JPS58134856A - Vessel made of plastic - 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 plastic containers. More specifically, the present invention relates to a plastic container that is particularly excellent in preventing permeation of alcohol-mixed hydrocarbons.

Various plastics are used as container materials for storing hydrocarbons in many fields, and one example of a container is an automobile gasoline tank (hereinafter abbreviated as GT).
As a plastic, polyethylene, especially ultra-high molecular weight high-density polyethylene, is the most promising in terms of economy, moldability, and strength, but stored gasoline gas or liquid easily scatters into the atmosphere through the polyethylene wall. That is, it is known to have a drawback of being inferior in permeation prevention ability.

In order to eliminate this drawback, we created containers made of polyethylene and polypropylene containing approximately 0 sulfur trioxide (803).
．． 1 to 20 volumes of dry inert gas, such as N2, C
After treatment with O2, SO2 and air, etc., or with a solution of S03 in a liquid polychlorinated aliphatic hydrocarbon such as methylene chloride, carbon tetrachloride, etc., the gaseous phase such as gaseous ammonia and methylamine is removed. When using a neutralizing agent, a hydroxide of an alkali metal or an alkaline earth metal, or a salt of a corresponding weak acid, washing and drying the container, or molding the container using a blow molding method, the volume is about 0. A method of fluorinating the inner surface of a container by blowing one or more reactive gases selected from the group consisting of SO2, CO1CO2,02, O12 friends and Br2 together with 1 to 20 fluorine, etc. is proposed.

On the other hand, there are concerns about oil supply shortages now and in the future, and the future of the gasoline situation in particular is becoming a serious problem that has become a social issue. In response to this, so-called Gasol, which is a mixture of alcohol and gasoline, has appeared as a new fuel in order to reduce consumption, and in countries such as Brazil, which are already suffering from oil shortages, it has been put into practical use under government guidance. Also, just recently in Japan, the Ministry of International Trade and Industry and the Agency for Natural Resources and Energy have begun considering the practical application of Gas All.

Among the permeation prevention means mentioned above, polyethylene (hereinafter referred to as P
The most practical type of GT is the one in which the inner surface of the gas (referred to as E) is neutralized with NH3 gas after SO3 treatment, and is already installed in some vehicles in the United States and other countries. However, when the present inventors conducted various permeation tests using gasoline and gas all on the above-mentioned treated containers, it was found that the permeation amount of gasoline alone was 1/10 to 1/40 of that of untreated containers. For gas all that has been confirmed to have excellent permeation prevention ability, for example, gasoline/methanol - 90/10 (volume ratio), the amount of permeation will be 1/3 to 1/10 (see the margin below), and the permeation prevention ability will be was found to decrease.

The reason for this decrease is currently under investigation, but it is presumed that the hydrophilic PE surface (PE-803NH) has a very good affinity for alcohol, making it less permeable. . Therefore, in order to improve the permeability of gas all, the PE surface needs to be hydrophobic and hydrophilic, that is, to have the ability to prevent the permeation of both gasoline and alcohol, and the inventors have attempted to improve this point. We have been carefully considering this.

As a result, for plastic containers that had been neutralized with H3 gas after S03 treatment, BaCl2, Ba
When the surface is treated with a solution containing an alkaline earth metal compound such as (OH)2.8H20, the permeation prevention ability is even better not only for gasoline alone but also for all gases.
The amount of permeation is 1 compared to the untreated product (no sulfonation treatment).
/40~L/6o or S03 treated /NH, neutralized products were found to have the alarming effect of being able to be improved to 115~L/10, leading to the completion of the invention.

That is, the gist of the present invention is a plastic container whose inner and/or outer surfaces are subjected to sulfonation treatment, followed by neutralization treatment, and then the surfaces are further treated with a solution containing an alkaline earth metal.

The base material of the plastic container used in the present invention is not particularly limited, but homopolymers of α-olefins such as ethylene, propylene, isobutylene, butene-14-methylpentene-1, etc., or combinations of these α-olefins are used. Copolymers, chlorinated polyethylene, ionomers,
So-called olefin polymers such as the above α-olefin and a small amount of monomer copolymers such as acrylic acid, methacrylic acid or alkyl esters thereof, and mixtures thereof may be mentioned.

A container obtained by molding the olefin polymer as described above by blow molding or the like is subjected to sulfonation treatment on the inner and/or outer surface. This sulfonation treatment method involves treating SO3 with a dry inert gas containing about 15-18 volumes of hydrogen, such as N2, CO2, SO3, or air, or with a liquid polychlorinated fat such as methylene chloride, carbon tetrachloride, etc. It may be treated with a solution of SO3 in group hydrocarbons. In such sulfonation treatment, for example, in the case of polyethylene, the S03 per unit surface area is 0.001 to 2.
0 my/cA introduced 0 The surface thus sulfonated is then subjected to a neutralization treatment. This neutralization treatment consists of alkali metal hydroxides or corresponding weak acid salts, alkaline earth metal hydroxides or corresponding weak acid salts, heavy metal chlorides or sulfates,
Treatment may be with dilute aqueous solutions of primary, secondary or tertiary amines, ammonium hydroxide, mixtures thereof, or with gas phase neutralizing agents such as gaseous ammonia, methylamine and the like. Usually, from an economic point of view etc., treatment using gaseous ammonia for 1 to several minutes is preferably used. By this neutralization treatment, the sulfonic acid groups on the surface are converted into sulfonic acid salts such as [PE-8o, NH,] in the case of ammonia gas neutralization.
is converted to

In the present invention, the treated surface that has been subjected to the sulfonation (hereinafter referred to as blank space) and then neutralization treatment is further treated with a solution containing an alkaline earth metal compound, usually an aqueous solution.

