JPH0367499B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a whitening treatment method and apparatus for crystallizing and whitening the opening of a polyethylene terephthalate resin container by heat treatment. The present invention relates to a whitening treatment method and apparatus for efficiently forming a whitening mouth. Conventionally, polyethylene terephthalate resin containers have been widely used as containers with excellent mechanical strength, gas barrier properties, transparency, etc. Such containers made of polyethylene terephthalate resin are usually obtained by forming an intermediate preform and then subjecting it to biaxial sharp stretching. However, since the opening of the preform serves as a gripping part in biaxial stretching, biaxial stretching is not necessary at all. The cap remains in an unstretched amorphous state without being stretched, and has lower heat resistance than other stretched parts, and if used for filling high-temperature contents, the cap may soften or change dimensions, causing the cap to deteriorate. There was a problem in that it became impossible to install the device, resulting in poor sealing performance. As a countermeasure against this problem, conventionally, the mouth part is heat-treated using radiant heat from the side or top surface to crystallize and whiten the mouth part, so-called whitening treatment, which increases rigidity and heat deformation resistance, and fills the mouth part with high temperature filling. Methods have been proposed to provide strength that can withstand. However, in general, when heating and whitening the mouth part, the mouth part softens due to heating and shrinks due to increased density during whitening, so even slight unevenness in heating causes the mouth part to deform and make it difficult to attach the cap. There were problems in that it became impossible to do so or caused poor sealing. This heating unevenness can be solved by performing whitening treatment by heating at a relatively low temperature of 140 to 180 degrees Celsius for a long time while rotating the mouth part around the central axis.
Although heating unevenness in the circumferential direction can be eliminated, heat treatment from the top surface takes too much time and has poor treatment efficiency even when heat whitening treatment is performed at a high temperature such as 200° C. or the melting point of polyethylene terephthalate resin. Furthermore, if the above-mentioned high-temperature heat treatment is performed from the side, a temperature difference will occur between the outer and inner surfaces of the mouth even when the mouth is rotated, and the mouth will become deformed due to the difference in the amount of shrinkage between the two. There was a problem. As a countermeasure to this problem, a method has been disclosed in which a core is inserted to prevent deformation inside the mouth during heat whitening treatment, but with this method, deformation is forcibly suppressed, so whitening occurs in a short time due to high temperature treatment. However, after whitening, the mouth part shrinks due to the increase in density due to whitening and crystallization, and the rigidity increases, so the mouth part tightly tightens the core. For this reason, it is necessary to provide a special mechanism to forcibly separate the two after the whitening process is completed, and the area around the opening is easily damaged during separation. An object of the present invention is to eliminate the drawbacks in the conventional whitening treatment of the mouth of polyethylene terephthalate resin containers, and to enable heat treatment to be carried out in a short time without deforming the mouth and without using a special core. Another object of the present invention is to provide a method and apparatus for manufacturing a polyethylene terephthalate resin container having an opening having excellent heat resistance, mechanical properties, dimensional stability, sealability, etc. The gist of the present invention is to provide a whitening treatment method for crystallizing and whitening the mouth of a polyethylene terephthalate resin container by heat treatment.
