JP2001019796A - Removal and recycle of vinylidene chloride-based resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for dissolving/extracting a polyvinylidene chloride resin-coated layer from an olefin-based resin substrate and for advantageously recycling the olefin-based resin substrate and dissolved/extracted matter at a low cost so as to be simultaneously and industrially returnable (repeatedly utilizable). SOLUTION: This method is to cut out an olefin resin-based substrate down to adequate size which is made of e.g. biaxial oriented polypropylene film and is coated with a polyvinylidene chloride-based resin, to mix the substrate pieces with an industrial solvent selected from the group consisting of a fraction from crude petroleum oil, volatile oil, lamp oil and light oil by stirring at 65-85 deg.C and to dissolve polyvinylidene chloride on the surface of the substrate film to be extracted/removed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for removing a vinylidene chloride resin from an olefin resin substrate having a vinylidene chloride resin coating layer, and combining the olefin resin substrate and the removed vinylidene chloride resin coating layer with each other. The present invention relates to a method for removing and reusing by low-temperature treatment, characterized in that two kinds of physical properties of an olefin resin and a vinylidene chloride resin can be returned (repeatedly used) without deteriorating the respective properties.

[0002]

2. Description of the Related Art Vinylidene chloride resins are excellent in oxygen and water vapor barrier properties. Therefore, those obtained by laminating vinylidene chloride resins on other resins (polyolefin, PET, etc.) are used for packaging films, sheets and molded containers. It is often used for such purposes. Trimming loss, defective products, and used molded products generated during the production process of these molded products are usually incinerated or landfilled. This causes air and groundwater contamination, which is a problem. In particular, this vinylidene chloride-based resin generates chlorine-based gas by heating and melting and burning,
From the viewpoint of environmental purification and resource saving measures, suppression of generation, promotion of reuse, and repeated use will be indispensable in constructing an environmental and economic system in the future. It is desired that the vinylidene chloride-based resin be separated from the oil, the olefin-based resin and the vinylidene chloride-based resin are separated and treated separately to be used as an industrial raw material.

As a method of recovering each resin component from a laminated film or a laminated film obtained by co-extrusion lamination, in which a resin film for each layer is once manufactured and bonded with an adhesive or the like, for example, the following method has been proposed. I have. (1) A method in which a laminated sheet is heated by a heating roll or the like to separate and collect each layer in a film state.
(JP-A-2-131907) (2) The vinylidene chloride resin laminate molded product is roughly pulverized, treated with hot water, and finely pulverized, and the pulverized product is slowly stirred in an aqueous medium containing a surfactant to obtain a vinylidene chloride resin. To settle and separate. (3) An olefin resin substrate having a vinylidene chloride-based resin coating layer was treated with an aqueous solution containing 0.1 wt% or more of a surfactant in an aqueous solution of 0.1 wt% or more.
A method for removing a vinylidene chloride-based resin from a surface of a resin substrate, wherein the stirring is performed at a temperature of 00 ° C. or higher and lower than a temperature at which the resin substrate melts. (JP-A-9-279066)

[0004] However, the method of (1) is similar to pulverized material, etc.
It cannot be applied to a film that is difficult to peel off.
The method (2) is an effective means for recovering the vinylidene chloride resin from the pulverized product, but it is necessary to pulverize the molded product to 1 mm or less. In recent years, technology has been developed in the direction of increasing the adhesive strength between the layers from the viewpoint of the performance of the laminated molded product, and as a result, the separation of the vinylidene chloride resin may not be sufficient in the conventional method. In particular, a film obtained by applying a liquid mainly composed of vinylidene chloride-based resin to a substrate such as a biaxially stretched polypropylene film, and drying,
Generally, the vinylidene chloride-based resin layer is very thin and firmly adhered to the substrate, but no simple and effective means for separating the layer from the substrate has been proposed.

