RU2113125C1 - Polyamide-based tubular film - Google Patents

Abstract

FIELD: food industry. SUBSTANCE: invention relates to biaxially oriented tubular film utilized in production of pastelike and plastic-state products submitted to heat treatment at 70 to 125 C. Film material, including polyamide 6 (77-83 wt parts), alifatic copolyamide (7-13 wt parts), aromatic polyamide containing hexamethylenediamine and terephthalic acid units (3-7 wt parts), and a copolymer including olefin units (0.1-5 wt parts), additionally contains ion-exchange resin (3-6 wt parts) and has, as alifatic copolyamide, polycaprolactam /hexamethylenediamine/ adipic acid copolymer and, as copolymer including olefin units, mixture of graft copolymers based on carboxylic and polycarboxylic acids. Tubular film may be multilayer, at least one its layer being composed as indicated above. EFFECT: reduced water, vapor, and oxygen-permeability and increased strength under heat treatment conditions. 6 cl, 2 tbl

Description

The invention relates to sleeve films based on polyamides and can be used to obtain a biaxially oriented sleeve film used in the production of pasty and viscous products subjected to heat treatment in the temperature range 70-125 ^o C. The invention relates, in particular, to the manufacture of sleeve film (shell) for cooked sausages, as well as processed cheeses, packed in the form of sausages, which are packaged, usually in a softened or viscous state.

 There are a large number of types of polymer film used in the production of pasty or fused packaged products.

 A known composition for producing a sausage shell containing polycaprolactone with a molecular weight of 1000-4000, 1,6-hexamethylenediisocyanate and 1,4-butanediol in the ratio of the listed components (parts by weight) 24-30, 50-40, 24, 84-27 , 0 [1].

To obtain a shell, the constituent parts of the composition are heated to 60-50 ^° C, followed by a temperature increase to 240 ^° C, and the resulting product is poured onto a polytetrafluoroethylene film. After 5 hours, the cast plate is granulated, reheated and blown extruded.

 The disadvantages of the known composition are the need to pre-prepare it before extrusion, which takes a lot of time. In addition, the film is obtained with a thickness of at least 0.05 mm and is suitable only for machine packing. The moisture content in the shell is 0.03%, it is enough to keep the shell in the process of filling in a stretched and elastic state, but water and water vapor during the cooking process increase the water content so that it negatively affects its mechanical characteristics.

 Polyamide-based casings are more susceptible to stretching and shrinkage, have high strength, and are also suitable not only for machine but also for manual stuffing.

 Known tubular film used in the manufacture of pasty foods, in particular sausages and cheese, containing at least one aliphatic polyamide and at least one ionomer resin and / or one modified copolymer of ethylene with vinyl acetate [2].

 As the polyamides in the known tubular film, polycaprolactam, polyamino enantamide, polyhexamethylene adipamide and / or polyhexamethylene sebacinamide are used individually or in mixture with each other, as well as copolymers of the aforementioned polyamides and polyaminooundecanamide or polylaurinlactam.

The thickness of the resulting tubular film is 0.050 mm, which is suitable only for machine packing, water permeability ranges from 12-28 g / m ² per day, and oxygen permeability from 15 to 30 cm ³ / m ² • day • bar.

The inventive film is made as follows: the components are mixed, plasticized at 260 ^o C and formed, preferably by extrusion of a sleeve with a blow. Next, a biaxial hood is produced with a stretch ratio of the hood along and across in the range from 1: 1.5 to 1: 4, and then the sleeve is thermofixed to stabilize the dimensions.

 However, the known technical solution does not allow to obtain thinner films for manual stuffing and to provide strength characteristics during cooking. With an incision in the shell, its tendency to rupture is manifested. To cook boiled sausages, minced meat must be filled into a well-known shell under a significant pressure of 0.3-0.6 bar. For manual stuffing of sausage stuffing, during which the filling pressure is insignificant, this shell is of little use, because after the technological cycle of cooking sausages folds and creases are formed.

 The closest technical solution to the proposed one is a polyamide-based tubular film used in the production of pasty and viscous food products (sausage casing), including polyamide 6, aliphatic copolyamide, aromatic polyamide containing hexamethylene diamine and terephthalic acid units and a copolymer comprising olefinic units 3 ].

