JPH08156202A - Multilayered injection-molded article - Google Patents

Abstract

PURPOSE: To enhance oxygen and light barrier properties at the time of packing by constituting a multilayered injection-molded article of five layers consisting of three kinds of thermoplastic resins and adhesive resins provided to thermoplastic resins and constituting the third layer of a gas barrier resin. CONSTITUTION: An ethylene/vinyl alcohol copolymer(EVOH) is suitable as a gas barrier resin 1 and, since this copolymer has no bonding strength with respect to a polyolefin resin 2 constituting surface layers, it is necessary to interpose adhesive layers 3 between polyolefin resin layers and EVOH of an intermediate layer. Only by imparting gas barrier capacity, a three-kind five- layer structure of surface layer/adhesive layer/gas barrier resin layer/adhesive layer/surface layer is constituted. By adding carbon black to a gas barrier resin or an adhesive resin, a highly functional multilayered plastic structure having both of gas barrier capacity and light blocking capacity can be formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plastic molded product having excellent gas barrier properties and light shielding properties, and more specifically, it requires oxygen gas barrier properties and light shielding properties for foods, beverages, cosmetics, pharmaceuticals and the like. A multi-layered plastic injection-molded container containing the contents, a cap, a lid,
The present invention relates to a multilayer injection molded product such as a preform.

[0002]

2. Description of the Related Art At present, ethylene-vinyl alcohol copolymer (hereinafter referred to as EVOH) is one of the resins having the best barrier performance against various gases such as oxygen.
It is widely used as a packaging material for beverages, cosmetics, pharmaceuticals, and other contents that require oxygen gas barrier properties.
However, the gas barrier performance of EVOH is affected by moisture, and when it absorbs moisture, the gas barrier performance of EVOH is significantly reduced. Therefore, EVOH is generally used for a plastic film, a plastic bottle or the like as an intermediate layer of a laminated structure so that EVOH does not come into direct contact with air.

Some foods, beverages, cosmetics and the like are contents that are deteriorated or deteriorated by ultraviolet rays or visible rays from the time of production and filling into containers until the contents are consumed. In general, even when sold in stores, the fluorescent light in the store or the fluorescent light in the showcase causes deterioration or alteration of the contents. As a material for packaging the contents that are required to have light-shielding performance, it is preferable that the material is colored with carbon black that does not transmit light rays. The resin material colored with carbon black is, for example, the actual Kaihei 6-51.
As shown in No. 112, it is the intermediate layer of the laminated structure or the innermost layer of the container, and the resin material forming the outer layer of the container has a color representing the image of the contents and a purchase by the consumer. It is used in a motivational color. However, although the container disclosed in Japanese Utility Model Laid-Open No. 6-51112 has a light-shielding property, it is polypropylene, polyethylene, polyethylene terephthalate, or the like in which carbon black is removed and not a resin having a gas barrier property.

Further, as a multi-layer plastic structure having both a light-shielding property and a gas barrier property, it is disclosed in Japanese Patent Laid-Open No. 3187/1994.
Although the one shown in Japanese Patent No. 5 is proposed, it is disclosed in Japanese Patent Laid-Open No. 6-3
The one shown in No. 1875 has a layer in which carbon black is added to high-density polyethylene and polypropylene in addition to the gas-barrier resin, so that each has two functions of light-shielding property and gas-barrier property. It is necessary to form a resin layer having a function, and there is still room for improvement in terms of cost problems and production efficiency due to the addition of one layer.

Further, as another prior art, Japanese Patent Laid-Open No. 5-20
Proposed is a laminated member as shown in No. 1463, which contains carbon black in EVOH for the purpose of sealing by induction heating and a dielectric sealing method when sealing for molding into a packaging container, The purpose is completely different from that of the present invention, and further, when it is formed by the multi-layer injection molding method as in the present invention, both sides of the layer to which carbon black is added cannot be completely covered with the polyolefin resin, including the end faces. However, there is a problem that the end surface of the layer to which carbon black is added is exposed and the appearance is impaired. Therefore, it was found that the technique of JP-A-5-201463 cannot be diverted as it is to achieve the object of the present invention.

