JPH0468055A - Hollow polyester container - Google Patents

Abstract

PURPOSE:To prepare a beautiful hollow container having a satin-like surface appearance by mixing a thermoplastic polyester resin with mica flakes having a specified particle size and allowing the mixture to undergo blow molding under biaxial orientation. CONSTITUTION:A mixture of 96.0-99.9wt.% thermoplastic polyester resin having an ethylene terephthalate unit as the main repeating unit with 0.1-4.0wt.% mica flakes having a mean particle size of 20mum or higher is blow molded under biaxial orientation at a total orientation ratio of 2 or higher.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a polyester hollow container having an excellent appearance. For more details, see cosmetics, shampoo, detergent,
This invention relates to a polyester hollow container suitable for storing foodstuffs, beverages, etc.

[Prior art] Polyethylene terephthalate has excellent mechanical properties and chemical resistance, and has relatively low gas permeability for oxygen, carbon dioxide, etc., and excellent transparency, so it is used in foods, beverages, and cosmetics. It is used as a material for containers such as In particular, it is attracting attention because it is suitable for use in cosmetic containers, caps, compact cases, etc. because it has excellent fragrance retention and chemical resistance, and does not alter the quality of the contents. By the way, even in the field of so-called biaxially stretch blow-molded hollow containers, there is a demand for not only molded products with excellent transparency but also molded products with excellent decorative properties. However, plastic molded products with normal pearlescent luster obtained by adding fine mica flakes, etc., simply have a pearlescent luster that is too bright and lack elegance and a sense of gravity.

In addition, for the purpose of obtaining a hollow container with a pearl appearance that combines elegance and profoundness, Japanese Patent Publication No. 1988-6258974 discloses that a thermoplastic polyester resin, a methacrylic resin, a saturated aliphatic polyolefin resin, or a styrene resin is used. An example is disclosed in which a hollow container is biaxially stretched and blow-molded with a mixture of at least one of the following, and is subjected to surface treatment by a sandblasting method or a coating method. However, since this technique requires two steps, molding and surface treatment, it takes a long time to obtain the product, making it impractical.

[Problems to be Solved by the Invention] The present inventors have overcome the drawbacks of hollow containers with fine mica flakes added and surface-treated hollow containers, and have created a satin-finished material that combines elegance, solidity, luxury, and texture. As a result of intensive research to develop a hollow container with a textured surface appearance, a hollow container obtained by biaxial stretch blow molding of a mixture of thermoplastic polyester resin and mica flakes of a specific particle size was found to have a satin-like surface appearance. The present invention was achieved by discovering that the material has excellent aesthetic appearance.

[Means for Solving the Problem] That is, the present invention provides a thermoplastic polyester resin (A) whose main repeating unit is an ethylene terephthalate unit.
A mixture consisting of 96.0 to 99.9% by weight and 4.0% by weight of mica flakes (B)O, having an average particle size of 20 or more, is stretched so that the total stretching ratio is 2 times or more. This invention relates to a polyester hollow container obtained by axial stretch blow molding.

The thermoplastic polyester resin used in the present invention is one in which the main portion of the repeating units constituting it, that is, preferably 75 mol% or more, consists of ethylene terephthalate units, and copolymerization components include isophthalic acid, adipic acid, Dicarboxylic acid components such as sebacic acid, p-β-oxyethoxybenzoic acid, diphenyl ether-4,4'-dicarboxylic acid, diphenoxyethane-4,4'-dicarboxylic acid, or alkyl ester derivatives thereof; and propylene glycol, Glycol components such as pukundiol, hexamethylene glycol, neopentyl gelcol, and cyclohexane dimetatool are used. As such a thermoplastic polyester resin, polymers obtained by either a method of performing polycondensation through transesterification or a method of performing polycondensation through direct esterification can also be used; The viscosity [η] is preferably in the range of 0.65 to 1.4, and such polymers with high intrinsic viscosity can be obtained by further obtaining the polymer obtained by the above-mentioned ordinary polymerization method by a known solid phase polymerization method. can. When the intrinsic viscosity is less than 0.65, the impact strength when the hollow container finally obtained is filled with contents and dropped is significantly reduced, and the chemical resistance is also reduced. On the other hand, if the intrinsic viscosity exceeds 1.4, moldability becomes extremely difficult, which is not preferable.

Note that the intrinsic viscosity [η] here is a value determined from the solution viscosity measured at 25° C. in a phenol/tetrachloroethane=50150 (weight ratio) solution.

Mica flakes in the present invention are not particularly limited, and include muscovite, biotite, rhodotite, phlogopite, sorta mica,
Although a single material such as iron mica may be used, in order to improve the design, it is preferable to use untreated mica flakes as a base coated with titanium dioxide.

