JPH1134246A - Gas barrier laminate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gas barrier laminate which can maintain a high gas resistant permeability for a long period of time. SOLUTION: The gas barrier laminate 7, for use in an interface between a gas and a liquid, comprises a composite layer 5, as a layer forming element, in which a resin elastic layer 4 is stacked on each of the top and bottom surfaces of a shielding composite layer 3 including a gas shielding layer 1 and a water shielding layer 2, and the layer 2 in the layer 3 is located nearer to the side of the liquid than the layer 1, wherein the layer 1 comprises a material containing a saponified matter of ethylene-vinylacetate copolymer. And the layer 2 comprises a polyolefin resin. The layer 4 comprises a material containing a polyamide resin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas barrier laminate which is used in accumulators and the like and which is required to have gas permeation resistance (gas barrier properties) and is used in diaphragms, bladders and the like.

[0002]

2. Description of the Related Art Generally, a diaphragm used for an accumulator or the like for transmitting a liquid pressure and formed so as to be deformed according to the pressure of the liquid without allowing the liquid to pass therethrough is disposed inside the accumulator or the like. The interior space is divided into two rooms. Then, a gas (gas) such as nitrogen gas is sealed in one of the chambers to become a pressure transmitting fluid,
A liquid such as brake fluid is supplied to another room according to the pressure of the liquid supply source. In this case, the gas sealed in one of the chambers gradually passes through the rubber thin film as the use period elapses, so that the gas sealing pressure is reduced and the function of the gas cannot be achieved.

Attempts have been made to improve the gas permeation resistance of the above-mentioned diaphragm. For example, a single saponified ethylene-vinyl acetate copolymer film is provided between two rubber thin films, and an adhesive layer is provided. A rubber-resin composite film provided interposed has been proposed (JP-A-2-165948). The saponified ethylene-vinyl acetate copolymer (hereinafter referred to as “EVO”)
H ") is excellent in gas permeation resistance, so that the rubber-resin composite film formed by using the film can maintain the gas sealing pressure. However, the above-mentioned rubber-resin composite membrane has a problem that its EVOH becomes
There is a problem that the film is cracked or peeled off.

[0004]

Therefore, the above EVOH
A proposal has been made in which a resin elastic film mainly composed of a polyamide resin is interposed between the film and the rubber thin film so that the EVOH film does not crack or the like. However, when such a structure is mounted on an accumulator and used for a long period of time, the gas permeation resistance gradually decreases (over time), and a new problem that the gas permeation resistance does not have excellent gas permeation is lost. Has occurred.

The present invention has been made in view of such circumstances, and has as its object to provide a gas barrier laminate capable of maintaining excellent gas permeability resistance for a long period of time.

[0006]

Means for Solving the Problems In order to achieve the above object, a gas barrier laminate of the present invention is a gas barrier laminate used at an interface between a gas and a liquid. A composite layer formed by laminating the following resin elastic layer (C) on both upper and lower surfaces of a shielding composite layer comprising a gas shielding layer (A) and a water shielding layer (B), and The water shielding layer (B) in the shielding composite layer is positioned closer to the liquid than the gas shielding layer (A). (A) A gas shielding layer made of a material containing EVOH. (B) A water shielding layer made of a polyolefin resin. (C) A resin elastic layer made of a material containing a polyamide resin.

That is, the inventor has conducted a series of studies on a gas barrier laminate capable of maintaining excellent gas permeability resistance for a long period of time. As a result, it has been found that the above-mentioned temporal deterioration of the gas permeation resistance is caused by the high water absorption of the liquid. That is, when the liquid is such a liquid, the liquid contains water over time, and this water passes through the rubber or polyamide resin constituting the gas barrier laminate, reaches the EVOH, and reaches the EVOH. This is because gas permeation resistance is reduced by water absorption. Therefore, the present inventor has proposed, as a layer for protecting the EVOH of the gas shielding layer (A) from moisture,
The intended purpose was achieved by devising a water shielding layer (B) made of a polyolefin resin having low water absorption and positioning the water shielding layer on the liquid side from the gas shielding layer (A). Therefore, in the present invention, "liquid" means a water-absorbing liquid that does not originally contain water, such as brake fluid, and that absorbs water with time to become water-containing, In addition, the concept includes a liquid containing water from the beginning.

[0008]

Next, an embodiment of the present invention will be described.

The gas barrier laminate of the present invention is, for example,
As shown in FIG. 1, a shielding composite layer 3 including a gas shielding layer 1 made of a material containing EVOH and a water shielding layer 2 made of a polyolefin resin is provided at the center thereof. A resin elastic layer 4 made of a material containing a polyamide resin is provided on both upper and lower surfaces to form a composite layer 5. Rubber elastic layers 6 are provided on both upper and lower surfaces of the resin elastic layer 4.

