JPH028051A - Laminate packaging material - Google Patents

Abstract

PURPOSE:To prevent blushing from being caused by hot water or an alcohol, prevent stress cracking resistance from being lowered and enable low- temperature heat sealing by using a mixed polyamide comprising a specified lowly crystalline or non-crystalline aromatic polyamide and a specified aliphatic copolymeric polyamide, for forming a heat-sealing layer. CONSTITUTION:A laminate packaging material comprises a heat-sealing layer formed by use of a mixed polyamide comprising 50-90pts.wt. of a lowly crystalline or non-crystalline aromatic polyamide and 50-10pts.wt. of an aliphatic copolymeric polyamide having a melting point of 120 deg.C or below. The aromatic polyamide can be obtained by polycondensation of a mixture containing terephthalic acid and isophthalic acid, as an acid component, with hexamethylenediamine as an aliphatic and/or alicyclic diamine component. The aliphatic copolymeric polyamide may be nylon 6/66, nylon 6/12, nylon 6/610, nylon 6/66/12 or the like. The mixed polyamide layer thus provided has favorable low-temperature heat-sealability, and excellent hot water resistance and alcohol resistance are ensured.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an excellent laminated packaging material having excellent flavor barrier properties, water resistance, alcohol resistance, and heat sealability.

BACKGROUND OF THE INVENTION In recent years, the use of plastic containers for juices, alcoholic beverages, etc. has rapidly progressed. In general, food container materials require strength, safety and hygiene, gas barrier properties, and heat sealability, so this laminate is often used in a laminated structure that uses multiple materials to take advantage of the strengths of each. It can be molded into a container by heat-sealing the inner surface of the container. Therefore, the material used for the innermost surface not only needs to have excellent heat-sealing properties, but also has safety and resistance to the contents because it comes into direct contact with the contents, and plays an important role. There is.

Moreover, in the case of juices and alcoholic beverages, in addition to the properties mentioned above, the taste and aroma must not change over time. There has been a desire for something with excellent flavor barrier properties, that is, properties that do not cause dryness.

The present inventors tested various plastic materials and found that low-crystalline or non-crystalline aromatic polyamides made of terephthalic acid and/or isophthalic acid and aliphatic and/or alicyclic diamines have excellent properties. I found out that

However, such aromatic polyamides have major drawbacks, such as whitening when they come into contact with hot water or alcohol, and reduced stress cracking resistance, so they are not suitable for high-temperature filling of juices, etc., or for alcohol-containing beverages. When used as a liquid, it cannot be used on surfaces that come into contact with liquids, and the advantage of flavor barrier properties cannot be utilized.

On the other hand, it is already known that aromatic polyamides such as those mentioned above are mixed with aliphatic polyamides and used as packaging materials (for example, JP-A No. 53-6355, JP-A No. 58-1998).
No. 28352, JP-A-62-41261, JP-A-62
-143969 etc.).

However, these proposals were not intended for packaging materials for flavor barriers, so even if aliphatic polyamide is the main component or aromatic polyamide is the main component, the aliphatic polyamide to be mixed with The target was exclusively high melting point general-purpose polyamides such as nylon 6 and nylon 66.

Polyamides mainly composed of aliphatic polyamides do not have good heat-sealing properties, oxygen barrier properties, or moisture permeability, so they cannot be used for the purpose of the present invention. Blends of aliphatic polyamides with high melting points have poor heat-sealing properties at low temperatures, and when the sealing temperature is raised, foaming occurs in the sealing area due to adsorbed water based on its water absorption properties. There was a problem that a satisfactory seal could not be obtained.

In addition, in the above-mentioned prior art, multilayer packaging materials including polyolefins and the like have been proposed, but in this case, these polyolefins and the like were used as the heat-sealing layer.

Multilayer packaging materials in which these polyolefins and the like are used as a sealing layer have a drawback of poor flavor barrier properties.