Known sleeve film contains (wt.):
a) polyamide 6;
b) from 5-50% to the total weight of all polymers in the aliphatic copolyamide layer, which is used as a copolyamide with elements of ε-caprolactam, hexamethylene diamine and azelaic acid (polyamide 6 / 6.9) and / or polyamide 6.12 as copolyamide from hexamethylenediamine and dodecanoic acid;
c) up to 20% of aromatic polyamide, partially aromatized with elements of hexamethylenediamine and terephthalic or isophthalic acids (PA 6-T or PA 6-T);
d) up to 20% of a copolymer containing olefin units of a polyolefin modified with carboxyl groups, mainly an ethylene / methacrylic acid copolymer.

 The sleeve film may contain dyes and / or pigments in small amounts.

The technology for the production of a single-layer and multi-layer sausage casing includes mixing and melting at a temperature of about 240 ^o C the components of the mixture in a special extruder until a uniform melt is obtained, extruding the latter through annular blown nozzles, forming a single sleeve, which is then stretched in the longitudinal and transverse directions under air pressure. The resulting film is fixed by additional heat treatment.

Obtained according to the prototype sleeve film shrinks from 5 to 25% (at 80 ^o C) in the fractional and transverse directions, has a thickness of 0.033-0.056 mm, can be multi-layer. The water permeability of the sausage casing ranges from 11.5 to 13.1 g / m ² • day, and the oxygen permeability from 13.6 to 18.5 cm ³ / m ² • day • bar.

 The multilayer sleeve film contains at least one layer of the aforementioned polyamide mixture. Other layers consist predominantly of polyamides (e.g., polyamide 6), polyamide blends, polyolefins (e.g., polyethylene or polypropylene), and also polyolefins containing binding functional groups. In addition, the layers can be made of copolymers with elements of ethylenically unsaturated monomers (for example, vinyl acetate, vinyl alcohol, acrylic and methacrylic acids), as well as vinylidene chloride or acrylonitrile copolymers, ionomer resins or the aforementioned polymers.

 The shell usually consists of 3-5 layers. Such a shell is obtained by coextrusion through ring nozzles, which are specially designed according to the number of layers. Multilayer shells, in comparison with single-layer ones, have higher water vapor resistance and impermeability to oxygen.

The disadvantage of both single-layer and multilayer tubular films, as claimed in [3], is their relatively high water vapor permeability and permeability to air oxygen, the indicators of which are priority for finished sausage products, since they determine the safety (spoilage) of the finished product and its weight loss. Moreover, the strength of the shell material for viscous products and sterilized sausages that require curing to a temperature of up to 125 ^o C is not high enough.

 The objective of the invention is to create a tubular film used in the production of pasty and viscous food products, with lower water permeability and permeability to oxygen, as well as increased strength characteristics in heat treatment conditions.

The problem is solved in that the sleeve film based on polyamides, including polyamide 6, an aliphatic copolyamide, an aromatic polyamide containing hexamethylene diamine and terephthalic acid units and a copolymer including olefin units, additionally contains an ionomer resin, and as an aliphatic copolymene polyamide polyamide and adipic acid, as a copolymer comprising olefinic units, a mixture of grafted copolymers based on carb derivatives is used onic and polycarboxylic acids in the following ratio of components (parts by weight):
Polyamide 6 - 77-83
Polycaprolactam copolymer with polyhexamethylenediamine and adipic acid - 7-13
Aromatic polyamide containing hexamethylenediamine and terephthalic acid units - 3-7
Ionomer resin - 3-6
A mixture of grafted copolymers based on derivatives of carboxylic and polycarboxylic acids is 0.1-5.

 As the ionomer resin, the zinc salt of an ethylene / methacrylic acid copolymer is used.

The proposed sleeve film uses a copolymer of polycaprolactam with polyhexamethylenediamine and adipic acid (polyamide 6 / 6.6 with elements of the formulas
-NH- (CH ₂ ) ₅ -CO-, -NH- (CH ₂ ) ₆ NH-, CO- (CH ₂ ) ₄ -CO-
with the number of units of monomers, respectively, 85, 7.5 and 7.5 wt.%.

 In the proposed sleeve film using a mixture of grafted copolymers based on derivatives of carboxylic and polycarboxylic acids with a content of grafted units from 0.3 to 0.9 wt.%.

The sleeve film can be multilayer, with at least one layer having the following composition (parts by weight):
Polyamide 6 - 77-83
Polycaprolactam copolymer with polyhexamethylenediamine and adipic acid - 7-13
Aromatic polyamide containing hexamethylenediamine and terephthalic acid units - 3-7
Ionomer resin - 3-6
A mixture of grafted copolymers based on derivatives of carboxylic and polycarboxylic acids is 0.1-5.