[0005] (3) As a solution, a biaxially stretched polypropylene film coated with polyvinylidene chloride is cut into an appropriate size and stirred at a temperature of 100 ° C or more in an aqueous solution having a surfactant concentration of 0.1% by weight or more. It is a method of treating and removing the polyvinylidene chloride on the film surface by embrittlement peeling,
Both (2) and (3) use a surfactant and are difficult to treat sewage. The application of a temperature of 100 ° C. or more causes deterioration of the olefin resin, and the vinylidene chloride resin is decomposed and colored to change into a substance that cannot be reused, so that this is not an industrially advantageous method. In addition, wastewater treatment and work processes are not simple, and cost is high and lacks economic efficiency.

[0006]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above situation, and is intended to efficiently separate and remove a vinylidene chloride resin layer applied to an olefin resin substrate from the surface of the substrate. An olefin-based resin and a vinylidene chloride-based resin are separately collected, and these two substances are recovered without deterioration and can be used immediately and repeatedly. Another object of the present invention is to provide a method which is very economical because solvents and the like in the treatment are recovered and used repeatedly, so that no waste is generated at low cost.

[0007]

That is, the present invention relates to an olefin-based resin substrate having a vinylidene chloride-based resin coating layer in a petroleum-based solvent by stirring at a temperature of 100 ° C. or lower, preferably 40 to 70 ° C. A method for removing a vinylidene chloride-based resin coating layer on the surface of a resin-based substrate.
More specifically, in the above method, the cut vinylidene chloride comprising a stirring vessel provided with a stirring device and filled with a petroleum solvent, and pipes respectively connected to upper and lower portions of the stirring vessel and provided with a stirring device. A piece of an olefin-based resin substrate having a system-based coating layer is circulated in the container and the pipe, and further collects and concentrates vinylidene chloride-based resin dissolved in a petroleum-based solvent on the side of the container. Since the new solvent generated by the machine is repeatedly injected into the stirring vessel, the vinylidene chloride-based resin is efficiently dissolved and extracted in a short time, and the fractionated and treated product is combined with a high-quality olefin-based resin. An innovative method for providing a vinylidene chloride resin is provided.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
The vinylidene chloride-based resin coating layer in the olefin-based resin substrate having the vinylidene chloride-based resin coating layer to which the present invention is applied is obtained by dissolving a vinylidene chloride-based resin in an organic solvent or dispersing an aqueous medium using an emulsifier or the like. It is formed by applying and drying the olefin-based resin substrate by a method such as roll coating, gravure coating, kiss coating, and air knife coating. However, the applied vinylidene chloride-based resin is excellent in that once dried, it is difficult to peel off and forms a film that is hardly soluble in any solvent. Examples of the vinylidene chloride-based resin include, in addition to polyvinylidene chloride, copolymers of vinylidene chloride with monomers such as vinyl chloride, (meth) acrylate, acrylonitrile α, and β-ethylenically unsaturated carboxylic acids. As the olefin resin, ethylene homopolymer, ethylene α-olefin copolymer,
Propylene homopolymer, propylene α-olefin copolymer, polybutene-1, poly-4-methylpentene-1
And the like. However, in recent years, technologies have been developed in the direction of increasing the adhesive strength of each layer from the viewpoint of the performance of laminated molded products, and additives that each company is good at, such as softeners, stabilizers, antibacterial agents, etc., are used. Use of kerosene (kerosene) is recommended, as it may be inefficient to deal with it. Of course, solvents other than kerosene can be used as well, but if the present invention is comprehensively judged, industrial economics must be emphasized. First, cost, availability, storage safety, and processing Kerosene is excellent in the present invention because it is necessary to consider operability and the like. However, it is not limited only to kerosene.

In the present invention, a series of industrial solvents include volatile oils (petroleum ether, petroleum benzine, ligroin, mineral spirits), kerosene, light oil, etc. as a direct fraction from crude oil. As mentioned above, when corresponding to additives, they may be used as a cleaning agent after being treated with only a single solvent selected from the above, and this may serve the purpose. The olefin-based substrate may have any shape such as a film, a sheet, a molded container, a tube and the like, and may have been subjected to treatment such as non-stretching, uniaxial stretching and biaxial stretching. Further, other materials such as paper fiber and metal may be attached or laminated.

