KR100371606B1 - A bi-axial oriented film having an excellent oxygen-barrier, and a process of preparing for the same - Google Patents

Abstract

The present invention is composed of a polymer containing a metha xylene group and an aliphatic polyamide, and the fibrils of the polymer containing the metha xylene group are formed in the film under the conditions of the following formula (I). A biaxially oriented film and a method for producing the same.

-Below-

4 ≤ L / W ≤ 20 (I)

Where L is the fibrill length and W is the width of the fibrils.

The film of the present invention is mainly used as fish meat, growth and processed food packaging materials thereof, which are easily degraded by oxygen.

Description

A bi-axial oriented film having an excellent oxygen-barrier, and a process of preparing for the same}

The present invention relates to a biaxially oriented film mainly used as a packaging film of fish meat, growth and processed foods thereof, which is very excellent in oxygen barrier property and is easily deteriorated by oxygen, and a method of manufacturing the same.

Currently, industrially used packaging films include polyethylene, polypropylene, polystyrene, polyvinyl chloride, and the like, which are mainly used for packaging products that are not deteriorated or deteriorated by oxygen.

Vinylidene chloride copolymers are mainly used for fish meat, growth and packaging of processed foods which are easily deteriorated by the presence of oxygen. However, although the vinylidene chloride copolymer film has the best oxygen barrier property among the conventional packaging films, the film has problems such as insufficient cold resistance, heat resistance, and poor mechanical properties. In addition, harmful chlorine gas is generated during incineration, causing environmental damage.

On the other hand, biaxially oriented films made of xylenediamine mainly composed of metha xylene diamine and polyxylene alkanedicarboxylic acid amide produced from aliphatic dicarboxylic acid are excellent in transparency, mechanical properties, cold resistance, heat resistance and oil resistance, in particular, gas barrier properties. It is very suitable for packaging use.

However, when this film is used for packaging, it is difficult to maintain hermetic state because the minute pinholes occur in the film a relatively large number of times when repeated repeated compression and decompression on the film makes it difficult to maintain airtightness. This is a limited problem.

Therefore, Japanese Patent Laid-Open No. 6-106815 discloses a method for producing a film using a mixture of aliphatic polyamide and metha xylene group-containing polyamide to improve oxygen barrier property and tearing property.

However, even in the above method, when the residence time becomes longer at a temperature of 290 ° C. or higher in the extruder, fine particles that are dispersed phases are formed in the sheet, and even when drawn, a range of methaxylene group-containing aromatic amides that impart oxygen barrier properties in the film is stretched. There is a problem that the oxygen barrier property is not formed because the fibril structure of the size is not formed.

An object of the present invention is to produce a biaxially stretched film suitable for packaging films having excellent mechanical properties such as oxygen barrier properties and pinhole resistance while solving the problems of the prior art.

The present invention is to provide a biaxially stretched film suitable for packaging films having excellent mechanical properties such as oxygen barrier properties and pinhole resistance, and a method of manufacturing the same.

The present invention relates to a biaxially oriented film excellent in oxygen barrier properties and mechanical properties so as to be suitable as a packaging film and a method of manufacturing the same. More specifically, the present invention is composed of a polymer containing a metha xylene group and an aliphatic polyamide, and oxygen blocking, wherein the fibrils of the polymer containing the metha xylene group are formed under the conditions of the formula (I) below. The present invention relates to a biaxially stretched film having excellent properties.

-Below-

4 ≤ L / W ≤ 20 (I)

Where L is the fibrill length and W is the width of the fibrils.

In addition, the present invention, in the production of a biaxially stretched film by extruding, biaxially stretching and heat-setting a polymer solution, containing a methaxylene group prepared by polymerization of xylenediamine containing metha xylene diamine and at least one aliphatic dicarboxylic acid 20-60 weight of polymer (A), melting | fusing point is 160 degreeC or more, glass transition temperature is 60 degrees C or less, and melting point difference with the polymer (A) containing the said metaxylene group is 40-80 weight of aliphatic polyamide which is 50 degrees C or less, melting point The present invention relates to a method for producing a biaxially stretched film having excellent oxygen barrier property, wherein the mixed polymer having a dobby ratio of 0.5 to 5.5 is extruded and stretched under a condition of a shear rate of 20 to 90 sec ⁻¹ in an extrusion die.

Hereinafter, the present invention will be described in detail.

The present invention is characterized in that a polymer having excellent oxygen barrier property is produced by forming a polymer containing a metaxylene group, which is a material having excellent oxygen barrier property, in a stretched film as a fibrill having a predetermined size range in a dispersed phase.