Problems to be Solved by the Invention In light of the current situation, the inventors conducted further studies in order to take advantage of the excellent advantages of aromatic polyamides, and as a result, found that:
It has been discovered that a polyamide composition containing a specific polyamide has excellent hot water resistance, alcohol resistance, and heat sealability, and is suitable as a material for food and beverages intended for flavor barrier properties. That is, the purpose of the present invention is to
An object of the present invention is to provide a laminated packaging material having flavor barrier properties that can be heat-sealed at low temperatures and has significantly improved tendency to whitening due to hot water or alcohol and a tendency to reduce stress crack resistance.

Structure of the Invention The laminated packaging material in the present invention is a low-crystalline or non-crystalline aromatic polyamide 5 comprising terephthalic acid and/or isophthalic acid and aliphatic and/or alicyclic diamine.
The heat-sealing layer is made of a mixed polyamide consisting of 0 to 90 parts by weight and 50 to 1 QfI parts of an aliphatic copolymer polyamide having a melting point of 210° C. or less.

A low-crystalline or non-crystalline aromatic polyamide consisting of terephthalic acid and/or isophthalic acid and aliphatic and/or alicyclic diamine is used as the aromatic polyamide, and by using such a polyamide, transparency,
A mixed polyamide layer with excellent gas barrier properties and low-temperature heat-sealing properties can be formed.

Examples of the aliphatic and/or alicyclic diamine include tetramethylene diamine, hexamethylene diamine, octamethylene diamine, decamethylene diamine, 2.2.4
Examples include trimethylhexamethylene diamine, 4-trimethylhexamethylene diamine, bis-(4-7minocyclohexyl)methane, or a mixture of two or more thereof.

In order to make polyamide with low crystallinity or non-crystallinity,
A method using a branched aliphatic diamine or an alicyclic diamine as the diamine component, or a method using a mixture of terephthalic acid and isophthalic acid as the acid component is used. Here, low crystallinity refers to a sample obtained by slowly cooling polyamide from a molten state, and the degree of crystallinity measured by X-ray diffraction is 10% or less, preferably 5% or less, and is considered non-crystalline. means that no endothermic peak is observed based on differential scanning calorimetry.

The aromatic polyamide particularly suitable for the present invention uses a mixture containing terephthalic acid and isophthalic acid in a molar ratio of 60/40 to 10,010 as the acidic component, and hexamethylene diamine as the aliphatic and/or alicyclic diamine component. This is an aromatic polyamide obtained by polycondensation using

Note that the aromatic polyamide in the present invention may be a copolymer containing 20 mol% or less of aliphatic polyamide.

In the present invention, the aromatic polyamide has a melting point of 210
A mixture of aliphatic copolymerized polyamides of 30% or less is used. As such aliphatic copolymer polyamide, nylon 6
/66, nylon 6/12, nylon 6/610, nylon 6/66/12, nylon 6/66/610, etc. These aliphatic copolymer polyamides have a melting point of 210°C or less, preferably in the range of 170 to 200°C. The melting point can be controlled by the copolymerization ratio. Among these aliphatic copolymer polyamides, nylon 6/66 is most preferably used from the viewpoint of transparency.

By using such a mixture with an aliphatic copolymerized polyamide as a heat-sealing layer, the mixed polyamide layer has good low-temperature heat-sealability and excellent hot water resistance and alcohol resistance. If a polyamide with a melting point exceeding 210°C, such as nylon 6 or nylon 66, is used instead of the aliphatic copolymer polyamide,
A film with good heat sealability cannot be obtained.

Even if polyamide has a melting point of 210°C or less, if nylon 11 or nylon 12, which is not a copolymerized polyamide, is used, it will be difficult to mix with aromatic polyamide, and not only will the transparency of the polyamide mixture layer be impaired, but also It is not possible to obtain a film with excellent sealing strength.

