JPH0930592A - Container for receiving acidic water - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a container which is suitable for storing acidic water or the like and has high water resistance, reactivity for chlorine, gas-barrier property and which can preserve and transport acidic water having low stability by forming at least an area of the container in contact with liquid stored therein from low density polyetylene, to which chlorine has been added beforehand. SOLUTION: A resin (LDPEcl) prepared by adding beforehand chlorine element of 0.1-0.2wt.% to low density polyethylene having density of 0.88-0.93g/cm<3> prepared by polymerizing ethylene under high pressure is used to form a bag- shaped material. In the bag-shaped material, the innermost surface thereof in contact with acidic water may be made of LDPEcl, or a single layer of LDPEcl or a multilayers, in which a resin layer having gas-barrier property used, as intermediate layer, in combinaton with an LDPEcl layer and further a low density polyethylene resin is used as an outermost layer, may be used. Consequently, the bag-shaped body, i.e., a container, has low permeability to gas and chlorine concentration at a surface in contact with stored liquid can be increased to restrain the reduction in the amounts of residual chlorine and dissolved oxygen so that germicidal effects can be stably maintained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a container used for filling acidic water, and more particularly to a container made of synthetic resin capable of stably storing acidic water.

[0002]

2. Description of the Related Art In recent years, electrolytic ionized water, particularly acidic water, has been used for disinfecting fingers and treating burns for preventing nosocomial infection in hospitals. At this time, as a container for storing acidic water, a glass bottle or a back-in-box that replaces a heavy or heavy glass bottle with a cardboard box as an exterior, and a bag body made of various films or a thin container made by blow molding as an interior is used. Has been done.

The interior storage container is required to have pinhole resistance, water resistance, chemical resistance, gas barrier property and the like. Usually, a single-walled thin container made of low-density polyethylene, low-density polypropylene, or the like, or a composite film having various configurations is used as the storage container. None of these necessarily meet the above requirements,
For example, it has poor chemical resistance (resistance to chlorination by dissolved chlorine, oxidation, cross-linking) and oxygen gas barrier properties, and was not suitable for acidic water, which has poor stability. A container that can store acidic water is desired.

[0004]

The container of the present invention is particularly suitable for storing acidic water and the like, and is excellent in water resistance, chlorine reactivity resistance, gas barrier property, etc. A container for containing acidic water, characterized in that at least the surface in contact with the contained liquid is low-density polyethylene to which chlorine has been added in advance.

The above-mentioned acidic water is acidic water (hereinafter referred to as acidic water) obtained by electrolyzing water or an aqueous solution obtained by adding a small amount of sodium chloride or potassium chloride to water. pH (hydrogen ion concentration) is 4.0 or less,
An ORP (oxidation-reduction potential) of 980 mV or higher, particularly a pH of 2.5 or lower and an ORP of 1100 mV or higher.

Surprisingly, the use of low-density polyethylene to which chlorine has been added to the surface of the innermost layer of the container surprisingly reduces the sterilizing power of the contained acidic water and allows stable storage. it can.

As the low-density polyethylene preliminarily chlorinated, for example, a low-density polyethylene resin having a density of 0.88 to 0.93 g / cm 3 obtained by polymerizing ethylene under high pressure and 0.1 to 2.0 of a chlorine element are previously added. A resin added with weight% (hereinafter referred to as LDPEcl) is used.

In order to add chlorine to the low density polyethylene, for example, there is a method of bringing a low density polyethylene resin powder before molding or a low density polyethylene resin molded product into contact with chlorine gas or a chlorine-containing liquid.

The structure of the container may be a rigid tank or the like, or a flexible bag-like material. In short, the surface of the innermost layer of the container is preliminarily chlorinated low density polyethylene. Should be used.

Further, in the above container, when a film material having a barrier property is laminated on the surface which is not in contact with the contained liquid, the amount of residual chlorine and the amount of dissolved oxygen in the acidic water are excellent due to the excellent gas barrier property. To reduce
It is possible to prevent the sterilizing power from decreasing.

