JPH046543B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a synthetic resin laminate that allows gas to be stably released to the outside over a desired period of time, and a method for manufacturing the same.

Attempts have been made to make synthetic resin molded articles emit a fragrance by mixing fragrances such as fragrances into synthetic resins and molding the mixture. However, the fragrances mixed into such synthetic resins are generally highly volatile, and therefore the fragrance is released in a short period of time, making it impossible to stably release the fragrance over a long period of time. For example, in Japanese Patent Publication No. 55-50058,
The fragrance is stabilized by clathrating it with cyclodextrin, and the fragrance clathrated with this cyclodextrin is mixed into the synthetic resin to emit fragrance continuously over a long period of time. Synthetic resin products have been proposed. However, even with these measures, because the synthetic resin containing the cyclodextrin clathrate compound comes into direct contact with the outside air, the scent is released relatively quickly, and it is difficult to stably emit the scent over a long period of time. I couldn't do it. Furthermore, in this method, the flavoring agent must be clathrated with cyclodextrin, and this must be dried and powdered, making the process cumbersome and disadvantageous in terms of cost.

The present invention has been made in view of these problems, and an object of the present invention is to provide a synthetic resin laminate that gradually releases gas stably over a longer period of time, and a method for manufacturing the same. It is something.

That is, the synthetic resin laminate according to the present invention has at least a three-layer structure, and the middle layer is made of a vinyl-based synthetic resin such as ethylene-vinyl acetate copolymer, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, or other vinyl-based synthetic resin. The vinyl-based synthetic resin is impregnated with a liquid volatile substance, and the volatile substance releases gas. Among the above-mentioned vinyl-based synthetic resins, ethylene-vinyl acetate copolymer in particular has a low melting point, so it can be extruded at a temperature lower than the boiling point of perfumes and insect repellents. The purpose of mixing other resins with the vinyl synthetic resin is to suppress the emission of volatile gases, to lower the cost by mixing inexpensive synthetic resins, or to reduce the cost by mixing the synthetic resins on both sides. This is to improve adhesion with the coating layer and to improve physical properties such as moldability. In addition, in order to impregnate the vinyl synthetic resin with a volatile substance, these resins are made into pellets or powder and immersed in a liquid volatile substance, and if necessary, they are forcibly heated using a tumbler, ribbon blender, etc. The impregnation may be carried out using standard mixing means.

Examples of volatile substances impregnated into the intermediate layer include fragrances such as bergamot, ginamic aldehyde, geraniol, and citronelle;
Insect repellents such as thymol and liunou can be used. These insect repellents are in powder form at room temperature, but
By heating the resin to a relatively low temperature through operations such as mixing, that is, below the softening point of the synthetic resin,
It is possible to make it into liquid form. Furthermore, since these perfumes and insect repellents themselves contain solvent elements in liquid form, they are easily impregnated into the vinyl synthetic resin constituting the intermediate layer.

Next, for the synthetic resin coating layers formed on both sides of this intermediate layer, at least one of the layers is made of a synthetic resin that does not have gas barrier properties. That is, one of both sides of the intermediate layer is coated and laminated with an inexpensive material, such as polyethylene, which does not have gas barrier properties. Such a synthetic resin coating layer that does not have gas barrier properties suppresses the release of gas from the volatile substance impregnated in the intermediate layer, thereby allowing the gas to be released gradually over a long period of time. It is something to do. If both sides of the intermediate layer are coated with a synthetic resin that does not have gas barrier properties, gas will be emitted from both sides. If it is coated with a synthetic resin that has no properties, gas will be emitted only from the other surface.

In such a synthetic resin laminate consisting of at least three layers, the intermediate layer is formed by extrusion molding, and the above-mentioned coating layer is laminated on both sides of the intermediate layer. More preferably, at least three layers will be molded simultaneously by coextrusion. In other words, 2
A laminate of at least three layers at once is created by connecting an extruder that extrudes a synthetic resin melt or three or more synthetic resin melts, extruding the resin in a cylindrical shape through an annular slit, and expanding it by blowing air into it. This results in a film of . When the three layers are molded simultaneously in this manner, heat is less likely to be transferred to the intermediate layer at the die, making it possible to suppress the release of volatile substances. The manufacturing method is not necessarily limited to coextrusion die molding, and may be, for example, coextrusion T-die molding, coextrusion blow molding, or lamination molding may be used in combination.

A film or sheet made of such a synthetic resin laminate may be used, for example, as a container for an aromatic agent or an outer bag. In other words, by impregnating the middle layer of this laminate with the same aromatic agent as the aromatic content, the same fragrance as the aromatic content is emitted from the container or outer bag, allowing the contents to be absorbed without opening the package. It becomes possible to check the fragrance of things in advance. Alternatively, if the synthetic resin of the intermediate layer is impregnated with an insect repellent, it can be used as a packaging agent for clothing, and the insect repellent effect makes it possible to protect the clothing from insects. Furthermore, a synthetic resin laminate in which the intermediate layer is impregnated with an insect repellent can be used, for example, as an agricultural film to protect agricultural crops from insects. Alternatively, the laminate in which the intermediate layer is impregnated with a perfume can be used as a building material, for example as an indoor wallpaper. Furthermore, if formed into a hollow container, it can be used as a container for detergents, shampoos, etc.