In the gas barrier laminate 7, the material for forming the gas shielding layer 1 is not particularly limited as long as it contains EVOH.
A composition [component (a)] composed of VOH or a quaternary copolymer of EVOH with a polyamide quaternary copolymer composed of polyamide 6, polyamide 66, polyamide 610 and polyamide 612 and ethylene-acrylic ester-maleic anhydride ternary copolymer A composition comprising a polymer (component (b)),
A composition [component (c)] or the like in which a polyamide multi-component copolymer comprising EVOH and a polyamide component containing at least two components of polyamide 6 and polyamide 66 and a maleic anhydride-modified ethylene-propylene copolymer are blended is used. Can be

When a composition (component (a)) made of EVOH is used as a material for forming the gas shielding layer 1, the gas shielding layer 1 having excellent gas permeation resistance can be formed at low cost. . Further, as a material for forming the gas shielding layer 1, a composition [(b) component] obtained by blending EVOH, a polyamide quaternary copolymer, and an ethylene-acrylate-maleic anhydride terpolymer is used. When used, in addition to good gas permeability resistance, it is possible to form the gas shielding layer 1 having excellent bending fatigue resistance especially in a low temperature environment. Further, as a material for forming the gas shielding layer 1, EV
When a composition (component (c)) comprising a mixture of OH, a polyamide multi-component copolymer and a maleic anhydride-modified ethylene-propylene copolymer is used, good gas transmission resistance and bending fatigue resistance are obtained. In addition, the moldability is excellent, and the dimensional accuracy of the obtained gas barrier laminate 7 is improved.

It is preferable to use the EVOH having an ethylene content of 25 to 50 mol%. Among them, those having an ethylene content of 32 mol% are preferred. That is, when the ethylene content is less than 25 mol%, the gas permeation resistance is improved, but the EVOH itself is hardened, the flexibility is reduced, and the EVOH tends to be unsuitable for applications having a bending motion. . Conversely, if the ethylene content exceeds 50 mol%, sufficient gas permeability resistance may not be ensured. The saponification degree of the vinyl acetate component in the EVOH is preferably set to 95 mol% or more, and more preferably 98 mol% or more, in consideration of gas permeability resistance and moldability.

Polyamide 6, Polyamide 66, Polyamide 610, Polyamide 6 used for component (b)
The polyamide quaternary copolymer composed of 12 components is EV
Polyamide 6 and polyamide 66 are preferred from the viewpoint that excellent bending fatigue resistance can be imparted without giving orientation to OH.
Is preferably set in the range of 50 to 80% by weight based on the total weight of the four components. That is, if the total blending ratio is less than 50% by weight, EV
This is because the amount of polyamide 6 and polyamide 66 having high compatibility with OH is too small, so that the reactivity between the polyamide quaternary copolymer and EVOH may be reduced, and the bending fatigue resistance may not be improved. On the other hand, if the total blending ratio exceeds 80% by weight, the amount of polyamide 6 and polyamide 66 having high compatibility with EVOH becomes too large, and the polyamide quaternary copolymer and EVOH react excessively to form a gel. This is because there is a possibility that the moldability may deteriorate.

The ethylene-acrylate-maleic anhydride terpolymer used for the component (b) is used together with the polyamide quaternary copolymer contained in the EVOH to reduce the elongation at break in a low-temperature environment. The reduction can be effectively suppressed, and the bending fatigue resistance is significantly improved.

In the above component (b), EVOH
[(P) component], a polyamide quaternary copolymer [(q) component], and an ethylene-acrylic acid ester-maleic anhydride terpolymer [(r) component]; p) / (q) / (r)] is (p) / (q) /
(R) = (60-90) / (5-35) / (5-35)
Is preferably set in the range. That is, E
If the mixing ratio of VOH is less than 60% by volume, EVOH
Is too small and gas permeation resistance may not be sufficiently exhibited.
If the content exceeds 0% by volume, the amount of the polyamide terpolymer and the ethylene-acrylate-maleic anhydride terpolymer may be too small to improve the bending fatigue resistance in a low-temperature environment. Because there is.

