JPH02191636A - Gas barrier film - Google Patents

Abstract

PURPOSE:To obtain the subject film, consisting of a liquid crystal polyester and a specific amount of poly-cyclohexylenedimethylene terephthalate, having a specified value or below of oxygen permeability, excellent in oxygen and water barrier properties and suitable as packing materials for foods, drinks, medicines, etc. CONSTITUTION:The objective film, consisting of (A) a liquid crystal polyester (preferably containing an acid component consisting essentially of phenylenedihydroxyacetic acid and terephthalic acid and a diol component consisting essentially of hydroquinone, phenylhydroquinone and resorcin) and (B) poly-1,4-cyclohexylenedimethylene terephthalate in an amount of 0.1-20wt.%, preferably 0.5-10wt.% based on the weight of the film and having <=0.8cc/m<2>.day/100mum oxygen permeability at 30 deg.C and 100RH% and preferably 3-200mum thickness.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a gas barrier film used as a packaging material for packaging foods, drinks, medicines, and various other articles.

[Conventional technology 1] Many foods, drinks, medicines, etc. dislike oxygen and water, and in order to package such items, it is necessary to pass oxygen and water (
Packaging materials made of high gas barrier films are used. Traditionally, polyvinylidene chloride has been used as a gas barrier film.

Ethylene-modified polyvinyl alcohol, aromatic nylon, etc. are used.

However, although polyvinylidene chloride has excellent oxygen and water barrier properties, it has poor extrusion stability during production, and there is also a risk of causing pollution.

Ethylene-modified polyvinyl alcohol has high oxygen barrier properties when dry, but has poor oxygen barrier properties when wet (below 100% relative humidity), and also has low water barrier properties.Furthermore, aromatic nylon also has a high oxygen barrier property when dry (relative humidity below 100%). It has similar drawbacks.

[Problems to be Solved by the Invention] Therefore, an object of the present invention is to provide a gas barrier that has good oxygen barrier properties and water barrier properties not only when dry but also when wet, and has excellent extrusion stability during production. The purpose is to provide sex films.

[Means for Solving the Problem] As a result of intensive research, the inventors of the present application have developed a film containing a certain proportion of poly-1,4-cyclohexylene dimethylene terephthalate (hereinafter sometimes referred to as PCT) in liquid crystal polyester. However, the present invention was completed by discovering that it has high oxygen barrier properties and water barrier properties even when wet.

That is, one aspect of the present invention is liquid crystal polyester.

0 for the weight of the film. l to 20% poly-1
, 4-cyclohexylene dimethylene ethylene terephthalate-1, and has an oxygen permeability of 0.8 cc/@7 days/l at 30° C. and 1% (10θR) of 0 μw or less. do.

[Effects of the Invention] The gas barrier film of the present invention has excellent M element barrier properties and water barrier properties not only when dry but also when wet.

Furthermore, the gas barrier film of the present invention has excellent extrusion stability during production, that is, there is no width fluctuation or surging when extruding a polymer, and furthermore, the film has excellent film formability and stretchability, that is, The film of the present invention is less prone to tearing or uneven thickness during extrusion or stretching, and has good thinning properties during production, making it possible to produce very thin films with a thickness of approximately 1 μm. Thin gas barrier films are advantageous for applications where transparency and flexibility are important, and for applications where manufacturing costs are low.

[Detailed Description of the Invention] As the liquid crystal polyester used in the gas barrier film of the present invention, for example, U.S. Pat. No. 4,552.943
Known liquid crystal polyesters such as those described in No. That is, as the acid component, phenylene dioxydiacetic acid and terephthalic acid, as the diol component, hydroquinone, phenylhydroquinone, resorcinol, or an aliphatic or alicyclic dialcohol having 8 or less carbon atoms, ie, for example, ethylene glycol, 1. 4-Butanediol! , 4-cyclohexane dimetatool, propylene glycol, diethylene glycol, 2.2.4
-1-dimethyl-1,3-bentanediol, 2.2-
Dimethyl-1,3-propanediol, 2,2-diethyl-1,3-propanediol, 2,2-diethyl-1
, 3-propanediol, 1,3-butanediol, 2-
Methyl-IJ-propanediol, 2,2-diethyl-
1,3-brobanediol, 2-methyl-2-pro-1,3-propanediol, 1,3-butanediol, 1,5-bentanediol, 1,6-bentanediol, 1,2-cyclohexane Polyesters having dimetatool, 1,3-cyclohexane dimetatool, 2,2,4,4-tetramethyl-1,3-cyclobutanedio-J, 0-1- or p-xylene diol, etc. be able to. In phenylenedioxydiacetic acid, which is one of the acid components, the position of the substituent bonded to the benzene ring may be in the ortho, meta, or polar position. The ratio with the acid is preferably 5:95 to 50:50 in molar ratio. Also, as the acid, diphenyldicarboxylic acid or the like may be used as a copolymerization component. Furthermore, as the diol component, among the above, hydroquinone, Phenylhydroquinone and resorcinol are preferred, and the diol components listed above can be used alone or in combination of two or more. In addition, components other than the above-mentioned acid component and diol component may be copolymerized as long as they do not impair the effects of the present invention. Benzoate, oxynaphthalene carboxylic acid, etc. may be used as a copolymerization component.

