JP2010036357A - Blow bottle made of synthetic resin and its molding method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a blow bottle having good quality that is obtained without a special measure to reduce cyclic trimmers, and its manufacturing method. <P>SOLUTION: The synthetic resin-made blow bottle is obtained by biaxial stretching blow moldings of two times with a heat treatment in between. The blow bottle consists of a synthetic resin material or a preform molding having a cyclic trimmers content of ≥0.40 wt.% and an intrinsic viscosity inherent to the material of 0.70-0.90 dl/g. Additionally, at least the body part of the bottle after completion of the blow molding has a density of ≥1.38 g/cm<SP>3</SP>. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a synthetic resin blow bottle and a method for molding the same, and the quality deterioration caused by adhesion of a cyclic trimer (a kind of oligomer) that cannot be avoided during the molding process of the blow bottle. It tries to avoid effectively.

  Bottles containing liquor, beverages, soy sauce and other seasoning liquids are easier to handle than glass bottles and can be manufactured efficiently. Blow bottles are frequently used.

  By the way, in this kind of blow bottle, especially a blow bottle (PET bottle) made of polyethylene terephthalate resin, a cyclic trimer (CT) contained in the resin material in the blow molding process is used as a preform or molded article. It was unavoidable that it was deposited on the outer surface and adhered to the surface of the mold.

Here, the adhesion of the cyclic trimer to the mold surface impairs the smoothness of the mold, and as a result, the surface of the bottle is roughened to ensure transparency. However, there is a problem that it becomes more difficult (has become cloudy (the HAZE value increases) as the number of moldings increases). For this reason, conventionally, the production line must be stopped and the mold must be frequently cleaned (decrease in productivity), and a special polymerization catalyst that suppresses the formation of cyclic trimers contained in the resin is used. Attempts have been made to use materials that have been used, other materials that have undergone reduction treatment of cyclic trimers, or materials that have been formulated to suppress the increase of cyclic trimers during preform molding. However (for example, refer to Patent Document 1), the conventional countermeasures limit the materials used, and thus are subject to significant economic constraints (an increase in cost is inevitable).
JP 2006-348166 A

  An object of the present invention is to propose a novel technique capable of efficiently producing a high-quality blow bottle without using a special material designed to reduce the cyclic trimer.

The present invention is a synthetic resin blow bottle obtained by two biaxial stretch blow molding sandwiching heat treatment,
The blow bottle is composed of a synthetic resin material or a preform molded body having a cyclic trimer content of 0.40% by weight or more and an intrinsic viscosity of the material itself of 0.70 to 0.90 dl / g, And at least the trunk | drum part of the bottle after completion | finish of blow molding is a synthetic resin blow bottle characterized by having a density of 1.38 g / cm ³ or more, and polyethylene terephthalate resin is used as the synthetic resin. Here, the content includes not only what is originally contained in the resin material but also what is generated by heat at the time of molding or blow molding of the preform.

In addition, the present invention uses a preform formed by extrusion molding or injection molding, and when molding a synthetic resin blow bottle by performing two biaxial stretch blow molding sandwiching heat treatment,
A synthetic resin blow characterized by using a synthetic resin material or preform having a cyclic trimer content of 0.40% by weight or more and an intrinsic viscosity of the material itself of 0.70 to 0.90 dl / g. This is a method of forming a bottle.

  As the synthetic resin material or preform used for blow molding, the cyclic trimer content is 0.40% by weight or more, preferably 0.40 to 0.60% by weight, It is possible to suppress the white turbidity of the bottle even when using 60% by weight or more.

  Even if a special synthetic resin material or preform that reduces the cyclic trimer is not used, the impact of the cyclic trimer on the bottle surface is reduced and there is no economic restriction (synthetic resin material) The range of selection is expanded), and the manufacturing cost can be reduced.

  Since the number of times for stopping the production line and cleaning the blow mold is reduced, efficient production becomes possible.

  The two biaxial stretch blow moldings that sandwich the heat treatment are the primary blow molding that blows air while performing the stretching process of the preform, and the double blow molding that performs the secondary blow molding to finish the final shape. A heat treatment step (a treatment for relieving residual stress by heat-shrinking a molded body obtained by primary blow molding) is incorporated during blow molding. In the primary blow molding of double blow molding, the annular trimer deposited on the outer surface of the primary blow molded product adheres to the inner surface of the primary blow mold. At this time, the reverse transition of the annular trimer from the inner surface of the mold to the primary blow-molded product is reduced. In addition, since the primary blow molding is performed in a state where the draw ratio is higher than that of the single blow molding, the intermediate molded product that has been heat-shrinked is subjected to secondary blow molding, so that the inner surface of the primary blow mold (Surface roughness) hardly affects the final molded product (secondary blow molded product). Also, in secondary blow molding, the cyclic trimer deposited on the surface of the intermediate molded body has already transferred to the mold at the time of primary blow molding, so that the amount of adhesion is very small. Transparency is less likely to be disturbed.