The blending ratio of aromatic polyamide and aliphatic copolyamide is 1. When the total of both is 100 parts by weight, the former is 50 parts by weight.
-90 parts by weight, preferably 60-80 parts by weight, and 50-10 parts by weight, preferably 40-20 parts by weight of the latter. If the blending ratio of the aromatic polyamide exceeds the above range, the hot water resistance and alcohol resistance will not be sufficiently improved, and if the blending ratio is smaller than the above range, the heat sealability will be poor. undesirable for this purpose.

The present invention is a laminated packaging material having the aforementioned mixed polyamide layer as a heat seal layer. The base material layer to be laminated with the mixed polyamide layer includes polyamide, polyester, polycarbonate, ethylene-vinyl alcohol copolymer, polyvinylidene chloride, polyvinyl chloride, polystyrene, aluminum foil, paper or polyolefin such as polyethylene, polypropylene, ethylene. , olefins such as propylene and vinyl esters such as vinyl acetate, α,β-unsaturated carboxylic acids such as acrylic acid and methacrylic acid, their esters, their salts, unsaturated carboxylic acid anhydrides such as maleic anhydride. Examples include copolymers with unsaturated glycidyl compounds such as glycidyl acrylate and glycidyl methacrylate.

Although these base material layers can be used as a single layer, they may also be used as multilayers.

Although the thickness of each layer of the laminate is arbitrary, for example, the mixed polyamide layer can be formed to have a thickness of about 10 to 200 pm, and the base material layer can be formed to have a thickness of 10 to 500 lLm.

In the present invention, the mixed polyamide layer is used by being molded into various molded bodies so as to serve as a heat-sealing layer. Specific examples include packaging bags, blow-molded containers, vacuum-formed containers, liquid paper containers, etc. In the case of 0 bags, two films are heat-sealed with the mixed polyamide layers facing each other, and in the case of blow-molded containers. By blow molding the mixed polyamide layer as the innermost surface, heat sealing is performed at the pinch-off area.

Effects of the Invention According to the present invention, it is possible to provide a packaging material having a heat-sealing layer with excellent flavor barrier properties, hot water resistance, alcohol resistance, and low-temperature heat-sealing properties, so that it can be used as a material for various food packaging and beverage containers. can do.

Examples 1-3. Comparative Examples 1 to 2 A polyamide obtained by polycondensation with a mixture of hexamethylene diamine and terephthalic acid/isophthalic acid = 30/70 mol % was used as an amorphous aromatic polyamide, and a melting point of 200°C was used as an aliphatic copolymer polyamide. Amorphous aromatic polyamide/aliphatic copolyamide mixtures having various compositions shown in Table 1 were prepared using nylon 6/66 copolyamide (manufactured by Toshi ■, trade name Amiran CM6041) using a 40 mmφ extruder. After extrusion at a temperature of 240°C,
The water-cooled strands were cut to obtain polyamide composition pellets.

Next, the polyamide composition was supplied to a 30 mmφ extruder of a cast film molding machine equipped with a coat hanger type die having a width of 300 mm, and after extrusion at a temperature of 240°C,
A film having a thickness of 50 ILm was formed by quenching with a metal roll.

Table 1 shows the results of evaluation of flavor adsorption, hot water resistance, alcohol resistance, and heat sealability of the obtained film.

Sakagi λ Uni 1 70 parts by weight of the same amorphous aromatic polyamide as in Examples 1 to 3 and Comparative Examples 1 to 2, and nylon 6 as the aliphatic polyamide (manufactured by Toshi ■: trade name Amilan cM1021XF)
After extruding a mixture consisting of 30 parts by weight of +i*y12 (manufactured by ATOCHEM, trade name Rilsan AESNOTL) at a temperature of 240°C using a 40 mmφ extruder, the water-cooled strands were cut to form polyamide composition pellets. Obtained.

Next, Table 1 shows the results of evaluating various physical properties of a 50 gm thick film molded in the same manner as Examples 1 to 3 and Comparative Examples 1 to 2.

Comparative Example 5: Flavor adsorption properties of a 50ILm film formed using low density polyethylene (Mitsui Petrochemicals NTA: trade name Mirason M401) at an extrusion temperature of 180°C in the same manner as in the Comparative Example above. The results of the evaluation were poor.