Such mica flakes are produced by suspending untreated base mica flakes in a dilute aqueous solution of titanyl sulfate, then rapidly heating to hydrolyze the titanyl sulfate, and continuously converting the hydrous titanium oxide layer into mica flakes. or by suspending mica flakes in hot water and adding a titanyl sulfate solution to hydrolyze the mica flakes.
It can be obtained by a method of continuously depositing a hydrous titanium oxide layer on mica flakes.

In the present invention, the hollow container is constructed from a mixture of the above-mentioned specific thermoplastic polyester resin blended with mica flakes having a large average particle size. The content of mica flakes with an average particle size of 20 pm or more in the mixture constituting such a hollow container needs to be 0.1 to 4.0% by weight, preferably 0.3 to 2.0% by weight. .

If the average particle size of the mica flakes to be blended is less than 20P, a distinct satin-like surface appearance cannot be obtained, which is not preferable.

If mica flakes are used in an amount less than 0.1% by weight, satin finish will not appear uniformly over the entire surface, which is not preferable.

On the other hand, if mica flakes are used in an amount exceeding 4.0% by weight, biaxial stretching is not possible, or even if biaxial stretching is possible, impact resistance is poor, which is not preferable.

If the total stretch ratio (described below) during biaxial stretch blow molding is less than 2 times, a sufficient matte appearance cannot be obtained.

Total stretching ratio = Longitudinal stretching ratio × Horizontal stretching ratio In the present invention, dyes and pigments, ultraviolet absorbers, and antistatic agents are added to the mixture composed of the above-mentioned material combinations within the scope of the purpose of the present invention. , it is possible to add additives such as nucleating agents.

The method for obtaining the hollow container having a satin-like surface appearance according to the present invention is to mix the above-mentioned thermoplastic polyester resin and mica flakes in a mixer, and then pelletize them in an extruder, and then reduce the moisture content to 0. Dry it until it becomes less than 0.01% and make it into a preform of the desired shape using an extrusion molding machine or an injection molding machine, or
Alternatively, a pre-dried material is directly fed to an extrusion molding machine or an injection molding machine to obtain a preform of the desired shape. Thereafter, these preforms can be obtained by heating and maintaining the stretching temperature at a temperature in the range of 80 to 160°C, for example, and performing biaxial stretch blow molding so that the total stretching ratio is 2 times or more.

[Examples] Hereinafter, the present invention will be explained in more detail with reference to Examples and Comparative Examples.

Intrinsic viscosity measured in phenol/tetrachloroethane (50150 weight ratio) solution at 25°C is 0.76 cff/g
polyethylene terephthalate (hereinafter abbreviated as PET)
Using a mixture in which mica flakes coated with titanium dioxide and having different average particle diameters were added in the amounts shown in Table 1, the mixture was molded using an injection molding machine under molding conditions of a resin temperature of 280°C and a mold temperature of 20°C. Diameter 32mm, inner diameter 24mm, length 120
It was molded into a cylindrical preform with a bottom of mm. The preform did not show satiny appearance.

Next, this preform was placed in a far-infrared heater while rotating and heated uniformly to a temperature of 120°C, then inserted into a blow mold at 20°C and compressed nitrogen was heated. Press fit inside the preform and
Blow molding was performed while performing biaxial stretching at the stretching ratio shown in the table to obtain a hollow container.

Table 1 shows the appearance observation results of the preform, the appearance observation results of the obtained hollow container, and the fracture height from the drop test.

Here, the fracture height by the drop test was determined as follows. That is, the bottle obtained by molding is filled with water, the cap is tightened, and the ASTM D-24
A drop test was conducted at 0°C according to the 63-74C method,
The fracture height was determined.

In addition, the appearance was visually observed. In the table, the appearance judgment is indicated as follows.

Items with a noticeable satin finish 0 Items with a satin finish ○ Items with a slight satin finish △ Items with no satin finish With this, it has become possible to provide a hollow container with a unique appearance never seen before.

The reason for this is that blending mica flakes with larger particle sizes than those normally used, with an average particle size of 20 pI or more, only shows a smooth surface appearance before biaxially stretched blow molding;
This is because when biaxially stretched blow molding is performed, the periphery of the mica flakes is not sufficiently stretched and bulges when observed microscopically.

Claims (1)

[Claims] Thermoplastic polyester resin (A) whose main repeating unit is an ethylene terephthalate unit 96.0-99.
Mica flakes (9% by weight and with an average particle size of 20 μm or more)
B) A polyester hollow container obtained by biaxially stretching blow molding a mixture consisting of 0.1 to 4.0% by weight so that the total stretching ratio is 2 times or more.