  In the present invention, a synthetic resin material or preform having a cyclic trimer content of 0.40% by weight or more is used because the cyclic trimer content is 0.40% by weight or more. Is obtained without any special treatment and is relatively inexpensive. It is possible to use those having a cyclic trimer content of 0.40 to 0.60% by weight, 0.60% by weight or more, and in this case, the range of selection of materials is further expanded.

  The intrinsic viscosity of the synthetic resin material itself is 0.70 to 0.90 dl / g, because the physical properties as a bottle can be secured and are in a commercially available range. The intrinsic viscosity is a value measured by a method in accordance with ASTM D-2857-1970.

In addition, at least the body part (excluding the mouth part and the bottom part) of the bottle after completion of blow molding has a density of 1.380 g / cm ³ or more (based on JIS K7112D method / density gradient tube method). However, by setting the density of the body portion to 1.380 g / cm ³ or more, it becomes possible to form a bottle with stable quality that can be filled with high-temperature contents.

Double blow molding is preferably carried out according to the following conditions.
Primary blow molding process:
Preform heating temperature: 100-120 ° C
Stretch ratio (area ratio): 5 to 10 times Mold temperature: 140 to 230 ° C
Heat treatment process:
Heat treatment temperature: 200 to 260 ° C. (Temperature is 10 to 60 ° C. higher than the temperature of the primary blow mold, and the primary blow molded product is sized to the same size as the secondary blow mold or slightly smaller by this heat treatment. Shrink and remove residual stress)
Secondary blow molding process:
Mold temperature: 90 to 150 ° C. (temperature several degrees higher than the filling temperature of the contents)
Stretch ratio: hardly stretches

  The above forming conditions are a suitable range when performing double blow molding, and may be outside the above range depending on the filling temperature of the contents, the capacity of the container, the design, etc., and are limited to the above molding conditions. Never happen.

Example Polyethylene terephthalate resin (resin A) having a cyclic trimer content of 0.50% by weight and an intrinsic viscosity of 0.82 dl / g and an intrinsic viscosity of 0.35% by weight of the cyclic trimer After forming a preform using polyethylene terephthalate resin (B resin) with an A of 0.76 dl / g, double blow molding and single blow molding are performed according to the following conditions, and the filling capacity of the contents becomes 500 ml Each blow bottle was manufactured, and the number of moldings until the HAZE (haze) value (a value representing the degree of transparency according to JIS K7105) at the center of the blow bottle reached 10% was investigated. Here, in single blow molding, a preform heated to a stretchable temperature is held in a mold set at a predetermined temperature, and stretched with a stretching rod and compressed air to be molded into a final product (bottle). Say the method.

Conditions for double blow molding Primary blow molding process: mold temperature 165 ° C
Heat treatment process: heat treatment temperature 200 ° C
Secondary blow molding height: mold temperature 100 ° C
Single blow molding conditions Blow molding process: Mold temperature 100 ° C

  As a result, when A resin was used, 18.3 times as many bottles could be molded by double blow molding as compared to single blow molding, and this greatly reduced the number of times the mold was cleaned. .

  On the other hand, when B resin was used, 7.9 times as many bottles could be molded by double blow molding as compared to single blow molding.

  Regarding the above-mentioned A resin, when the change state (change amount) of the cyclic trimer was examined, the amount of the cyclic trimer at the preform stage increased to about 1.2 times that of the resin material. In any of molded products, heat-shrink products, and secondary blow-molded products (products), the amount of cyclic trimer remains about 1.2 times the same as the preform stage, and there is no significant change in the value. It was confirmed.

  A blow bottle with good quality can be provided without applying a special prescription for reducing the cyclic trimer.

Claims (3)

A synthetic resin blow bottle obtained by two biaxial stretch blow moldings sandwiching heat treatment,
The blow bottle is composed of a synthetic resin material or a preform molded body having a cyclic trimer content of 0.40% by weight or more and an intrinsic viscosity of the material itself of 0.70 to 0.90 dl / g, A synthetic resin blow bottle characterized in that at least a body portion of the bottle after completion of blow molding has a density of 1.38 g / cm ³ or more.   The synthetic resin blow bottle according to claim 1, wherein the synthetic resin is a polyethylene terephthalate resin. Using a preform formed by extrusion molding or injection molding, in forming a synthetic resin blow bottle by performing two biaxial stretch blow molding sandwiching heat treatment,
A synthetic resin blow characterized by using a synthetic resin material or preform having a cyclic trimer content of 0.40% by weight or more and an intrinsic viscosity of the material itself of 0.70 to 0.90 dl / g. Bottle molding method.