 Other layers of the multilayer sleeve film may be made of polyamides, or polyamide mixtures, or polyolefins, or polyolefins containing functional groups, or copolymers with elements of ethylenically unsaturated monomers, or vinylindene chloride or acrylonitrile copolymers, or ionomer resins, or mixtures of these polymers.

 The sleeve film may contain, if necessary, additional dyes, pigments and / or processing aids. The proportion of these components is relatively small, so that the main characteristics of the film remain unchanged.

Below, the components of the sleeve film are indicated as:
1) polyamide 6,
2) a copolymer of polycaprolactam with polyhexamethylenediamine and adipic acid,
3) an aromatic polyamide containing hexamethylenediamine and terephthalic acid units,
4) ionomer resin,
5) a mixture of grafted copolymers based on derivatives of carboxylic and polycarboxylic acids.

 As grafted copolymers, for example, an acrylic polymer with grafted groups of maleic anhydride, linear low density polyethylene with grafted groups of maleic anhydride and ethylene-propylene rubber with grafted groups of maleic anhydride are used.

 A mixture of grafted copolymers based on derivatives of carboxylic and polycarboxylic acids allows the introduction of a polycaprolactam-polyhexamethylenediamine-azelaic acid copolymer and other, more readily available and more readily available copolymers, for example polycaprolactamide-polymexylamine-hexamethoxymethyl copolymer used in the manufacture of known tubular films.

Due to the preferred use of the combination of components of the sleeve film in the following ratio: from 79-81% of the weight of component 1), from 9 to 11% of component 2), from 4 to 6% of component 3), from 4 to 5% of component 4), from 0 5 to 1.5% of component 5) properties are achieved that both the individual components of the composition and the known compositions of the sleeve films do not possess, namely: higher water vapor and oxygen impermeability, and, moreover, it is thermostable up to 125 ^o C and not subject to breaks during heat treatment (cooking).

Example 1. A mixture of:
1) 80 parts by weight ordinary polycaprolactam granulate (polyamide 6) with a relative viscosity of 4 (measured per 1 g of granulate in 100 ml of 96% sulfuric acid at 20 ^o C);
2) 10 parts by weight of a copolymer of polycaprolactam with polyhexamethylenediamine and adipic acid (polyamide 6 / 6.6) with a relative viscosity of 3.32 (measured per 1 g of granulate in 100 ml of 96% sulfuric acid at 20 ^o C);
3) 5 parts by weight of aromatic polyamide with elements of hexamethylenediamine and terephthalic acid (Celar PA 3426, Du Pont de Nemour Inc.) (melting index 90 g for 10 min at 275 ^o C and a load of 10 kg);
4) 4 parts by weight an ionomer resin - a copolymer of ethylene / methacrylic acid with a content of 2-20% methacrylic acid with a melting index of 2.5 g per 10 min at 190 ^o C and 2.16 kg load and the type of ion is Zn (Cerlin N 1652, Du Pont);
5a) 0.5 parts by weight an acrylic polymer with grafted groups of maleic anhydride (Fusabond A, Du Pont) (melting index 3.5 g per 10 min at 280 ^o C and 2.16 kg load);
5b) 0.5 parts by weight linear low density polyethylene with grafted groups of maleic anhydride (Fusabond E, Du Pont) (melting index 3.0 g at 280 ^o C for 10 min and 2.16 kg of load).

Components 1-5 in the indicated amounts are thoroughly mixed and loaded into the hopper of the extruder, where the mixture of granules at 255 ^o C is homogenized to a homogeneous melt. The latter is fed to the annular head of the extruder, when passing through which the primary sleeve is formed. The primary sleeve emerging from the extruder is sharply cooled and then heated to give ductility followed by a biaxial hood, which is carried out with compressed air. Further, the formed sleeve enters the heat-setting furnace, where the process of its stabilization takes place. Then the sleeve is cooled, and then served on the receiver, where they are wound folded onto a cardboard sleeve.

 Example 2. To obtain a multilayer sleeve film, the following polymer mixtures are used.

Mixture 1:
1) 80 parts by weight conventional polycaprolactam granulate (polyamide 6) (as in Example 1);
2) 10 wt. including copolymer of polycaprolactam with polyhexamethylenediamine and adipic acid (polyamide 6 / 6.6) (according to example 1);
3) 5 parts by weight aromatic polyamide with elements of hexamethylenediamine and terephthalic acid (according to example 1);
4) 4 parts by weight ionomer resin - ethylene / methacrylic acid copolymer with a content of 2-20% methacrylic acid (according to example 1);
5a) 0.5 parts by weight maleic anhydride grafted acrylic polymer (as in Example 1);
5b) 0.5 parts by weight linear low density polyethylene with grafted groups of maleic anhydride (according to note 1).