In the solvent treatment step of the present invention, the olefin resin substrate having the vinylidene chloride resin coating layer is preferably cut into an irregular size of, for example, about 5 mm square or less. The contact area with the stirring blade in the pipe is large, and the passage through the pipe during circulation is good. However, when the objects to be processed are stacked,
In the case where there are many bag binding thermocompression bonding parts, it is desired to further finely pulverize the workpiece.

It is sufficient that the processing temperature is 100 ° C. or less, and the processing time is not particularly limited. Usually, about 15 to 60 minutes is preferable. Considering the physical properties of the processed material, the temperature is set as low as possible and the time is set short. It is better to carry out through small trial production experiments of the processed material in advance.

[0012]

EXAMPLE 1 A 30 μm thick biaxially oriented polypropylene film coated on one side with a vinylidene chloride resin having a thickness of 5 μm was cut into an irregular shape of about 5 mm square or less. And 280 ml of kerosene (commercially available) are charged into a container having a filter plate attached to the lower portion of the stirrer and stirred.
After heating at 85 ° C for 15 minutes, the heating was stopped and the temperature was returned to room temperature, followed by filtration, and the vinylidene chloride resin was immediately recovered from the filtrate by a concentrator, and the solvent was returned to the original container with a stirrer, and the same operation as above was performed. Do.

These two operations are performed for a total of 30 minutes, and the filtrate is recovered as before, and the two recovered materials are combined and dried to finish. Table 1 shows the color tone, the polyvinylidene chloride resin removal rate, and the residual chlorine amount of the obtained polypropylene. The removal rate of the polyvinylidene chloride-based resin was easily evaluated by visual judgment based on the smell when a small amount of the sample was put on a spatula and heating and the color tone at the time of melting, and the residual chlorine amount was measured by ion chromatography.

Example 2 The heating temperature was kept low at 65 ° C., and the heating time was set to twice in 20 minutes. The other steps were the same as in Example 1, but the processing was insufficient. By repeating the process once, the same product as in Example 1 could be obtained. When the temperature is low, it takes a long time to process, but when compared and evaluated, the same physical property results were obtained.

[Table 1]

[0015]

According to the method of the present invention, it is possible to efficiently remove a vinylidene chloride-based resin coating layer from an olefin-based resin substrate coated with a vinylidene chloride-based resin, including a film made of only polyvinylidene chloride-based resin. In addition, both the substrate and the removed vinylidene chloride resin can be returned (used repeatedly). Since it is indispensable to construct an environmental economic system from the viewpoint of protecting the environment and resources at present, the present invention is an invention with features not found in the past that meets this viewpoint.

Further, since the present invention is processed at a low temperature, the object to be processed including the substrate and the coating layer, the solvent and the like are not degraded, so that it is an industrially excellent processing method. All the treated products maintain the same physical properties as the commercial products, and the quality of the olefin-based resin base is not different from the test results such as stress at yield, pile tension at break, and elongation at break. Is kept. This is a revolutionary method that does not generate any waste liquid.

Claims (4)

[Claims] An olefin resin substrate having a vinylidene chloride-based resin coating layer is stirred and dissolved in a petroleum-based solvent at a low temperature of 100 ° C. or less to dissolve and remove the vinylidene chloride-based resin coating layer on the surface of the resin substrate. A method of separating an olefin-based resin substrate and a dissolved extract of vinylidene oil-based resin, whereby two regenerated substances can be reused at the same time. 2. The method according to claim 1, wherein the stirring and dissolving process is continuously operated in an apparatus having both stirring and extraction. 3. The method according to claim 1, wherein the olefin resin is polypropylene. 4. The method according to claim 1, wherein the processing temperature in part or all of the stirring and dissolving processing is 120 ° C. or higher and the temperature at which the resin substrate melts.