[0006]

Therefore, in order to solve the above-mentioned problems of the prior art, even when foods, beverages, cosmetics and pharmaceuticals are packaged, there is a blocking property against both oxygen and light, and It is an object of the present invention to provide a multilayer injection molded product having a simple structure.

[0007]

DISCLOSURE OF THE INVENTION The present invention comprises three layers of thermoplastic resin and five layers of adhesive resin provided between the thermoplastic resins, and an outer surface layer which is the first layer from the outside, and The inner surface layer, which is the fifth layer from the outer surface layer, is formed of a polyolefin resin, and the second inner layer is adjacent to the outer surface layer and the fourth inner layer is adjacent to the inner surface layer. Is formed of an adhesive resin, the third layer is made of a gas barrier resin, and carbon is contained in at least one of the second layer, the third layer, and the fourth layer. It is a multi-layer injection-molded article characterized by the addition of black.

The details will be described below. As shown in FIG. 1, the gas barrier resin (1) used in the present invention
EVOH is suitable for use as an intermediate layer EVOH
Since there is no adhesive force between the polyolefin resin and the polyolefin resin (2) forming the surface layer, it is necessary to interpose the adhesive resin (3) between the polyolefin resin and EVOH of the intermediate layer. That is, only by imparting gas barrier performance, a layer structure of three types and five layers of surface layer / adhesive layer / gas barrier resin layer / adhesive layer / surface layer is required.

Carbon black added to an adhesive resin or a gas barrier resin is one of the pigments having the best light-shielding performance, and is a substance that is deteriorated or deteriorated by the light of foods, cosmetics, pharmaceuticals, etc. Although it is sometimes used as a material, by adding carbon black to a gas barrier resin or adhesive resin, it is possible to obtain a highly functional multi-layer plastic structure having two functions of gas barrier performance and light shielding performance. Became possible.

Since the carbon black pigment does not come into direct contact with the contents by using the light shielding layer as the intermediate layer or the gas barrier layer of the innermost layer, the carbon black pigment does not elute into the contents due to the contents. . Therefore, the polyolefin resin for the surface layer should be selected so that the polyolefin resin and the adhesive resin have no components that elute into the contents.

The multilayer plastic structure of the present invention can be molded by extrusion molding or blow molding, but when it is manufactured by a multilayer injection molding method, it is manufactured by vacuum molding from a sheet obtained by extrusion molding. Compared with, it is possible to reduce the amount of wasted material resin other than molded articles such as burrs. Furthermore, even if the container performance required for the contents emphasizes either gas barrier performance or light shielding performance, using a multi-layer injection molding machine allows adjustment of the injection amount, injection rate, and injection start time. Since the thickness ratio of the surface layer, the adhesive layer, and the intermediate layer can be arbitrarily set, it is possible to provide a multi-layered plastic structure that meets the requirements of a wider range of contents.

[0012]

The multi-layered plastic structure of the present invention has three kinds of five layers by using three kinds of materials, and can provide two functions of gas barrier performance and light shielding performance by simple means.

Further, even when only one of the gas barrier performance and the light shielding performance is important, the multilayer injection molding method can be used to arbitrarily set the thickness ratio of the surface layer, the intermediate layer and the adhesive layer. It is possible to adjust the gas barrier performance and the light-shielding performance by adjusting, and in the light-shielding performance, the layer to which the carbon black pigment is added can be selected as the intermediate layer and the adhesive layer, or can be further added by adding both. The range of adjustment is wide, and the performance required for the container can be widely applied regardless of the contents.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to embodiments. <Example> The surface layer was colored with titanium white pigment.
Polypropylene, polyolefin-based adhesive tree for the adhesive layer
Add 2% by weight of carbon black pigment to the fat and middle layer
Using colored EVOH having an ethylene content of 38 mol%
A cup-shaped container of three types and five layers is formed by the multilayer injection molding method.
Shaped The wall thickness is 0.8 mm and the surface area is 0.012 m. ²
Is. Oxygen in a container with an internal capacity of 150 cc obtained by the above configuration
When the transmittance was measured by the Mocon method, it was 0.005 cc /
pg / day, wavelength 190 nm to 850 nm
The light transmittance between them was 0.1% or less. More
Outer surface layer and container inner surface layer that the contents directly touch
Is EVOH colored with a carbon black pigment
Well conceals the black color of the
Polypropylene colored with the used titanium white pigment
It shows almost the same color as that of the EVOH of the intermediate layer.
The black color of carbon black was not visible from the outside.

