JPS60225754A - Composite oriented film and manufacture thereof - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a composite stretched film with excellent strength and oxygen and water vapor barrier properties, and a method for producing the same.

Among the qualities generally required for food packaging films, strength, especially flexural strength, is extremely important, but other qualities such as transparency, heat resistance, and dimensional stability must be met and flexural strength There are very few films that are good. Polyamide biaxially stretched film is one of the few films that satisfy these conditions and is widely used in food packaging applications.

Next, if the film has oxygen gas and water vapor barrier properties, when the film is used for food packaging, it will have the effect of extending the shelf life of the food, making it useful as a high-grade packaging film. Saponified ethylene-vinyl acetate copolymer (hereinafter abbreviated as EVO11) film is a film with excellent barrier properties, and is used as a high-grade food packaging film J.
However, both non-oriented and oriented films have a drawback of low bending strength. In particular, in order to improve the barrier performance [this tendency is stronger when the ethylene component in 1 VOIl is reduced]. Furthermore, when the ethylene content decreases, the barrier performance under dry conditions is good, but the iJ humidity decreases and the barrier performance under high humidity conditions rapidly decreases.

The present inventors have arrived at the present invention as a result of research into ways to effectively utilize the qualities of polyamide film and EV (+11 film).
+ film is laminated to eliminate the strength defects of the Ij V OI+ film, and polyvinylidene chloride (hereinafter referred to as PVD), which has excellent moisture resistance, is added to the surface of the E V OI+ film.
A layer (abbreviated as C) is provided to prevent the barrier properties of the VOI+ film from deteriorating under high humidity conditions.Next, these laminated films are biaxially oriented to create a film that maximizes the qualities of each polymer. It is.

Strength of polyamide film due to biaxial orientation,
Not only does the strength, transparency, and barrier properties of the EVO11 film improve, but surprisingly, the barrier properties of pvocJji and the adhesive strength between IEVOII/PVDCJW are also significantly improved.

The function of the polyamide film in the composite stretched film of the present invention is the quality of the product film, that is, the practical strength that a packaging film should have, such as bending strength, pine water, etc.
In the process of manufacturing a composite stretched filn, which increases bag strength and bag drop strength, it also has the effect of improving biaxial stretchability.

l! VOI+ film, especially EV with low ethylene content
The stretchability of 011 film is not necessarily good, and when stretching a single film, unrestricted stretching, breakage during stretching, etc. occur easily, and there are many restrictions on the stretching ratio, stretching temperature, stretching speed, etc. However, polyamide film When laminated with a polyamide film and stretched, the polyamide film becomes a carrier for the stretching deformation process, and the stretching ratio in the longitudinal and lateral directions is mainly controlled throughout the stretching process. Stretched uniformly.

The IE V O11 film constructed according to the present invention not only has gas barrier properties in terms of quality, but also has a relatively high Young's modulus that covers the low Young's modulus of polyamide film, strengthens the stiffness of the composite stretched film, and is suitable for post-processing. Improve workability. For example, a uniaxially stretched film of nylon 6 is desired to have a thickness of 1571 or more from the viewpoint of workability, but in the case of the composite film of the present invention, a thickness of 12 μm is sufficient for workability if the polymer 7 thickness structure is well designed. may be obtained.

The polyamide film, which is a component of the present invention, refers to linear polyamide films such as nylon 6, nylon 66, and nylon 12, and copolymers containing these components.

These include mixtures, etc., with additives such as lubricants and antistatic agents added thereto. E V OH has an ethylene content of 15 to 59 mol% and a saponification degree of 98% or more. The lower the ethylene content, the better the quality of the composite stretched film in terms of barrier properties and heat resistance, but the prevention of fisheyes during /8 melt extrusion and the operability of biaxial stretching become more difficult.

PVOC is a copolymer of vinyl chloride, acrylonitrile, acrylic ester, etc. within the range that does not change the basic performance of polyvinylidene chloride.

These PVDCs are applied to the IEVOI+ film surface as an aqueous latex, solvent solution. Lattefux has a high moisture-proofing performance due to its high content of polyvinylidene chloride.

/8 The bottle life of the liquid becomes too short and the uniformity and coating properties deteriorate.

In the composite film of the present invention, the PVDC layer is 0.5 to 0.5 after stretching.
2μ is preferred and also a polyamide 1° layer and pvonW4
The thickness ratio is in the range of 3 to 7:3, and the optimum composition ratio is determined depending on the purpose of the application. Further, the effects of the present invention are most clearly exhibited when the total thickness of the composite stretched film is in the range of 12 to 30 microns.

Next, the manufacturing method of the present invention will be explained.

Lamination of the polyamide film and the IEVO11 film is carried out using a coextrusion device that is at least basically a combination of three extruders and a 3NT die. Here, the third extruder is for the adhesive resin poured between the polyamide layer and the UVoII layer.As the adhesive resin, a modified polyolefin resin is generally used, but in the method of the present invention, a modified polyolefin resin is used. Since shearing force acts on the interface during biaxial stretching and may impair adhesion, sufficient preparation is required when selecting the type of adhesive resin and layer thickness. If particularly strong adhesive strength is required, it may be desirable to use a crosslinkable adhesive. After applying 1M of polyamide)/[VOH laminated non-oriented film by co-extrusion method, the [1VO1+
Aqueous latex or solvent solution is applied to the surface to form a multilayer coating, and dried until at least the coated surface loses its tackiness. Coating is done by the air knife method, gravure roll method, Riha-Throl method, Harkot method, etc., and drying is done in an arch-type, floating-type drying oven, etc. p before stretching
The primary purpose of applying VOC is to biaxially orient the PVDC layer as well to improve its barrier performance, but the other effect is that this method can improve I
It was found that the adhesion between EVOH/PVD (1) was improved. The reason for this is not clear to the inventor, but it is thought to be related to the effect of the high temperature heat treatment performed after stretching. When applying D C water-based latex, the water in the coating liquid migrates into E V O II and
The effect of plasticizing 1+ and increasing the stretchability of IEVOll is recognized. A laminated film having a multilayer structure coated with I'VDC is oriented on two wheels by a simultaneous biaxial stretching method, and the selection of the simultaneous biaxial stretching method as the stretching method is the biggest factor in realizing the present invention. As the biaxial stretching method of the flat method, there are two-stage biaxial stretching method and simultaneous biaxial stretching method, but the present invention cannot be realized by biaxial biaxial stretching. polyamide.

