JPS59187535A - Biaxial stretched blow vessel made of polyester having pearly surface gloss - 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 a biaxially stretched blow container made of polyester having a pearl-like surface luster.

Biaxially stretched blow containers made of polyester, especially polyethylene terephthalate, have become widely used as containers for seasonings, cosmetics, carbonated drinks, etc. due to their excellent mechanical properties, transparency, chemical resistance, gas barrier properties, etc. Ta. However, when looking at the appearance of containers, most containers are colorless and transparent or transparent and colored. However, in the field of cosmetic containers, where importance is placed on the appearance and decorative aspect of the container, containers with pearl-like surface luster are desired.

Conventional techniques for obtaining pearl-like surface luster include a method of adding pearl pigments and a method of adding a specific thermoplastic material, as described in Japanese Patent Publication No. 37-37-67 and Japanese Patent Publication No. 3-A-2'732g. There is a method of molding a blended resin composition, but it has drawbacks such as the toxicity of additives, cracks in the cage part during injection molding, crystallization of the parison, peeling between layers, and complicated blending. .

The present inventor has arrived at the present invention as a result of studies aimed at improving the drawbacks of the above-mentioned conventional methods.

In other words, the present invention provides a container made of polyester containing polyethylene terephthalate as a main component, which has a pearl-like surface over substantially the entire surface of the container body, the outer surface of which has better transparency than the inner surface. This invention relates to a biaxially stretched blow container made of glossy polyester.

The polyester in the present invention includes a homopolymer consisting of terephthalic acid and ethylene glycol, and a copolymer obtained by copolymerizing terephthalic acid and ethylene glycol with another third component. Such copolymers are known, and the third component is usually an aromatic dicarboxylic acid such as inphthalic acid, naphthalene dicarboxylic acid, an oxycarboxylic acid such as p-hydroxybenzoic acid,
Polyalkylene glycols such as globylene glycol, tetramethylene dalycol, neopentyl glyco-#nato(D-fulkylene glycol, polyethylene glycol, etc.) are used.The ratio of the third component in the copolymer is preferably less than I''i30i30 molti. .

Alternatively, polyethylene terephthalate may be blended with another polyester resin having the above-mentioned copolymer component. Furthermore, commonly used additives such as stabilizers, color tone improvers, and colorants may also be included.

In particular, if a parison that maintains its transparency is biaxially stretched and blown by the above-mentioned method, containers having pearl-like surface luster in various tones can be obtained, and the decorative effect is enhanced, which is preferable.

The polyester used in the present invention has an intrinsic viscosity of 0.6 or more, and the resulting container preferably has an intrinsic viscosity of 0.57 or more. If the intrinsic viscosity is too low, mechanical strength problems will occur.

The container having a pearl-like surface luster according to the present invention can be obtained by changing the transparency of the outer surface and the inner surface of the container so that the transparency of the outer surface is better than the transparency of the inner surface.

Such a container having different transparency inside and outside can be manufactured as follows.

In the process of heating, stretching and blowing the parison, the temperature of the inner surface of the parison is intentionally set higher than the normal stretching temperature /QC-2
0C lower, the temperature of the outer surface of the parison is the normal stretching temperature,
For example, after heating to gsc to 103C, biaxial stretching blowing is performed, and during the stretching blowing, only the inside of the parison is whitened and stretched, while the outer surface is stretched while remaining transparent. To perform this method easily) <In the method of heating linno from the outside, it is better to shorten the heating time compared to the normal heating time.

In the hot parison method, a method in which cold air is blown onto the inner surface of the parison is preferable.

Another method is to apply Pariso/ from the inside to l10C~/J.
The inner surface of the parison is heated to OC to cause crystallization at high temperature, while the outer surface of the parison is heated to the normal stretching temperature.
For example, a method may be used in which a container is heated to gsC~/θ5°C and biaxially stretched and blown to whiten the inner surface and have a transparent outer surface.

In the container of the present invention, it is necessary that the outer surface has better transparency than the inner surface over substantially the entire body, and the haze of the outer surface is 5% or less, more preferably 7% or less, and the inner surface has a haze of 5% or less, more preferably 7% or less. - 30 grams or more, more preferably 6 grams or more.

Most preferably, the inner surface undergoes a whitening phenomenon while the outer surface maintains transparency.

As described above, the container having a pearl-like luster obtained by the method on the left is an excellent container that is preferable in terms of food hygiene and has no peeling property between the front and back.

The present invention will be explained in more detail below using Examples.

Example 7~λ and Comparative Example/~λ Tep 7r of polyethylene terephthalate with an intrinsic viscosity of 0.7 g (with this polyethylene terephthalate base, copper cap 0/anine) and monoazo yellow pigment A colored masterbatch containing the following was blended at a ratio of /S:/, and vacuum-dried at /6otZ for 72 hours. From this lens, Toshiba Machine's injection molding machine l560
Using type B, 2! ;mmφX/! ;OmmL
A transparent green parison with a diameter of 1 mm was molded. After heating this Nokirison from the outside for the time shown in Table 1 with an infrared heater,
, a container with a capacity of 2 tons. However, the heating time value varies depending on the heater voltage, installation position, etc., and is not absolute. The haze of the container body was measured using a haze meter manufactured by Nippon Denshoku Kogyo ■, and the values are shown in Table/.

The haze on the outer surface of the container can be represented by the haze of Comparative Example under normal stretch blowing conditions. Since the haze obtained in Comparative Example// is an extremely small value, it is considered that the haze value obtained in the other examples is approximately equal to the haze value of the inner surface of the container.

The outer layer of the container obtained in Table/Example/ was transparent green, the inner layer was less transparent, and a green-7 color container was obtained that was almost silvery overall and had a pearl-like surface luster. .

The outer layer and inner layer of this container were extremely difficult to peel off.

In Example C, a container was obtained which was more translucent than in Example 1 and had a pearl-like surface luster.

Comparative Example/ is the condition for molding a normal transparent stretch-blown container, and pearl-like surface gloss cannot be obtained.

Comparative Example 2 has a slightly inferior transparency compared to Comparative Example 2, and no pearl-like surface luster is observed.

Sender: Mitsubishi Chemical Industries, Ltd. Representative Patent Attorney Hase - Others/Names

Claims (1)

[Claims] (1) A container made of polyester whose main component is polyethylene terephthalate, the outer surface of which is more transparent than the inner surface over substantially the entire body of the container, and which has a pearl-like surface luster. Biaxially stretched blow container