  • the sausage weight loss is 2 % or more in one month.
  • the shirrability of a casing film is evaluated based on the easiness of shirring (a processing for conversion into a form of bellows for facilitating the filling with a pasty content material) according to the following standard.
  • a casing is flexible and effectively shirrable, resulting in no recognizable inter-layer peeling or pinholes after the shirring.
  • a casing is shirrable, not resulting in inter- layer peeling or pinholes but being curled so that the tight sealing by clipping becomes difficult.
  • a casing is too hard to be sufficiently folded.
  • An inflation bubble somewhat pitches up and down, but can be stably formed.
  • Example or Comparative Example a plurality of resins selected so as to provide a layer structure shown in any one of Tables 1 - 3 appearing hereinafter (indicated in the order of 1st., 2nd., ... from the inside to the outside) with resins indicated by abbreviated symbols, of which the meanings are described hereinafter, were extruded and formed into a casing film, thereby obtaining various multilayer casing films.
  • the respective resins for providing a multilayer casing film were extruded through separate extruders and introduced into an annular die to be co-extruded into a parison having a laminated structure.
  • the parison was then cooled by showered cool water and formed into a tubular form corresponding to a lay-flat width in a range of 19 - 74 mm.
  • the resultant parison was caused to pass through a warm water bath at 70 - 80 °C in 2 to 3 sec, and biaxially stretched simultaneously in 2.0 to 3.0 times in a machine direction (MD) and 2.5 to 3.8 times in a transverse direction (TD) by inflation, followed by annealing at a temperature in a range of 60 - 100 °C for causing relaxation of 0 - 10 % in MD and 0 - 10 % in TD.
  • the resultant biaxially stretched tubular casing film had a lay-flat width in a range of 50 - 210 mm and a thickness in a range of 35 - 50 ⁇ m.
  • the abbreviation symbols used in Tables 1 - 3 for indicating the used resins respectively have the following meanings.
  • ⁇ Adhesive polyolefin resin> m-VL.l: acid-modified VLDPE; "ADMER NF587”, made by Mitsui Kagaku K.K. ; (Tm 123 °C) .
  • m-VL.3 acid-modified VLDPE; "ADMER SF 730", made by Mitsui Kagaku K.K.
  • Numeral in ( ) represents a thickness in ⁇ m.
  • Numerals separated by "/" (slush) represent values measured in MD and TD, respectively.
  • Ny6. 3 contains 5 wt. % of lubricant master batch.
  • a polyamide/polyolefin- based multilayer casing film formed by stretching and utilizing the properties of a nylon 6-polyamide layer suitable as a casing material for a pasty content material to the higher degree by disposing a relatively thin polyolefin layer via adhesive polyolefin layers between a relatively thick outer layer and a relatively narrow inner layer respectively of nylon 6-based polyamide.
  • the casing film is particularly suited as a casing material for pasty meat products, such as sausage and ham but is also suitable as a casing of an analogous products using a pasty material, such as cheese.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Laminated Bodies (AREA)
  • Wrappers (AREA)
  • Shaping By String And By Release Of Stress In Plastics And The Like (AREA)

Abstract

L'invention concerne un boyau multicouche à base de nylon 6 destiné à envelopper de la viande pâteuse, utilisant les propriétés mécaniques excellentes d'une couche de nylon 6 au plus haut niveau de stratification avec une couche polyoléfinique. Ce boyau multicouche se compose d'une structure stratifiée formée par (a) une couche externe polyamide comprenant du nylon 6, (b) une couche interne polyamide comprenant un co(-)polyamide et (c) une couche polyoléfinique non polaire prise en sandwich entre une paire de couches polyoléfiniques adhésives disposées entre les couches externe et interne polyamide (a) et (b) et ayant une épaisseur inférieure ou égale à celle de la couche externe polyamide (a), la couche externe polyamide (a) ayant une épaisseur comprise entre 1 et 4,5 fois celle de la couche interne polyamide (b).
PCT/JP2002/003766 2001-04-18 2002-04-16 Boyau multicouche a base de nylon 6 Ceased WO2002085619A1 (fr)

Applications Claiming Priority (2)

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JP2001-119357 2001-04-18
JP2001119357A JP2002307626A (ja) 2001-04-18 2001-04-18 ナイロン６系多層ケーシングフィルム

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Cited By (5)

