JPS643664B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a plastic multilayer container, and more particularly to a plastic multilayer container that has a high-grade processed glass appearance, excellent hygiene, adhesive properties, heat shrinkage resistance, and mechanical strength. Plastic containers, such as containers made of thermoplastic resins such as polyvinyl chloride, polycarbonate, polystyrene, polyacrylonitrile, polyester, and polyolefin resin, are widely used as containers for foods, beverages, cosmetics, medicines, and the like. In particular, containers made of polyester resin, typified by polyethylene terephthalate, have excellent transparency, gas permeation resistance,
Due to its excellent water vapor permeability, safety, and mechanical properties, it has been used in a variety of applications in recent years as containers for carbonated beverages, edible oils, sauces, bean oil, seasonings, pharmaceuticals, cosmetics, alcoholic beverages, etc. . Although most plastic containers, typically made of polyester resin, have excellent transparency, such transparent containers are unsatisfactory in terms of the high-class appearance of the container. As a way to make the appearance of the container more luxurious,
For example, there is a method of imparting minute irregularities to the outer surface of the container as seen in glass containers to give it a so-called ground glass appearance, or a method of imparting a large number of striped patterns to the outer surface. As a method of imparting a similar appearance to plastic containers, a method of processing the plastic containers to create a pattern similar to that of a blow mold is generally used. However, the method of transferring the pattern by applying processing to the molding die has the disadvantage that the pattern is transferred only to the outer surface of the container, resulting in a lack of depth in appearance.
Air may exist between the mold surface and the outer surface of the container during molding, and this air cannot escape sufficiently, resulting in the pattern of the mold not being sufficiently transferred to the container, and molding in which the container sticks to the mold surface. In addition, solids such as low polymers accumulate in the finely engraved parts of the mold and are transferred to the outer surface of the container, resulting in defects in appearance. In addition, as a method of manufacturing a processed glass-like container such as frosted glass using polyester resin, a method of sandblasting a polyester container or a bottomed parison, which is an intermediate material thereof, and roughening its surface, or a method of manufacturing a bottomed parison, which is an intermediate material thereof, is used. A method has been proposed in which crystallization is performed by solvent treatment, followed by biaxial orientation. However, these intermediate treatments or post-processing involve chemical or physical changes during or after container manufacturing, resulting in poor productivity and difficulty in always imparting a processed glass appearance under constant conditions. In addition, there is a method in which a parison with a bottom, which is an intermediate material, is crystallized by heating and then blow molding is performed, or a method in which a parison with a bottom is crystallized by slow cooling during injection molding is used and blow molding is performed. However, it is difficult to control the crystallization of bottomed parisons, and parisons that are too crystallized throughout are not stretched to the shape of the blowing mold during blow molding, resulting in complete shaping. It has the disadvantage that it cannot be done. Furthermore, attempts have been made to add inorganic inert particles such as tartar or clay to polyester resin and to obtain processed glass-like containers by blow molding. Particles added during molding act as a so-called crystallization nucleating agent that promotes the crystallization of polyester, so they may cause crystallization in the thick part of the seated parison or in the injection port during injection molding. If there is significant whitening and the injection port becomes the bottom of the container, there are problems such as a significant drop in the drop impact strength of the container. A processed glass-like container has not been obtained. The inventors of the present invention have conducted intensive studies to obtain a container that has improved heat shrinkage resistance and mechanical strength, and has an excellent processed glass appearance compared to containers obtained by conventional molding. By stretching a preformed multilayer structure containing a thermoplastic resin layer containing a specific proportion of glass particles in the shape of
The inventors have discovered that it is possible to obtain a plastic multilayer container that is excellent in hygiene, heat shrinkage resistance, and mechanical strength such as buckling strength, pressure deformation resistance, and decompression resistance deformation, and has thus arrived at the present invention. That is, the present invention provides a multilayer container having two or more thermoplastic resin layers, and at least one layer other than the innermost layer.
The layer is a thermoplastic resin layer containing 0.1 to 30% by weight of glass particles, and is a plastic multilayer container having a portion stretched in at least one direction. The thermoplastic resin referred to in the present invention is a thermoplastic resin that can be molded into a container by a molding method that involves stretching, such as blow molding, vacuum molding, and pressure forming. Preferred thermoplastic resins are shown in Table 1. Among these, those having a light transparency of 70% or more are more preferable because they form a good frosty appearance, and polyester resins are particularly preferable because the effects of the present invention are particularly exhibited.

[However, V ₀ : Bottle volume before filling with hot water, V: Bottle volume after hot water filling process]

Buckling strength: Toyo Sokki TENSILON/UTM--
500 was used to apply a load to an empty bottle in the vertical direction at a head speed of 5 mm/min, and the load at which the bottle deformed was determined. Pressure resistance strength: 10% by water pressure machine in a bottle filled with water
Water pressure was applied at a speed of Kg/cm ² G/min, and the pressure at which the bottle burst was determined. Light transmittance: Measured using an integrating sphere type light transmittance measuring device (measured at a thickness of 0.3 m/m) JIS K-
By 6714. When this light transmittance takes a value of 20% or more, a processed glass look appears. Examples 1 to 4 and Comparative Example 1 Polyester multilayer oriented containers having the inner layer and outer layer compositions shown in Table 2 were molded using a 150D multilayer oriented blow molding machine manufactured by Nissei ASB Machinery Co., Ltd. The polyester resin used was a polyethylene terephthalate resin with an intrinsic viscosity of 0.75 and polyethylene terephthalate master pellets with an intrinsic viscosity of 0.70 containing 20 wt% glass particles, phthalocyanine blue, and quinophthalone, which were dried in a hot air dryer. . The stretching ratio of the body of the multilayer container is approximately 2 times in the vertical direction and approximately 4 times in the horizontal direction, and the dimensions of the container are approximately 200 mm in height, approximately 70 mm in diameter, and the wall thickness of the body is 0.2 to 0.2 mm in the outer layer.
The diameter was 0.3 mm, the inner layer was 0.2 to 0.3 mm, and the volume was about 500 ml. From Table 2, multilayer containers with a layer made of polyester containing 0.5% by weight or more of glass granules have higher hot water shrinkage, buckling strength, and pressure resistance than containers without a layer containing glass granules. It can be seen that the mechanical strengths such as strength and interlayer adhesion strength are significantly superior, and the improvement effect of the present invention is remarkable.

[Table] Examples 5 to 6 and Comparative Examples 2 to 3 A molding machine that was modified from a Sumitomo Heavy Industries, Ltd. model SE-51/BA-2 high-speed blow molding machine to be able to mold three types and three layers of containers was used. A container with a three-layer structure shown in Table 3 was molded using the resin. Table 3 shows the molding conditions and the results of evaluating the obtained bottles.

[Table] Condition-1 is 30 rpm centered on the middle part of the container.
The container was rotated for 4 hours at a rotation speed of . Condition-2 is that the body of the container is subjected to repeated buckling deformation in the lateral direction at a rate of approximately 30 times per minute for 2 hours continuously so that the amount of deformation is approximately 1/5 of the diameter of the body.

Claims (1)

[Scope of Claims] 1. A multilayer container having two or more thermoplastic resin layers, in which at least one layer other than the innermost layer is a thermoplastic resin layer containing 0.1 to 30% by weight of glass particles, CLAIMS 1. A plastic multilayer container having a section that is stretched in at least one direction. 2. The plastic multilayer container according to claim 1, wherein at least one layer is a polyester resin containing ethylene terephthalate as a main component. 3. The plastic multilayer container according to claim 1 or 2, wherein the container is a bottle produced by a biaxial stretch blow molding method.