The present invention is composed of 20 to 60 weight of polymer (A) containing metha xylene group and 40 to 80 weight of aliphatic polyamide, and a mixed polymer having a melt viscosity ratio of 0.5 to 5.5 under a shear rate of 20 to 90 sec ⁻¹ in an extrusion die. Extrusion, biaxial stretching and heat setting produce biaxially oriented films.

The polymer containing the said metha xylene group is manufactured by superposition | polymerization of the xylene diamine which has metha xylene diamine as a main component, and 1 or more types of aliphatic dicarboxylic acid. Specifically, homopolymers such as polymethylene adipamide, polymethylene sequamide, polymethylene styrene veramide, etc., metha xylene / paraxylene adipamide copolymers, metha xylene / paraxylene pimeramide copolymers, meta Nylon with repeating unit of polyxyleneadipamide and amide bond in xylene / paraxylene aramid copolymer, metha xylene / paraxylene sepacamide copolymer, metha xylene / paraxylene, adiamide / cefacarmide copolymer 6, nylon 66, nylon 12 and the like and the like can be used.

As xylenediamine which has metha xylene diamine as a main component, the thing which contains 30 weight or less of para xylene diamine together with metha xylene diamine can also be used.

Aliphatic polyamides include homopolymers such as nylon 6, nylon 12, nylon 66, nylon 6.10, aliphatic copolyamides such as nylon 6/66 copolymer, nylon 6 / 6.10 copolymer, nylon 66 / 6.10 copolymer, and caprolactam. Copolyamides containing a minimum amount of aromatics are typically used by copolymerizing a main component, a nylon salt of hexamethylenediamine and isophthalic acid, a nylon salt of metha xylenediamine and adipic acid, and the like.

It is more preferable that carbon number of the said aliphatic dicarboxylic acid is 6-10. If necessary for the mixed polymer solution, stabilizers, ultraviolet absorbers, antistatic agents, plasticizers, lubricants, antiblocking agents, pigments, and other thermoplastics may be added. The molecular weight of each component should be set to have a high melt viscosity such that a uniform membrane surface is maintained when the mixed mixture is melted and extruded. If the melt viscosity is too high, extrusion operation is difficult, so it is usually preferred to have a relative viscosity of 0.5 to 5.5.

When the polymer (A) content containing a metha xylene group is less than 20 weight, there exists a problem that oxygen barrier property falls. Also is 20sec ^-1 shear rate in the case where the blending is poor and exceeds 90sec ^-1, the particles are difficult to form in the sheet with amino retardation (Amidation) is less than the reaction.

Generally, the following method is known as a manufacturing method of a polyamide biaxially stretched film. Tenta method for stretching the heated unstretched film in two directions with a clip, and a tube-shaped biaxial which stretches longitudinally and simultaneously by feeding a pressurized gas into the tube by heating the unstretched tubular film to a temperature that can be stretched between two sets of nip rolls. There is stretching. Furthermore, in addition to the simultaneous biaxial stretching method in the tenter system, there is a sequential biaxial stretching method in which an unstretched film is stretched in one direction by a roll and then stretched by a clip in a right angle direction.

In the method of the present invention, the unstretched film can be produced by a melting method such as a T-die method, an inflation method, or a dry method. For example, in the case of producing a film by TiDy in the melting method, the film material is heated to a melting point or more and extruded from the TiDy into a film, and a roll or a solution having a temperature of 20 to 80 占 폚 that is below the secondary transition point of each composition. It is prepared by cooling. The stretching ratio is 1.5 to 6 times, and the stretching temperature is preferably 40 to 150 ° C. For thermal stability of the film, the heat setting treatment is preferably performed for 5 minutes or less, more preferably 5 to 60 seconds, at a temperature higher than the maximum drawing temperature and below the melting point.

If the temperature of the roll or solution is higher than the secondary transition point of the mixed polymer, a flat film is not obtained and uniform stretching becomes difficult in the next stretching process. In addition, when extruded at a high temperature of 290 ° C. or higher in the extruder or stayed for a long time, the dispersed phase forms fine particles in the sheet, and thus, the fibril structure is not formed in the film, resulting in a decrease in oxygen barrier property.

On the film of this invention, fibrils of the polymer containing a metha xylene group are formed on condition of the following formula (I), and it is excellent in oxygen barrier property.

4 ≤ L / W ≤ 20 (I)

Where L is the fibrill length and W is the width of the fibrils.