The present invention will be explained below with reference to an illustrated embodiment. First, an ethylene vinyl acetate copolymer resin (trade name Evatate, manufactured by Sumitomo Chemical Industries, Ltd.) was used as the intermediate layer, and the synthetic resin constituting the intermediate layer was impregnated with 10% by weight of geraniol, citronellol, or a mixture thereof. Ta. That is, liquid geraniol, citronellol, or a mixture thereof and pellets of ethylene vinyl acetate copolymer resin are placed in a tumbler and mixed and stirred overnight, thereby adding geraniol, citronellol,
Or impregnated with a mixture thereof. Then, the ethylene vinyl acetate copolymer resin impregnated with geraniol etc. and polyethylene are mixed at a ratio of 1:1, and this is mixed into the first layer forming the intermediate layer connected to the die 1 shown in FIG. It was designed to be supplied to extruder 2. The second extruder 3 connected to the die 1 was supplied with synthetic resin for forming inner and outer layers covering both sides of the intermediate layer. The synthetic resin constituting the inner and outer layers was a mixture of ethylene vinyl acetate copolymer resin and polyethylene in a ratio of 1:4.

These resins are injected into the die 1 as shown in FIG. The three-layer structure was extruded from the slit 7 into a cylindrical shape. The three-layer synthetic resin laminate formed into a cylindrical shape and extruded from the die 1 was expanded by compressed air supplied from the die 1, thereby stretching the laminate in the radial direction. In this way, by so-called coextrusion inflation molding, a three-layer synthetic resin laminate was obtained in which coating layers 9 and 10 were formed on both sides of the intermediate layer 8, respectively, as shown in FIG. The thickness of the laminate obtained here was 0.05 mm, and a film-like laminate was obtained.

In the synthetic resin film made of this three-layer laminate, the ethylene-vinyl acetate copolymer constituting the intermediate layer 8 is impregnated with geraniol, citronellol, or a mixture thereof, and the gases emitted from these have gas barrier properties. The scent was gradually released to the outside through the coating layers 9 and 10 on both sides, which did not have any odor. As a result of severe tests, it was confirmed that the emission of this incense did not change much over a long period of time. In addition, it was confirmed that single-layer molding using only a synthetic resin for the intermediate layer impregnated with a fragrance such as geraniol, which was conducted prior to the experiment in the above example, caused a foaming phenomenon and was not usable as a film. However, such a foaming phenomenon did not appear in the three-layer laminate molded by coextrusion.

As described above, in the synthetic resin laminate according to the present invention, the intermediate layer is composed of a vinyl synthetic resin impregnated with a volatile substance, and coating layers are formed on both sides of the intermediate layer, and at least one coating layer is formed on both sides of the synthetic resin laminate. Since it is made of a synthetic resin that does not have gas barrier properties, the gas from the volatile substance is gradually released through this synthetic resin that does not have gas barrier properties. Therefore, it becomes possible to produce odor or fragrance stably over a long period of time. Furthermore, gas diffusion can be controlled as desired by changing the thickness and material of the synthetic resin that does not have gas barrier properties. Furthermore, if both of the pair of coating layers are made of a synthetic resin that does not have gas barrier properties, gas will be emitted from both sides, and if only one of the coating layers is made of a resin that does not have gas barrier properties, gas will be emitted from only one side. It becomes possible to dissipate.

[Brief explanation of drawings]

FIG. 1 is a plan view showing an inflation molding apparatus for manufacturing a synthetic resin laminate according to an embodiment of the present invention, FIG. FIG. 3 is a cross-sectional view of the synthetic resin laminate thus obtained. In addition, in the symbols used in the drawings, 8...intermediate layer, 9, 10...covering layer.

Claims (1)

[Claims] 1. Consists of a synthetic resin laminate of at least three layers,
The intermediate layer is composed of a vinyl synthetic resin impregnated with a volatile substance or a mixture of this vinyl synthetic resin and other synthetic resin, and at least one of the coating layers on both sides of the intermediate layer is The intermediate layer is made of a synthetic resin that does not have gas barrier properties, and the gas emitted from the volatile substance impregnated in the intermediate layer is gradually released to the outside through the resin layer that does not have gas barrier properties. Synthetic resin laminate. 2. Impregnating vinyl synthetic resin with a volatile substance,
An intermediate layer is formed by this synthetic resin alone or by mixing this resin with one or more other synthetic resins by extrusion molding, and a synthetic resin coating layer is formed on both sides of this intermediate layer by extrusion molding. However, at least one of the pair of synthetic resin coating layers is made of a resin that does not have gas barrier properties,
A method for producing a synthetic resin laminate, characterized in that a synthetic resin laminate of at least three layers is formed by this process. 3. At least 3 of the above by coextrusion molding method.
3. The method for producing a synthetic resin laminate according to claim 2, wherein the layers are simultaneously laminated and molded.