Both IEVOll and IEVOL have strong crystallinity, and when two-stage biaxial stretching is applied, crystallization progresses during the second stage of stretching, inhibiting the second stage's stretchability. The reason for this is that IIVDC sticks to the hot rolls in roll-type stretching machines.

A simultaneous biaxial stretching machine is a machine in which both ends of a non-oriented film are held by clips attached to an endless link chain, and the film is heated to the stretching temperature in a preheating zone where the film is stretched in parallel.
In the next stretching zone, the distance between the opposing clips widens toward the end, resulting in stretching in the lateral direction, and at the same time, the pitch between the clips in the machine direction gradually increases, increasing the advancing speed of the clips, resulting in stretching in the longitudinal direction. be done. Next to the stretching thin, the clip runs in parallel, and there is a heat treatment zone where the clip runs at a constant speed and is blown with high temperature hot air.
The stretched film is heated in a heated oven.

In the case of the present invention, the stretching ratio in the machine direction is 3 to 3.3 times.

3 to 3.5 times in the transverse direction is suitable, and the stretching temperature is 60 to 15
It is 0°C. Heat treatment temperature is as same as soil! 4 V 011
In the case of EV leaves with the same composition, 1
In the case of the present invention, since it is reinforced with polyamide having a higher melting point, it is possible to heat treat it at a higher temperature than when stretched alone. For example, in the case of UV OI+ with a melting point of 185°C, when stretched alone at 175°C or higher, it will not remain. Although it may break due to stretching stress, if nylon 6 is laminated,
It does not break even when the temperature is raised to its melting point, and therefore it can be heat-treated at the highest temperature within the range where orientation relaxation is permitted.

Furthermore, the adhesive strength between polyamide (7) and EVO (11) is often increased by the high-temperature heat treatment process, and the adhesive strength that has decreased due to the shear stress at the interface generated in the stretching process is recovered again. The film after heat treatment has both ears trimmed 1!
& It is rolled up to become a product, but the trimming selvedge part is made of polyamide alone or at least polyamide/ [! VOH
It is necessary to make a laminate of

This is because when PVDCm is gripped by a clip of a stretching machine, it accumulates on the clip and causes stretching and cutting. By using a coextrusion die, CVO with a width narrower than that of the polyamide layer is produced.
If nlW is laminated, the l-rimming selvage becomes a single polyamide layer and can be easily recycled.

The biaxially stretched laminated film can be corona treated as necessary.
Post-processing such as linking is performed. The thus obtained composite stretched film was printed, further coated with a sealan [- and a laminate].
・It can be used as packaging material.

The present invention provides at least polyamide l-'/IEVOII
/ This relates to a composite stretched film including a two-layer component of PVDC, and a film in which another layer is further superimposed on the two-layer component is also included in the present invention. For example, it is a composite film in which pvoc[ is provided not only on the ν011 side but also on the polyamide side, and in this case, the oxygen and water vapor barrier properties of the obtained film are further improved.

The present invention was achieved by skillfully combining polyamide, IEVO II, and PVDC, each of which has its own unique characteristics, and by maximizing the possibilities of the in-line coating method and simultaneous biaxial stretching method. This produces an ideal packaging film, which has great industrial value.

Next, the present invention will be specifically explained with reference to Examples.

Examples and Comparative Examples Iron 6, IEVOI+ with ethylene content of 30 mol%
Three types of non-oriented laminated films with different thickness configurations were obtained by melting a carboxylic acid-modified polyolefin adhesive using three extruders, extruding it through a multi-manifold three-layer die, and rapidly cooling it with a cooling roll. . IE of the obtained film
PV containing 92% by weight of hnylidene chloride component on VO11 side
After applying the OC aqueous latex, it was fed into a simultaneous biaxial stretching machine and simultaneously biaxially stretched 3.0 times in the longitudinal direction and 3.3 times in the transverse direction to obtain three types of composite stretched films. The thickness structure (adhesive layer thickness is 0.5 to 1 μm) and physical properties of the 1M film are shown in the table in comparison with those of biaxially stretched films of nylon 6 and EVOII alone.

As is clear from the table, the EVOI film of the present invention has improved bending resistance without losing its oxygen gas barrier properties, and the moisture-proofing effect of the oriented PVDCN reduces the barrier properties of the IEVOI+ film even under high humidity conditions. There are few.

Patent applicant: Unideka Co., Ltd.

Claims (1)

[Scope of Claims] 1. A laminated film composed of at least multiple layers of polyamide/saponified ethylene/vinyl acetate copolymer/polyvinylidene chloride, and each of the multilayers is bidirectionally oriented. A composite stretched film featuring: 2. After applying polyvinylidene chloride aqueous latex or solvent solution to the saponified ethylene/vinyl acetate copolymer film surface of the unoriented laminated film of polyamide/saponified ethylene/vinyl acetate copolymer composition laminated by coextrusion method. A method for producing a composite stretched film, which comprises simultaneously biaxially stretching the laminated film.