In a bag-like article having at least two layers on one side, which has a synthetic resin layer forming a liquid storage portion in the center and a void portion formed outside thereof to have a synthetic resin layer, the synthetic resin which is in contact with the storage liquid. If a container for containing acidic water is used, in which the surface of the layer is made of low-density polyethylene to which chlorine is added in advance, there is an effect that the void portion has a buffering effect and pinholes are less likely to occur.

A more specific bag-shaped object will be described as an example.

In the bag-like material, the innermost surface in contact with acidic water may be LDPEcl, and even if it is a single layer of LDPEcl,
A gas barrier resin layer as an intermediate layer on the LDPEcl layer,
Further, it may be a multi-layer structure product in which a polyolefin resin layer of low-density polyethylene, linear low-density polyethylene, or ethylene-vinyl acetate copolymer is combined as the outermost layer.

Even if the bag is easily deformed, pinholes are unlikely to occur because the innermost surface of the LDPE is a chlorine addition product in the above range and is relatively soft. The innermost LDP
Ecl is heat-sealed by high-frequency heating method or ultrasonic heating method to have a sealed portion with practical seal strength, and the resin layer is arranged as the outermost layer. The mouth can be heat-sealed.

As the intermediate layer, nylon 6 and nylon 6
6. A polyamide resin layer composed mainly of nylon 6 constitutional units, terephthalic acid, a copolymer consisting of constitutional units of isophthalic acid and hexamethylenediamine, or a mixture thereof, and a resin having an ethylene content of 30 to 60 mol% A single layer of a saponified ethylene vinyl acetate copolymer layer having a degree of conversion of 95% or more, or a composite gas barrier layer of a polyamide resin layer and a saponified layer of an ethylene vinyl acetate copolymer is provided.

A polyolefin-based adhesive resin layer may be disposed between these layers to improve the adhesive strength and pinhole resistance. As the polyolefin-based adhesive resin layer, a modified polyolefin resin grafted with at least one monomer selected from unsaturated carboxylic acids or derivatives thereof can be preferably used.

The thickness of the innermost LDPEcl layer is 5 to 100 μm, the outermost polyolefin resin layer is 5 to 200 μm, the intermediate layer is about 5 to 60 μm, and the adhesive resin layer is 5 to 30 μm. Micron is preferred.

The present invention relates to the constitution of a container for storing acidic water,
Since the surface in contact with the stored liquid is made of low-density polyethylene to which chlorine has been added in advance, it is possible to suppress the reduction of the residual chlorine amount and the dissolved oxygen amount of the acidic water, and to reduce the sterilization effect and enable stable storage.

The reason for this is that since the polarities are small, the degree of freedom of the constituent molecular chains is high, and the movement of the chains is restricted by adding chlorine atoms of high polarity to the low density polyethylene which is permeable to gas. It is considered that this is because it becomes difficult for gas to permeate, and the chlorine concentration on the surface in contact with the stored liquid becomes high, so that the difference from the chlorine concentration in acidic water becomes small and adsorption becomes difficult.

[0020]

[Example] As acidic water, an aqueous solution of sodium chloride was added dropwise to pure water and electrolyzed to obtain a pH of 2.5-2.
6, ORP is 1170mV, residual chlorine amount is 32ppm,
Prepare the one with dissolved oxygen amount of 20-25 mg / l,
This was filled in a container shown below and stored at room temperature for 1 to 14 days, and pH (measured using a pH composite electrode), ORP
(Measurement using ORP composite electrode), residual chlorine amount (measured by iodine titration method), dissolved oxygen amount (measured by diaphragm electrode method) were measured and their changes were evaluated. The results are shown in Table 1.

It should be noted that when the value of pH is large, the acidic water changes and becomes neutral, and when the value of ORP is small, the acidic water changes and becomes neutral, and the residual chlorine content and dissolved oxygen content are numerical values. A smaller value means that the bactericidal power decreases.

The pH values in Table 1 are measured according to JIS K 010.
According to the glass electrode method described in 1, the measurement of residual chlorine content is JIS
The iodine titration method described in K 0101 and the amount of dissolved oxygen were measured in accordance with the diaphragm electrode method described in JIS K 0101. The method of measuring the redox potential was not specified in JIS standard, but was measured by the widely used platinum electrode method.