The polyamide multi-component copolymer comprising a polyamide component containing at least two components of polyamide 6 and polyamide 66 used in the component (c) is EV.
From the viewpoint that excellent bending fatigue resistance can be imparted without giving orientation to OH, the above polyamide 6 and polyamide 66
Is 50 to 50% of the total polyamide component.
Preferably, it is set in the range of 80% by weight. That is, if the total blending ratio is less than 50% by weight,
This is because the amount of polyamide 6 and polyamide 66 having high compatibility with EVOH is too small, the reactivity between the polyamide multi-component copolymer and EVOH is reduced, and there is a possibility that the bending fatigue resistance cannot be improved. Conversely, if the total blending ratio exceeds 80% by weight, the amount of polyamide 6 and polyamide 66 having high compatibility with EVOH becomes too large, and the polyamide multi-component copolymer and EVOH excessively react and gel. This is because the moldability may be deteriorated. Polyamide components other than the above two components include polyamide 11 and polyamide 1
2, polyamide 69, polyamide 610, polyamide 6
12 and the like.

The maleic anhydride-modified ethylene-propylene copolymer used in the component (c) is obtained by adding maleic anhydride to an ethylene-propylene copolymer. And by using together with the polyamide multi-component copolymer to be contained in the EVOH, it is possible to effectively suppress a decrease in elongation at break in a low-temperature environment,
Flexural fatigue resistance is significantly improved.

In the above component (c), EVOH
The weight-based compounding ratio of [(x) component], polyamide multi-component copolymer [(y) component], and maleic anhydride-modified ethylene-propylene copolymer [(z) component] [(x) /
(Y) / (z)] is (x) / (y) / (z) = (60
-85) / (5-30) / (10-35). That is, if the compounding ratio of EVOH is less than 60% by weight, the compounding amount of EVOH may be too small and gas permeation resistance may not be sufficiently exhibited, and the compounding ratio of EVOH exceeds 85% by weight. This is because the amount of the polyamide multi-component copolymer and the maleic anhydride-modified ethylene-propylene copolymer may be too small to improve the bending fatigue resistance in a low-temperature environment.

Examples of the polyolefin resin used as a material for forming the water shielding layer 2 include polyethylene, polypropylene, polybutene-1 and the like. Other than these, α, such as ethylene, propylene, and butene-1,
A copolymer of olefins or a copolymer of an α-olefin with another component, for example, a vinyl compound such as styrene, vinyl acetate or acrylonitrile may be used. Furthermore, using an unsaturated carboxylic acid such as maleic acid, fumaric acid, or acrylic acid, an ester or an acid anhydride thereof, or a product obtained by adding a hydroxyl group or an epoxy group to these polyolefin-based resins to improve adhesiveness. The one given may be used. Because these polyolefin resins have low water absorption, water permeation can be significantly reduced,
Therefore, the gas barrier laminate 7 obtained does not decrease the gas permeation resistance.

Examples of the polyamide resin used as a material for forming the resin elastic layer 4 include polyamide 6, polyamide 66, polyamide 610, polyamide 612 and the like, and these may be used alone or in combination. If such a polyamide resin contains the above-mentioned polyamide 6 or polyamide 66, the melting point of EVOH is approximated, so that various mixtures of polyamide 6 and other polyamide resins should be used. Is possible. In particular, when a polyolefin-based resin is blended with a polyamide resin, water permeation can be suppressed even in the resin elastic layer 4 due to the low water-absorbing polyolefin-based resin. A product having excellent properties can be obtained.

As the material for forming the rubber elastic layer 6, acrylonitrile-butadiene copolymer rubber (NBR), butyl rubber (IIR), epichlorohydrin-ethylene oxide copolymer rubber (ECO), fluoro rubber, chlorinated butyl rubber (Cl-IIR) ) And the like.
Above all, Cl-IIR is preferable because flexibility can be given to the entire gas barrier laminate 7 and an effect of not causing a crack or the like due to bending motion can be sufficiently obtained.

The gas barrier laminate of the present invention is manufactured, for example, as follows. That is, the material for forming the gas shielding layer 1, the material for forming the water shielding layer 2, and the material for forming the resin elastic layer 4 are co-extruded using an extruder, so that the gas shielding layer 1 and the water shielding layer are coextruded. The resin elastic layer 4 is integrally formed on both the upper and lower surfaces of the shielding composite layer 3 including 2. In this case, the bonding interface between the gas shielding layer 1 and the resin elastic layer 4 is bonded by melting them, so that an adhesive is not required. On the other hand, the bonding interface between the water shielding layer 2 and the resin elastic layer 4 is usually
Similar to the above, they are bonded by melting. However, when a copolymer of α-olefins is used as a material for forming the water shielding layer 2, they are not bonded by the melting of both. Must be applied.