Alkaline earth metals include B in Group Ia of the periodic table.
e, Mg%Ca%Sv, Ba, Rc, etc. Among them, Mg%Ca is the most easily available metal.
, Ba are preferred.

The metal compounds include chloride, bromide, iodide, fluoride, hydroxide, hypochlorite, dichromate, carbonate,
Examples include nitrates, sulfates, acetates, formates, valerates, glyconates, cinnamates, androthylic acid, and butyrates, but in the present invention, these salts are used from the viewpoint of ease of handling and economical efficiency. chloride which is soluble in water among the compounds or salts of
Hydroxides, acetates and the like are preferred. Specifically, preferred are magnesium chloride, calcium chloride, barium chloride, barium hydroxide, magnesium acetate, calcium acetate, barium acetate, and the like. There is no particular limit to the concentration in the aqueous solution, but it is selected from approximately 0.1q6 to saturated concentration and approximately 0.5
A concentration of ~5% is sufficient.

There are no particular restrictions on the treatment temperature, but it ranges from room temperature to the boiling point of water (100'), and the treatment time, like the sulfonation treatment, is determined in relation to the desired barrier properties, but is approximately several tens of seconds. ~ several tens of minutes Usually, a treatment of 1 to 10 minutes is sufficient. Examples of treatment methods include, for example, introducing an aqueous solution of the metal compound into a container and holding it at a constant temperature for a certain period of time;
An example of this method is to use a pipe equipped with a porous nozzle to spray the solution in a shower-like manner onto the surface of the container for a certain period of time. The surface treated in this way is washed thoroughly with water if necessary, and finally dried. By this aqueous solution treatment of the alkaline earth metal compound, approximately 0.0
001-0.05 m97 cut of alkaline earth metal is introduced.

The container obtained in this way has excellent permeation prevention ability not only for gasoline alone but also for alcohol mixed hydrocarbons such as gasoline/methanol and gasoline/ethanol, and is permeable for water-containing gasoline as well as alcohol mixed gasoline (Gas All) Excellent prevention ability. Although the durability of this barrier film is currently under investigation, it is a treatment method that is superior in durability and has a high level of practical application, at least compared to a membrane treated with ammonia neutralization after sulfonation treatment.

Hereinafter, the present invention will be specifically explained in detail by giving examples.

Examples r to 8, Comparative Example 1 High density polyethylene () as polyethylene - Erode melt index - 5,0 g/10 = i =, Density =
0.9459Arl) using carbon black 2
A cylindrical container having an average wall thickness of 2-1, an internal volume of about 1000 crI, and an internal surface area of about 650 crA was obtained by blow molding. After replacing the inside of this container with dry nitrogen gas, nitrogen gas containing about 13 volumes of S03 at a rice grain temperature of 70°C was introduced into the container at a flow rate of about 21/-i for 120 seconds under the same atmosphere. It was held for 8 minutes.

Next, nitrogen gas was introduced at a flow rate of 517 m for 5 minutes at room temperature to purge unreacted S03 gas, and NH3 gas was introduced at room temperature for 2
The material was introduced into the container at a flow rate of 21 j/m per minute to neutralize the surface with NH3, and then thoroughly washed with water and dried (Comparative Example 1). The interior of the thus treated container was filled with a 3 wt % aqueous solution of the chlorides of various metals shown in Table 1, held at each temperature and for each time shown in Table 1, thoroughly washed with water, and dried.

Fill these containers with 500 cc of regular gasoline or mixed gasoline mixed with methanol 10%, 20%, and ethanol 10% by volume, and condition the container at 40°C for 7 days, then discard all the contents and make a new one. Fill the container with 500 cc of the same liquid used for conditioning, leave it in an explosion-proof constant temperature room at 40°C, measure the weight of this container at any time, track the weight loss, and calculate the permeation amount per day. Ta. Furthermore, comparative example 1
The amount of permeation was determined in the same manner for containers that had not been subjected to NH3 neutralization treatment and containers that had been blow molded as blanks and were not treated. As is clear from the amount of permeation in Table 1, the container of the present invention has much better permeation prevention ability than the blank as well as the container of Comparative Example 1.

Examples 1 to 8 were carried out in the same manner as in Examples 1 to 8, except that hydroxides and acetates of various metals shown in Table 2 were used instead of the chlorides used in Examples 1 to 8. However, the contents are gasoline/methanol 90
/10 (capacity ratio).

As is clear from the amount of permeation in Table 2, the container of the present invention has excellent permeation prevention ability.

Table 2

Claims (1)

[Claims] A plastic container whose inner and/or outer surfaces are subjected to sulfonation treatment, followed by neutralization treatment, and then the surfaces are further treated with a solution containing an alkaline earth metal.