* Cited by examiner, † Cited by third party
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JP2002307626A (ja) * 2001-04-18 2002-10-23 Kureha Chem Ind Co Ltd ナイロン６系多層ケーシングフィルム
WO2010026369A1 (fr) * 2008-09-02 2010-03-11 Steamfast Europe Limited Feuille de conditionnement alimentaire améliorée pour une utilisation dans des fours à micro-ondes
DE102009057862A1 (de) * 2009-12-11 2011-06-16 Huhtamaki Forchheim Zweigniederlassung Der Huhtamaki Deutschland Gmbh & Co. Kg Mehrschichtfolie mit hoher Durchstoß- und Weiterreißfestigkeit
US7964229B2 (en) 2002-11-12 2011-06-21 E.I. Du Pont De Nemours And Company Films comprising a liquid-absorbant inner layer and an impermeable outer layer
WO2017046595A1 (fr) * 2015-09-18 2017-03-23 Johnson Matthey Public Limited Company Emballage alimentaire

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DE102008062937A1 (de) * 2008-12-23 2010-07-01 Kuhne Anlagenbau Gmbh Mehrschichtige, schlauchförmige Nahrungsmittelfolie

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EP0879560A1 (fr) * 1997-05-21 1998-11-25 Kalle Nalo GmbH & Co. KG Enveloppe multicouche orienté biaxialement pour aliments contenant deux couches barrières à l'oxygène
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EP0603676A1 (fr) * 1992-12-23 1994-06-29 Wolff Walsrode Aktiengesellschaft Boyau de saucisses multicouche coextrudé et étiré biaxialement sans soudure avec barrière à oxygène amélioré
US5612104A (en) * 1993-11-19 1997-03-18 Naturin Gmbh Five-layer, biaxially stretched tubular film for packaging and encasing pasty food stuffs
DE19650383A1 (de) * 1996-12-05 1998-06-10 Basf Ag Mehrschichtige Schlauchfolien
EP0879560A1 (fr) * 1997-05-21 1998-11-25 Kalle Nalo GmbH & Co. KG Enveloppe multicouche orienté biaxialement pour aliments contenant deux couches barrières à l'oxygène
DE19814924A1 (de) * 1998-04-03 1999-10-07 Basf Ag Schlauchfolien
DE19855867A1 (de) * 1998-12-03 1999-05-27 Basf Ag Mehrschichtige Schlauchfolien
EP1084962A2 (fr) * 1999-09-14 2001-03-21 Wolff Walsrode AG Feuille multicouche synthétique étirée biaxialement pour boyaux de saucisses avec barrière à oxygène

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2002307626A (ja) * 2001-04-18 2002-10-23 Kureha Chem Ind Co Ltd ナイロン６系多層ケーシングフィルム
US7964229B2 (en) 2002-11-12 2011-06-21 E.I. Du Pont De Nemours And Company Films comprising a liquid-absorbant inner layer and an impermeable outer layer
US7964055B2 (en) 2002-11-12 2011-06-21 E. I. Du Pont De Nemours And Company Films comprising a liquid-absorbant inner layer and an impermeable outer layer
US7964226B2 (en) 2002-11-12 2011-06-21 E.I. Du Pont De Nemours And Company Films comprising a liquid-absorbant inner layer and an impermeable outer layer
US7968134B2 (en) 2002-11-12 2011-06-28 E.I. Du Pont De Nemours And Company Films comprising a liquid-absorbant inner layer and an impermeable outer layer
WO2010026369A1 (fr) * 2008-09-02 2010-03-11 Steamfast Europe Limited Feuille de conditionnement alimentaire améliorée pour une utilisation dans des fours à micro-ondes
US8931955B2 (en) 2008-09-02 2015-01-13 Excelsior Technologies Limited Food packaging sheet for use in microwave ovens
DE102009057862A1 (de) * 2009-12-11 2011-06-16 Huhtamaki Forchheim Zweigniederlassung Der Huhtamaki Deutschland Gmbh & Co. Kg Mehrschichtfolie mit hoher Durchstoß- und Weiterreißfestigkeit
US9752325B2 (en) 2009-12-11 2017-09-05 Infiana Germany Gmbh & Co. Kg Multi-layer film having a high puncture resistance and resistance to further tearing
WO2017046595A1 (fr) * 2015-09-18 2017-03-23 Johnson Matthey Public Limited Company Emballage alimentaire
US11180268B2 (en) 2015-09-18 2021-11-23 Stepac L.A. Ltd. Food packaging

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