Next, on both upper and lower surfaces of the resin elastic layer 4,
A conventionally known adhesive is applied. Then, after laminating the rubber elastic layer 6 formed in a layer shape thereon, and vulcanizing and bonding, the gas barrier laminate 7 shown in FIG. 1 is obtained. The gas barrier laminate 7 is used such that the water shielding layer 2 in the shielding composite layer 3 is positioned closer to the liquid than the gas shielding layer 1.

In addition, a gas barrier laminate can be obtained by a conventionally known method such as a lamination method in addition to the above-mentioned production method.

In the gas barrier laminate 7 thus obtained, the water shielding layer 2 made of a low water-absorbing polyolefin resin is formed on the liquid side of the gas shielding layer 1, so that the gas permeation of water causes The gas permeation resistance of the shielding layer 1 does not decrease, and excellent gas permeation resistance can be maintained for a long period of time.

The gas shielding layer 1 has a thickness of 10 to 10.
It is preferable that the distance is set in the range of 100 μm. More preferably, it is in the range of 25 to 85 μm. That is, by setting the value within the above range, gas permeation can be effectively suppressed.

The water shielding layer 2 has a thickness of 20 to 1
It is preferable that the distance is set in the range of 00 μm. More preferably, it is in the range of 30 to 70 μm. That is,
This is because, by being set in the above range, the permeation of water can be effectively suppressed, and the gas permeation resistance due to the absorption of EVOH does not significantly decrease.

The thickness of the resin elastic layer 4 is 15
It is preferable that the distance be set in the range of 150 μm.
More preferably, it is in the range of 50 to 110 μm. That is, by setting the value within the above range, the obtained gas barrier laminate 7 can be given appropriate flexibility.

Further, the thickness of the rubber elastic layer 6 is 50
Preferably, it is set in the range of 0 to 1500 μm. More preferably, it is in the range of 700 to 1500 μm. That is, by setting the value within the above range, the obtained gas barrier laminate 7 can be given appropriate flexibility.

It should be noted that the gas barrier laminate of the present invention is not limited to the above laminated structure, and may have a structure as shown in FIG. 2, for example. That is, the water shielding layer 2 is formed on the liquid-side surface (lower surface) of the gas shielding layer 1, and the resin elastic layer 4 'and the gas shielding layer 1' are formed on the gas-side surface (upper surface) of the gas shielding layer 1. The shielding composite layer 3 may be formed by laminating an arbitrary number of layers in this order. Then, a resin elastic layer 4 is formed on both upper and lower surfaces of the shielding composite layer 3, and a rubber elastic layer 6 is formed on both upper and lower surfaces of the resin elastic layer 4. In the case of the structure shown in FIG. 2, the layers of the resin elastic layer 4 'and the gas shielding layer 1' formed on the upper surface of the gas shielding layer 1 from the viewpoint of the bending fatigue resistance of the obtained gas barrier laminate 7 '. Is preferably about 2 to 6.

The gas barrier laminate of the present invention is generally used for diaphragms such as accumulators, bladders, and the like. In addition to these, for example, tanks for storing liquids and the like, pipes for transporting them, etc. It can be used as a member for a gas / liquid interface.

Next, examples will be described together with comparative examples.

[0033]

Embodiments 1 and 2 First, E was used as a material for forming a gas shielding layer.
VOH (ethylene content 32 mol%, Kuraray F-
101), a polyolefin resin (HDPE, Admer manufactured by Mitsui Petrochemicals) is prepared as a material for forming the water shielding layer, and a polyamide resin (Super Tough Nylon ST811 manufactured by DuPont) is formed as a material for forming the resin elastic layer.
HS) was prepared. Further, Cl-IIR (JSR1066 manufactured by Nippon Synthetic Rubber Co., Ltd.) was prepared as a material for forming the rubber elastic layer. Next, the material for forming a gas shielding layer, the material for forming a water shielding layer, and the material for forming a resin elastic layer were co-extruded using an extruder to produce a six-layer laminate. Next, a conventionally known adhesive was applied to both the upper and lower surfaces of the six-layer laminate, and a rubber elastic layer forming material was press-formed into a layer using a press, followed by vulcanization bonding. Thus, the gas barrier laminate 7a shown in FIG. 3 was obtained. The thickness of each layer is shown in Table 1 below.

[0034]

Comparative Examples 1 to 3 A gas barrier laminate was obtained in the same manner as in Example 1 except that the water shielding layer was not formed and the thickness of each layer was as shown in Table 1 below.

[0035]

[Table 1]

[0036]

Example 3 Next, in the same manner as in Example 1, an eight-layer laminate was produced by coextrusion from an extruder, and rubber elastic layers were formed on the upper and lower surfaces of the eight-layer laminate. Thus, the gas barrier laminate 7b shown in FIG. 4 was obtained.