PCT used in the gas barrier film of the present invention is
It is a polyester mainly containing 1,4-cyclohexane dimetatool as a glycol component and mainly terephthalic acid as a dicarboxylic acid component.The molecular weight is not necessarily high, but it can be as low as 2000 degrees, and generally the molecular weight is 2000 degrees. ~200.000 degree is preferable, and it is preferable that 90% or more of the glycol component is 1,4-polycyclohexane dimetatool in order to improve the oxygen barrier property when wet, and 80 mol of the acid component is preferable. % or more is preferably terephthalic acid for the same reason.
However, as long as it does not adversely affect the effects of the present invention, a small amount, preferably 10 mol% or less, of other glycol components may be included, and a small amount, preferably 20 mol% or less, of other acid components may be included. 780 mol% PC, which may contain
and 20 mol% of isophthalic acid can be preferably employed.

The content of PCT in the gas barrier film of the present invention is
1 to 20% by weight, preferably 0.5% to 1% by weight
It is 0% by weight. If the PCT content deviates from this range, the oxygen barrier properties during wet conditions will be impaired.

The gas barrier film of the present invention is heated at 30°C.

Oxygen transmission rate at 100RH% is 0.8 ce/+m
”day/ton UVa or less.This oxygen transmission rate is 0.
．． If it is larger than 8 ccl/day/100 μm, the oxygen barrier property when wet is poor.

The thickness of the gas barrier film of the present invention is not particularly limited, but is usually 0.5 μm to 400 μm.

Preferably, the thickness is about 3gg+ to 200μ layers.

In addition to the above-mentioned liquid crystal polyester and PCT, the gas barrier film of the present invention may optionally contain additives that are usually added to polyesters, such as stabilizers, lubricants, and antistatic agents.

2. Other polymers may be blended within a range that does not adversely affect the effects of the present invention.9 The gas barrier film of the present invention may be non-oriented, but from the viewpoint of gas barrier properties and mechanical strength. Monoaxially or biaxially stretched is preferable.

The gas barrier film of the present invention is produced by uniformly mixing liquid crystalline polyester, PCT, and necessary (inert particles, additives, etc.), melt extruding using a melt extruder such as Extrugoo, cooling, A film can be formed by stretching.The drying conditions for the polymer chips are not particularly limited, but usually 170°C for about 3 hours is appropriate.The extrusion temperature is not particularly limited, but usually 5 to 20°C.
The temperature is about 0°C to 360°C, preferably about 250°C to 348°C. Casting is preferably carried out by an electrostatic application method, and the temperature of the casting drum is not particularly limited, but is usually 5°C to 60°C, preferably 15°C to 40°C. Further, stretching may or may not be carried out after cooling, but when stretching is carried out, it is usually at a temperature of 70°C to 150°C, preferably 85°C to 120°C, and usually 2.5 times to 100°C. It is carried out at a stretching ratio of 6.0 times. After f-stretching, it is preferable to heat set the film, usually at a temperature of 150°C to 280°C, preferably 165°C to 250°C, for usually 1 to 20 seconds, preferably 5 seconds to 1
This is done for 5 seconds.

When a gas barrier film is laminated on a polyolefin film, it can also be produced by coextruding it with a polyolefin film having an adhesive layer, casting in a water tank, stretching, and heat-setting.

Next, a method for measuring physical property values related to the present invention and a method for evaluating effects performed in the following examples will be explained.

ill M elementary transmittance is measured according to ASTM Rho 3985 using a measuring device manufactured by Modern Control.