[Example 1] A bag-like product having an internal capacity of 5 liters, which was made of a low-density polyethylene sheet (density 0.91) having a thickness of 0.4 to 0.8 mm, had a ph of 2.7 or less and ORP1.
A bag-like product containing about 0.8% by weight of chlorine was obtained by filling the treated acidic water with 170 mv or more and 30 ppm or more of residual chlorine and leaving it for 1 week, and then discarding the treated acidic water.

[Comparative Example 1] The bag-shaped material having an internal capacity of 5 liters used in the above-mentioned [Example 1] was used as it was without adding chlorine.

[Example 2] A low-density polyethylene film having a thickness of 50 µ (density 0.90) was overlaid and heat-sealed to form a bag having an internal volume of 1 liter.
2.7 or less, ORP1170mv or more, residual chlorine 30p
After filling the treated acidic water of pm or more and leaving it for 1 week, the treated acidic water was discarded to obtain a bag-shaped product to which about 0.7% by weight of chlorine was added.

[Comparative Example 2] An ultra-low density polyethylene film (density 0.90) having a thickness of 50 µm used in the above-mentioned [Example 2] was overlaid and heat-sealed to form a bag having an internal volume of 1 liter. Was prepared and used as it was without adding chlorine.

[Example 3] A low-density polyethylene film (density 0.92) having a thickness of 90 µ was used as an interior film, and a neopentyl glycol-terephthalic acid copolymer layer 30 µ, a polyamide layer 9 µ, and an ethylene vinyl acetate copolymer were added thereto. 20 μ of saponified polymer layer and 55 μ of ethylene vinyl acetate copolymer layer were laminated by a co-extrusion method through a polyolefin adhesive layer of 16 μ, and the outer films were laminated and heat-sealed together with the low-density polyethylene layers of the inner film. To make a two-layer bag with an internal volume of 1 liter, and fill it with treated acidic water with a ph of 2.7 or less, ORP1170 mv or more, and residual chlorine of 30 ppm or more, and leave it for 1 week, then discard the treated acidic water. By this, about 0.7% by weight
A bag-shaped product to which chlorine was added was obtained.

Example 4 Low-density polyethylene film layer (density 0.92) having a thickness of 50 μm, polyamide layer 10
μ, saponified ethylene vinyl acetate copolymer layer 20μ
A film obtained by laminating the above by a coextrusion method through a polyolefin adhesive layer 16μ is heat-sealed to the low density polyethylene layers to form a bag having an internal volume of 1 liter, and ph 2.7 or less, ORP1170 mv or more. After filling with acidic water with residual chlorine of 30 ppm or more and leaving it for 1 week,
By discarding the treated acidic water, a bag-shaped product containing about 0.7% by weight of chlorine was obtained.

[0029]

[Table 1] From Table 1, in the case of using a bag-like material having an internal capacity of 5 liters, which is made of a low-density polyethylene sheet (density 0.91) having a thickness of 0.4 to 0.8 mm, chlorine is added in Example 1
Even if the filling period is 14 days, the ORP is 1
Since 160 mV is maintained and residual chlorine is also kept at 16 ppm and the decrease is small, the sterilizing effect of acidic water is not reduced and stable storage is possible, but in the case of Comparative Example 1 in which chlorine is not added, ORP is 1145 mV, residual chlorine It can be seen that the value also drops to 9 ppm.

The bag-shaped material having an internal volume of 1 liter was the one on the 14th day when chlorine was added, and the dissolved oxygen was 14.8 to 16.0 mg / L. Residual chlorine also remains at 16 ppm, showing a small decrease, whereas in Comparative Example 2 in which chlorine is not added, the ORP drops to 1148 mV on the 14th day of the filling period, and the residual chlorine also drops to 7 ppm. I understand.

[0031]

EFFECTS OF THE INVENTION The present invention is a container for containing acidic water, characterized in that at least the surface in contact with the contained liquid is low density polyethylene which has been chlorinated beforehand. Since the decrease in the oxygen content is small, the sterilization effect is small and the acidic water can be stably stored.

Claims (1)

[Claims] 1. A container for containing acidic water, characterized in that at least the surface in contact with the contained liquid is low-density polyethylene chlorinated in advance.