[0037]

Example 4 Similarly to Example 1, a ten-layer laminate was produced by coextrusion from an extruder, and rubber elastic layers were formed on both upper and lower surfaces of the ten-layer laminate. Thus, the gas barrier laminate 7c shown in FIG. 5 was obtained.

Using the gas barrier laminate thus obtained, a nitrogen gas permeation test was performed by the method described below, and the results are shown in Table 2 below.

[Nitrogen Gas Permeation Test] First, the obtained gas barrier laminate was formed so as to have a surface area of 100 cm ^2, and this was formed into an interface between a nitrogen gas and a liquid composed of brake fluid, and a nitrogen gas and a brake fluid. 10 water
Each was installed at the interface with the liquid containing the volume%. Next, the nitrogen gas permeation amount of the gas barrier laminate was set to 1
The measurement was performed under the conditions of 00 ° C. × 1000 hr × 150 kgf / cm ² .

[0040]

[Table 2]

In all of the above embodiments, the water shielding layer is provided on the liquid (brake fluid) side of the gas shielding layer, so that the amount of water reaching the gas shielding layer can be significantly reduced.
It can be seen that excellent gas permeation resistance is maintained for a long time. On the other hand, in Comparative Examples 1 to 3, since the water shielding layer was not formed, moisture permeated to the gas shielding layer, indicating that the gas permeability resistance was reduced.

[0042]

As described above, the gas barrier laminate of the present invention comprises a gas-shielding layer made of a material containing EVOH and a water-shielding layer made of a polyolefin-based resin. Is provided with a resin elastic layer made of a material containing a polyamide resin, and the water shielding layer in the shielding composite layer is positioned closer to the liquid than the gas shielding layer. For this reason, it is possible to reduce the amount of water reaching the gas shielding layer, and it is possible to significantly reduce the absorption of EVOH by the gas shielding layer. Therefore, the gas barrier laminate of the present invention can maintain excellent gas permeability resistance for a long period of time. In addition, since a resin elastic layer made of a forming material containing a polyamide resin is formed on both the upper and lower surfaces of the shielding composite layer, even if the resin elastic layer is used for repeated applications such as bending motion, the elasticity of the resin elastic layer can be reduced. There is an advantage that cracks or the like are not generated in the gas barrier laminate by using force.

In the gas barrier laminate of the present invention, when rubber elastic layers are formed on the upper and lower surfaces of the resin elastic layer via an adhesive layer, the excellent elastic force of the rubber elastic layer can be utilized. Very flexible,
It has the advantage of being more excellent in bending fatigue resistance.

Further, in the gas barrier laminate of the present invention, an arbitrary number of laminated resin elastic layers and gas shielding layers as the above-mentioned shielding composite layer is very excellent in gas permeation resistance and bending fatigue resistance. And has the advantage that its excellent performance can be maintained for a long period of time.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing an example of a gas barrier laminate of the present invention.

FIG. 2 is a cross-sectional view showing another example of the gas barrier laminate of the present invention.

FIG. 3 is a sectional view showing an embodiment of the gas barrier laminate of the present invention.

FIG. 4 is a sectional view showing another embodiment of the gas barrier laminate of the present invention.

FIG. 5 is a sectional view showing still another embodiment of the gas barrier laminate of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 gas shielding layer 2 water shielding layer 3 shielding composite layer 4 resin elastic layer 5 composite layer 7 gas barrier laminate

Claims (3)

[Claims] 1. A gas barrier laminate used at an interface between a gas and a liquid, wherein the gas barrier laminate comprises the following gas shielding layer (A) and water shielding layer (B). A composite layer formed by laminating the following resin elastic layers (C) on both upper and lower surfaces as a layer forming element, and the water shielding layer (B) in the shielding composite layer is a gas shielding layer (A)
A gas barrier laminate characterized by being positioned on the liquid side. (A) A gas shielding layer comprising a material containing a saponified ethylene-vinyl acetate copolymer. (B) A water shielding layer made of a polyolefin resin. (C) A resin elastic layer made of a material containing a polyamide resin. 2. The gas barrier laminate according to claim 1, wherein rubber elastic layers are laminated on both upper and lower surfaces of the resin elastic layer (C) via an adhesive layer. 3. The shielding composite layer, wherein a gas shielding layer (A) is laminated on one surface of a water shielding layer (B), and a resin elastic layer (C) and a gas shielding layer are disposed on one surface of the gas shielding layer (A). 3. The gas barrier laminate according to claim 1, wherein (A) and an arbitrary number of the laminates are alternately laminated in this order. 4.