The mouth of a container made of polyethylene terephthalate resin, characterized in that the whitening treatment is performed separately on the upper part of the mouth and the side parts of the mouth, and after the whitening treatment is applied to the upper part of the mouth, the side parts of the mouth are whitened. A whitening treatment method, a shielding mechanism for shielding a portion other than the mouth of a polyethylene terephthalate resin container from a heat source, and a holding mechanism for holding the container with the other than the mouth shielded by the shielding mechanism and rotating it in the circumferential direction of the container mouth. a container rotation and movement device comprising a rotation mechanism, a movement mechanism on which the holding and rotation mechanism is placed and moved along a predetermined trajectory; a container mouth heating mechanism provided above a passage position of the container mouth that moves on a predetermined trajectory; It consists of a mouth side heating mechanism provided on the side of the passage position of the container mouth moving on a predetermined trajectory, and a mouth upper heating mechanism, a mouth heating mechanism, and a mouth heating mechanism in the moving direction of the container mouth moving on a predetermined trajectory. There is provided an apparatus for whitening the mouth of a polyethylene terephthalate resin container, characterized in that side heating mechanisms are arranged in this order. Next, the present invention will be explained based on the accompanying drawings. FIG. 1 shows an example of a mechanism for heating and whitening the upper part of the mouth of a polyethylene terephthalate resin container according to the present invention. A heating source 9 consisting of a rod-shaped infrared heater 7 and a reflecting plate 8,
They are arranged in two rows above the passing positions where the container openings 2 made of polyethylene terephthalate resin are housed and held in the container rotation moving device 24 and pass along a predetermined trajectory, and when the openings 2 pass along a predetermined trajectory below between the heating sources, Upper mouth heating mechanism 10 for heating the vicinity of the upper end 3
has been established. In addition, when whitening the mouth part 2, a container rotating and moving device 24 which shields areas other than the mouth part of the container below the heating mechanism 10 and moves the container in a predetermined orbit while rotating is used to house the part 6 other than the mouth part of the container. A cylindrical shielding mechanism 12 is provided as a shielding mechanism for shielding from the heat source 9. Further, as a mechanism for holding and rotating the shielding mechanism 12, a holding/rotating mechanism 14 is provided which is rotatably held and fixed on a conveyor table 18 via a bearing 13. The holding/rotating mechanism 14 has a groove surface 15 with a semicircular cross section provided on the outer circumferential surface of the pressing roller 17.
The belt 16 was brought into contact with the belt 16 which was pressed under tension, and the movement of the belt 16 made it possible to rotate in the circumferential direction of the container opening on the conveyor table 18. The moving mechanism 23 on which the holding and rotating mechanism 14 is placed and moved along a predetermined track includes a guide rail 21 provided along a predetermined track;
A moving mechanism 23 consisting of a transport platform 18 equipped with two guide rollers 19 that sandwich the guide rail 21 from both sides and a chained roller 20 connected to a drive source (not shown) via a chain 22.
has been established. FIG. 2 shows an example of a mechanism for heating and whitening the mouth side surface 4 of the polyethylene terephthalate resin container 1, and includes a shielding mechanism 12 other than the mouth similar to that shown in FIG. Holding rotation mechanism 1
4. A heating source 9 similar to that shown in the first figure is attached to the side surface of the passage zone of the container mouth 2 which passes through a predetermined trajectory by the container mouth rotation moving device 24 consisting of the moving mechanism 23.
Mouth side heating mechanism 1 arranged in two rows across the
1 was established. FIG. 3 illustrates the positional relationship of the mouth heating mechanisms in the mouth whitening treatment apparatus of the present invention, which includes the mouth upper heating mechanism 10, the mouth side side heating mechanism 11, and the container rotation moving device 24. . In the present invention, it is necessary to heat and whiten the upper part of the mouth, then heat the side parts of the mouth, and whiten the entire mouth. The upper mouth heating mechanism 10 and the mouth side heating mechanism 11 are arranged in this order with respect to the moving direction of the rotational movement device 24. Next, to explain the operation of the present invention, as a first step, the polyethylene terephthalate resin container 1 shown in FIG. ) while being rotated by a belt 16 driven by
It is pulled by a drive source (not shown) through a chain 22 and moves along a predetermined trajectory, passing under the upper mouth heating mechanism 10, so that the vicinity of the upper end of the mouth 2 is uniformly heated and whitened in the circumferential direction. be done. This part is most likely to be deformed during the heat whitening treatment, and plays an important role as a sealing surface when the cap is installed. When the entire mouth portion 2 is whitened by the heat treatment in step 4, it is effective in preventing deformation of the entire mouth portion 2. Generally, the density of the untreated mouth part is about 1.335g/ ^cm3 ,