Mixture II: 70 parts by weight low density polyethylene with a melting index of 0.2 g per 10 min at 190 ^o C and 2.16 kg of load and 30 wt. including linear low density polyethylene modified with maleic anhydride with a melting index of 3 g for 10 minutes at 190 ^o C and a load of 2.16 kg

 Mixture III: prepared similarly to mixture I.

Mixtures I, II, III are plasticized in three single-screw extruders at 240 ^° C. into homogeneous alloys, then mixed into 3-layer ring nozzles and coextruded into a sleeve. The latter is processed into a biaxially oriented and thermofixed sleeve film.

With a total film thickness of 0.055 mm, the layers have the following thickness:
outer layer (mixture I) - 0.030 mm
middle layer (mixture II) - 0.015 mm
inner layer (mixture III) - 0.010 mm.

 Examples 3-10 of the composition of the sleeve film are given in table. one.

 The properties of the claimed sleeve films according to the used compositions of examples 1-10 are presented in table. 2.

 The sleeve film obtained according to the invention meets the requirements necessary for its use, in particular, in the production of cooked sausages and processed cheeses. The film thickness for machine stuffing of sausage stuffing is 0.037-0.040 mm, for manual stuffing 0.030-0.033 mm.

The sleeve film remains strong enough and at high temperatures, up to about 125 ^o C, has great elasticity and is soft to the touch, adheres to the contents even after complete cooling, practically does not precipitate jelly and grease between the sausage meat and the casing, filling strength and accuracy the caliber of sausages made in such casings does not decrease; there is no adhesion of food products to the sleeve film.

 A distinctive feature of the claimed sleeve film is its low water and oxygen permeability, which determines the high degree of preservation of the finished product (oxidizability and weight loss), as well as its thermal stability.

 The strength of the shell is maintained during the heat treatment, the percentage of loaves damaged during cooking is no more than 1% per 1000 finished products.

Claims (4)

1. A polyamide-based sleeve film comprising polyamide 6, an aliphatic copolyamide, an aromatic polyamide containing hexamethylenediamine and terephthalic acid units and a copolymer comprising olefin units, characterized in that it further comprises an ionomer resin, as an aliphatic copolyamide aminomethylene copolyamide and adipic acid, and as a copolymer comprising olefinic units, a mixture of grafted copolymers based on carboxylic derivatives and likarbonovyh acids at the following component ratio, mass parts .:
Polyamide 6 - 77 - 83
Polycaprolactam copolymer with polyhexamethylenediamine and adipic acid - 7 - 13
Aromatic polyamide containing hexamethylenediamine and terephthalic acid units - 3 - 7
Ionomer resin - 3 - 6
A mixture of grafted copolymers based on derivatives of carboxylic and polycarboxylic acids - 0.1 - 5.0
2. The film according to claim 1, characterized in that the zinc salt of the ethylene / methacrylic acid copolymer is used as the ionomer resin.  3. The film according to claim 1, characterized in that a copolymer of polycaprolactam with polyhexamethylenediamine and adipic acid is used with the number of monomer units of 85, 7.5 and 7.5 wt.%, Respectively.  4. The film according to claim 1, characterized in that they use a mixture of grafted copolymers based on derivatives of carboxylic and polycarboxylic acids with a content of grafted units of 0.3 to 0.9 wt.%. 5. The film according to claim 1, characterized in that it is made multilayer, while at least one layer has the following composition, parts by weight:
Polyamide 6 - 77 - 83
Polycaprolactam copolymer with polyhexamethylenediamine and adipic acid - 7 - 13
Aromatic polyamide containing hexamethylenediamine and terephthalic acid units - 3 - 7
Ionomer resin - 3 - 6
A mixture of grafted copolymers based on derivatives of carboxylic and polycarboxylic acids - 0.1 - 5.0
6. The film according to claim 4, characterized in that the other layers of the multilayer tubular film can be made of polyamides, or polyamide mixtures, or polyolefins, or polyolefins containing binding functional groups, or copolymers with elements of ethylenically unsaturated monomers, or vinylidene chloride or acrylonitrile copolymers, or ionomer resins or mixtures of these polymers.

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