JP2744441B2 - Multilayer container - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a multilayer container having good storability, which is mainly used for packaging foods. More specifically, the present invention relates to a plastic multilayer container having a white surface color and excellent light-shielding properties.

[Conventional technology]

Conventionally, a white plastic container is made of a thermoplastic resin such as a polypropylene resin (PP), a polystyrene resin (PS), or a polyvinyl chloride resin (PVC) containing titanium pigments in an amount of 2 to 5%.
Weight-% added colored resin single-layer products, or ethylene-vinyl alcohol copolymer (EVOH)
Multilayer products that combine barrier layers such as and polyvinylidene chloride (PVDC) are used.

A plastic container to which a titanium-based pigment is added has a significantly reduced light transmission compared to a plastic container to which no pigment is added. Although it depends on the type of the resin and the amount of the titanium-based pigment added, the transmittance decreases to 1/10 to 1/100. However, the slight transmission of light causes discoloration or deterioration of the contents, and the preservability was not sufficient.

In order to improve the light blocking effect, it is effective to make the whole black or brown, but it lacks cleanliness and fashionability as a food container.

A multilayer container in which a black or brown colored layer is sandwiched between layers colored white with a titanium-based pigment is also being studied, but due to the black or brown color cast of the intermediate layer, it is hard to say that it is white in appearance. Only color was obtained.

White containers are very popular as food containers because of their cleanliness. However, a sufficient light-shielding property could not be obtained only by adding a titanium-based pigment for whitening.

[Problems to be solved by the invention]

An object of the present invention is to provide a plastic container having a white surface color and excellent light-shielding properties.

[Means for solving the problem]

The present invention is characterized in that a plastic layer colored substantially with an aluminum pigment is sandwiched between plastic layers colored by adding 2 to 7% by weight of a titanium pigment and has excellent light-shielding properties. It is a plastic multilayer container.

The layer containing the aluminum pigment of the present invention is effective in shading, and has a small effect of transferring the surface layer to white.The aluminum pigment is a scale-like silver pigment, and therefore contains the aluminum pigment. It is considered that aluminum scales overlap in the layer to form a layer similar to the aluminum film. Therefore, the ability to reflect light is large and the light shielding property is excellent. Further, since the color is silver-white, which is a color close to white, the effect of color transfer to the outer white-colored layer is small.

Aluminum pigments include powder and paste. There is no difference in effect, but paste is easier to use.

The concentration of the aluminum pigment is determined by the required performance and the thickness of the layer containing the aluminum pigment. Even if the density is high, it does not affect the white appearance, and it can be used even at a high density. Practically, 1 to 20% by weight is appropriate.

The layer colored white with the titanium-based pigment serving as the outer layer of the present invention is a layer for making the appearance look white, and a commonly used coloring method can be applied. Preferably, 2 to 7% by weight of Lucia type titanium oxide having excellent hiding power among titanium-based pigments
It is good to add. The thickness is preferably as thick as possible, but is practical if it is 100 μ or more.

Thus, a white plastic container having excellent light-shielding properties can be obtained in a plastic container having a configuration in which a layer containing an aluminum pigment is sandwiched between layers colored with a titanium-based pigment.

Note that the layer configuration only needs to substantially include the above-mentioned layer configuration, and the effect is not changed even if another transparent or nearly white plastic layer is included. Examples include a layer containing an ethylene-vinyl alcohol copolymer or a modified olefin in the intermediate layer, and an uncolored polypropylene resin, polyester resin in the inner layer of the container, or a layer of GP-polystyrene polycarbonate resin in the outer layer. There is something. It is known that blocking and shielding light from oxygen gas is effective in preventing the deterioration of foods, and it is better to include a layer of ethylene-vinyl alcohol copolymer or polyvinylidene chloride resin with excellent gas barrier properties. It is valid.

Although the manufacturing method is not particularly limited, each layer,
Each separately prepared, a multi-layer sheet obtained by dry lamination, or a multi-layer sheet obtained by co-extrusion,
The most common method is to make a container by vacuum forming or pressure forming.

〔Example〕

Example-1 Sheets having the configurations shown in Samples Nos. A to F and Comparative Examples 1 to 5 in Table 1 were vacuum-formed to have a diameter of 65 mm, a depth of 25 mm, and a capacity of 70.
Made a cc container. The finished container was visually evaluated for whiteness and light-shielding properties. 500mm x 500mm
Drill a φ60mm hole in the center of a square, 2mm thick iron plate, attach it to the iron plate so that the bottom of the container is in the center of the hole, hit the sunlight from the other side at a right angle and compare the brightness by visual inspection did.

Example-2 PP360μ containing 4% titanium pigment / modified PP40μ containing 4% aluminum pigment / EVOH40μ / modified PP40μ containing 2% aluminum pigment /
When a coextruded sheet made of PP360μ containing 4% of titanium pigment was used and evaluated in the same manner as in Example 1, the same result as that of Sample No. D of Example 1 was obtained.

Example-3 Uncolored PP50μ / PP340μ with 4% titanium / Aluminum pigment 1
When a co-extruded sheet composed of 0% PP / titanium 4% PP350μ was evaluated in the same manner as in Example 1, it was uncolored.
There was no difference between the case where the PP was inside and the case where the PP was outside, and the result was the same as that of the sample No. E of Example 1.

Example-4 The container obtained in the sample No. D of Example-1 and the container obtained in the configuration of Comparative Example-4 were filled with 15 g of the existing ramen, and the polyester 12
Heat-sealed with a lid made of μ / aluminum 9μ / PP40μ was used as a sample. The sample was irradiated with a fluorescent lamp at 30 ° C. for one month from the bottom of the container and taken out.
Of the sample No. D compared with that of Comparative Example-4,
There was little change in taste.

〔The invention's effect〕

The multilayer container of the present invention has excellent light-shielding properties that were conventionally obtained only in black or brown, and since the surface color is white, deterioration of contents such as food due to light can be prevented, and suitable for long-term storage Thus, a container full of cleanliness can be obtained.

Claims (1)

(57) [Claims] An excellent light-shielding property comprising a structure in which a plastic layer substantially colored with an aluminum pigment is sandwiched between plastic layers colored by adding 2 to 7% by weight of a titanium-based pigment. Plastic multilayer container.