(2) Water vapor barrier property The smaller the water vapor permeability, the better the water vapor barrier property. Water vapor permeability is in accordance with JIS 2-208.

Measured by cup method at 40°C and 90RH%.

(3) Extrusion stability The presence or absence of width fluctuations and surging during melt extrusion of the polymer was observed. The thickness of the film at this time was kept constant at 15 μι.

4 Negative 5 J O: When the film has no medium fluctuations or thickness fluctuations and can be formed stably for a long period of time △: The appearance is good and stable film formation with no medium fluctuations has been formed, but the thickness does not fluctuate. (4) Stretchable film The presence or absence of tearing and thickness unevenness during stretching of the film were observed.

Heel [ILヱ0: When a film with a uniform thickness can be obtained without tearing even if stretched 3 times in the transverse direction at 85°C to 120°C Δ: Can be stretched 3 times in the lateral direction at 85°C to 120°C (5) Melt and extrude the thin film-forming polymer from the die and cast it on a cast drum at 25°C while applying a draft. Cool and mold in close contact with.

Δ: Lower limit of film thickness obtained from 5μ to 100μ
X when uva: When the obtained lower limit film thickness exceeds 1100a [Example] The present invention will be described in more detail below based on Examples.

However, the present invention is not limited to the following examples.

叉J091 As the acid component, 60 mol% of terephthalic acid and 40 mol% of phenylenedioxydiacetic acid, and as the diol component, hydroquinone were reacted at 290°C for 3 hours according to a conventional method,
A liquid crystal polyester was produced. On the other hand, according to a conventional method, 80 mol% of dimethyl terephthalate, 20 mol% of dimethyl hisisophthalate as the acid component, 1,4-cyclohexane dimetatool as the diol component, and 1,4-cyclohexane dimetatool as the catalyst for the acid component.

Transesterification was carried out using 0.05 mol % titanium oxide by heating under stirring in an autoclave, followed by polycondensation to obtain PCT.

A blend consisting of 90% by weight of the above liquid crystal polyester and the above PCTIO was melt extruded at 340°C and cooled on a casting drum maintained at 40°C while applying an electrostatic charge to obtain an unstretched film. This unstretched film was stretched 3.5 times in a tenter at a temperature of 120°C. Grip both ends of the obtained uniaxially stretched film with clips.

Heat treatment was performed at 270''C for 5 seconds to obtain a film having a thickness of 10μ.

The obtained film was measured for oxygen permeability and water permeability at 30°C and 100RH%. Furthermore, extrusion stability, stretchability, and thinning properties during production were evaluated. The results are shown in the table below.

As is clear from the table below, the gas barrier film of the present invention produced as described above has excellent oxygen barrier properties and water barrier properties when wet, and also has excellent extrusion stability, stretchability, and thin film properties during production. It also had excellent chemical properties.

A film was produced in the same manner as in Example 1, except that liquid crystal polyester containing no PCT was used as a comparative raw material,
As in Example 1, the oxygen permeability and water permeability, as well as the extrusion stability during production, stretchability, and thin film forming properties were evaluated. The results are shown in the table below.

As is clear from the table below, although this film has excellent oxygen barrier properties when wet, its water barrier properties are somewhat poor, and its extrusion stability, stretchability, and thinning properties during production are poor.

A film was manufactured in the same manner as in Example 1, except that PET with an intrinsic viscosity of 0.65 was used in place of PCT, and the oxygen permeability, water permeability, and during manufacturing were determined in the same manner as in Example 1. Extrusion stability, stretchability, and thinning properties were evaluated. The results are shown in the table below.

As is clear from the table below, this film has poor oxygen barrier properties and water barrier properties when wet, and has poor extrusion stability during manufacturing.
It has poor thinning properties and somewhat poor stretchability.

Claims (2)

[Claims] (1) Liquid crystal polyester and 0% relative to the weight of the film
．． 1 to 20% of poly-1,4-cyclohexylene dimethylene terephthalate, 30°C, 100R
Oxygen transmission rate at H% is 0.8cc/m^2・day/1
A gas barrier film having a thickness of 00 μm or less. (2) The gas barrier film according to claim 1, wherein the liquid crystal polyester mainly contains phenylenedioxydiacetic acid and terephthalic acid as an acid component, and hydroquinone, phenylhydroquinone, or resorcinol as a diol component.