In the whitening treatment of the upper part of the mouth of the present invention, at least 1/20 of the total length of the mouth from the upper end surface 5 of the mouth has a density
It is necessary to carry out heat whitening treatment until the density reaches 1.35 g/cm ³ or more, and the above effect will not be exhibited if the density after whitening treatment is less than 1.35 g/cm ³ or if the length of the whitened portion is less than 1/20. Next, as a second step, the polyethylene terephthalate resin container 1 is passed through the heat source arrangement process shown in the second figure in the same manner as shown in the first figure, and the side surface 4 of the mouth part 2 is heated to whiten the whole mouth part. . In this second stage of heat treatment, the sides of the mouth which were insufficiently transformed in the first stage are heated to whiten them, but the heat whitening treatment must be carried out until the average density of the entire mouth becomes at least 1.35 g/cm ³ . is desirable, and below that, the effects of the present invention cannot be expected. Second aspect of the present invention
In the heat whitening treatment in the first stage, the upper part of the mouth, which is most easily deformed, has already been whitened and is in a fixed state with improved heat resistance. is hardly deformed, and by performing the divided heating process of the present invention, the entire mouth can be whitened in a good manner in a short time without using a special core. Examples are shown in Table 1. Heating method A listed in Table 1 means that the whitening treatment is performed only with the mouth upper heating mechanism shown in the first diagram, and heating method B represents that the whitening treatment is performed only with the mouth side heating mechanism. Simultaneous use of A and B indicates that the mouth portion is heat-treated from the top and side surfaces simultaneously using methods A and B as heat sources. Table 1 shows that only those heat-treated according to the present invention were treated in a short time without deformation, and the present invention dramatically improves the efficiency of mouth whitening treatment of polyethylene terephthalate resin containers. , it is clear that it greatly contributes to improving productivity. In the explanation of the present invention using drawings, for convenience, the opening whitening treatment is explained using the shape of a preform, which is an intermediate body of a polyethylene terephthalate resin container, as an example. Similar effects were obtained when the test was performed on the mouth of the container. 【table】

[Brief explanation of drawings]

Figure 1 shows the mouth heating whitening treatment of the present invention.
Part 1 of the mechanism for heating and whitening the upper part of the mouth
FIG. 2 is a partial sectional view showing an example of a mechanism for heating and whitening the side surface of the mouth in the mouth heating whitening treatment of the present invention; FIG. FIG. 2 is a schematic diagram showing an example of the positional relationship of each mechanism and device in the mouth whitening treatment device consisting of the mouth upper heating mechanism, the mouth side side heating mechanism, and the container rotation moving device. 1... Polyethylene terephthalate resin container,
2... Container opening, 7... Rod-shaped heater, 8... Reflector,
9...Heating source, 10...Mouth upper heating mechanism, 12...Shielding mechanism, 11...Mouth side heating mechanism, 13...Bearing, 14...Holding rotation mechanism, 19...Guide roller, 20...Roller, 21...Guide rail ,2
2... Chain, 14... Holding rotation mechanism, 23... Moving mechanism.

Claims (1)

[Claims] 1. In a whitening treatment method in which the mouth of a polyethylene terephthalate resin container is crystallized and whitened by heat treatment, the whitening treatment is performed separately on the upper part of the mouth and the side parts of the mouth, and A method for whitening the mouth of a polyethylene terephthalate resin container, which comprises whitening the upper part of the container and then whitening the side surface of the mouth. 2. After whitening the upper part of the mouth to a density of at least 1/20 of the total length of the mouth from the upper end of the polyethylene terephthalate resin container to 1.35 g/cm ³ or more, whitening the sides of the mouth by heating. 2. The method for whitening the mouth according to item 1, wherein the average density of the entire mouth is 1.35 g/cm ³ or more. 3. A shielding mechanism that shields a portion of the polyethylene terephthalate resin container other than the mouth from a heat source;
A container rotating and moving device comprising: a holding and rotating mechanism that holds a container whose portion other than the mouth is shielded by the shielding mechanism and rotates it in the circumferential direction of the container's mouth; and a moving mechanism that places the holding and rotating mechanism and moves it along a predetermined trajectory. , an upper opening heating mechanism provided above the passing position of the container opening moving on a predetermined trajectory, and an opening side heating mechanism provided on the side of the passing position of the container opening moving on a predetermined trajectory. , an upper opening heating mechanism for moving the heating mechanism along a predetermined trajectory in the moving direction of the container opening;
A mouth whitening treatment device for a polyethylene terephthalate resin container, characterized in that a mouth side heating mechanism is arranged in this order.