In addition, the physical properties of the film in the above-mentioned Examples and Comparative Examples were evaluated by the following method.

(1) Flavor adsorption properties A film with a size of 20 x 40 mm was immersed in D-limonene, spearmint oil, and methyl salicylate solution, and the weight change rate of the film was measured after 21 days of storage at room temperature, and the weight change rate was 5. If it was within %, it was considered good, and if it was 5% or more, it was considered bad.

(2) Hot water resistance Changes in light transmittance of the film before and after immersion in hot water at 85° C. for 30 minutes were evaluated and used as a measure of hot water resistance. The light transmittance was measured at 546 using a transmeter manufactured by Murakami Color ■.
The ratio of the transmitted light that passed through the film to the incident light of 4 m was determined. The higher the light transmittance, the better the transparency of the film, and the smaller the change in the light transmittance of the film before and after hot water treatment, the better the hot water resistance.

(3) Alcohol Resistance The film was immersed in ethanol, and the change in light transmittance was measured for the film before immersion and after 1 week of immersion and storage at room temperature in the same manner as in the hot water resistance evaluation. The smaller the change in light transmittance of the film after ethanol treatment tJ, the better the alcohol resistance.

(4) Heat seal strength tester Using a heat sealer made by Sangyo ■, seal two overlapping films with a seal width of 10 mm and a seal pressure of 2 kg.
/cm2. After heat-sealing with a sealing time of 0.7 seconds, cut into 15 mm width and peeled with a Shimabara Seisakusho Autograph at a tensile speed of 300 mm/min, the maximum value was defined as the heat-seal strength. do.

E1.1 The innermost layer is a 20Bm thick cast film of the aromatic polyamide/aliphatic copolyamide mixture used in Example 2, and the outer layer is 9JLm of aluminum foil, and the outermost layer is 121Lm of polyethylene terephthalate. A composite film in which films were laminated was obtained by a dry lamination method.

Next, the innermost layer sides of this composite film were stacked one on top of the other, and the peripheral edge of one was sealed using a heat sealer at a sealing temperature, pressure, time, and sealing width of 150°C and 2 kg/cm, respectively.
A bag with a size of 150 x 200 mm (outer dimensions) was prepared by heat sealing under the conditions of m21 seconds and 10 mm (7).

After filling this bag with 100% orange juice and sealing the other side of the bag under the same conditions as above, the flavor of the orange juice will hardly change after storing the sample in an atmosphere of 5℃ for 21 days. There was no.

In addition, the results of evaluating the heat seal strength were 200
It was good at 0g/15mm.

Example 5 Amorphous aromatic polyamide/aliphatic copolyamide mixture used in Example 2 and high-density polyethylene type adhesive resin (manufactured by DuPont, trade name: Pinell E-206)
Using high-density polyethylene (manufactured by Mitsui Petrochemical Industries, Ltd., trade name HIZEX 3000B), a multi-layer blow molding machine with a capacity of 500 cc was used to form a one-layer structure (inner surface) of polyamide mixture/adhesive resin/high-density polyethylene (outer surface) = 600
A 1500/300 lum three-layer bottle was molded.

Fill this bottle with 100% orange juice and seal the sample with a metal cap.
There was almost no change in the flavor of the orange juice after storage for 12 hours. In addition, we dropped the bottle from a height of 1.2 m and observed the damage at the pinch-off part, but there was no damage.
It showed good pinch-off sealing performance.

July 27, 1986

Claims (1)

[Claims] 1. 50 to 90 parts by weight of a low-crystalline or non-crystalline aromatic polyamide consisting of terephthalic acid and/or isophthalic acid and aliphatic and/or alicyclic diamine and a melting point of 21
A laminated packaging material having a heat-sealing layer made of a mixed polyamide comprising 50 to 10 parts by weight of an aliphatic copolymer polyamide at a temperature of 0°C or lower.