The present invention will be described in more detail with reference to the following examples and comparative examples. However, the present invention is not limited only to the following examples.

Example 1

A polymer containing 20 weights of polycaprolactam (A) as an aliphatic polyamide and 80 weights of polymethaxyleneadipamide (B) as a polymer containing a metaxylene group, and a mixed polymer having a melt viscosity ratio of 1.5 was added to the extruder for 3 minutes at 270 ° C. After the retention, the sheet was extruded at a shear rate in an extrusion die of 50 sec ⁻¹ , biaxially stretched at a draw ratio of 2.0 times at a temperature of 70 ° C., and heat-set at 200 ° C. for 20 seconds to prepare a biaxially stretched film. The results of evaluating the physical properties of the produced biaxially stretched film are shown in Table 2.

Example 2 to Example 3 and Comparative Example 1 to Comparative Example 3

A biaxially oriented film was prepared in the same process and conditions as in Example 1 except that the polymer mixing ratio and the residence time in the extruder were changed as shown in Table 1. The results of evaluating the physical properties of the produced biaxially stretched film are shown in Table 2.

<Table 1> Manufacturing Conditions

division Polymer mixing ratio (A: B) Residence time in extruder Example 1 20:80 3 minutes Example 2 40:60 1 minute Example 3 30:70 4 minutes Comparative Example 1 20:80 6 minutes Comparative Example 2 40:60 7 minutes Comparative Example 3 100: 0 6 minutes

<Table 2> Property Evaluation Results

division Modulus (kg / ㎡) Breaking strength (kg / ㎡) Elongation at Break () Fibrillation phenomenon (L / W) Moisture permeability (g / ㎡, day, atm) Oxygen permeability coefficient (g / ㎡ · day · atm) Bell Lateral Bell Lateral Example 1 310 29 31 108 84 8.2 30 12 Example 2 320 32 38 130 81 12.5 28 8 Example 3 300 35 33 112 92 15.6 31 10 Comparative Example 1 160 25 23 73 63 2.0 48 23 Comparative Example 2 290 24 25 89 78 35.7 37 18 Comparative Example 3 280 29 27 110 97 - 83 35

The biaxially oriented film of the present invention is excellent in oxygen barrier property, pinhole resistance and mechanical properties, and has low humidity dependence, making it suitable for packaging films.

Claims (5)

In preparing a biaxially oriented film by extruding, biaxially stretching and heat-setting a polymer solution, a polymer containing a metaxylene group prepared by polymerization of xylenediamine mainly containing metha xylene diamine and at least one aliphatic dicarboxylic acid (A) 20 to 60% by weight, melting point of 160 ° C or higher, glass transition temperature of 60 ° C or lower, and melting point difference of 40 ~ 80% by weight of aliphatic polyamide having a melting point difference between the polymer (A) containing the methacrylic group and 50 ° C or lower, and melt viscosity ratio Of a biaxially oriented film having excellent oxygen barrier properties, characterized in that the polymer of 0.5 to 5.5 is extruded under the condition that the shear rate in the extrusion die is 20 to 90 sec ^-1 and the residence time of the mixed polymer in the extruder is 5 minutes or less. Manufacturing method. The method for producing a biaxially oriented film having excellent oxygen barrier properties according to claim 1, wherein paraxylenediamine is contained in xylenediamine having metha xylenediamine as a main component of 30 wt% or less. The method for producing a biaxially oriented film having excellent oxygen barrier property according to claim 1, wherein the aliphatic dicarboxylic acid has 6 to 10 carbon atoms. In preparing a biaxially oriented film by extruding, biaxially stretching and heat-setting a polymer solution, a polymer containing a metaxylene group prepared by polymerization of xylenediamine mainly containing metha xylene diamine and at least one aliphatic dicarboxylic acid (A) It consists of 40-80 weight% of aliphatic polyamides which are 20-60 weight%, melting | fusing point 160 degreeC or more, glass transition temperature of 60 degrees C or less, and melting | fusing point difference with the said polymer (A) containing methacrylic group is 50 degrees C or less, Fibril of the polymer containing a metha xylene group is formed in the film on condition of the following formula (I), The biaxially stretched film excellent in the oxygen barrier property characterized by the above-mentioned. -Below- 4 ≤ L / W ≤ 20 (I) Where L is the fibrill length and W is the width of the fibrils. The biaxially oriented film having excellent oxygen barrier property according to claim 4, wherein the polymer containing a metha xylene group is polymethaxylene adipamide.