Comparative Example 1 Multilayer injection using polypropylene colored with a titanium white pigment for the surface layer, a polyolefin-based adhesive resin for the adhesive layer, and EVOH having a pigment-free ethylene content of 38 mol% for the intermediate layer. A cup-shaped container of three types and five layers was molded by the molding method. The wall thickness is 0.
At 8 mm, the surface area is 0.012 m ² . The oxygen permeability of a container having an internal capacity of 150 cc obtained in the above-mentioned configuration was 0.006 cc / pg / day when measured by the Mocon method, and the maximum light transmittance was about 20 when measured at a wavelength of 190 nm to 850 nm. % Transparent.

<Comparative Example 2> A multi-layer injection molding method using polypropylene colored with a titanium white pigment for the surface layer, a polyolefin adhesive resin for the adhesive layer, and polypropylene for the surface layer colored with a carbon black pigment for the intermediate layer. Thus, a cup-shaped container of 5 layers of 3 types was molded. The wall thickness is 0.8 mm and the surface area is 0.012 m ² . The oxygen permeability of a container having an internal capacity of 150 cc obtained by the above-mentioned constitution was 0.2 cc / pg / day when measured by the Mocon method, and the light transmittance in the wavelength range of 190 nm to 850 nm was 0.1% or less. there were. The outer appearance of the container well hides the black color of the intermediate layer, and the white color of the outer appearance is almost the same as the color of polypropylene colored with the titanium white pigment used for the surface layer.

[0017]

As is apparent from the above description, the multilayer plastic structure of the present invention has a five-layer structure using at least three kinds of molding materials, and therefore has a high gas barrier performance and a high light shielding performance. It is possible to add the two functions of the above in a single layer, and it is possible to handle a wider range of contents than before.

Further, if the molding is carried out by the multi-layer injection molding method, the end face of the layer to which carbon black is added can be completely covered, so that the appearance is not spoiled, and
When the gas-barrier resin layer is the third layer, the gas-barrier layer, including both end faces thereof, is completely covered with, for example, a polypropylene-based resin having an excellent water-vapor barrier property. It is possible to prevent deterioration of the gas barrier property of the gas barrier layer due to humidity.

Further, if the molding is carried out by the multi-layer injection molding method, it is possible to provide the multi-functional plastic container having the functionality while keeping the production cost low because the waste of the material is small and the production process is small.

Further, by forming a five-layer structure by using three kinds of molding materials, higher gas barrier performance and higher light shielding performance are added, so that a wider range of contents can be dealt with.

[0021]

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

[Explanation of symbols]

 1: Gas barrier resin 2: Polyolefin resin 3: Adhesive resin

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location B32B 27/20 A 9349-4F 27/28 102 9349-4F // B29K 23:00 105: 16 507 : 04 B29L 9:00

Claims (5)

[Claims] 1. An outer surface layer which is a first layer from the outside and a fifth layer from the outer surface layer, which is composed of five layers of three kinds of thermoplastic resins and an adhesive resin provided between the thermoplastic resins. The inner surface layer that is the layer of is formed of a polyolefin resin, and the inner second layer adjacent to the outer surface layer and the inner fourth layer adjacent to the inner surface layer are formed of an adhesive resin. The third layer is made of a gas barrier resin, and carbon black is added to at least one of the second layer, the third layer and the fourth layer. Multi-layer injection molded product. 2. The multilayer injection-molded article according to claim 1, wherein carbon black is added to the third layer. 3. The multi-layer injection molded article according to claim 1, wherein carbon black is added to the second layer and the fourth layer. 4. The multilayer injection-molded article according to claim 2, wherein carbon black is added to all of the second, third and fourth layers. 5. The multilayer plastic structure according to claim 1, wherein the outer surface layer and the inner surface layer are formed of a resin colored in a color other than white or black.